Estimating the demand for irrigation water in a humid climate: A case study from the southeastern United States

The southeastern United States typically receives more than 130 cm of precipitation per year. In this region, as in others around the world, irrigation is used as a supplement to rainfall. Over the past thirty years the number of hectares under irrigation in the region has grown considerably, as has population. Policy makers are currently searching for effective tools to address water demand. This study tests the effect of water costs, crop prices and technology on the multiple crop production decision using supplemental irrigation. Results for Georgia row crop producers indicate water demand is modestly affected by water price (with elasticities between −0.01 and −0.17), but more so by crop price (with elasticities between 0.5 and 0.82). Results also suggest adoption of lower pressure irrigation systems does not necessarily lead to lower water application rates on corn, cotton, peanuts, and soybeans.     

The cultivation-cattle complex in Western Darfur

The agricultural/livestock system of a 40,000 km² area in western Sudan is described. Details of the three main components—traditional rainfed agriculture, small-scale irrigation and animal husbandry—are given. Data on crop yields and livestock production at both the unit level and the system level are provided. Millet is the main cereal crop overall but sorghum occupies an important place in the intensively cultivated alluvial zones. Cash crops, including groundnuts, chillies and okra for drying, are of some importance. Onions are the main winter irrigated crop while mangoes and citrus are important tree crops. The livestock sector is dominated by cattle which account for more than 75% of the livestock units present. Gross output of the area at 1976 prices was calculated at £Sud 14·8 to £Sud 16·2 million (US$ 41·4 to US$ 45·4 million) equivalent to £Sud 41·7 to £Sud 45·6 per head of population and £Sud 3·70 to £Sud 4·05 per hectare. Of these totals between 33 and 36% could be attributed to livestock production.     

大豆振兴背景下吉林省大豆供给反应研究——基于Nerlove模型的实证分析

大豆振兴背景下,大豆成为吉林省农业结构调整的关键作物。本文利用1985—2019年吉林省大豆相关数据,通过建立Nerlove模型对大豆供给反应进行分析,得出吉林省大豆短期供给价格弹性为0.23,而长期供给价格弹性为0.39,表明大豆供给对价格反应较为迟缓,缺乏弹性。测得预期价格调整系数为0.72,调整时滞为1.39,表明大豆种植户在调整种植面积行为上的滞后期约为1年。通过对吉林省大豆供给反应影响因素分析发现滞后一期的大豆播种面积、大豆市场价格、大豆与玉米单位面积收益比和大豆相关政策都对当期大豆播种面积有显著影响。基于此本文剖析了各影响因素的作用机理,提出深化农业供给侧结构性改革、完善米豆轮作制度和大豆生产者补贴政策,稳定价格、改善大豆与玉米的比价关系,提高大豆种植收益等建议,以鼓励吉林省农户大豆种植积极性,保障大豆良性供给。     

Gains from crop diversification in the Sudan Gezira scheme

Land allocation in Gezira irrigation scheme (the Gezira) has, for the most part, been based on the political judgement of the government rather than economic criteria. This paper determined optimum crop combinations for the Gezira using the mean-variance (M-V) model. This large-scale gravity-irrigated project which was started for export cotton cultivation on 27,372 feddan (11,496 ha) in 1927 has now expanded to over two million feddan, and has a multi crop production system. Sources of production uncertainty include government control of prices, often announced after planting, and crop area in favor of cotton. Diversification was analyzed under various levels of risk using, in contrast to what is in the reviewed literature, both cross sectional and time series farm level data. The cross-sectional data comprised of net farm returns of 100 farmers for the 1987/1988 season, and the time series data were average net farm returns from the same area from 1971 to 1988. Cropping decisions in the Gezira are mostly based on cross-sectional data from a sample of tenants in the preceding season. This paper estimated variance and covariance parameters of observed net margins of both sets of data and found significant differences in the results. The certainty equivalence results used to evaluate crop diversification showed that current policies of controlling crop acreage lead to inefficient land use; and that farmers diversify into wheat and groundnuts out of cotton when cross-section data were used; and from groundnuts to cotton and wheat when time series data were used.     

