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1
Jiang, Xiaohu, and Long He. "Investigation of Effective Irrigation Strategies for High-Density Apple Orchards in Pennsylvania." Agronomy 11, no. 4 (April 10, 2021): 732. http://dx.doi.org/10.3390/agronomy11040732.
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Irrigation helps grow agricultural crops in dry areas and during periods of inadequate rainfall. Proper irrigation could improve both crop productivity and produce quality. For high density apple orchards, water relations are even more important. Most irrigation in tree fruit orchards is applied based on grower’s experience or simple observations, which may lead to over- or under-irrigation. To investigate an effective irrigation strategy in high-density apple orchard, three irrigation methods were tested including soil moisture-based, evapotranspiration (ET)-based and conventional methods. In soil moisture-based irrigation, soil water content and soil water potential sensors were measured side by side. In ET-based irrigation, daily ET (ETc) and accumulated water deficit were calculated. Conventional method was based on the experience of the operator. The experiment was conducted from early June through middle of October (one growing season). Lastly, water consumption, fruit yield and fruit quality were analyzed for these irrigation strategies. Results indicated that the soil moisture-based irrigation used least water, with 10.8% and 4.8% less than ET-based and conventional methods, respectively. The yield from the rows with the soil moisture-based irrigation was slightly higher than the other two, while the fruit quality was similar. The outcome from this study proved the effectiveness of using soil moisture sensors for irrigation scheduling and could be an important step for future automatic irrigation system.
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Wang, Wenqian, Mingxiu Gao, and Jiafan Wang. "Hyperspectral parameters and prediction model of soil moisture in apple orchards." IOP Conference Series: Earth and Environmental Science 687, no. 1 (March 1, 2021): 012085. http://dx.doi.org/10.1088/1755-1315/687/1/012085.
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Hou, Tingting, Yanping Wang, Fuxing Guo, Qiong Jia, Xinnan Wu, Enguang Wang, and Jingbo Hong. "Soil Respiration Characteristics and Influencing Factors for Apple Orchards in Different Regions on the Loess Plateau of Shaanxi Province." Sustainability 13, no. 9 (April 24, 2021): 4780. http://dx.doi.org/10.3390/su13094780.
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To explore the characteristics of the spatial and temporal variation in soil respiration (SR) in orchard ecosystems in different regions of the Loess Plateau of Shaanxi Province and to distinguish the controlling factors, representative orchards were studied from April to October 2019. We conducted SR measurements in five locations, including Mizhi dangta (MZ), Ansai Liuzhuang (AS), Luochuan houzitou (LC), Fuping meijiaping (FP), and Yangling Wuquan (YL). The results indicated that the SR of each orchard showed clear seasonal variation. The SR increased with the distance from the trunk at the tree scale, while gradually increasing from north to south on the regional scale (p < 0.05). The soil temperature and soil moisture were the main factors controlling the seasonal changes in SR in the orchards. On the tree scale, the fine root biomass was the main factor causing the tree-scale spatial variability. At the regional scale, SR was mainly influenced by the differences in the soil temperature, soil moisture, soil organic carbon, soil bulk density and pH. In agricultural management practices, the cumulative soil respiration was higher with irrigated treatment than with non-irrigated (NI) treatment (p < 0.05). In addition, traditional surface drip irrigation (SDI) and root injection irrigation (RII) showed great differences in soil respiration in the early and late stages of irrigation (p < 0.05), and the soil moisture was the main controlling factor. Compared with no tillage (NI), green cover (GC), deep tillage (DT), and shallow tillage (ST) increased the SR by 57%, 36% and 14%, respectively (p < 0.05). Due to the great temporal and spatial variation in the SR in our study area, we determined that the soil respiration in the orchards was affected not only by environmental factors but also by agricultural measures. Therefore, greater attention should be paid to human factors when exploring SR to ensure that orchard management can promote the economic benefits of the orchards without greatly impacting the environment.
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Tang, Min, Hongchen Li, Chao Zhang, Xining Zhao, Xiaodong Gao, and Pute Wu. "Mulching Measures Improve Soil Moisture in Rain-Fed Jujube (Ziziphus jujuba Mill.) Orchards in the Loess Hilly Region of China." Sustainability 13, no. 2 (January 11, 2021): 610. http://dx.doi.org/10.3390/su13020610.
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Water shortage is the main bottleneck restricting the sustainable development of rain-fed jujube (Ziziphus jujuba Mill.) orchards in the loess hilly region of China. Given the effect of mulching on soil moisture conservation, straw mulching (SM) and jujube branch mulching (BM) were applied to a rain-fed jujube orchard in this study. Soil moisture dynamics, soil water storage, water consumption, and soil moisture attenuation after typical rainfall under SM, BM, and clean tillage (CT) were studied. The results showed the following: (1) The 0–60 cm soil layer was the seasonal fluctuation layer of soil moisture under SM, BM, and CT in both the normal precipitation year and the dry year studied. The moisture contents of the 0–60, 60–160, and 160–280 cm soil layers under SM and BM were higher than that under CT in the three experimental years studied, and SM showed the most obvious effect of increasing soil moisture. (2) SM and BM showed a significant soil water storage effect in all of the jujube growth stages, and SM had a better water storage effect than BM. (3) SM reduced the amount of water consumption by 94.3, 60.8, and 121.3 mm compared to CT in the whole jujube growth period in 2014, 2015, and 2016, respectively. The amount of water consumption of BM decreased by 34.8 and 31.0 mm compared to that of CT in the whole growth period in 2014 and 2015, respectively. (4) CT had the maximum soil moisture loss rate under continuous drought after rainfall. The soil moisture loss rate of CT was above 37.3% on the eleventh day after typical rainfall in 2014, 2015, and 2016. With the extension of drought, the soil moisture loss rate under SM increased slowly. This study suggests that SM is the best mulching measure for rain-fed jujube orchards, and pruned jujube branches can also be used for in situ mulching to obtain a certain moisture conservation effect.
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Tang, Min, Hongchen Li, Chao Zhang, Xining Zhao, Xiaodong Gao, and Pute Wu. "Mulching Measures Improve Soil Moisture in Rain-Fed Jujube (Ziziphus jujuba Mill.) Orchards in the Loess Hilly Region of China." Sustainability 13, no. 2 (January 11, 2021): 610. http://dx.doi.org/10.3390/su13020610.
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Water shortage is the main bottleneck restricting the sustainable development of rain-fed jujube (Ziziphus jujuba Mill.) orchards in the loess hilly region of China. Given the effect of mulching on soil moisture conservation, straw mulching (SM) and jujube branch mulching (BM) were applied to a rain-fed jujube orchard in this study. Soil moisture dynamics, soil water storage, water consumption, and soil moisture attenuation after typical rainfall under SM, BM, and clean tillage (CT) were studied. The results showed the following: (1) The 0–60 cm soil layer was the seasonal fluctuation layer of soil moisture under SM, BM, and CT in both the normal precipitation year and the dry year studied. The moisture contents of the 0–60, 60–160, and 160–280 cm soil layers under SM and BM were higher than that under CT in the three experimental years studied, and SM showed the most obvious effect of increasing soil moisture. (2) SM and BM showed a significant soil water storage effect in all of the jujube growth stages, and SM had a better water storage effect than BM. (3) SM reduced the amount of water consumption by 94.3, 60.8, and 121.3 mm compared to CT in the whole jujube growth period in 2014, 2015, and 2016, respectively. The amount of water consumption of BM decreased by 34.8 and 31.0 mm compared to that of CT in the whole growth period in 2014 and 2015, respectively. (4) CT had the maximum soil moisture loss rate under continuous drought after rainfall. The soil moisture loss rate of CT was above 37.3% on the eleventh day after typical rainfall in 2014, 2015, and 2016. With the extension of drought, the soil moisture loss rate under SM increased slowly. This study suggests that SM is the best mulching measure for rain-fed jujube orchards, and pruned jujube branches can also be used for in situ mulching to obtain a certain moisture conservation effect.
