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Summary A simulation model capable of predicting the yield response of corn to a limited water supply was developed by combining two existing mathematical models. The resulting computer model was evaluated using experimental data taken under a wide range of soil moisture conditions. The soil profile water balances was simulated using SWATRE and SUCROS was used to model the crop growth in response to environmental conditions. In addition to the integration of the two existing models, some minor changes were made to each in an effort to improve the accuracy of the combined models. The model input parameters were derived entirely from published literature. The experimental data necessary for model validation were available from irrigation studies at the Sandhills Agricultural Laboratory of the University of Nebraska. These experiments not only provided the required input soil and climatic data, but also the observed irrigation levels, soil moisture distributions and crop yield required for model validation. Initial evaluation of the computer model indicates that the combined model adequately describes crop evapotranspiration, soil moisture extraction and crop yield under a fairly wide range of soil moisture stress. Additional modifications for the prediction of leaf area expansion and senescence, especially under moisture stress, are needed to improve the accuracy of the model. 相似文献
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《Agricultural Water Management》1999,41(1):41-56
The purpose of the study was to evaluate and derive the optimum spacing of contour vegetative barriers (CVB) of locally adapted, drought resistant plant species as soil and water conservation measures for rainfed crop-fields in an arid region. Adapted perennial grasses performed the best and formed effective barriers against soil erosion. Runoff volume and specific peak discharge were reduced by 28 to 97% and 22 to 96%, respectively using CVB with negligible soil loss. The resultant increase in soil moisture storage increased pearl millet crop yield by 35%. Hydrologic processes with respect to crop response for digitally generated CVB layouts were simulated using the distributed numerical models SWAMREG (rainfall-runoff) and SWACROP (moisture storage-plant transpiration-crop yield), and a personal computer-based geographic information system (GIS) for designing optimum CVB spacing. Inputs needed for these models are soil hydraulic parameters, daily meteorological data, and crop characteristics. Simulated outputs were validated with the observed runoff, soil moisture storage and pearl millet yield data. At an optimum simulated vertical spacing of CVB between 0.5 and 0.6 m, 24% reduction in runoff resulted in better moisture regime and crop yield improvement by 70% over control. 相似文献
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《Agricultural Water Management》1999,41(1):57-70
The salinity condition in the root zone hinders moisture extraction from soil by plants, because of osmotic potential development in soil water due to presence of salts, which ultimately, decreases transpiration of plants and thereby affects crop yield. Therefore, an effort was made in this study to quantify the impact of salinity on soil water availability to plants. The movement of salts under irrigation and evapotranspiration regimes in root zone of soil profile was studied throughout the growing season of wheat crop with adopting exponential pattern of root water uptake. A model was developed to analyze soil water balance to find out moisture deficit because of salinity. A non-linear relationship was formulated between moisture content and salt concentration for simultaneous prediction. The Crank–Nicolson method of Finite Differencing was used to solve the differential equations of soil water and solute transport. The effect of various salt concentrations on transpiration was analyzed to develop a relationship between relative evapotranspiration and relative yield. Relationships among salt concentration, matric potential, moisture deficit and actual transpiration were also established to provide better understanding about impact of salinization and to provide guidelines for obtaining better crop yields in saline soils. 相似文献