An agronomic, economic and behavioral analysis of N application to cotton and wheat in post-Soviet Uzbekistan

Cotton and winter wheat play a vital role in Uzbek agriculture: the first crop is a vital component of the national export revenues, while the latter is key in achieving independence from grain imports. Due to these strategic roles in the national economy, both crops are part of the state procurement system and, hence, are subject to strict regulations imposed to ensure budget revenues and self-sufficiency. However, many factors cause the divergence of crop yields from their technically maximum levels. We analyzed those factors, which hamper achieving the optimum response to fertilizer applications. In a stepwise procedure, we (i) reviewed the technical and financial optimum yield responses of cotton and winter wheat production to fertilizer applications and (ii) analyzed the changes of fertilizer-to-product price ratios to shed light on the agronomic and economic performance of cotton and wheat in the post-Soviet agricultural system of Uzbekistan. The analysis combined data from long-term, historical yield and fertilizer responses, agronomic N-fertilizer response experiments, and socio-economic farm surveys. Quadratic yield-response functions were used to derive economic and technical optimum rates of N-fertilizer applications. Based on the parameterized function and fertilizer-to-product price ratios observed for 1996-2003, we analyzed the difference between recommended fertilization and economic optimum application rates. Results showed that under the state procurement system, Uzbek farmers may not necessarily tend to maximize the profits from their cotton and wheat production. The level of subsidies and the differential crop support by the state induce farmers to follow the official fertilizer recommendations to ensure that they fulfill the production targets even if it implies higher production costs. The present gaps between the officially recorded yields and those technically achievable given the agro-ecological conditions in Uzbekistan cannot be narrowed by only improving N-fertilizer management. It would require additional efforts to improve cotton and wheat yields.     

Deficit irrigation in a production setting: canopy temperature as an adjunct to ET estimates

Water available for agricultural use is declining worldwide as a result of both declining water resources and increasing application costs. Managing crop irrigation under conditions where the water need cannot be fully met represents the future of irrigation in many areas. On the southern high plains of Texas there is interest among producers to reduce the amount of water applied to cotton. In this study, a producer’s efforts to reduce water application to a cotton crop were assessed in terms of a comparison between evapotranspiration, rainfall, and irrigation that is widely used in the region. The producer was able to reduce water application to meet intended reductions relative to the evapotranspiration estimates but, depending on the method used for calculating the crop water need, he tended to over water the crop in two out of three intended deficit irrigation regimes. Analysis of continuously monitored canopy temperatures provided verification of over-irrigation. Continuously monitored canopy temperature is proposed as a useful adjunct to evapotranspiration approaches to deficit irrigation management.     

Effect of changing energy prices on commodity prices and farm income

Tatonnement programming is used to examine the effect of energy prices on commodity prices and farm income. This method uses a national interregional linear programming model in conjunction with demand equations for feedgrains, soybeans and wheat. This spatial programming model is solved iteratively with these demand functions using an algorithm based upon the Walrasian tatonnement process. While the model is static in nature, it indicates that once adjustment to a doubling of energy prices occurs returns to land will increase by 10·8%. Commodity prices will increase 24·1, 18·7 and 9·9% for feedgrains, wheat and soybean, respectively, and demand will decrease 2·2, 1·9, and 0·9% for these same three commodities.     

Conserving water in arid regions: Exploring the economic feasibility of alternative crops

Urban expansion in western arid regions has increased competition for available water supplies, encouraging more efficient agricultural water use. The implementation of alternative low water-use crops is one option for producers, but is it economically feasible? This study uses the EPIC model to model yields to alternative crop production under differing irrigation levels. Risk analysis, or the distribution of returns, to alternative crop production is examined through the use of SIMETAR. Data on current and alternative crops for this study include cost and return studies, producer interviews, and field trials in Northwest Nevada. Study results show that there are alternative crops that could be feasibly substituted for alfalfa or used as a diversification strategy, while reducing water use by at least one-half.     

