A pasture production model for use in a whole farm simulator

Modular simulation models of crop and animal enterprises can be used in concert to simulate a particular whole farm operation and thus provide management information for individual farmers and farm advisers. This paper reports the development of a pasture module for such a whole farm simulator designed to study irrigation management in New Zealand. The model (CANPAS) describes the production of perennial ryegrass/white clover pastures under either dryland or irrigated conditions. Seasonal growth studies and the principles of ecological physiology form the theoretical base of CANPAS. Whenever possible, parts of other models were also used. With time steps of one day, CANPAS predicts the net above-ground yield of live and dead herbage, herbage digestibility, leaf area index and soil water supply. Harvested yields are also predicted for simulated grazing or cutting managements, assuming part of the above-ground yield of live and dead herbage is left as stubble. Field measurements of harvested pasture yields from the Canterbury Plains of New Zealand were used to validate the model. Validation procedure included the use of a simple set of statistical tests. The final version (CANPAS III) gave an overall r² of 0·83, but poorer performance was found under some test managements. Discussion covers the general aspects of this kind of modelling as well as the specific details of the pasture module.     

Pasture and forage crop systems for non-irrigated dairy farms in southern Australia. 1. Physical production and economic performance

The dairy industry in southern Australia relies on perennial ryegrass pasture to supply 60–70% of the diet of lactating cows. Improvements in the amount and quality of home-grown forage used for dairy cow feeding are critical for further productivity gains in the industry. A modeling approach was used to estimate the effects of changing the forage system on farm business profit. Base models (using 100% of farm area in perennial ryegrass pasture) were constructed for above-average (Top 40%) and high performing (Top 10%) farm types typical of two locations: Terang in southwest Victoria and Ellinbank in Gippsland, eastern Victoria. These models were then re-simulated using different forage base options such as: oversowing annual ryegrass, winter crops (annual ryegrass monoculture, winter cereal grown for whole crop silage), summer crops (grazing brassicas, maize), combinations of these (double cropping), or summer shoulder pasture (notionally based on tall fescue) on between 10% and 100% of farm area.     

Impacts of cropping systems on soil nitrogen storage and loss

Organic and low-input cropping systems that use more C inputs are alternatives to conventional systems for sustaining long-term soil fertility. An understanding of the impacts of these cropping systems on N balance (N applied minus N removed in harvested plant material), storage and loss is necessary to improve long-term soil fertility and minimize the risk of environmental pollution. An evaluation of 4-year rotations of organic (N from legumes and composted manures), low-input (N from legumes and reduced amounts of synthetic fertilizers), and conventional (conv-4, N from synthetic fertilizers) and a conventional 2-year rotation (conv-2, N from synthetic fertilizers) on N balance, storage and loss was conducted from 1989 to 1998. Compared to the conv-2 system, the organic and conv-4 systems showed 119 and 8% greater cumulative N balances, respectively, over the duration of the study. However, N balance in the low-input system was 19% less than in conv-2 system. After 10 years of differential management, total N in the top 15 cm of soil was 1.46 g kg⁻¹ in the organic, 1.26 g kg⁻¹ in the low-input, 1.13 g kg⁻¹ in the conv-4, and 1.1 g kg⁻¹ in the conv-2 system. Compared to the conv-2 system, cumulative N losses for the organic, low-input and conv-4 systems were lower by 80, 92, and 10%, respectively. These findings suggest that organic and low-input cropping systems that add C to soil have the potential for storing N and making it available for future crop use, while minimizing the risk of environmental pollution.     