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Downer, Jim, Ben Faber, and John Menge. "Factors Affecting Root Rot Control in Mulched Avocado Orchards." HortTechnology 12, no. 4 (January 2002): 601–5. http://dx.doi.org/10.21273/horttech.12.4.601.
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Mulches can exert positive (disease controlling) or negative (disease enhancing) potential when applied to young avocado (Persea americana) trees. Regulation of root disease in avocado is a complicated process that is affected by host resistance, inoculum density, temperature, soil salinity and soil water potential. There are short-term immediate effects from mulching and subtle long-term effects that regulate disease caused by the root rot pathogen Phytophthora cinnamomi. Short-term effects include increased soil moisture and soil temperature moderation. Long-term effects include increases of: soil mineral nutrients, soil aggregation and drainage; microbial activity; and cellulase enzyme activities. Biological control of Phytophthora in mulched soil is partially regulated by cellulase enzyme activities. This soil enzyme concept of biological control is discussed in regard to the classical Ashburner method of biological control.
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Huang, Ying, Zu Lian Zhang, and Ke Sheng Jin. "Active Limit Equilibrium Method of the Stability Analysis for Soil Slopes." Advanced Materials Research 594-597 (November 2012): 636–41. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.636.
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The stability of the soil slopes can be judged according to the critical moisture content and the actual moisture content when the soil slopes be in the limit equilibrium state. From the perspective of earth pressure, the critical moisture content is the moisture content when the soil slopes be in the active limit equilibrium state, at this time, the active earth pressure is 0. The critical moisture content can be determined and the stability of the slopes can be judged according to the relationship of the soil parameters and the moisture content and the active earth pressure being 0. The critical moisture content of the upright or declining cohesionless slopes can be determined according to the relationship of the internal friction angle and the moisture content. The critical moisture content of the upright cohesive slopes can be determined by solving the equation of the critical moisture content. For the declining cohesive slopes, first, the cohesive soil having the cohesion and internal friction angle is replaced by only having the equivalent internal friction angle of the cohesionless soil according to the principle of the equal strength, then, the critical moisture content can be determined according to the relationship of the equivalent internal friction angle and the moisture content of the declining cohesionless.
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Gao, Peng, Jiaxing Xie, Mingxin Yang, Ping Zhou, Wenbin Chen, Gaotian Liang, Yufeng Chen, Xiongzhe Han, and Weixing Wang. "Improved Soil Moisture and Electrical Conductivity Prediction of Citrus Orchards Based on IoT Using Deep Bidirectional LSTM." Agriculture 11, no. 7 (July 7, 2021): 635. http://dx.doi.org/10.3390/agriculture11070635.
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In order to create an irrigation scheduling plan for use in large-area citrus orchards, an environmental information collection system of citrus orchards was established based on the Internet of Things (IoT). With the environmental information data, deep bidirectional long short-term memory (Bid-LSTM) networks are proposed to improve soil moisture (SM) and soil electrical conductivity (SEC) predictions, providing a meaningful reference for the irrigation and fertilization of citrus orchards. The IoT system contains SM, SEC, air temperature and humidity, wind speed, and precipitation sensors, while the mean absolute error (MAE), root mean square error (RMSE), and coefficient of determination (R2) were calculated to evaluate the performance of the models. The performance of the deep Bid-LSTM model was compared with a multi-layer neural network (MLNN). The results for the performance criteria reveal that the proposed deep Bid-LSTM networks perform better than the MLNN model, according to many of the evaluation indicators of this study.
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Wang, Bing Ru, Yong Ju Hu, and Xin Qiu. "SWCC Based Prediction Model of Equilibrium Moisture of Clay Subgrade with High Groundwater Table." Key Engineering Materials 579-580 (September 2013): 906–10. http://dx.doi.org/10.4028/www.scientific.net/kem.579-580.906.
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To accurately calibrate the working range of equilibrium moisture of clay subgrade, according to unsaturated soil mechanics basic theories, the filter paper method was used to measure matrix suction and to establish soil-water characteristic curve (SWCC) model with reflecting function between moisture and metrics suction. The prediction method about the working range of equilibrium moisture of unsaturated clay subgrade was proposed and the model was tested. The results show that equilibrium moisture of clay subgrade out the affected range of the precipitation and evaporation is mainly controlled by the impact of groundwater. The Fredlund & Xing model can better characterize the unsaturated cohesive subgrade soil humidity and the correlation matrix suction and the model parameters possessed highly reliability. The prediction result of clay subgrade's equilibrium moisture on groundwater control area has high uniformity with experimental result. The prediction method is reasonable and reliable. The results provide new perspectives and standpoints to objectively characterize the equilibrium moisture status of unsaturated clay subgrade.
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Liao, Renkuan, Wenyong Wu, Yaqi Hu, Qiannan Huang, and Hua Yan. "Quantifying moisture availability in soil profiles of cherry orchards under different irrigation regimes." Agricultural Water Management 225 (November 2019): 105780. http://dx.doi.org/10.1016/j.agwat.2019.105780.
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Hua, Lei, Jianen Gao, Meifang Zhou, and Shilun Bai. "Impacts of Relative Elevation on Soil Nutrients and Apple Quality in the Hilly-Gully Region of the Loess Plateau, China." Sustainability 13, no. 3 (January 26, 2021): 1293. http://dx.doi.org/10.3390/su13031293.
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Relative elevation, as one of the decisive factors to the redistribution of soil water, nutrients, sunshine, and temperature in a region influences apple yield and quality by adjusting soil water and nutrients. To explore the impact of relative elevation on apple quality, this research investigated the conditions of soil moisture and nutrients at different elevations of terrace apple orchards in the hilly-gully region of the Loess Plateau. The results showed that soil water content decreases when the elevation increased, whereas soil nutrients fluctuated significantly at different elevations of terrace orchards and the contents were lower than the standard level of the Loess Plateau, especially soil organic matter, but total potassium was higher. The apple firmness increased when the elevation increased and had a good linear relationship with elevation. Apple vitamin C content in weed-covered orchards was higher than in the ploughing and weeding management orchards. The impact of soil nutrients, including soil water, nitrogen, phosphorus, and potassium on apple quality were concentrated in soluble solid and total acid. Irrational irrigation or partial use of nutrients, such as more use of nitrogen and less use of phosphorus and potassium, may deteriorate the apple quality. Therefore, we suggested that the amount of irrigation be increased appropriately with the raising of elevation. Moreover, part of the weed should be kept to cover the orchard, as well as mowing regularly and covering the surface. This would not only improve water use efficiency and increase soil organic matter content, it would also maintain apple quality and ensure sustainable development of the apple orchards.
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Kellum, Darby S., Manoj K. Shukla, John Mexal, and Sanjit Deb. "Greenhouse Gas Emissions from Pecan Orchards in Semiarid Southern New Mexico." HortScience 53, no. 5 (May 2018): 704–9. http://dx.doi.org/10.21273/hortsci12773-17.