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水肥一体化下不同滴灌带配置对玉米产量的影响 总被引：1，自引：0，他引：1
针对水肥一体化下不同滴灌带配置方式对作物产量的影响,结合实际探究了当铺设50 m长滴灌带、设置6种不同首部压力时,毛管首、中、尾部的土壤含水率、干物质质量积累量对作物产量的影响。结果表明:滴灌带类型差异使得土壤的平均含水率在生育期内变化规律有所差异,滴头采用内镶贴片式(N0. 30)时土壤含水率变化规律呈较明显的先下降后上升趋势,且随着滴头流量的增大,在全生育期土壤含水率变化越平缓;滴头采用侧翼迷宫式(L0. 15)时土壤含水率变化趋势平缓,且随着滴头流量的增大,在全生育期土壤含水率变化越显著。L0. 15下全生育期土壤含水率均满足作物生长的需求,可以为作物提供充足水分;流入滴灌带的肥液流速越低、长度越长,附着在管壁的肥料质量越多,尾部作物的肥料利用率越低,致使养分吸收少,作物产量降低。对不同处理下毛管的首、中、尾部产量均匀性进行分析表明,随着滴灌带长度的增加,N0. 30的作物产量均匀性逐渐降低,L0. 15的作物产量均匀性逐渐上升,故不同滴头流量对沿滴灌带长度方向的产量均匀性有一定影响。 相似文献
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Obtaining soil physical field data for simulating soil moisture regimes and associated potato growth
Soil moisture regimes under potatoes were monitored during two growing seasons in a sandy loam and a silty clay loam soil in The Netherlands. Measured moisture contents were used to validate those calculated using the simulation model SWATRE. The model requires hydraulic conductivity, moisture retention, rooting-depth and soil cover data, which were obtained in this study. Measured groundwater levels formed the lower boundary condition and precipitation and potential evapotranspiration the upper boundary condition of the model flow system. Calculated moisture contents agreed well with measured values, but only when in situ moisture retention curves were used and when the effects of cracking in the silty clay loam soil were expressed by modifying the ?-θ function. The moisture supply capacity of the sandy loam soil was highest, particularly in the first growing season and this was interpreted as a major reason for the corresponding higher yields. Simulation can be used for predicting the soil moisture supply capacity in the context of land evaluation, when soil-cover and rooting depth are standardized, for example by simulating growth of a grass crop. 相似文献
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Geospatial estimation of soil moisture in rain-fed paddy fields using SCS-CN-based model 总被引：1，自引：0，他引：1
Paddy fields are characterized by standing water and saturation condition during the entire crop growth period. However, in sub-humid and semi-arid areas, scarce rainfall and intermittent dry spells often cause soil moisture depletion resulting in unsaturated condition in the fields. These distinctive characteristics of the paddy fields have significant influence on the runoff generation and soil moisture retention characteristics of the watershed. In this study, the objective is to extend the application of the Soil Conservation Services Curve Number (SCS-CN)-based models for the geospatial and temporal simulation of soil moisture to paddy field-dominated agricultural watersheds in the water scarce areas. Different SCS-CN-based models, integrated with the soil moisture balance equation, are used to estimate the surface runoff and soil moisture content wherein, the spatial variation in the soil hydraulic characteristics is used to calculate the geospatial variation in soil moisture content. Physical significance of the terms initial abstraction (Ia) and potential maximum retention (S) in these models and their influence on the estimation of runoff and soil moisture are analysed in detail. A new SCS-CN-based model for soil moisture simulation (SCS-CN-SMS), to improve the soil moisture estimation, is proposed in this paper. The proposed model is built up on the soil moisture balance equation to account for the effect of ponding condition and soil moisture variation between the dry and saturation condition. The method is tested with 3 years observed surface runoff data and crop production