共查询到20条相似文献，搜索用时 375 毫秒
1.
《Agricultural Water Management》2005,75(3):194-225
Agriculture is the main non-point polluter of groundwater in irrigated areas as fertilizers and other agrochemicals are the main contaminants in the water that drains out of the root zone to recharge the aquifer. Nitrates from fertilizers, dissolved in percolation losses from rice fields, are the source of pollution considered. The concentration of nitrates in the percolated water depends on the distributed field water and nitrogen balances over the area. Its concentration in the groundwater depends on the total recharge, pollution loading, groundwater flow and solute transport within the aquifer. The development and application of a GIS based decision support framework that integrates field scale models of these processes for assessment of non-point-source pollution of groundwater in canal irrigation project areas is presented. The GIS is used for representing the spatial variations in input data over the area and map the output of the recharge and nitrogen balance models. The latter are used to provide the spatially distributed recharge and pollutant load inputs to the distributed groundwater flow and transport models, respectively. Alternate strategies for water and fertilizer use can be evaluated using this framework to ensure long-term sustainability of productive agriculture in large irrigation projects. The development and application of the framework is illustrated by taking a case study of a large canal irrigation system in India. 相似文献
2.
Optimal decision schemes for agricultural water quality management planning with imprecise objective 总被引：1，自引：0，他引：1
Agricultural activities are the main sources of water pollution to surface water and groundwater in rural areas. Extensive soil disturbance and application of fertilizer and manure in agriculture cause nonpoint source losses of soil and nutrients such as nitrogen and phosphorus. How to generate preferred decision schemes for agricultural activities that cause such nonpoint source water pollution is a critical issue for the decision makers. In this study, an inexact agricultural water quality management (IAWQM) model is developed and applied to a case study to generate optimal decision schemes for integrated water quality management within an agricultural system. The model is based on a hybrid fuzzy possibilistic robust programming approach, which improves upon the existing fuzzy possibilistic programming and fuzzy robust programming methods by allowing fuzzy information in the model's objective and constraints to be directly communicated into the optimization processes and resulting solutions. Optimal decision schemes for agricultural activities can be generated, including cropping area, manure/fertilizer applied, and livestock husbandry size, where implications of water quality/quantity restrictions for achieving regional economic development objectives are studied. The results of the case study indicate that useful information can be obtained through the proposed IAWQM model for providing feasible decision schemes, which reflect tradeoffs between economic and environmental considerations. The decision variables are useful for the decision makers to justify and/or adjust the decision schemes for agricultural activities through incorporation of their implicit knowledge on water quality management. 相似文献
3.
One challenge in predictive modelling of productivity for pastures varying in topography, soils or management is to achieve the prediction over space with acceptable accuracy. As a new modelling approach, the decision tree has been shown to have high predictive accuracy; while geographical information systems (GISs), with their strong ability to deal with spatial factors, have been widely used in environmental modelling. Integration of a decision tree approach with a GIS offers a potential solution in meeting this challenge. In this study, decision tree models were developed for annual and seasonal pasture productivity (aboveground dry matter in kg/ha) using environmental and management variables and the outputs of these decision trees were integrated with a GIS to get predictions of pasture productivity in a hill-pasture grazing system. Results showed that the decision tree model for annual pasture productivity adequately predicted 91% of cases in the model validation, and the GIS-based prediction for annual pasture productivity was verified in three of four test farmlets. The decision tree models also revealed the relative importance of environmental and management variables and their interaction in influencing pasture productivity. Hill slope, soil Olsen P and annual P fertiliser input were the most significant variables influencing annual pasture productivity, while hill slope, annual P fertiliser input, autumn rainfall and soil Olsen P were the most significant variables influencing spring, summer, autumn and winter pasture productivity, respectively. The successful integration of the decision tree model with a GIS in this study provided a platform to predict pasture productivity for pastures with heterogeneous environmental variables and management features, and to present model predictions over space for further application and investigation. This modelling approach can be used as, or incorporated in, decision support systems to improve pasture management, and to investigate the interrelationship between pasture productivity and environmental and management variables. 相似文献
4.