United States demand for hardwood plywood imports: A distributed lag model

A theoretical model of the United States demand for hardwood plywood imports was developed. Demand derives from activity in the construction industry where costs are minimised subject to a generalised Cobb-Douglas technology. This static model was then modified to reflect dynamic adjustments of imports to prices and housing starts. The resulting model was estimated with monthly data for the period January, 1974 to December, 1979. The choice of either c.i.f., f.a.s. or customs data did not significantly affect the statistical results. No significant substitution was apparent between imported hardwood plywood and domestic hardwood or softwood plywood. Import data appeared to be explained by expectations on housing starts and relative prices. Importers' expectations were represented by Cagan's adaptive expectations model and by Almon's polynomial lag equation. The latter model, relating imports to (i) housing starts and (ii) import prices, gave significantly better results. The maximum lag was of 9 months, with a mean lag of 4·5 months. The long-term elasticity of imports with respect to housing starts was estimated at 1·10 (±0·12). The long-term elasticity with respect to real price was ?1·98 (±0·24), using the price of all commodities as the deflator.     

Potassium carryover dynamics and optimal application policies in cotton production

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.     

Optimizing supplemental irrigation: Tradeoffs between profitability and sustainability

Water production functions are used to model yield response to various levels of supplemental irrigation (SI), to assess water productivity coefficients, and to identify optimum irrigation under various input-output price scenarios. The SI production function is taken as the difference between the total water production function (irrigation + rain) and that of rainwater. Theoretical analysis of the unconstrained objective function shows that the seasonal depth of SI to maximize profit occurs when the marginal product of water equals the ratio of unit water cost to unit product sale price. Applying this analysis to wheat in northern Syria, the production functions of SI under different rainfall conditions are developed. Coupled with current and projected water costs and wheat sale prices, the functions are used to develop an easy-to-use chart for determining seasonal irrigation rates to maximize profit under a range of seasonal rainfall amounts.Results show that, for a given seasonal rainfall, there is a critical value for the ratio of irrigation cost to production price beyond which SI becomes less profitable than rainfed production. Higher product prices and lower irrigation costs encourage the use of more water. Policies supporting high wheat prices and low irrigation costs encourage maximizing yields but with low water productivity. The resulting farmer practice threatens the sustainability of water resources. Balancing profitability versus sustainability is a challenge for policy makers. Our analysis can help national and local water authorities and policy makers determine appropriate policies for water valuation and allocation; and assist extension services and farmers in planning irrigation infrastructure and farm water management.     

Evapotranspiration and water use of full and deficit irrigated cotton in the Mediterranean environment in northern Syria

Cotton (Gossypium hirsutum L.) is the most important industrial and summer cash crop in Syria and many other countries in the arid areas but there are concerns about future production levels, given the high water requirements and the decline in water availability. Most farmers in Syria aim to maximize yield per unit of land regardless of the quantity of water applied. Water losses can be reduced and water productivity (yield per unit of water consumed) improved by applying deficit irrigation, but this requires a better understanding of crop response to various levels of water stress. This paper presents results from a 3-year study (2004-2006) conducted in northern Syria to quantify cotton yield response to different levels of water and fertilizer. The experiment included four irrigation levels and three levels of nitrogen (N) fertilizer under drip irrigation. The overall mean cotton (lint plus seed, or lintseed) yield was 2502 kg ha⁻¹, ranging from 1520 kg ha⁻¹ under 40% irrigation to 3460 kg ha⁻¹ under 100% irrigation. Mean water productivity (WP_ET) was 0.36 kg lintseed per m³ of crop actual evapotranspiration (ET_c), ranging from 0.32 kg m⁻³ under 40% irrigation to 0.39 kg m⁻³ under the 100% treatment. Results suggest that deficit irrigation does not improve biological water productivity of drip-irrigated cotton. Water and fertilizer levels (especially the former) have significant effects on yield, crop growth and WP_ET. Water, but not N level, has a highly significant effect on crop ET_c. The study provides production functions relating cotton yield to ET_c as well as soil water content at planting. These functions are useful for irrigation optimization and for forecasting the impact of water rationing and drought on regional water budgets and agricultural economies. The WP_ET values obtained in this study compare well with those reported from the southwestern USA, Argentina and other developed cotton producing regions. Most importantly, these WP_ET values are double the current values in Syria, suggesting that improved irrigation water and system management can improve WP_ET, and thus enhance conservation and sustainability in this water-scarce region.     