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Greenhouse gas (GHG) emissions are fueling global climate change, with methane and nitrous oxide being the primary agricultural gases emitted. It has been shown that N2O emissions correlate to moisture content fluctuations; however, emissions from agricultural fields in the semiarid regions of the Southwest where rewetting events occur regularly are not well established. The scope of this study was to quantify GHG emissions in correlation to soil moisture fluctuations and fertilizer application. The study was conducted continuously in two pecan [Carya illinoinensis (Wangenh.) K. Koch] orchards between Aug. 2010 and Aug. 2011 on a sandy loam soil (La Mancha) and a silty clay loam soil (Leyendecker), both under normal management practices. The small chamber technique was used to measure GHGs. Emissions varied greatly throughout the year. The largest flux of CO2 at La Mancha and Leyendecker both occurred during a drying event immediately following an irrigation event: 84,642.49 μg·m−2·h−1 and 30,338.24 μg·m−2·h−1, respectively. The net CH4 flux at Leyendecker and La Mancha was close to zero with the largest emissions occurring during wetting events. Results showed that N2O emissions were maintained near the baseline except for the few days following an irrigation event. The largest emission peak at La Mancha occurred after irrigation and nitrogen application: 322.06 μg·m−2·h−1. The largest emission peaks of 26.37 and 1.13 μg·m−2·h−1 at Leyendecker and La Mancha, respectively, occurred after irrigation, nitrogen application, and tillage. Nitrogen application was the driving factor affecting N2O emissions at La Mancha, whereas soil moisture content was the driving factor at Leyendecker. Emission factors (EFs) at La Mancha and Leyendecker were 0.49% and 0.05%, respectively. A thorough accounting of GHG emissions is necessary for budgeting and identifying mitigation policy.
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Othman, Yahia, Caiti Steele, Dawn VanLeeuwen, and Rolston St. Hilaire. "Hyperspectral Surface Reflectance Data Detect Low Moisture Status of Pecan Orchards during Flood Irrigation." Journal of the American Society for Horticultural Science 140, no. 5 (September 2015): 449–58. http://dx.doi.org/10.21273/jashs.140.5.449.
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For large fields, remote sensing might permit plant low moisture status to be detected early, and this may improve drought detection and monitoring. The objective of this study was to determine whether canopy and soil surface reflectance data derived from a handheld spectroradiometer can detect moisture status assessed using midday stem water potential (ψsmd) in pecan (Carya illinoinensis) during cyclic flood irrigations. We conducted the study simultaneously on two mature pecan orchards, one in a sandy loam (La Mancha) and the other in a clay loam (Leyendecker) soil. We were particularly interested in detecting moisture status in the −0.90 to −1.5 MPa ψsmd range because our previous studies indicated this was the critical range for irrigating pecan. Midday stem water potential, photosynthesis (A) and canopy and soil surface reflectance measurements were taken over the course of irrigation dry-down cycles at ψsmd levels of −0.40 to −0.85 MPa (well watered) and −0.9 to −1.5 MPa (water deficit). The decline in A averaged 34% in La Mancha and 25% in Leyendecker orchard when ψsmd ranged from −0.9 to −1.5 MPa. Average canopy surface reflectance of well-watered trees (ψsmd −0.4 to −0.85 MPa) was significantly higher than the same trees experiencing water deficits (ψsmd −0.9 to −1.5 MPa) within the 350- to 2500-nm bands range. Conversely, soil surface reflectance of well-watered trees was lower than water deficit trees over all bands. At both orchards, coefficient of determinations between ψsmd and all soil and canopy bands and surface reflectance indices were less than 0.62. But discriminant analysis models derived from combining soil and canopy reflectance data of well-watered and water-deficit trees had high classification accuracy (overall and cross-validation classification accuracy >80%). A discriminant model that included triangular vegetation index (TVI), photochemical reflectance index (PRI), and normalized soil moisture index (NSMI) had 85% overall accuracy and 82% cross-validation accuracy at La Mancha orchard. At Leyendecker, either a discriminant model weighted with two soil bands (690 and 2430 nm) or a discriminant model that used PRI and soil band 2430 nm had an overall classification and cross-validation accuracy of 99%. In summary, the results presented here suggest that canopy and soil hyperspectral data derived from a handheld spectroradiometer hold promise for discerning the ψsmd of pecan orchards subjected to flood irrigation.
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Zhang, Rui, and Jian-long Zheng. "Study of the Moisture Equilibrium of Highway Expansive Soil Embankments." Journal of Highway and Transportation Research and Development (English Edition) 8, no. 3 (September 2014): 13–24. http://dx.doi.org/10.1061/jhtrcq.0000392.
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Marquis, François, Claude Camiré, and Marius Lachance. "Distribution des cations basiques et de l'aluminium dans la solution de sol de l'horizon humifère d'une érablière fertilisée: représentativité des extraits de sol saturé à l'eau." Canadian Journal of Soil Science 79, no. 1 (February 1, 1999): 47–55. http://dx.doi.org/10.4141/s97-080.
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Soil solution analysis may provide useful information on nutrition status and Al toxicity in soil. Nevertheless, obtaining soil solutions in low-moisture soils causes a problem. Saturated extracts may act as an alternative for getting information on soil solution. Their effectiveness in assessing representative base cations and aluminum distribution in soil solution was demonstrated in this study. Saturated extracts, which were obtained from air drying and fresh soil, were compared with the "true" soil solution for base distribution and base/Al ratio. Molar fraction and equilibrium ratio in the "true" soil solution depended on soil moisture before extraction. Nevertheless, they were less affected by this approach than intrinsic concentrations. The results showed that molar fraction and equilibrium ratio in soil solution can be predicted from the molar fraction or equilibrium ratio in saturated extracts and soil moisture information, however, saturated extracts obtained from fresh soil were better models. Base/Al ratios in saturated extracts were closely dependent on pH extracts but they were not well linked with the same ratio in soil solution. Key words: Soil solution, molar fraction, equilibrium ratio, soil acidity, sugar maple, Acer saccharum
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Choi, Hyun-Sug, Curt Rom, and Jason McAfee. "(317) Effects of Different Organic Mulch on Soil Physical Characteristics and Leaf Nutrition in Apple Orchards." HortScience 40, no. 4 (July 2005): 1027D—1027. http://dx.doi.org/10.21273/hortsci.40.4.1027d.
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Mulch may affect soil chemistry, soil microclimate, biological communities, and tree performance. The trial was conducted to evaluate the effects of different orchard mulches on leaf nutrition, soil moisture, bulk density, root density, and water infiltration for understanding potential use in organic orchards for weed control and as a nutrient resource. Black plastic, hardwood chips, and shredded white paper were applied to three apple cultivars, `Gala', `Jonagold', and `Braeburn' on M.9 rootstocks. A control was sprayed with contact herbicide. Trees grown in hardwood mulch had the highest foliar P and K in year 3. Trees in other mulches showed no difference of leaf nutrition in year 5. All treatments had consistently higher soil moisture than control in year 1, 2, and 4. Mulch did not affect soil bulk density in year 2. The root density was lowest under black plastic mulch in year 2, but was similar in all treatments in year 3. In year 2, water infiltration was fastest in hardwood mulch and control treatments.
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Villa, Yocelyn B., Sat Darshan S. Khalsa, Rebecca Ryals, Roger A. Duncan, Patrick H. Brown, and Stephen C. Hart. "Organic matter amendments improve soil fertility in almond orchards of contrasting soil texture." Nutrient Cycling in Agroecosystems 120, no. 3 (June 24, 2021): 343–61. http://dx.doi.org/10.1007/s10705-021-10154-5.
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AbstractThe effects of organic matter amendments (OMA) on soil fertility in permanent cropping systems like orchards is under-studied compared to annual cropping systems. We evaluated experimentally the impact of OMAs on soil fertility in almond (Prunus dulcis) orchards over a two-year period with annual applications. Two OMAs, derived from composted green waste (GWC) or composted manure wood chips (MWC), were applied as surface mulch and compared to a control at two sites with different soil textures (sandy loam and loamy sand). OMAs increased soil moisture content (0–0.1 m depth) at both sites by 27–37%. Both amendments increased soil inorganic N at the sandy loam (GWC: 194%; MWC: 114%) and loamy sand (GWC: 277%; MWC: 114%) sites the month following application, but soil inorganic N concentrations quickly decreased to values similar to those of control plots. After two-years, the GWC and the MWC amendments increased the soil cation exchange capacity (CEC) by 112% and 29%, respectively, in the sandy loam site, but no change was observed in the loamy sand site. The greatest increase in soil extractable K occurred in the GWC-amended plots at the sandy loam site even though the initial K concentration of MWC was higher. Both OMAs increased soil organic carbon (SOC) after two years, but the SOC increase in the GWC-amended plots was greater. Our results suggest that OMAs can significantly improve soil fertility after one or two annual applications, and that fertility gains appear to be dependent on soil texture than the nutrient concentrations of the OMA.
