ECONOMIC ANALYSIS OF ON-FARM SOLUTIONS TO DRAINAGE PROBLEMS IN IRRIGATED AGRICULTURE

Agricultural production in many semi-arid areas over the world is affected by poor drainage and saline conditions. Optimal agricultural management can be considerably different under these conditions than in locations where these problems do not occur. A long-run steady-state model is developed to analyse several management strategies for a farm with limited natural drainage and no access to off farm facilities. The model is applied to a representative farm in California. Under optimal management, the results suggest relatively small evaporation ponds, a reduction in water application, and little change in cropping patterns. Some drainage reuse is optimal when only variable reuse costs are considered. Returns to land and management are positive in all cases considered and benefits from a free off-farm facility are approximately $260/ha.     

A MIXED INTEGER LINEAR PROGRAMMING EVALUATION OF SALINITY AND WATERLOGGING CONTROL OPTIONS IN THE MURRAY-DARLING BASIN OF AUSTRALIA

Pollution of the River Murray by salt imposes costs on domestic and industrial users in Adelaide and to irrigators on the River Murray. Salt enters the Murray-Darling system through saline ground water aquifers and from irrigation and drainage of saline land. Irrigation and drainage generate benefits from improved agricultural productivity and impose costs through increased salt loads to the Murray-Darling system. The salinity of the River Murray can be reduced by pumping highly saline ground water into evaporation basins before it enters the River Murray. This paper presents a mixed integer linear programming model which is used to determine the mix of ground water interception schemes and land improvement schemes that minimises the net present value (over a time horizon of 30 years) of total Murray-Darling Basin costs due to salinity and waterlogging. By varying a target salinity level, the mix of works that yields various salinity targets in the River Murray at minimum cost is obtained. The sensitivity of the optimal solution to prescribed changes in costs and benefits of projects and to a longer planning horizon is examined.     

Optimal management of annual ryegrass (Lolium rigidum Gaud.) in phase rotations in the Western Australian Wheatbelt*

Lucerne (Medicago sativa L.) helps to prevent soil salinisation in the Western Australian Wheatbelt by reducing recharge to saline water tables. There is broad consensus, though, that it is not sufficiently profitable to motivate producers to plant it at the intensity at which considerable off‐site benefits would be conferred. This paper employs a multiple‐phase optimal control model to explore the value of this perennial pasture for the management of herbicide‐resistant annual ryegrass (Lolium rigidum Gaud.) in a crop–pasture rotation, given the difficulty of observing this value in practice. The availability of selective herbicides for efficient weed control is found to determine whether or not it is profitable to adopt lucerne pasture under optimal management. Herbicide resistance requires producers to employ costly, non‐selective treatments for in‐crop weed control. Thus, it motivates the adoption of perennial pasture in which cost‐effective forms of control can be implemented. Moreover, this result is robust to feasible changes in the current economic environment.     

Coping with drought with innovative pricing systems: the case of two irrigation water management companies in France

In recent years, France has been facing particularly severe drought periods especially in summer. In a country where agriculture is the largest water user, some irrigation management companies have implemented innovative pricing systems to handle this situation. The objective of this article is to analyze the impact of these new management systems on farmers’ incomes, the revenue of the management companies, and the amount of water used. To do that, we develop a methodology using a stochastic model that simulates the representative farmer's optimal behavior in a context of climatic variability. An empirical application is made with a crop growth model and data collected from the Midi‐Pyrenees region. The results show that using these specific nonlinear pricing systems allow irrigation water managers to reduce the impact of drought on production. Moreover, the type of pricing implemented depends on the characteristics and capabilities of the water company. More particularly, these pricing systems can be used to anticipate agricultural water demand in order to avoid imbalance with water availability.     

Investment in site-specific crop management under uncertainty: implications for nitrogen pollution control and environmental policy

This paper applies an option‐pricing model to analyze the impact of uncertainty about output prices and expectations of declining fixed costs on the optimal timing of investment in site‐specific crop management (SSCM). It also analyzes the extent to which the level of spatial variability in soil conditions can mitigate the value of waiting to invest in SSCM and influence the optimal timing of adoption and create a preference for custom hiring rather than owner purchase of equipment. Numerical simulations show that while the net present value (NPV) rule predicts that immediate adoption is profitable under most of the soil conditions considered here, recognition of the option value of investment indicates that it is preferable to delay investment in SSCM for at least 3 years unless average soil quality is high and the variability in soil quality and fertility is high. The use of the option value approach reveals that the value of waiting to invest in SSCM raises the cost‐share subsidy rates required to induce immediate adoption above the levels indicated by the NPV rule.     