Profitability analysis of a farming system in Africa

This analysis questions the assumptions that in a traditional farming system food production is primarily for home consumption and is not competitive with export crop (cocoa) production. Government planners and policy makers must look at the total operation of a farmer to understand the role of food crop production. In the case of Ghana in 1981 they needed to seek ways to make cocoa production relatively more profitable if the goal of increased cocoa production from small farms were to succeed.The analysis indicates why farmers were devoting scarce resources, particularly labor, to producing food crops in Ghana in 1981. Food crops were the most profitable both (1) in 1981 and (2) when the flow of income from the life of the trees was considered. Clearly, the farmers were demonstrating that they were rational economic men.In order to get an idea of what price cocoa must bring for it to be as profitable as the food crop systems, the price of cocoa was varied with all other prices held constant. The price of cocoa would have had to be approximately ¢400 per load of 30 kilograms in 1981. The government purchase price was ¢120 per load. Nor surprisingly, cocoa production in Ghana was declining steadily.     

Water status response of corn and cotton to altered irrigation

Water is a primary limiting factor to crop production and thus crop water status is essential information for management decisions. Corn and cotton were grown in the field under two constant water regimes. The low water level (WL) was 0.662PET (potential evapotranspiration) in corn and rainfall for cotton. The high water level (WH) was 1.02PET for both crops. Two transient water treatments in each crop began as the two constant water level treatments but then the water inputs were reversed and the change in water status was monitored. When the transient water treatments were initiated, corn was at the V14 and V16 growth stages in the WL and WH treatments, respectively, and cotton was 2 weeks past first bloom for both water levels. The purpose of the experiment was to compare the sensitivity of leaf water potential (LWP) and crop canopy temperature to changes in irrigation rate. The transient water treatment of each crop that relieved water stress (TLH) changed from WL to WH and the treatment which induced water stress changed from WH to WL (THL). The LWP values of the transient water treatments reversed 5 and 8 days after reversing water input rates to corn in 1998 and 1999, respectively, and after 3 days in both years for cotton. A reversal in canopy temperatures, expressed as the amount of daily time that the temperature was above 28°C (DST), was not detected between the TLH and THL treatments of corn after 25 days in 1998 or after 13 days in 1999. The DST values of the cotton transient water treatments reversed after 4 days in 1998 and 5 days in 1999, when the values of THL became greater than for TLH. Corn tassels, which apparently transpire less than leaves, were forming at the beginning of the transient water treatments and their presence in the view of the infrared thermocouples may have reduced the apparent radiometric temperature difference between the transient water treatments. During the water status adjustment period following the initiation of the transient water treatments, there were significant linear relationships between LWP and DST in cotton in both years but only in 1998 in corn. Cotton canopy temperature could be used to rapidly monitor an entire field in contrast to LWP which accurately measures plant water status but cannot provide automated measurements across a large area.     

Environmental and cost efficiency of pesticide use in transgenic and conventional cotton production

This study focuses on the quantification of pesticide use efficiency for producers of transgenic cotton versus conventional cotton in order to test for the improvement promised by the genetically engineered crop. The environmental and cost efficiency of pesticide use is assessed by means of data envelopment analysis (DEA) and the external effects of pesticide are quantified by means of the pesticide leaching potential. To account for the fact that conditions other than the ‘treatment” (seed type) are not equal in farm surveys the study employs a second step Tobit regression. The data are from a survey of cotton growers in North Carolina, USA. Differences in environmental efficiency are found to be significant between herbicide tolerant and stacked gene (herbicide tolerant and insect resistant) cotton and between stacked gene and conventional cotton. In contrast, no statistically significant differences are found for efficiency of pest control cost. In the follow-up Tobit regression, differences in production environment and in farm, farmer and field characteristics are accounted for so that the contribution of seed type to efficiency can be observed. The regression results confirm the importance of stacked gene cotton for improving the environmental efficiency of pesticide use in cotton. In contrast, seed type was not significant in explaining differences in cost efficiency among North Carolina cotton growers. The new technology reduces pesticide application but these benefits are curbed by the high price of cotton seed (technology fee).     