Using EPIC model to manage irrigated cotton and maize 总被引：1，自引：0，他引：1
Simulation models are becoming of interest as a decision support system for management and assessment of crop water use and of crop production. The Environmental Policy Integrated Climate (EPIC) model was used to evaluate its application as a decision support tool for irrigation management of cotton and maize under South Texas conditions. Simulation of the model was performed to determine crop yield, crop water use, and the relationships between the yield and crop water use parameters such as crop evapotranspiration (ETc) and water use efficiency (WUE). We measured actual ETc using a weighing lysimeter and crop yields by field sampling, and then calibrated the model. The measured variables were compared with simulated variables using EPIC. Simulated ETc agreed with the lysimeter, in general, but some simulated ETc were biased compared with measured ETc. EPIC also simulated the variability in crop yields at different irrigation regimes. Furthermore, EPIC was used to simulate yield responses at various irrigation regimes with farm fields’ data. Maize required ∼700 mm of water input and ∼650 mm of ETc to achieve a maximum yield of 8.5 Mg ha−1 while cotton required between 700 and 900 mm of water input and between 650 and 750 mm of ETc to achieve a maximum yield of 2.0-2.5 Mg ha−1. The simulation results demonstrate that the EPIC model can be used as a decision support tool for the crops under full and deficit irrigation conditions in South Texas. EPIC appears to be effective in making long-term and pre-season decisions for irrigation management of crops, while reference ET and phenologically based crop coefficients can be used for in-season irrigation management. 相似文献
5.
This paper presents results from an analysis of the economic potential for soil carbon sequestration in the Nioro region of Senegal’s Peanut Basin. This analysis was based on the linkage of site-specific biophysical models and economic simulation models using the Tradeoff Analysis System to simulate farmers’ participation in contracts to sequester soil carbon. Available soils and climate data were used to implement the DSSAT/Century models to estimate crop yields and changes in soil carbon stocks under nine scenarios of increased fertilizer use and increased incorporation of crop residues in a peanut-millet rotation. Data from the 2001 farm survey conducted by the Ecole Nationale d’Economie Appliquée were used to parameterize a spatially explicit econometric-process simulation model for the peanut-millet production system. The economic simulation model was used to simulate a carbon-payment scheme that requires farmers to apply higher fertilizer rates and incorporate some crop residues into the soil. The results show that the combination of increased fertilizer use and crop residue incorporation could result in the supply of marketable quantities of carbon that could be sequestered in the soils of the Nioro region. However, the sensitivity of results to the levels of labor costs of incorporating crop residues, the value of crop residues, and the transaction costs of implementing carbon payment schemes, suggests the need for better data on these variables and for an accurate assessment of the capabilities of local institutions to implement carbon contracts. 相似文献
6.
基于BP神经网络的粮食产量与化肥用量相关性研究 总被引：3，自引：0，他引：3
针对太湖流域化肥用量和粮食产量数据,利用BP神经网络算法,建立了粮食产量与化肥用量之间的关系模型,以指导化肥减施增效。共收集了1980—2014年共35a太湖流域16个县市每个县市的单位面积化肥用量和单位面积粮食产量数据。通过自回归滑动平均模型（ARMA）,对两类数据进行时间序列分析,对数据中存在的缺项进行了填补。实验表明,对于单位面积粮食产量数据,用ARMA(2,6)模型能够达到较佳的填补效果,均方误差小于0.2,R2＞0.85。对于单位面积化肥用量数据,用ARMA(3,7)模型较优,均方误差小于0.02,R2>0.80。说明ARMA模型数据填补效果较好。将填补后的不同县的数据通过BP神经网络建立模型,描述了各县市单位面积化肥用量和粮食产量的关联关系。实验表明,该方法拟合的均方误差小于0.12,R2＞0.80,说明BP神经网络是一种准确度较高的拟合方法。通过分析各县拟合结果,表明化肥用量有阈值,化肥用量低于该阈值,粮食产量将会较快速增长,高于该阈值,粮食产量将不再增长,过多的施用化肥并不能取得高产。 相似文献
7.