沿海围垦区水资源优化配置与联合调度

江苏沿海围垦规模巨大,世界尚无先例。沿海滩涂开发利用,水资源保障是关键,而围垦区水资源优化配置与联合调度技术又是水资源保障关键技术之一。分析国内外水资源优化配置研究现状,研究围垦区水资源需求管理措施、盐碱环境下多水源多用户淡水资源联合调度技术以及围垦区水资源优化配置,以实现沿海围垦区水资源公平、高效和可持续利用。     

Adoption potential of nitrate mitigation practices: an ecosystem services approach

Nitrate pollution from agricultural drainage has caused water quality concerns worldwide, but there are several promising technologies to help mitigate this environmental degradation. While these practices primarily aim to improve water quality, they may also provide other ‘additive’ benefits or ecosystem services and the awareness of such benefits may influence their potential to be adopted by farmers. To investigate the impact that perceived ecosystem services has on a practice's adoption potential, we used a mixed methods approach consisting of a literature review, producer surveys, and a group discussion to explore farmer interest in and perceived benefits (on-farm and regional) of seven subsurface drainage nitrate reduction practices (controlled drainage, bioreactors, wetlands, nitrogen management rate, nitrogen management timing, cover crops, and diversified crop rotations). The nitrogen management practices were shown to be accessible and realistic options for water quality improvement as they elicited high interest and had the highest level of compatibility. However, these practices did not provide many other complementary ecosystem services. Conversely, wetlands had a high literature review-derived ecosystem service count, but were considered to have low compatibility, and survey respondents indicated less interest in this practice. The practice of cover cropping showed more moderate, yet consistently positive results for all factors.     

大型水利工程质量氛围的内涵及影响因素分析

结合Lewin场论,分析工程质量氛围与场论的相似性,对工程质量氛围的内涵进行研究,深化对质量氛围的理解。在此基础上,将影响水利工程质量氛围的因素划分为个体、环境、信息沟通3个维度,得到质量意识、质量态度、质量能力、物质环境、制度环境、管理环境、信息收集、沟通方式8个影响因素。基于DEMATEL模型,探讨了各因素之间的关系,结果表明:管理环境、制度环境和质量意识3个因素对工程建设的质量氛围影响较大;制度环境、沟通方式、质量意识3个因素对其他因素起主动影响作用。     

基于四分图模型的农民村庄整治满意度研究——以江苏丰县华山村为样本

[目的]通过分析江苏省丰县华山镇华山村村民调查数据,从道路、桥梁、水利、建筑和环保5个方面,对农民村庄整治满意度进行分析。[方法]运用四分图模型,选取江苏省丰县华山镇华山村农民的调查数据,选取乱堆乱放、农宅环境、公共绿化、路灯安装、桥梁整修、广场建设、河道疏浚、公厕整治、供水质量、外墙整修、道路整治、垃圾处理、农厕整改、污水处理等14个指标对农民村庄整治满意度进行研究。[结果]满意度评价结果与实际调查情况大体一致,农民对村庄整治总体满意,其中对河道疏浚和公厕整治项目满意度较高,对因资金缺乏引起供水质量、外墙整修和农厕整改等整治不彻底的项目评价较低;村庄整治中,农民对路灯安装和道路整治项目最为看重;其次是供水质量、桥梁整修、垃圾处理、污水处理和外墙整修等5项指标。另外,规划质量、管理机制是否健全等也一定程度影响农民满意度。[结论]建议采取多渠道筹集资金、科学制定规划方案、激发村民参与积极性和建立长效管理机制等措施提升农民村庄整治满意度。     

Farm‐specific Adjustment Costs in Dutch Pig Farming

This paper develops a dynamic model of investment under rational expectations, assuming farm‐specific production technologies and adjustment cost structures. The model distinguishes regimes of negative, zero and positive investments and maintains that it is optimal for a farmer not to invest for a range of shadow prices, depending on thresholds for positive and negative investments. The model is applied to a rotating sample of Dutch pig farms over the period 1980–1996. Farm‐specific parameters of the adjustment cost function and production technology are obtained using Generalised Maximum Entropy estimation. Cluster analysis using the farm‐specific adjustment cost parameters indicates that five groups of farms with distinct adjustment cost structures can be identified. A tobit regression analysis is used to explain the impact of different socio‐economic factors on the size of the threshold between positive and negative investments.     