Producer behaviour,market structure and technology in Indian dairy industry: Some managerial implications

In a competitive agricultural commodity market, a parity can be expected between the prices of the raw materials and the prices of the final products. This paper attempts to show that such a parity does not exist between the price of liquid milk and the prices of milk fat and SNF in the forms in which they are produced in India, because the traditional milk producers do not have access to a technology that enables them to convert the SNF contained in their milk into products which have ready markets.This fact has given the modern dairy co-operatives of the rural milk producers a significant economic advantage in their competition with the traditional producers, since they have been able to give their members access to such a technology.This paper argues that the new, developing dairy co-operatives should devise their long-term strategies with a view to exploiting this economic advantage while it exists; for, in the long run, this advantage must disappear as competition among the dairy co-operatives in the markets for liquid milk and milk products increases.     

基于BILSTM的棉花价格预测建模与分析

棉花市场价格指数波动是一个非常复杂的非线性系统,具有随机波动特性,容易受到气象、金融、政策和国际环境影响。在现有研究棉花价格的数据集特征的基础上如政策、国际环境、进出口、产量等,增加气候因素对棉花价格影响的数据特征如降水、日照、湿度等,并对数据进行收集、整理及预处理。基于棉花价格的波动特性,采用双向长短期记忆网络BiLSTM(bidirectional long short-term memory, BiLSTM)模型对棉花价格进行预测,使用长短期记忆网络LSTM(Long Short Term Memory Network, LSTM)和LightGbm模型进行对比试验。由于随机梯度下降(SGD)优化器在训练的过程中产生频繁波动,较多情况下得到的是局部最优值。采用SWA(Stochastic Weight Averaging)优化算法取SGD轨迹的多点简单平均值对SGD进行优化,避免SGD在梯度下降过程中的频繁波动问题,使其模型能将Loss和损失值收敛至全局最优,进一步提高训练的稳定性。试验结果表明:BILSTM模型能够很好地对测试集价格曲线进行拟合,误差值最小,价格预测精度较高;采用SWA算法优化的LSTM和BILSTM网络结构收敛至全局最优,平均绝对误差(MAE)分别提高18%和43%。该模型能够更精确地表现棉花市场价格波动规律,帮助棉花市场从业者和投资者优化经营策略。     

Computer assisted management decisions for beef production systems

A linear programming model was developed to determine management policy for a yearly planning horizon on a typical 1320 acre (535 ha) Southern Colorado mountain ranch. Income producing activities (selling cattle and hay and leasing land) and cost activities (buying cattle, borrowing capital, feeding supplements, purchasing fertiliser and fuel, hiring labour and leasing land) were defined for three land types through four seasons.The purpose of the modelling effort was to determine the level of each activity (cow herd size, yearling herd size and area of meadow to be harvested for hay) that resulted in maximum net return for the ranch subject to resource limitation on land, labour and capital. In addition, sensitivity and shadow price analyses revealed expansion options that would be profitable during existing economic conditions.The optimal management plan, using 3 April, 1975 prices, called for grazing 199 head of 450 lb (204 kg) steers and 52 head of 530 lb (240 kg) steers. The plan also called for purchasing and spreading 42 tons (38 MT) of nitrogen and 10 tons (9 MT) of phosphorus on Land I and for growing, harvesting and selling 742 tons (674 MT) of hay. This optimal management plan produced a net return of $27,642. In addition, the optimal plan showed that hay production began replacing beef production when the price of hay was $35·48/ton (39·08/MT) and that the maximum amount of hay was produced with the price increased to $50·00/ton ($55·00/MT).     

An economic evaluation of sugar cane production under different water supply systems in Thailand

In a vegetative crop like sugar cane, soil water stress will invariably result in reduced growth and yield. Under inadequate rainfall conditions such a crop needs supplemental irrigation to maximize the yield.The present article discusses the relationship between sugar cane yield and rainfall/irrigation requirements. Special attention is given to the potential sugar cane yields and benefit/cost ratios in the Malaiman area in Thailand, under four water conveyance systems (from low- to high-density irrigation and drainage network) and under optimized rainfed cultivation.A linear relationship between cane yield and water use is applied for the prediction of potential crop yields for the various water conveyance systems. These yields are compared with the actual cane production in pilot areas with different irrigation infrastructure, which has been monitored over a period of years. Actual yields fall short of predicted in all cases. This is mainly be attributed to the low cane prices, resulting in sub-optimal cultivation practices by the farmers.Prediction of potential sugar cane yields for local circumstances is quite possible. At present sugar cane price levels, development of a low-density irrigation infrastructure seems to be the most economical solution.