加纳农业机械化发展潜力及制约因素（摘选）

作为政府职能的一部分实现联合国千年计划,即到2015年消除饥饿和极度贫困,为了实现经济可持续增长就需要现代化的农业。就这个问题而言,基于食品安全的必要性,在撒哈拉以南的非洲地区和加纳,发展的重点正逐步转向农业机械化。如果没有行之有效的农业机械化,加纳的食品和农业部门将无法达到预期的经济影响。该文旨在归纳农业机械化的制约因素,提出适合加纳的有效的机械化途径。主要制约机械化的因素包括缺乏熟练的农机操作人员,农场规模小,不适当的政府政策和农机成本高。在认识到机械化对于国家农业发展中的巨大作用后,就需要制定适合的土地所有制政策框架,鼓励联合经营和定制雇佣机械,向农民传授有关投资知识,鼓励标准服务投入。      

Systematic design and evaluation of crop rotations enhancing soil conservation, soil fertility and farm income: a case study for vegetable farms in South Uruguay

Rapid changes in the social and economic environment in which agriculture is developing, together with the deterioration of the natural resource base threatens sustainability of farm systems in many areas of the world. For vegetable farms in South Uruguay, survival in the long term depends upon the development of production systems able to reduce soil erosion, maintain or improve physical and biological soil fertility, and increase farmer’s income to socially acceptable levels. We propose a model-based explorative land use study to support the re-orientation of vegetable production systems in South Uruguay. In this paper we present a new method to quantitatively integrate agricultural, environmental and socio-economic aspects of agricultural land use based on explicit design objectives. We describe the method followed to design and evaluate a wide variety of land use activities for Canelón Grande (South Uruguay) and we illustrate the usefulness of this approach in an ex-ante evaluation of new farming systems using data from 25 farms in this region. Land use activities resulted from systematic combination of crops and inter-crop activities into crop rotations, different crop management techniques (i.e., mechanisation, irrigation and crop protection) and animal production. We identified and quantified all possible rotations and estimated inputs and outputs at crop rotation scale, explicitly considering interactions among crops. Relevant inputs and outputs (i.e., soil erosion, balance of soil organic matter and nutrients, environmental impact of pesticides, labour and machinery requirements, and economic performance) of each land use activity were quantified using different quantitative methods and following the target-oriented approach. By applying the methodology presented in this paper we were able to design and evaluate 336,128 land use activities suitable for the different soil types in Canelón Grande and for farms with different availability of resources, i.e., land, labour, soil quality, capital and water for irrigation. After theoretical evaluation, a large subset of these land use activities showed promise for reducing soil erosion, maintaining soil organic matter content of the soil and increasing farmer’s income, allowing improvement of current farming systems in the region and providing a widely diverse set of strategic options for farmers in the region to choose from. This method can be used as a stand-alone tool to explore options at the field and farm scale or to generate input for optimisation models to explore options at the farm or regional scale.     

Typology of cereal-sheep farming systems in Castile-La Mancha (south-central Spain)

There is still no pan-European assessment of the typology of low-intensity farming systems and of the changes which they are undergoing under current European Union (EU) farm policy. This study examines the variability of farm structure and farming practices of a typical cereal-sheep farming system under continental Mediterranean conditions with the aim of providing regional data of policy relevance. The collection of quantitative and qualitative data was planned with collaborative effort from regional extension agencies and followed the Delphi technique. Arable land in Castile-La Mancha occupied more than 70% of total agricultural land in 1997, the rest being natural pasture, shrub-steppe, and Mediterranean forest. Dry low-intensity arable systems still included a sizeable proportion of fallow to cropped land (20%) or somewhat more than 1,000,000 ha, and the winter cereal stubble was often grazed by sheep. These systems were of low intensity in the sense that they used low inputs per ha, particularly of nutrients and agrochemicals. They involved the exploitation of land, particularly for grazing, on an open and large scale. In this sense, they can also be considered extensive systems. On average, only 20% of arable farmers kept sheep, while 80% of the sheep producers were landless pastoralists. Young farmers tend to be disinclined to became involved in the sheep sector, because of the harsh working conditions of sheep farming operations. Response to new economic circumstances involved the evolution of traditional practices with corresponding lower use of farm labour. Although still low-intensive, these systems can be considered as modified forms of traditional practices which have responded to new technologies and the need to cut labour costs. The new objectives for agriculture in Castile-La Mancha, must create or maintain a way of life that is socially and economically attractive to young farmers, without the acceptance of environmentally damaging practices. These new objectives will require a new regionally-targeted EU aid scheme. In turn, there is a need to understand regional agriculture systems before we can hope to achieve successful policy.     