《Agricultural Systems》2005,84(2):155-169
Analyses were performed to evaluate the impact of resources and technological inputs on farm production in northwestern China, including five provincial districts of Shaanxi, Gansu, Ningxia, Qinghai, and Xinjiang. The gross value of farm production using 1978 constant prices was chosen to be the dependent variable in data analysis. Input variables included the irrigation ratio, farm labour, fertilizer application, and farm machinery. Multivariate statistical analysis (correlation and regression) was used to characterize the relationships between the gross value of farm production and various input variables. The gross value of farm production in the region increased fivefold during the study period, and was strongly associated with resource use and technological inputs. The gross value of farm production was significantly correlated with the irrigation ratio in Shaanxi, Gansu, and Ningxia, where the irrigation ratio was relatively low compared with the national averages. The increase in irrigation ratio in these provincial districts explained 9–19% of the growth in farm output from 1978 to 1998. Technological inputs of chemical fertilizer and farm machinery were significantly associated with farming output in all provincial districts. During the study period, the application of technological inputs increased two to eightfold, and contributed about 45% in the growth of farming output in the region. Farm production was also found to be significantly correlated with labour input. Results of this study indicated that water use efficiency and irrigation management need to be improved for future agricultural development, and further advances in farm mechanization and technology application are key for increasing farm production with limited water resources in this semi-arid area. 相似文献
8.
Information about soil nutrient carryover dynamics can assist cotton producers with the optimal management of potassium (K) fertilizer. Optimal K management promotes cotton plant health, may decrease input costs, and increases cotton lint yields. A dynamic programming model was developed to determine optimal K application rates and economic returns under different soil information scenarios based on cotton yield response to K fertilizer and fertilizer carryover estimates from a multi-year field trial. A Monte Carlo analysis was conducted to simulate the impact of stochastic input and lint prices and cotton yield on K management over a five-period planning horizon. Results suggest that soil test data could provide important information about K carryover potential, which may lead to more efficient fertilizer use and higher profit margins for cotton producers. 相似文献
9.
为了探明水肥配施对枸杞生长、产量和品质等方面的综合影响,以获取最适水肥配施方案,设置3个不同灌溉定额(194,254,313 mm)和3个不同N-P2O5-K2O配比施肥量(135-45-90,180-60-120,225-75-90 kg/hm2)9个组合,采用完全随机设计,利用AHP和熵权法相结合的综合评判方法对枸杞的4类一级指标和12类二级指标进行综合评判,以构建枸杞水肥配施综合评判模型.通过最小二乘法对AHP法和熵权法进行优化组合,计算综合评判权重,以自然间断法将综合评判权重进行分类,确定水肥配施方案的决策依据.以综合评判指数为因变量,以灌溉定额和总施肥量为自变量进行逐步二项式回归分析,建立回归方程,分析水肥耦合下对综合评价指数的影响,并确定在综合评价指数最大时对应的水肥配施方案.结果表明,综合评判指数随水肥施量增加呈先升高后降低的趋势,与生产实际相符;各类因素对综合评判指数的影响中,粒度、百粒重、干果产量和总糖这4个因素对枸杞生长的综合评判影响较大,占总评判指数73.3%以上.基于AHP和熵权法组合优化后得出的枸杞最优水肥方案:灌溉定额为252~278 mm(不含春冬灌),配比施肥量(N-P2O5-K2O)为197-66-131 kg/hm2~203-68-135 kg/hm2,枸杞综合效益最佳. 相似文献
10.
在传统滴灌施肥的基础上设计与之结合的磁化装置,并实现以IPC+PLC为中心的监控系统,该系统通过线圈产生可调的稳恒磁场,在外加磁场环境下使肥料与水融合,提高水肥耦合效应,在此基础上由操作人员通过上位机人机界面实现对滴灌施肥过程的全程实时监控。能够实现控制量的输入,控制过程状态变量的采集,显示和保存（时实曲线、历史曲线、数据库操作等）,数据处理结果的输出、打印及数据查询。 相似文献
11.