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Groenevelt, P. H. "Hydrostatics of frozen soil." Canadian Journal of Soil Science 90, no. 3 (August 1, 2010): 403–8. http://dx.doi.org/10.4141/cjss09032.
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An outline is presented of the relations between the energy status of water and the content of liquid water and ice in frozen soils. The theory formulates the dependence of the soil moisture characteristic (moisture retention curve) of a frozen soil on the load pressure and the temperature. This formulation requires the definition of the envelope-pressure potentials and the frost potentials of the soil moisture and the ice present in the soil. These potentials are expressed in terms of the void ratio, the moisture ratio, the ice ratio, the moisture ratio equivalent, and the ice ratio equivalent. The relations between these variables are intrinsic properties of the porous medium. They have to be determined by experiment or deduced from indirect measurements. The present theory facilitates such deductions. The measurement of the equilibrium soil moisture and ice pressures in frozen soil is more difficult than the measurement of the volume ratios. Thus, it may be advantageous to deduce the former from the latter. Some data from the literature are used to demonstrate the use of indirect measurements in order to obtain the required properties.Key words: Soil water, soil ice, Maxwell relations, envelope-pressure potentials, frost potentials
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Liao, Ren Kuan, Pei Ling Yang, Shu Mei Ren, Hang Yi, Bo Zhou, and Zhu Zhou. "Effects of Typical Chemical Agents on Prevention of Non-Point-Source (NPS) Pollution in a Sloping Orchard." Advanced Materials Research 550-553 (July 2012): 1168–72. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.1168.
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In this paper, two typical chemical agents SAP and PAM were selected to reduce NPS pollution. Soil water content, nutrient transport and soil erosion have been researched. The results showed that the water deep percolation was reduced and the moisture of root zone increased by 3.6%-12.69% after chemical agents application; PAM can immobile soil grains, and significantly reduce soil erosion on sloping land by 25.5%-53.4%. The synergies of PAM and SAP can significantly influence transport of nutrients in the soil vertical profile, moreover, the content of nutrient was enriched in root zone that the content of Nitrate-N increased 14.7% and Ammonium-N increased 9.8%. It can been found that CL2 (SAP150 kg/k㎡+PAM4.5 kg/k㎡) treatment is superior to CL1 (SAP150 kg/k㎡+PAM2.25 kg/k㎡) in soil moisture conservation and reducing NPS pollution in two slopes orchards.
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Massman, W. J. "A non-equilibrium model for soil heating and moisture transport during extreme surface heating." Geoscientific Model Development Discussions 8, no. 3 (March 6, 2015): 2555–603. http://dx.doi.org/10.5194/gmdd-8-2555-2015.
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Abstract. With increasing use of prescribed fire by land managers and increasing likelihood of wildfires due to climate change comes the need to improve modeling capability of extreme heating of soils during fires. This issue is addressed here by developing a one-dimensional non-equilibrium model of soil evaporation and transport of heat, soil moisture, and water vapor, for use with surface forcing ranging from daily solar cycles to extreme conditions encountered during fires. The model employs a linearized Crank–Nicolson scheme for the conservation equations of energy and mass and its performance is evaluated against dynamic soil temperature and moisture observations obtained during laboratory experiments on soil samples exposed to surface heat fluxes ranging between 10 000 and 50 000 W m−2. The Hertz–Knudsen equation is the basis for constructing the model's non-equilibrium evaporative source term. The model includes a dynamic residual soil moisture as a function of temperature and soil water potential, which allows the model to capture some of the dynamic aspects of the strongly bound soil moisture that seems to require temperatures well beyond 150 °C to fully evaporate. Furthermore, the model emulates the observed increase in soil moisture ahead of the drying front and the hiatus in the soil temperature rise during the strongly evaporative stage of drying. It also captures the observed rapid evaporation of soil moisture that occurs at relatively low temperatures (50–90 °C). Sensitivity analyses indicate that the model's success results primarily from the use of a temperature and moisture potential dependent condensation coefficient in the evaporative source term. The model's solution for water vapor density (and vapor pressure), which can exceed one standard atmosphere, cannot be experimentally verified, but they are supported by results from (earlier and very different) models developed for somewhat different purposes and for different porous media. Overall, this non-equilibrium model provides a much more physically realistic simulation over a previous equilibrium model developed for the same purpose. Current model performance strongly suggests that it is now ready for testing under field conditions.
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Potter, Marisa T., Richard J. Heerema, Jill Schroeder, Jamshid Ashigh, Dawn VanLeeuwen, and Cheryl Fiore. "Mature Pecan Orchard Floor Vegetation Management: Impacts on Tree Water Status, Nutrient Content, and Nut Production." HortScience 47, no. 6 (June 2012): 727–32. http://dx.doi.org/10.21273/hortsci.47.6.727.
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Pecan [Carya illinoinensis (Wangenh.) K. Koch] growers are advised to control orchard floor vegetation when establishing new orchards, but there is not a set recommendation for vegetation control in mature orchards. The objective of this study was to measure the effect of orchard floor vegetation on water and nitrogen (N) status of flood-irrigated mature pecan trees. Four treatments studied were: completely vegetated orchard floor, vegetation-free inner area directly under the tree canopy with vegetation in the outer area, completely vegetation-free, and vegetated inner area under the canopy with a vegetation-free outer area. Treatments were organized as a 2 × 2 factorial structure with inner and outer treatment factors, both with levels vegetated and vegetation-free. Soil moisture and tree midday stem water potential (MSWP) were measured during irrigation cycles to evaluate the development of water stress in the pecan trees. Soil moisture data showed a significant outer main effect when the soil in the entire orchard was the driest, that is, just before irrigation events. Areas with vegetation cover that were exposed to full sun were significantly drier than shaded vegetated areas and vegetation-free areas in the orchard floor. However, this was not correlated with differences in tree water status as indicated by MSWP. Leaf tissue and soil analyses showed no significant differences in N concentrations among treatments in either year. Treatments with orchard floor vegetation in the outer area had significantly higher yield efficiency and marginally significant improvements in percent kernel fill and number of nuts per kilogram. Our findings suggest that there may be more benefits to maintaining orchard floor vegetation in mature orchards than were previously acknowledged.
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Amvrosiadi, Nino, Kevin Bishop, and Jan Seibert. "Soil moisture storage estimation based on steady vertical fluxes under equilibrium." Journal of Hydrology 553 (October 2017): 798–804. http://dx.doi.org/10.1016/j.jhydrol.2017.08.042.
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Bautista, I., G. Cruz-Romero, J. R. Castel, and C. Ramos. "SPATIAL AND TIME VARIABILITY OF SOIL MOISTURE IN CITRUS ORCHARDS AS MEASURED BY NEUTRON PROBE." Acta Horticulturae, no. 171 (July 1985): 61–74. http://dx.doi.org/10.17660/actahortic.1985.171.5.
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Ekka, Akankasha Ankita, Dileep Kumar, Anand Prakash Singh, and Awtar Singh. "Variation in physico-chemical properties of soil under different agri-horti system in Vindhyan region." Journal of Applied and Natural Science 9, no. 2 (June 1, 2017): 1187–93. http://dx.doi.org/10.31018/jans.v9i2.1344.