statistics from a part of the Gandeshwari sub-watershed in West Bengal, India. The entire study area is divided into cells of 20 m × 20 m. Various components of the soil moisture balance equation are estimated for each cell as a function of the soil moisture content. Remote Sensing Technique and Geographic Information System (GIS) are used to extract and integrate the spatially distributed land use and soil characteristics. The Hortonion overland flow concept adopted in the SCS-CN method is used to estimate the soil hydraulic characteristics of each cell in which the curve number is used to infer the spatial variation of the land use and soil characteristics. Even though the original SCS-CN method and the existing modified versions are efficient for runoff estimation, these models are found to be inappropriate for the estimation of soil moisture distribution. On the other hand, the proposed SCS-CN-SMS model gives better results for both runoff and soil moisture simulation and is, therefore, more suitable for the hydrological modeling of paddy field-dominated agricultural watersheds. 相似文献
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Debashis Chakraborty Shantha Nagarajan V.K. Gupta R.N. Garg A. Sarkar K.S. Sundara Sarma 《Agricultural Water Management》2008,95(12):1323-1334
Mulching is one of the important agronomic practices in conserving the soil moisture and modifying the soil physical environment. Wheat, the second most important cereal crop in India, is sensitive to soil moisture stress. Field experiments were conducted during winter seasons of 2004-2005 and 2005-2006 in a sandy loam soil to evaluate the soil and plant water status in wheat under synthetic (transparent and black polyethylene) and organic (rice husk) mulches with limited irrigation and compared with adequate irrigation with no mulch (conventional practices by the farmers). Though all the mulch treatments improved the soil moisture status, rice husk was found to be superior in maintaining optimum soil moisture condition for crop use. The residual soil moisture was also minimum, indicating effective utilization of moisture by the crop under RH. The plant water status, as evaluated by relative water content and leaf water potential were favourable under RH. Specific leaf weight, root length density and dry biomass were also greater in this treatment. Optimum soil and canopy thermal environment of wheat with limited fluctuations were observed under RH, even during dry periods. This produced comparable yield with less water use, enhancing the water use efficiency. Therefore, it may be concluded that under limited irrigation condition, RH mulching will be beneficial for wheat as it is able to maintain better soil and plant water status, leading to higher grain yield and enhanced water use efficiency. 相似文献
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针对塑料地膜对农业生产造成的严重污染问题,运用对照处理方法,探讨了液体地膜覆盖对夏玉米生长发育及产量等方面的影响。结果表明,液膜覆盖使夏玉米株高和茎粗均比对照偏大,其中,低水分处理下差异最为显著。夏玉米叶面积指数低水分处理时液膜覆盖在生育前期较对照偏大,生育后期偏小;而中、高水分下液膜覆盖叶面积指数在整个生育期内均比对照偏大。液膜覆盖使夏玉米光合速率和蒸腾速率显著增大,有利于光合产物的形成。低水分处理下液膜覆盖增产效果最好,增产率达到56.97%,产投比为1.695,高水分下液膜覆盖增产效果最差,增产率仅为15.57%,液膜覆盖产投比小于对照。研究认为,夏玉米液膜覆盖能有效抵抗干旱逆境从而达到节水增产的显著效果。 相似文献
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为了构建能够反映作物长势的综合性指标以及准确估测作物产量,采用粒子滤波算法同化CERES-Wheat模型模拟和基于Landsat数据反演的叶面积指数(Leaf area index,LAI)、地上生物量和0~20 cm土壤含水率,获取冬小麦主要生育期以天为尺度的变量同化值,分析不同生育时期的LAI、地上生物量和土壤含水率同化值与实测单产的相关性,并应用熵值的组合预测方法确定不同状态变量影响籽粒产量的权重,进而生成综合性指数,并分析其与实测单产的相关性。结果表明,LAI、地上生物量和土壤含水率同化值和田间实测值间的均方根误差(Root mean square error,RMSE)以及平均相对误差(Mean relative error,MRE)均低于这些变量模拟值和实测值间的RMSE和MRE,说明数据同化方法提高了时间序列LAI、地上生物量和土壤含水率的模拟精度。基于不同状态变量的权重生成的综合性指数与实测单产间的相关性大于单个变量与实测单产间的相关性;基于综合性指数构建小麦单产估测模型,其估产精度(R2=0.78,RMSE为330 kg/hm2)分别比基于LAI、地上生物量和土壤含水率建立模型的估产精度显著提高,表明构建的综合性指数充分结合了不同变量在作物估产方面的优势,可用于高精度的冬小麦单产估测。 相似文献