This paper presents a macro–micro analysis of the impact of policy reforms in China on agricultural production, input use and soil quality change for a major rice-producing area, namely Jiangxi province. This is done in three steps. First, a quantitative assessment is made of the impact of market liberalization policies on the economic environment of farm households in Jiangxi province. Econometric analyses based on provincial, national and world market data are used to explain changes in rice and fertilizer prices in Jiangxi province over time. Next, the impact of China’s recent income support policy and latest price trends on farm household choices with respect to activity choice (particularly rice and livestock) and input use (fertilizers, pesticides, manure) is assessed for two villages with different degrees of market access in north-east Jiangxi province. Two village-level general equilibrium models are used to analyse household decision-making and interactions between households within these villages. The parameters are estimated and calibrated from an extensive survey held in these villages in the year 2000. Finally, the impact of land tenure policy on farm management decisions (labour, manure and chemical input use), soil quality (available P and K and total N and C) and rice yields is analysed through an econometric analysis of plot-level data for three villages. Two-stage least squares (2SLS) is used to control for interactions with yields and for feedbacks towards input use. The paper ends with a number of suggestions for policy adjustments that would reduce the problem of natural soil compaction in the research area. 相似文献
12.
《Agricultural Systems》1998,57(1):1-11
We demonstrate the influence of optimal input cost sharing on the riskneutral tenant's input choice and income. We determine the share arrangements that generate an efficient outcome compared with the owner-operator's input choices. In an illustration with a corn-peanut rotation in Alabama, we use parametric programming to determine the tenant's optimal input cost share for corn fertilizer, a key input, while varying the output shares and cost shares of other inputs. The tenant's income above variable costs is highest when the cost share permits the level of fertilizer to reach the efficient level, at which the optimal fertilizer cost share is higher than both the output share and the cost share for other inputs. Owners and tenants may benefit from negotiating shares rather than applying simple rules setting all input cost and output shares equal. 相似文献
13.
A method of implementing a computer-based management information system is outlined. The procedure involves the derivation of tables containing recommendations to spray or to refrain from applying spray against leaf rust on barley for various combinations of conditions. The tables contain recommendations for three broad categories of farmer attitude to risk. The value of the information contained in the tables is estimated. It is concluded that such tables should be of use in situations where access to computing facilities is undersirable or non-existent, and where user input is to be minimised. 相似文献
14.
基于自动导航的小麦精准对行深施追肥机设计与试验 总被引：2，自引：0，他引：2
针对冬小麦返青期地表追施氮肥使氮素挥发导致肥料利用率低的问题,结合目前在小麦追肥过程中缺少深施氮肥作业装备的现状,进行了基于拖拉机自动导航技术实现精准对行深施氮肥的技术研究,设计了小麦精准对行精量深施追肥机。追肥机采用安装有自动导航系统的拖拉机牵引实现精准对行,以RTK-GNSS接收机测取的作业速度为基准,通过液压系统驱动排肥机构工作,双圆盘开沟器开沟深施,采用PID控制排肥轴转速与车辆行驶速度实现实时匹配,达到精量控制追肥量的目的。田间试验结果表明:设置目标追肥量为200 kg/hm2,车辆行驶速度为5 km/h时,追肥机能完成对行深施追肥作业,机具对行作业误差在±6 cm以内,追肥量偏差小于9%,可满足实际生产需求;对照撒肥机表层撒肥作业,每公顷减施氮肥25 kg左右,小麦每公顷增产486.5 kg左右。 相似文献
15.
为解决小麦断根机施肥作业过程中施肥铲施肥不精准问题，设计一种基于OpenCV的施肥铲精准对行系统。以Jetson Nano为处理器，将摄像头采集到的图像信息通过OpenCV进行处理，能够精准找到小麦垄行之间的中心坐标位置，以此来得到每个施肥层中施肥铲的相对位置，将得到的位置信息传到STM32F103C8T6再次进行处理，通过相应的控制系统进而调整分层施肥铲的位置。将摄像头所取得的像素点坐标与人工测量的实际坐标进行对比分析，结果表明，此识别方法在光照强度充足的情况下，对小麦中心坐标的识别正确率均高达90%以上，具有较好的识别效果。此识别方法为以后断根机施肥处理装置的设计提供了可靠的理论基础。 相似文献
16.