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Adoption of unsuitable production system may lead to deterioration of soil physico-chemical properties. Hence, it becomes important to assess the impact of various production systems. For this purpose, a study was carried out to find out variation in physico-chemical properties of soil in agri-horti system based four orchards of Rajiv Gandhi South Campus, Banaras Hindu University, Mirzapur, India. Soil samples were collected from the orchards of custard apple (Annona reticulate), guava (Psidium guajava), bael (Aegle marmelos) and crane berry (Carissa carandas) from two depths (0-15 and 15-30 cm) separately within canopy and out of canopy of different plants. The results of the study revealed that all the agri-horti systems were effective in bringing gradual improvement in the physico-chemical properties of the soil. Among different orchards tried, the custard apple system resulted in the highest improvement in temperature (27.16 oC), moisture (24.53 %) and water-holding capacity (41.80 %), whereas crane berry based system recorded better result in case of bulk density, porosity, electrical conductivity, pH, organic carbon, available N (187.55 kg ha-1) and K (193.46 kg ha-1). Custard apple based system recorded highest DTPA extractable micronutrients (Zn 0.54, Fe 17.23, Cu 0.88 and Mn14.72 mg ka-1).
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Massman, W. J. "A non-equilibrium model for soil heating and moisture transport during extreme surface heating: the soil (heat–moisture–vapor) HMV-Model Version 1." Geoscientific Model Development 8, no. 11 (November 6, 2015): 3659–80. http://dx.doi.org/10.5194/gmd-8-3659-2015.
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Abstract. Increased use of prescribed fire by land managers and the increasing likelihood of wildfires due to climate change require an improved modeling capability of extreme heating of soils during fires. This issue is addressed here by developing and testing the soil (heat–moisture–vapor) HMV-model, a 1-D (one-dimensional) non-equilibrium (liquid–vapor phase change) model of soil evaporation that simulates the coupled simultaneous transport of heat, soil moisture, and water vapor. This model is intended for use with surface forcing ranging from daily solar cycles to extreme conditions encountered during fires. It employs a linearized Crank–Nicolson scheme for the conservation equations of energy and mass and its performance is evaluated against dynamic soil temperature and moisture observations, which were obtained during laboratory experiments on soil samples exposed to surface heat fluxes ranging between 10 000 and 50 000 W m−2. The Hertz–Knudsen equation is the basis for constructing the model's non-equilibrium evaporative source term. Some unusual aspects of the model that were found to be extremely important to the model's performance include (1) a dynamic (temperature and moisture potential dependent) condensation coefficient associated with the evaporative source term, (2) an infrared radiation component to the soil's thermal conductivity, and (3) a dynamic residual soil moisture. This last term, which is parameterized as a function of temperature and soil water potential, is incorporated into the water retention curve and hydraulic conductivity functions in order to improve the model's ability to capture the evaporative dynamics of the strongly bound soil moisture, which requires temperatures well beyond 150 °C to fully evaporate. The model also includes film flow, although this phenomenon did not contribute much to the model's overall performance. In general, the model simulates the laboratory-observed temperature dynamics quite well, but is less precise (but still good) at capturing the moisture dynamics. The model emulates the observed increase in soil moisture ahead of the drying front and the hiatus in the soil temperature rise during the strongly evaporative stage of drying. It also captures the observed rapid evaporation of soil moisture that occurs at relatively low temperatures (50–90 °C), and can provide quite accurate predictions of the total amount of soil moisture evaporated during the laboratory experiments. The model's solution for water vapor density (and vapor pressure), which can exceed 1 standard atmosphere, cannot be experimentally verified, but they are supported by results from (earlier and very different) models developed for somewhat different purposes and for different porous media. Overall, this non-equilibrium model provides a much more physically realistic simulation over a previous equilibrium model developed for the same purpose. Current model performance strongly suggests that it is now ready for testing under field conditions.
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Abobatta, Waleed Fouad. "Fruit orchards under climate change conditions: adaptation strategies and management." Journal of Applied Biotechnology & Bioengineering 8, no. 3 (2021): 99–102. http://dx.doi.org/10.15406/jabb.2021.08.00260.
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Under global warming and climate change conditions fruit orchards facing different environmental challenges which cause negative impacts on the growth and productivity of various fruit trees particularly in arid and semi-arid areas, various abiotic stress such as rising temperature, drought, heatwaves, and soil salinity represented a major challenge for growth and productivity of fruit orchards. Fruit trees used different strategies to cope with abiotic stress and minimize their adverse effects. Plants used different physiological, anatomical, and morphological mechanisms to tolerate abiotic stress, such as ion homeostasis, synthesis of more compatible solute, polyamines production, antioxidant regulation, closing stomata, in addition tol modification of root system, abscission of the leaves partially, compactness canopy, reducing leaf size, furthermore, under abiotic stress plants produce various organic solutes to cope with Reactive Oxygen solutes like Proline, in addition, using proper management practices that include providing adequate nutrients requirement particularly Potassium and Calcium, maintain soil moisture, using proper rootstocks tolerant for drought and salinity stress as well as exogenous application of plant growth substances could sustain orchards growth and productivity
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Fernando Zanoelo, Everton. "Equilibrium Moisture Isotherms for Mate Leaves." Biosystems Engineering 92, no. 4 (December 2005): 445–52. http://dx.doi.org/10.1016/j.biosystemseng.2005.08.012.
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Willett, Mike, T. J. Smith, A. B. Peterson, H. Hinman, R. G. Stevens, T. Ley, P. Tvergyak, K. M. Williams, K. M. Maib, and J. W. Watson. "Growing Profitable Apple Orchards in Replant Sites: An Interdisciplinary Team Approach in Washington State." HortTechnology 4, no. 2 (April 1994): 175–81. http://dx.doi.org/10.21273/horttech.4.2.175.
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In the mid-1980s, a statewide educational program was initiated to help improve productivity in replanted apple orchards. This effort began with a study of the background of the problem in Washington and an assessment of the problems growers faced when replanting orchards. An array of potential limiting factors were identified-most important, specific apple replant disease (SARD)-but also low soil pH, poor irrigation practices, arsenic (As) spray residues in the soil, soil compaction, nematodes, nutrient deficiencies, and selection of the appropriate orchard system. The educational program was delivered using a variety of methods to reach audience members with different learning styles and to provide various levels of technical information, focusing on ways to correct all limiting factors in replant situations. Results have been: Acceptance of soil fumigation as a management tool: increased recognition of soil physical, chemical, and moisture problems; reduced reliance on seedling rootstock, and an increase in the use of dwarfing, precocious understocks; and better apple tree growth and production in old apple orchard soils.
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Nagy, Gábor, Dénes Lóczy, Szabolcs Czigány, Ervin Pirkhoffer, Szabolcs Ákos Fábián, Rok Ciglič, and Mateja Ferk. "Soil moisture retention on slopes under different agricultural land uses in hilly regions of Southern Transdanubia." Hungarian Geographical Bulletin 69, no. 3 (October 2, 2020): 263–80. http://dx.doi.org/10.15201/hungeobull.69.3.3.
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Increasingly severe weather extremes are predicted as one of the consequences of climate change. According to climatic models, weather extremities induce higher risks for both flood and drought in the Carpathian Basin. Throughout the 19th and 20th centuries, flood control relied on cost-intensive engineering structures, but recently ecological solutions have come to the fore. Flood hazard on major rivers could be mitigated if multiple and cumulative water retention opportunities are exploited on the upper sections of tributary catchments. Appropriate land use and landscape pattern changes can shift the infiltration to run-off ratio to the benefit of the former. In the Transdanubian Hills of Southwest Hungary three study areas with different agricultural land use types had been selected and investigated for the impact of landscape micro-features on soil moisture retention capacity with the purpose of conserving water from wet periods for the times of drought. Marked differences in moisture dynamics have been detected between arable land, grasslands and orchards. This fact underlines the need for integrated soil and water conservation. Drought risk was found to be the highest on ploughland. Favourable soil water budgets have been observed in the fields as a function of land use: less intensive types, like grazing land and orchards (particularly tree rows), were identified as places of high water retention capacity. Although serious water stress conditions were also reached in the orchard, it markedly mitigated drought conditions compared to the ploughland.