A method for exploring sustainable development options at farm scale: a case study for vegetable farms in South Uruguay

The methodology presented in this paper aims at analysing whether there is room for improvement of vegetable farmers’ income in Canelón Grande (Uruguay), while reducing soil erosion and improving physical and biological soil fertility, and to gain insight in the influence of farmers’ resource availability on the opportunities for sustainable development. The (generic) approach we developed to support re-design of farming systems in this region is unique in dealing with complex temporal interactions in crop rotations and spatial heterogeneity on farms in one integrated method, while revealing trade-off between economic and environmental objectives. Rather than an arbitrary sub-set, all feasible crop rotations were generated, using a tool named ROTAT. The crop rotations were combined with a range of production techniques according to pre-defined design criteria to create a wide variety of alternative production activities at the field scale. We used process-based simulation models supplemented with empirical data and expert knowledge to quantify inputs and outputs of production activities. We developed a mixed integer linear programming model (MILP), named Farm Images, to allocate production activities to a farm with land units differing in soil quality, while maximising or minimising socio-economic and environmental objectives, subject to constraints at the farm level. Production activities comprised current practices as well as activities new to the area. We used Farm Images to design farm systems for seven existing farms in Canelón Grande with different resource availability. The farm systems designed by the model had higher family income than current systems for six of the seven farms studied. The estimated average soil erosion per ha decreased by a factor of 2–4 in the farm systems proposed compared to the current systems, while the rate of change of soil organic matter increased from negative in the current systems to +130 to +280 kg ha⁻¹ yr⁻¹ in the proposed farm systems. The degree to which the objectives could be achieved was strongly affected by farm resource endowment, i.e., particularly by the fraction of the area irrigated, soil quality and labour availability per ha. The study suggests that decreasing the area of vegetable crops by introducing long crop rotations with pastures and green manure during the inter-crop periods and integrating beef cattle production into the farm systems would often be a better strategy than the actual farmers’ practice.     

Competing use of organic resources, village-level interactions between farm types and climate variability in a communal area of NE Zimbabwe

In communal areas of NE Zimbabwe, feed resources are collectively managed, with herds grazing on grasslands during the rainy season and mainly on crop residues during the dry season, which creates interactions between farmers and competition for organic resources. Addition of crop residues or animal manure is needed to sustain agricultural production on inherently poor soils. Objectives of this study were to assess the effect of village-level interactions on carbon and nutrient flows, and to explore their impact on the long-term productivity of different farm types under climate variability. Crop and cattle management data collected in Murewa Communal area, NE Zimbabwe was used together with a dynamic farm-scale simulation model (NUANCES-FARMSIM) to simulate village-level interactions. Simulations showed that grasslands support most cattle feed intake (c. 75%), and that crop residues produced by non-cattle farmers sustain about 30% of the dry season feed intake. Removal of crop residues (0.3-0.4 t C ha⁻¹ yr⁻¹) from fields of non-cattle farmers resulted in a long-term decrease in crop yields. No-access to crop residues of non-cattle farmers increased soil C modestly and improved yields in the long-term, but not enough to meet household energy requirements. Harvest of grain and removal of most crop residues by grazing cattle caused a long-term decline in soil C stocks for all farm types. The smallest decrease (−0.5 t C ha⁻¹) was observed for most fertile fields of cattle farmers, who manure their fields. Cattle farmers needed to access 4-10 ha of grassland to apply 3 t of manure ha⁻¹ yr⁻¹. Rainfall variability intensifies crop-livestock interactions increasing competition for biomass to feed livestock (short-term effect) or to rehabilitate soils (long-term effect). Prolonged dry seasons and low availability of crop residues may lead to cattle losses, with negative impact in turn on availability of draught power, affecting area under cultivation in consecutive seasons until farmers re-stock. Increasing mineral fertiliser use concurrently with keeping crop residues in fertile fields and allocating manure to poor fields appears to be a promising strategy to boost crop and cattle productivity at village level. The likelihood of this scenario being implemented depends on availability of fertilisers and decision of farmers to invest in rehabilitating soils to obtain benefits in the long-term. Adaptation options cannot be blind to what occurs beyond field and farm level, because otherwise recommendations from research and development do not fit the local conditions and farmers tend to ignore them.     