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【目的】确定大田黄瓜最适宜的灌溉频率和灌水量。【方法】试验于2018年在华北水利水电大学农业高效用水试验场进行,以20cm标准蒸发皿的累积蒸发量(E20)作为灌水依据,灌溉处理分为2个灌溉间隔(I1:3d;I2:6d)和3种水面蒸发系数(K1:0.5;K2:0.7;K3:0.9),共6个处理,对黄瓜耗水特性、产量构成和水分利用效率进行了分析。【结果】黄瓜整个生育期耗水量在380~570mm之间波动,黄瓜的产量在18.2~46.1t/hm2之间波动。从不同灌水频率组合来看,I2K3处理的产量最高,其中,K3处理的早期产量最高,而I1与I2处理的水分利用效率无明显差异。果实数与灌水量之间、耗水量与产量之间均呈正线性相关关系。【结论】建议对于田间黄瓜栽培,灌溉间隔设置为6d,蒸发皿系数选择0.9为宜。 相似文献
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Because of the spatial and temporal variabilities of the advance infiltration process, furrow irrigation investigations should not be limited to a single furrow irrigation event when using a modelling approach. The paper deals with the development and application of simulation of furrow irrigation practices (SOFIP), a model used to analyse furrow irrigation practices that take into account spatial and temporal variabilities of the advance infiltration process. SOFIP can be used to compare alternative furrow irrigation management strategies and find options that mitigate local deep-percolation risks while ensuring a crop yield level that is acceptable to the farmer. The model is comprised of three distinct modelling elements. The first element is RAIEOPT, a hydraulic model that predicts the advance infiltration process. Infiltration prediction in RAIEOPT depends on a soil moisture deficit parameter. PILOTE, a crop model, which is designed to simulate soil water balance and predict yield values, updates the soil moisture parameter. This parameter is an input of a parameter generator (PG), the third model component, which in turn provides RAIEOPT with the data required to simulate irrigation at the scale of an N-furrow set. The study of sources of variability and their impact on irrigation advance, based on field observations, allowed us to build a robust PG. Model applications show that irrigation practices must account for inter-furrow advance variability when optimising furrow irrigation systems. The impact of advance variability on deep percolation and crop yield losses depends on both climatic conditions and irrigation practices. 相似文献
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为了开展大范围的冬小麦干旱预警,以中国北方冬小麦区为实例,构建了土壤水分动态预报模型,结合未来10 d高精度天气要素预报、土壤自动水分观测和冬小麦发育期观测数据,建立了北方冬小麦区干旱预警系统。利用该系统对2018年4—5月进行逐日的冬小麦干旱预警,对干旱预警产品的分析表明:系统对未来10 d土壤相对湿度预报的决定系数在0. 63～0. 91之间,均方根误差在5. 6%～18. 2%之间,预报时效越近,准确率越高。从不同的干旱等级预测准确率看,对于干旱等级较高的重旱和特旱预报准确率较高,轻旱和中旱的预报准确率略低。该系统基本满足冬小麦干旱预警需求,对国家级农业气象部门大范围农业干旱监测和预警业务是有益的补充。 相似文献
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为评估农业机械作业对大豆产量的影响，本文开展不同机型、不同压实次数的拖拉机压实试验，获取不同压实环境中的土壤物理性质和大豆产量数据，分别从影响大豆产量的机械因素、土壤因素和复合因素出发，使用多元线性回归(Multiple linear regression, MLR)、随机森林(Random forest, RF)、自适应增强模型(Adaptive boosting, AdaBoost)、人工神经网络(Artificial neural network, ANN)4种机器学习算法建立大豆产量影响预测模型，对模型性能及模型特征重要性进行综合分析。研究结果表明，机械作业与大豆产量间关系复杂，集成学习算法(AdaBoost和RF)所建立的模型具有更好的拟合效果，模型决定系数更高；利用复合因素对大豆产量建立的模型拟合度最高，其次为机械因素和土壤因素，其中基于AdaBoost的复合因素对大豆产量影响模型其拟合程度最优，其R2为0.92,MAE为1.33%,RMSE为1.86%;机械因素、土壤因素都会影响大豆产量，其中机械压实次数以及表层和亚表层的土壤坚实度为影响大豆产量的重... 相似文献
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土壤墒情是精细农业发展的关键,传统的土壤墒情监测手段落后,仅仅依靠手持设备进行人工采集,需要耗费大量的人力物力,且墒情信息获取缺乏实时性和全面性,对农田灌溉工作和农作物的生长造成了较大的影响。为此,引入了云计算技术,构建了基于云计算平台的农田土壤墒情信息系统,通过对土壤墒情信息系统的功能需求分析,完成了信息系统总体架构的设计,并对土壤墒情信息处理流程进行了优化分析。研究结果表明:基于云计算平台的农田土壤墒情信息系统能够保证墒情信息获取的实时性、有效性,同时墒情信息采集全面,数据共享及时,对实现精细农业具有主要意义。 相似文献
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Summary The effect of soil moisture regimes on the grain and straw yield, consumptive water use (Cu) and its relation with evaporation from free water surface (Eo), water use efficiency and soil moisture extraction pattern of lentil was studied in a field experiment conducted at the Indian Agricultural Research Institute, New Delhi during the fall-spring season of the crop years 1979–1980 and 1980–1981. The grain and straw yield, consumptive water use rate, Cu/Eo ratio and water use efficiency increased with an increase in irrigation frequency. Consumptive water use rate increased as the crop season advanced and reached its peak value during flowering and grain filling stage. The Cu/Eo ratio attained its minimum