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Baldi, Elena, Maurizio Quartieri, Enrico Muzzi, Massimo Noferini, and Moreno Toselli. "Use of In Situ Soil Solution Electric Conductivity to Evaluate Mineral N in Commercial Orchards: Preliminary Results." Horticulturae 6, no. 3 (July 8, 2020): 39. http://dx.doi.org/10.3390/horticulturae6030039.
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The aim of the present experiment was to evaluate the effectiveness of soil electrical conductivity (EC) measurement as a fast tool to assess mineral nitrogen (N) in orchards, in order to define precise N inputs that can help farmers to reduce useless fertilizer application. During one vegetative season, seven orchards of different species, supplied with mineral or organic fertilization, were monitored. Nitrate soil concentration was measured monthly by laboratory analyses, while soil EC and moisture were recorded continuously by soil probes. Nitrate and EC were positively correlated, laying the foundation for the identification of a fast and reliable index. However, while some dates showed a high Pearson correlation coefficient, no correlation was found for others. The correlation was not affected by type of fertilizer, and was higher in silty-clay-loam than in loam soils. Pooling all of the data, a significant correlation with a Pearson coefficient of 0.75 was found. The soil optimal nitrate N availability was defined by an EC in the range of 0.3 to 0.6 mS cm−1. Although these are only preliminary results, our data are promising, showing a good suitability of soil EC measurement as a means to monitor soil mineral N availability.
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Matheron, M. E., M. Porchas, and J. C. Matejka. "Distribution and Seasonal Population Dynamics of Phytophthora citrophthora and P. parasitica in Arizona Citrus Orchards and Effect of Fungicides on Tree Health." Plant Disease 81, no. 12 (December 1997): 1384–90. http://dx.doi.org/10.1094/pdis.1997.81.12.1384.
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The distribution and seasonal population dynamics of Phytophthora citrophthora and P. parasitica within citrus orchards in southwestern and central Arizona were determined over a multiple-year period. In central Arizona, P. citrophthora alone, P. parasitica alone, or both pathogens together were recovered from 7, 37, and 41% of sampled orchards, respectively, whereas in the southwestern production area, the same pathogens alone or in combination were recovered from 17, 50, and 17% of sampled orchards, respectively. For a 6-year period, the average population density of P. parasitica in southwestern Arizona was 16.7 propagules/g of dry soil. For 2 of 3 years, the population density of P. citrophthora at the 10-cm soil depth was significantly higher in the spring than in the preceding winter or the following autumn season. There were no significant seasonal multiple-year differences in population levels of P. parasitica. Propagule densities of both pathogens, as well as root densities, generally decreased as soil depth increased from 10 to 60 cm. No consistent significant correlation was detected between propagule density of either pathogen and soil temperature or soil moisture at the time of collection. A multiple-year treatment program with fosetyl-Al or metalaxyl resulted in significantly healthier tree canopies and higher root densities compared to nontreated trees; however, population densities of P. citrophthora and P. parasitica did not differ significantly when nontreated trees were compared to those receiving fungicide treatments.
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Somers, B., V. Gysels, W. W. Verstraeten, S. Delalieux, and P. Coppin. "Modelling moisture-induced soil reflectance changes in cultivated sandy soils: a case study in citrus orchards." European Journal of Soil Science 61, no. 6 (October 14, 2010): 1091–105. http://dx.doi.org/10.1111/j.1365-2389.2010.01305.x.
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McLaren, R. G., C. P. Rooney, and L. M. Condron. "Control of lead solubility in soil contaminated with lead shot: effect of soil moisture and temperature." Soil Research 47, no. 3 (2009): 296. http://dx.doi.org/10.1071/sr08195.
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An incubation experiment was carried out to assess the rate of oxidation of lead (Pb) shot and subsequent transfer of Pb to the soil under different soil moisture and temperature regimes. Lead was readily released from Pb shot into the soil environment due to rapid corrosion of the Pb shot; however, the rate of Pb shot dissolution was slower at 70% than at 100% field moisture capacity. The corrosion and development of crust material on Pb shot, and corresponding increases in soil solution Pb and Pb associated with the soil solid phase, were also slower at 10°C than 25 or 30°C. Soil moisture and temperature also influenced the speciation of soil solution Pb as modelled using WHAM 6, mainly through the effects of moisture and temperature on soil pH, total soluble Pb, and dissolved organic C. The rate of approach to equilibrium of the Pb shot–soil–soil solution system will be much slower where soil moisture and temperature limit Pb shot corrosion. Calculated free ion Pb2+ concentrations suggest that after 6 months, almost all samples contaminated with Pb shot exceeded soil critical limits for Pb toxicity.
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Miyamoto, Seiichi, and Monte Nesbitt. "Effectiveness of Soil Salinity Management Practices in Basin-irrigated Pecan Orchards." HortTechnology 21, no. 5 (October 2011): 569–76. http://dx.doi.org/10.21273/horttech.21.5.569.
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Soil salinity management is a factor for successful production of pecan (Carya illinoinensis) in arid southwestern United States. An exploratory study was performed to evaluate the effect of various soil management practices on salt leaching in basin-irrigated orchards developed on alluvial soils (Torrifluvents, Entisols) of the middle Rio Grande Basin. The practices evaluated were ripping, minimum-till chiseling, and soil profile modification. For ripping, parabolic shanks were passed through the center section (4 to 8 ft wide) between each tree row to a depth ranging from 18 to 36 inches. Minimum-till chisels included 7- and 30-inch shanks, equipped with coulters to reduce break up of the ground surface. Soil profile modification consisted of trenching with a backhoe and profile mixing with a large excavator. The effectiveness of these methods was evaluated by measuring soil salinity and moisture in treated and untreated zones at 17 test sites. Both ripping and minimum-till deep chiseling helped improve salt leaching, and the effectiveness of salt leaching increased as working depths approach the thickness of the clayey layer. However, annual ripping of the center section of each tree row space may not provide wide enough zones to alleviate salt stress to the trees. Straight shanks prune but do not lift tree roots, thus appearing to be better suited for chiseling closer to tree rows. Soil profile modification was highly effective in leaching salts. From the view of minimizing soil aggregate destruction and of maintaining a leveled floor, minimum-till deep chiseling, followed by the use of sand-topdressing and minimum-till shallow chisels for maintenance may prove to be more desirable than conventional ripping, especially in soil types consisting of silty clay loam.
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Ungureanu, Nicoleta, Valentin Vlăduţ, and Dan Cujbescu. "Soil compaction under the wheel of a sprayer." E3S Web of Conferences 112 (2019): 03027. http://dx.doi.org/10.1051/e3sconf/201911203027.
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Soil degradation by artificial compaction is recognized by the European Union as a major environmental and agricultural problem. Artificial compaction has worsened with the intensification of mechanized agriculture where heavier machinery is used, often moving on soils with high moisture. Experimental research was designed to determine the influence of five wheel loads and tire inflation pressures, on the contact area, the shape of footprint and the contact pressure, under the wheel of a machine for high accuracy application of phytosanitary treatments in orchards. It was found that the only situation when compaction does not occur is when the tank is empty (2.45 kN wheel load), at lowest tire inflation pressure of 100 kPa. Subsoil compaction (at 0.3-0.4 m) occurs when the sprayer machine’s tank is filled with different amounts of liquid. With empty tank, the sprayer only causes topsoil compaction.