Efficient versus Sustainable Livestock Grazing in the Sahel

To date, there is no consensus on optimal stocking rates in the semi‐arid Sahel. We develop a model for livestock management based on a detailed analysis of ecosystem dynamics, and we apply it to calculate optimal and sustainable livestock stocking rates in a Sahelian rangeland. The general model accounts for stochastic rainfall and the long‐term impact of grazing on rangeland productivity. For the case study area, the model shows that the optimal stocking rate is higher than the sustainable stocking rate. Hence, with current prices, it is optimal for the pastoralist society to deplete their resource base. In our case study, we also find that the current stocking rate exceeds the optimal stocking rate, which adds to soil depletion.     

Cost and trade impacts of environmental regulations: effluent control and the New Zealand dairy sector

New Zealand legislation sets standards for water quality. Nitrogen leaching from dairy effluent compromises these standards, with the consequent move being toward land-based effluent disposal. The cost of this to the dairy sector was estimated and a Computable General Equilibrium (CGE) model (GTAP) was used to investigate the impact of additional production costs on NZ's dairy export trade. Two scenarios were analysed: first, NZ acts unilaterally in imposing water quality regulations, second, the other principal dairy exporters act in a similar fashion. Changes in trade patterns vary from insignificant to large, depending on the scenario analysed.     

Cost-effectiveness of alternative green payment policies for conservation technology adoption with heterogeneous land quality

This paper quantitatively analyses the cost‐effectiveness of alternative green payment policies designed to achieve a targeted level of pollution control by heterogeneous microunits. These green payment policies include cost‐share subsidies that share the fixed costs of adoption of a conservation technology and/or input reduction subsidies to reduce the use of a polluting input. The paper shows that unlike a pollution tax that achieves abatement through three mechanisms, a negative extensive margin effect, a negative intensive margin effect and a technology switching effect, a cost‐share subsidy and an input reduction subsidy are much more restricted in the types of incentives they provide for conservation of polluting inputs and adoption of a conservation technology to control pollution. Moreover, they may lead to varying levels of expansion of land under production. Costs of abatement with alternative policies and implications for production and government payments are compared using a simulation model for controlling drainage from irrigated cotton production in California, with drip irrigation as a conservation technology.     

Nonfarm employment,agricultural intensification,and productivity change: empirical findings from Uganda

This article uses panel data from the Living Standards Measurement Study‐Integrated Surveys on Agriculture for Uganda to assess the farm‐level effects of nonfarm employment on agricultural intensification and productivity change. A sample selection model is used to account for both unobserved heterogeneity and potential simultaneity between agricultural production and nonfarm income. Results show that nonfarm employment can have differential impacts on farm technology intensity and productivity. Nonfarm income is found to have a positive impact on farm hired labor and improved seed intensity; a negative effect on on‐farm family labor use; and no significant impact on fertilizer, soil water management, and joint use of farm technologies. The econometric evidence also indicates that agricultural productivity declines as nonfarm income increases. Taken together, our findings reveal important trade‐offs between nonfarm employment and income and farm productivity growth under smallholder agriculture. The results indicated that targeted policies are required to reduce these potential trade‐offs between nonfarm employment and agricultural intensification and productivity change.     

Adapting the optimal selective-logging of Scots pine (Pinus sylvestris L.) stands in NE Spain to increasing CO2 concentrations

Predicted increases in CO₂ concentrations will affect forest ecosystems. In particular, they will impact tree growth, which in turn affects reproduction and mortality and consequently, forest planning. This study integrates different climate change scenarios of future biogeochemical processes and an economic model into a forest management model to determine the optimal selective-logging regime of Scots pine stands. It analyzes the economic implications of the management changes in comparison with the business as usual strategy. Adaption to new climatic conditions shows that it is optimal to increase the number of standing trees and to reduce the age of the logged trees. The results suggest that the failure to adapt the management regime has clear implications on the profitability of forests. Moreover, they show that higher mortality is likely to have a significant impact on the optimal forest management regime.     