Kari Hyytiäinen Jarkko K. NiemiKauko Koikkalainen Taru PalosuoTapio Salo 《Agricultural Systems》2011,104(8):634-644
The study develops a bio-economic crop management model that internalizes the environmental cost of nitrate pollution, accounts for stochastic weather, and includes an option for split fertilization. The integrated model is designed to indicate whether a producer can benefit from applying fertilizer several times during the growing season, in response to crop needs, rather than a single time, at sowing. The model is parameterized for the cultivation of spring malting barley (Hordeum vulgare L.) in Southern Finland. The costs of negative externalities from nitrogen leaching are internalized in the landowner’s decision problem through a pollution tax. The results indicate that without a pollution tax a single application of fertilizer gauged to meet the needs of the entire season is optimal. With a tax, the benefits of split application - applying varying amounts of fertilizer at selected stages of the growing season - increase significantly. In comparison to a single application of fertilizer at sowing, split fertilization improves yields, increases the total amount of fertilizer used, and reduces nitrogen leaching. 相似文献
17.
18.
Border fertigation: field experiments and a simple model 总被引：6，自引：1，他引：6
Fertilizers are commonly dissolved in border irrigation water. However, there are no available procedures for the proper
design and management of surface fertigation. A series of experiments was conducted to determine the uniformity of fertilizer
application under varying inflow discharges and fertilizer application times in blocked-end borders. Results from the fertigation
evaluations showed that the fertilizer distribution uniformity of the low half (DULH) ranged from 2.9 to 51.6%, while water
DULH ranged from 63.5 to 96.9%. A simplified border fertigation model based on one-dimensional convection was formulated and
applied to the simulation of the experiments. The model was able to explain 43.8% of the variability in the fertilizer DULH.
Application of the model to selected case studies revealed that short-duration applications, such as those resulting from
instantaneous release of fertilizer into the irrigation stream, often produce low uniformities. This is particularly true
for early applications in blocked-end borders and for early and late applications in level basins. In both irrigation systems,
application of fertilizer at a constant rate during the entire irrigation event is frequently the best solution. In the presence
of runoff, the model can be used to find a compromise between fertilizer application uniformity and runoff losses. Finally,
if large deep percolation losses are expected, the model can identify uniform fertigation options based on late applications
of fertilizer.
Received: 8 August 1996 相似文献
19.
为实现水稻施肥知识图谱自动化构建,为后续构建水稻施肥决策系统提供基础,定义了水稻施肥体系数据结构并制作水稻施肥数据集,结合水稻施肥数据特点,添加单位标注器,并改进CASREL解码加入隐藏层,提出了基于RoBERTa-wwm编码+改进CASREL解码的信息抽取模型,同时针对编码与解码环节进行试验对比。结果表明,基于该模型的F1值达到91.86%,与对比模型相比有较为显著的提升。基于改进RoBERTa-wwm-CASREL的信息抽取模型能有效提高水稻施肥信息抽取效果,为水稻施肥知识图谱构建以及施肥决策系统提供基础。 相似文献
20.
模拟撒施肥料下的一维畦灌地表水流与溶质运移过程可为采用先进的畦灌液体施肥方式提供对比依据。该文基于湍流理论垂向流速线性与对数分布规律及不可压缩流体力学连续方程,构造沿畦长及任意垂向断面的非均布流速场和溶质浓度场,建立起撒施肥料下的一维畦灌地表水流与溶质运移模型,并利用典型畦灌施肥试验结果,检验该模型的模拟效果。结果表明,建立的模型不仅具有在撒施肥料状况下较好模拟地表水流运动和溶质浓度时间变化过程的能力,还具备较佳的水量和溶质质量守恒性,从而为评价撒施肥料下的畦灌施肥系统性能及与其它施肥方式下的畦灌施肥系统性能对比,提供了实用的数值模拟工具。 相似文献