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Subin, Zachary M., Charles D. Koven, William J. Riley, Margaret S. Torn, David M. Lawrence, and Sean C. Swenson. "Effects of Soil Moisture on the Responses of Soil Temperatures to Climate Change in Cold Regions*." Journal of Climate 26, no. 10 (May 8, 2013): 3139–58. http://dx.doi.org/10.1175/jcli-d-12-00305.1.
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Abstract At high latitudes, changes in soil moisture could alter soil temperatures independently of air temperature changes by interacting with the snow thermal rectifier. The authors investigated this mechanism with model experiments in the Community Land Model 4 (CLM4) with prescribed atmospheric forcing and vegetation state. Under equilibrium historical conditions, increasing CO2 concentrations experienced by plants from 285 to 857 ppm caused local increases in soil water-filled pore space of 0.1–0.2 in some regions throughout the globe. In permafrost regions that experienced this moistening, vertical- and annual- mean soil temperatures increased by up to 3°C (0.27°C averaged over all permafrost areas). A similar pattern of moistening and consequent warming occurred in simulations with prescribed June–September (JJAS) rainfall increases of 25% over historical values, a level of increase commensurate with projected future rainfall increases. There was a strong sensitivity of the moistening responses to the baseline hydrological state. Experiments with perturbed physics confirmed that the simulated warming in permafrost soils was caused by increases in the soil latent heat of fusion per unit volume and in the soil thermal conductivity due to the increased moisture. In transient Representative Concentration Pathway 8.5 (RCP8.5) scenario experiments, soil warming due to increased CO2 or JJAS rainfall was smaller in magnitude and spatial extent than in the equilibrium experiments. Active-layer deepening associated with soil moisture changes occurred over less than 8% of the current permafrost area because increased heat of fusion and soil thermal conductivity had compensating effects on active-layer depth. Ongoing modeling challenges make these results tentative.
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Paltineanu, Cristian, Leinar Septar, and Cristina Moale. "Crop Water Stress in Peach Orchards and Relationships with Soil Moisture Content in a Chernozem of Dobrogea." Journal of Irrigation and Drainage Engineering 139, no. 1 (January 2013): 20–25. http://dx.doi.org/10.1061/(asce)ir.1943-4774.0000492.
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Huang, Jun, Juan Wang, Xining Zhao, Pute Wu, Zhiming Qi, and Hongbing Li. "Effects of permanent ground cover on soil moisture in jujube orchards under sloping ground: A simulation study." Agricultural Water Management 138 (May 2014): 68–77. http://dx.doi.org/10.1016/j.agwat.2014.03.002.
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Ding, Wenbin, Fei Wang, Yunyun Dong, Kai Jin, Chenyu Cong, Jianqiao Han, and Wenyan Ge. "Effects of rainwater harvesting system on soil moisture in rain-fed orchards on the Chinese Loess Plateau." Agricultural Water Management 243 (January 2021): 106496. http://dx.doi.org/10.1016/j.agwat.2020.106496.
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Durán, Norberto, and Rubén A. Ortíz. "Efectos de algunas propiedades físicas del suelo y la precipitación sobre la producción de la palma aceitera (Elaeis guineensis) en Centroamérica." Agronomía Mesoamericana 6 (June 2, 2016): 07. http://dx.doi.org/10.15517/am.v6i0.24802.
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The soil aeration and hydric shortage greatly influence oil palm yield in Central America. This assay was conducted to identify and quantify the effect of the physical properties of the soil and rainfall on the yield of oil palm orchards in Coto and Quepos (Costa Rica) and San Alejo (Honduras). The following soil characteristics were evaluated: texture, moisture retention (pF), gravimetric moisture, drain water, total porosity, aerial space, large pore percentage, penetration resistance and tensimeter readings. These evaluations were conducted on 20 fruit bearing plots (in each locality) located within representative soil units; classified as: a) well drained (Fluventic Eutropepts), b) inperfect or moderately drained (Fluvaquentic Eutropepts) and c) poorly drained (Tropaquepts). San Alejo also shows soils with low base saturation (Dystropepts and Psamments). Twenty four additional plots were analyzed in this latter orchard to relate their yield with the catographic units. Regression and corre lation analysis were run for the three localities. The main limiting factors on production were: poor soil aeration en Coto, poor soil aeration and hydric shortage en Quepos, and poor aeration, low base saturation and sandy textures in San Alejo.
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Zeng, Xubin, and Mark Decker. "Improving the Numerical Solution of Soil Moisture–Based Richards Equation for Land Models with a Deep or Shallow Water Table." Journal of Hydrometeorology 10, no. 1 (February 1, 2009): 308–19. http://dx.doi.org/10.1175/2008jhm1011.1.
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Abstract The soil moisture–based Richards equation is widely used in land models for weather and climate studies, but its numerical solution using the mass-conservative scheme in the Community Land Model is found to be deficient when the water table is within the model domain. Furthermore, these deficiencies cannot be reduced by using a smaller grid spacing. The numerical errors are much smaller when the water table is below the model domain. These deficiencies were overlooked in the past, most likely because of the more dominant influence of the free drainage bottom boundary condition used by many land models. They are fixed here by explicitly subtracting the hydrostatic equilibrium soil moisture distribution from the Richards equation. This equilibrium distribution can be derived at each time step from a constant hydraulic (i.e., capillary plus gravitational) potential above the water table, representing a steady-state solution of the Richards equation. Furthermore, because the free drainage condition has serious deficiencies, a new bottom boundary condition based on the equilibrium soil moisture distribution at each time step is proposed that also provides an effective and direct coupling between groundwater and surface water.
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Baker, C. S., J. S. VanderGheynst, and L. P. Walker. "Equilibrium Moisture Isotherms for Synthetic Food Waste And Biosolids Composts." Compost Science & Utilization 7, no. 1 (January 1999): 6–13. http://dx.doi.org/10.1080/1065657x.1999.10701947.
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Gwak, Yong-Seok, Sang-Hyun Kim, and Su-Jin Kim. "Comparison of Soil Evaporation Using Equilibrium Evaporation, Eddy-Covariance and Surface Soil Moisture on the Forest Hillslope." Journal of Environmental Science International 22, no. 1 (January 31, 2013): 119–29. http://dx.doi.org/10.5322/jes.2013.22.1.119.
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Entezari, M., A. Esmaeily, and S. Niazmardi. "ESTIMATION OF SOIL MOISTURE AND EARTH’S SURFACE TEMPERATURE USING LANDSAT-8 SATELLITE DATA." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W18 (October 18, 2019): 327–30. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w18-327-2019.
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Abstract. Soil moisture estimation is essential for optimal water and soil resources management. Surface soil moisture is an important variable in the natural water cycle, which plays an important role in the global equilibrium of water and energy due to its impact on hydrological, ecological and meteorological processes. Soil moisture changes due to the variability of soil characteristics, topography and vegetation in time and place. Soil moisture measurements are performed directly using in situ methods and indirect, by means of transfer functions or remote sensing. Since in-site measurements are usually costly and time-consuming in large areas, we can use methods such as remote sensing to estimate soil moisture at very large scales. The purpose of this study is to estimate soil moisture using surface temperature and vegetation indices for large areas. In this paper, ground temperature was calculated using Landsat-8 thermal band for Mashhad city and was used to estimate the soil moisture content of the study area. The results showed that urban areas had the highest temperature and less humidity at the time of imaging. For this purpose, using the LANDSAT 8 images, the indices were extracted and validated with soil moisture data. In this research, the study area was described and then, using the extracted indices, the estimated model was obtained. The results showed that there is a good correlation between surface soil moisture content with LST and NDVI indices (95%). The results of the verification of the soil moisture estimation model also showed that this model with a mean error of less than 0.001 can predict the surface moisture content, this small amount of error indicates the precision of the proposed model for estimating surface moisture.