Land use scenario development as a tool for watershed management within the Rio Mannu Basin

The Rio Mannu River Basin (Sardinia, Italy) is undergoing a process of agricultural intensification. Like many Mediterranean areas, this basin is characterized by water shortages and diffuse pollution from agricultural sources. Hence the objective of this study was to develop possible land use and land management scenarios that could constitute an alternative to the current watershed management. Several land use and land management scenarios were formulated and analyzed with local stakeholders, and two were selected and simulated as realistic in consideration of the socio-economical aspects of the study area. Scenario 1 involves agricultural practices that include a reduction in fertilizer use to meet the Water Framework Directive requirements for “good” status of water bodies. Scenario 2 introduces rapeseed cultivation, replacing durum wheat in a small area, to investigate the impact of biofuel plant cultivation on water quality. Each option was assessed by considering the effects on water quality, crop yields and economic benefits. The Soil and Water Assessment Tool (SWAT) model was applied to simulate hydrological processes and evaluate current and future nutrient loads. This model requires adequate streamflow data for calibration and validation. However, as is the case for many Mediterranean basins, insufficient data were available. Therefore, a methodology was developed and tested to calibrate hydrological processes based on the transposition of a parameter set from a gauged catchment located in the same region. This study suggests that a sound use of fertilizers could substantially reduce the amount of nutrients flowing into surface waters, although the effects of such a policy on crop yield and farm income would be negative in some cases. Moreover, the results clearly predict that the replacement of durum wheat with rapeseed (a biofuel crop), could offer a margin of profit, but would have a negative impact on water quality due to increased nutrient losses. Consequently, this option is unsuitable for this area. Furthermore, it can be inferred from these results that the promotion of the use of energy from renewable sources may have a negative impact on the objectives of the EU Water Framework Directive. Clearly, this process needs to be regulated, taking into account environmental and socio-economical aspects.     

The welfare costs of urban outdoor water restrictions

Outdoor water restrictions are usually implemented as bans on a particular type of watering technology (sprinklers), which allow households to substitute for labour-intensive (hand-held) watering. This paper presents a household production model approach to analysing the impact of sprinkler restrictions on consumer welfare and their efficacy as a demand management tool. Central to our empirical analysis is an experimentally derived production function which describes the relationship between irrigation and lawn quality. We demonstrate that for a typical consumer complete sprinkler bans may be little more effective than milder restrictions policies, but are substantially more costly to the household.     

The impact of water price uncertainty on the adoption of precision irrigation systems

We examine whether a firm is more or less likely to adopt precision technology when input prices are stochastic. The results are important to determining whether programs and contracts that reduce input price uncertainty may deter the adoption of conservation practices. An economic model of the technology adoption decision shows that the net effect of input price risk is ambiguous and depends on several factors including the shutdown effect, the mean price effect, the precision expansion effect, and the risk aversion effect. An empirical implementation of the model relies on data on water price and irrigation technology adoption observed in a California irrigation district over the period 1999–2002. The results show that a stable input price increases the adoption of precision technology, but the impact depends on crop choice and land quality characteristics.     

Drinking water and off‐farm labour supply: between‐gender and within‐gender bias

In this paper, we use the China Health and Nutrition Survey (CHNS) panel data to analyse the impact of drinking water on off‐farm labour supply. A two‐stage least squares (2SLS) multivariate Tobit regression model with random effects was applied. We find that impacts of drinking water conditions on off‐farm labour supply may be greater for women than men but depends on the specific family role or family structure. A strong within‐gender effect exists in households. For example, daughters are not sensitive to water access nor water quality, but householder's spouses are sensitive to water access, and daughters‐in‐law are sensitive to water quality. Our findings suggest that infrastructure development in improved access to safe water has contributed positively to reductions in traditional gender biases, evening the playing field between daughters, daughters‐in‐law, mothers and mothers‐in‐law. We also find that water the infrastructure program may actually encourage off‐farm labour mobility, reducing the supply of agricultural labour and the share of household labour on the farm. Thus, a broader approach to water policy should also include public investment in achieving greater labour efficiency and productivity.     

Cost‐effective regulation of nonpoint emissions from pastoral agriculture: a stochastic analysis

Nutrient emissions from pastoral agriculture are a global cause of declining water quality. Their management is complicated through variability arising from climate and soil influences. This paper compares the implications of input‐based policies and direct restrictions on leaching to achieve 10 and 20 per cent reductions in nitrogen (N) load, in the context of pasture‐based New Zealand dairy farms. The most important mitigation practices on these farms are de‐intensification (involving reductions in N fertiliser application and stocking rate) and the application of nitrification inhibitors. A stylised conceptual model, incorporating both sources of variability, is used to identify the implications of alternative policies. Direct restriction of estimated N leaching is the most cost‐effective policy to reduce N leaching by 10 and 20 per cent. These results indicate the general insufficiency of input‐based mechanisms for water quality improvement, given the low correlation between input use and leaching, possible substitution with unrestricted inputs and their failure to motivate the use of mitigation strategies. Additionally, model output indicates that inherent variability in water quality, mainly due to climate influences, can dominate the benefits of regulatory action in any given year.