values 35 and 105 days after sowing at branching and grain filling stages. Depletion of soil moisture was most from the top 0–30 cm soil layer followed by 30–60 cm soil layer and was least from 90–120 cm soil layer. The pattern of soil moisture depletion was also influenced by soil moisture regime. During the vegetative and flowering stage the percent contribution from the top 0–30 cm soil layer decreased and that from the lower soil layers (30–60, 60–90, and 90–120 cm) increased with an increase in the soil moisture tension, however, the actual amount of moisture depleted from all the soil layers was always higher under low soil moisture tension regime than under high soil moisture tension regime. During the grain development stage the soil moisture treatment had no significant effect on the relative contribution from different soil layers under low and high soil moisture tension as the crop was irrigated at the same time under both these treatments. However, with no irrigation, the percent contribution from top soil layer continued to decrease, and from lower soil layers continued to increase, as the crop advanced from flowering stage to grain development stage. 相似文献
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绿州灌区麦田节水高产适宜土壤水分指标研究 总被引：2，自引：0，他引：2
土壤水分适宜指标是节水高产栽培的基础。本文采用二次回归旋转设计和回归分析方法,研究了麦田土壤水分的变化特征及其与主要水分生理因子的相关性,认为０～６０ｃｍ 是影响春小麦生长和产量的主要层次,并与叶水势、蒸腾强度和气孔阻力之间存在极显著的相关关系。在此基础上,研究提出了产量高于１２０００ｋｇ／ｈｍ ２ 和水分生产率大于１２．４５ｋｇ／ｍ ｍ ．ｈｍ ２ 时不同生育阶段适宜土壤水分下限指标。经示范印证,具有很强的可行性 相似文献
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Water use and water use efficiency of sweet corn under different weather conditions and soil moisture regimes 总被引：1，自引：0，他引：1
Axel Garcia y Garcia Larry C. Guerra Gerrit Hoogenboom 《Agricultural Water Management》2009,96(10):1369-1376
Plant growth and development are influenced by weather conditions that also affect water use (WU) and water use efficiency (WUE) and ultimately, yield. The overall goal of this study was to determine the impact of weather and soil moisture conditions on WU and WUE of sweet corn (Zea mays L. var rugosa). An experiment consisting on three planting dates was conducted in 2006 at The University of Georgia, USA. A sweet corn genotype sh2 was planted on March 27 under irrigated and rainfed conditions and on April 10 and 25 under irrigated conditions only. Soil moisture was monitored using PR2 probes. Rainfall and irrigation were recorded with rain gauges installed in the experimental area while other weather variables were recorded with an automatic weather station located nearby. A water balance was used to obtain the crop's daily evapotranspiration (ETc). WUE was calculated as the ratio of fresh and dry matter ear yield and cumulative ETc. The potential soil moisture deficit (Dp) approach was used to determine the crop's moisture stress. Results were analyzed using a single degree freedom contrast, linear regression, and the least significant difference. WU and WUE of sweet corn were both markedly affected by the intra-seasonal weather variability and Dp. For both variables, significant (p < 0.05) differences were found between planting dates under irrigated conditions and between the irrigated and rainfed treatments. WU was as high as 268 mm for the April 10 planting date under irrigated conditions and as low as 122 mm for the March 27 planting date under rainfed conditions. The maximum soil moisture deficit was reached at the milky kernel stage and was as high as 343 mm for the March 27 planting date under rainfed conditions and as low as 260 mm for the April 10 planting date under irrigated conditions. Further work should focus on the impact of the intra-seasonal weather variability and soil moisture conditions during different crop stages to determine critical periods that affect yield. 相似文献
20.
土壤水流动系统及其应用初探 总被引：6，自引：1，他引：5
靳孟贵 《中国农村水利水电》1998,(5):7-10
土壤水流动系统是由水势场，介质场，水化学学场，温度场耦合而成，并在时空四维上不断演变化的动态系统，土壤水调控就是通过综合措施改善水流动系统的上下边界年及浅部介质特性，优化田间微水文系统、微气候系统及土壤水流动系统。 相似文献