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BACCHI, O. O. S., K. REICHARDT, J. C. M. OLIVEIRA, and D. R. NIELSEN. "Gamma-ray beam attenuation as an auxiliary technique for the evaluation of the soil water retention curve." Scientia Agricola 55, no. 3 (1998): 498–502. http://dx.doi.org/10.1590/s0103-90161998000300019.
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The soil water retention curve is fundamental for the hydraulic characterization of a soil and has many applications in agricultural research as well as in practical agriculture. A new procedure for soil moisture and soil bulk density evaluation inside closed pressure chambers through gamma-ray beam attenuation is presented. The proposed procedure presents several advantages in relation to the traditional process: avoids the need of continuous sample manipulation; minimizes the problem of hysteresis; allows a more precise evaluation of soil moisture by taking into account changes of soil bulk density due to swelling or shrinking on addition or removal of water; allows frequent evaluation of soil moisture without the need of opening the pressure chamber; allows a more precise judgement of equilibrium; reduces drastically the time of the determination of the retention curve and allows easy automation of data acquisition by a computer.
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G. O. Ondier, T. J. Siebenmorgen, R. C. Bautista, and A. Mauromoustakos. "Equilibrium Moisture Contents of Pureline, Hybrid, and Parboiled Rice." Transactions of the ASABE 54, no. 3 (2011): 1007–13. http://dx.doi.org/10.13031/2013.37085.
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Bohnhoff, David R., and Rhonda K. Bohnhoff. "Equilibrium Moisture Content of Hazelnut Husks, Shells, and Kernels." Transactions of the ASABE 62, no. 5 (2019): 1075–86. http://dx.doi.org/10.13031/trans.13257.
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Abstract. Hybrid hazelnuts that are predominately a cross between the American hazelnut () and the European hazelnut () are being grown and evaluated as part of an effort to develop a thriving hazelnut industry for the Upper Midwest of the U.S. Along with this plant development effort, researchers are investigating and assessing various harvesting and processing methods and equipment in an effort to create a robust and food-safe production industry. One harvesting alternative is to pick hazelnut clusters off plants before the nuts fully ripen and fall to the ground, an approach that requires greater attention to drying. Whether entire clusters are dried or the nuts are separated from the husks prior to drying is a decision that will be influenced by the drying requirements and potential uses for these hazelnut fractions. To this end, a study was undertaken to establish desorption isotherms for the husks, shells, and kernels of hybrid hazelnuts grown in the Upper Midwest. Clusters were hand-picked from shrubs in Wisconsin and immediately placed in 18 different controlled environments (six different relative humidity levels at three different temperatures). Actual moisture conditioning took place over saturated salt solutions in specially fabricated biomaterial moisture conditioning units. After a six-week period during which the clusters reached equilibrium with their environment via desorption, they were separated into husk, shell, and kernel fractions and returned to their respective conditioning units. After another six weeks in the conditioning units, the moisture content (MC) of each fraction was determined by oven-drying at 103°C for 48 h. Under equilibrium conditions, the kernel MC was found to be only 37% of that for shells, whereas the equilibrium moisture content (EMC) values for husks were on average 14% greater than those for shells. On a dry basis, the average cluster mass was 32.9% husk, 43.9% shell, and 23.2% kernel. Likewise, on a dry basis, the average whole nut mass was 65.5% shell and 34.5% kernel. The desorption data were fit to the Modified Henderson, Modified Chung-Pfost, Modified Halsey, Modified Oswin, and Modified GAB equations. Overall, the best fit to the experimental data was provided by the Modified Chung-Pfost equation with parameters determined using equilibrium relative humidity (ERH) as the dependent variable in regression analyses. For ERH values above 0.70, the temperature-modified form of the GAB equation is recommended for predicting desorption EMC values for hazelnut fractions. Keywords: Desorption, Equilibrium moisture content, Equilibrium relative humidity, Hazelnuts, Kernels, Nuts, Shells, Water activity.
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Mateja, Muršec, Leveque Jean, Chaussod Remi, and Curmi Pierre. "The impact of drip irrigation on soil quality in sloping orchards developed on marl – A case study." Plant, Soil and Environment 64, No. 1 (January 16, 2018): 20–25. http://dx.doi.org/10.17221/623/2017-pse.
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The impact of drip irrigation on structural stability of soil aggregates was studied in soils of an apple (Malus domestica Borkh.) orchard, developed on marl. The field study was carried out in a sloping (20%) terrain in the north-eastern Slovenia at three slope positions (upslope, mid-slope and downslope), involving a comparison of irrigated versus non-irrigated situations after 6 years of drip irrigation practice. Structural stability was studied in three soil layers (0–5, 5–15 and 15–30 cm) at the end of the irrigation season (in September). In the same samples, soil organic carbon, total carbonates and soil moisture contents were determined. Drip irrigation significantly reduced structural stability and soil organic carbon in the surface soil layer (0–5 cm), while total carbonates increased. Based on the whole set of data, structural stability was strongly positively correlated with total carbonates and negatively correlated with soil organic carbon. This means that the effect of higher level of organic matter mineralisation on structural stability, due to irrigation, is counterbalanced by the increase of total carbonates content in the fine textured calcareous soils. Thus, a negative effect of irrigation on soil organic carbon had less destructive consequences on structural stability than expected.
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Di Giuseppe, Francesca, Davide Cesari, and Giovanni Bonafé. "Soil Initialization Strategy for Use in Limited-Area Weather Prediction Systems." Monthly Weather Review 139, no. 6 (June 1, 2011): 1844–60. http://dx.doi.org/10.1175/2011mwr3279.1.
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Abstract Three diverse methods of initializing soil moisture and temperature in limited-area numerical weather prediction models are compared and assessed through the use of nonstandard surface observations to identify the approach that best combines ease of implementation, improvement in forecast skill, and realistic estimations of soil parameters. The first method initializes the limited-area model soil prognostic variables by a simple interpolation from a parent global model that is used to provide the lateral boundary conditions for the forecasts, thus ensuring that the limited-area model’s soil field cannot evolve far from the host model. The second method uses the soil properties generated by a previous limited-area model forecast, allowing the soil moisture to evolve over time to a new equilibrium consistent with the regional model’s hydrological cycle. The third method implements a new local soil moisture variational analysis system that uses screen-level temperature to adjust the soil water content, allowing the use of high-resolution station data that may be available to a regional meteorological service. The methods are tested in a suite of short-term weather forecasts performed with the Consortium for Small Scale Modeling (COSMO) model over the period September–November 2008, using the ECMWF Integrated Forecast System (IFS) model to provide the lateral boundary conditions. Extensive comparisons to observations show that substantial improvements in forecast skills are achievable with improved soil temperature initialization while a smaller additional benefit in the prediction of surface fluxes is possible with the soil moisture analysis. The analysis suggests that keeping the model prognostic variables close to equilibrium with the soil state, especially for temperature, is more relevant than correcting the soil moisture initial values. In particular, if a local soil analysis system is not available, it seems preferable to adopt an “open loop” strategy rather than the interpolation from the host global model analysis. This appears to be especially true for the COSMO model in its current operational configuration since the soil–vegetation–atmosphere transfer (SVAT) scheme of the ECMWF global host model and that of COSMO are radically diverse.
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Ji, Zhi Qiang, Xue Yan Xu, and Chuan Kai Zhao. "Study on Model of Heat and Moisture Transfer in Freezing Soil." Applied Mechanics and Materials 170-173 (May 2012): 97–100. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.97.
Full textAbstract:
The purpose of this paper is to present a numerical model of coupled heat, moisture transfer and their effects on the porosity changes of soil during the freezing process. Coupling among heat, moisture, and mechanical deformations is solved based on finite element method. The equilibrium equations of freezing process are investigated based on segregation theory. The numerical model is applied to a 2D problem of a laboratory frost heave test. Numerical simulation reveals the porosity characters during the freezing process. The frost depths and deformations also the porosity in consideration of the orthotropic properties of frozen soil is discussed.