Technology adoption by resource-poor farmers: considering the implications of peak-season labor costs

Seasonally-specific cultivation patterns of farm crop enterprises often create periodic labor shortages. New technologies that require labor inputs during such labor-scarce seasons are less likely to be adopted. Financial ex ante assessments of technology alternatives, however, neglect the implications of seasonal labor shortages. Standard returns to labor estimates assume that the value of labor to farmers is constant despite temporary increases in demand. This paper develops an alternative measure, returns to opportunity-costed labor (RTOCL), which discerns the seasonally-changing costs of labor. RTOCL more accurately reflects farmer decision criteria and serves as a useful measure in ex ante analysis of technology interventions. A case study of a bush fallow agricultural system in the Peruvian Amazon illustrates how seasonal labor shortages lead to farm management tradeoffs that affect the prospects of technology adoption. Two improvements of a new upland rice variety are contrasted: higher yield versus early maturity. Empirical results of an agro-economic mathematical model reveal that the early maturity characteristic enables rice to become more complementary to peak-season labor demands of the agricultural system. This early maturity characteristic permits farmers to cultivate larger areas and reap greater financial benefits than a variety with a high yield characteristic. Model results support the need to address heterogeneous seasonal labor demands when developing and disseminating agricultural technologies intended to benefit resource-poor farmers.     

Adaptation and evaluation of the integrated farm system model to simulate temperate multiple-species pastures

Whole-farm simulation provides a tool for predicting the effects of farm management strategies on farm productivity and profitability. One such model, the Integrated Farm System Model (IFSM), was modified to allow representation of up to four forage species coexisting in a pasture mixture. The model was calibrated to simulate net herbage accumulation (NHA) observed during six periods of a 2002 experiment in a 3-species pasture in Pennsylvania, USA, composed of orchardgrass (Dactylis glomerata L.), white clover (Trifolium repens L.), and chicory (Cichorium intybus L.). The model also predicted sward botanical composition, total annual NHA, crude protein (CP), and neutral detergent fiber (NDF). Sensitivity analysis showed that predictions of NHA were most sensitive to both chicory and orchardgrass specific leaf area and partitioning of photosynthate to the shoot, as well as chicory photosynthetic efficiency. The model was evaluated against data from the same 3-species pasture in 2003 as well as a 2-species pasture (lacking chicory) from the same experiment in 2002 and 2003. Predictions of total annual NHA in 2- and 3-species pastures were within ±18% of observed values, though predictions of within-season NHA were less accurate. Predictions of botanical composition tended to remain within ±15% of observed values by species. Predictions of within-season CP and NDF concentrations in the whole sward tended to remain within ±22% and ±15%, respectively. Given the generality and realism required of IFSM, the degree of precision in the modified pasture submodel is acceptable for achieving IFSM’s primary goal of comparing the effects of different management scenarios on forage productivity and the long-term profitability and environmental impact of farms.     

农户对农机服务购买行为的差异性分析——基于303份微观调查数据的研究

为分析农户的农机服务采纳行为的主要影响因素,以湖北省和山东省的303份农户层面微观调查数据为例,采用Probit模型和Logstic模型分析影响农户采纳农机服务行为机理。研究结果表明:农户的身体健康状况、耕地是否有坡地、耕地块数及是否有非农经历均对农户的机耕、机收以及机播是否购买农机服务有着显著影响,且农户对于不同环节(机耕、机播以及机收)农机服务的购买行为的影响因素及程度均有所差异;农户身体健康状况、拥有农机现值、是否务工兼顾种植,以及耕地是否有坡地均对农户采纳农机服务的数量有显著性影响。     

The early economic impact of a nutrient management decision support system (NuMaSS) on small farm households cultivating maize on acidic, upland soils in the Philippines

Maize is the most important crop in upland areas in the Philippines, but production lags behind potential in many areas, especially those with acid soils. The Nutrient Management Support System (NuMaSS), a computer-based decision aid, provides soil and crop-based recommendations for nutrient amendments and lime. Development and trials of the NuMaSS were carried out on upland maize farms in Isabela province in the northern Philippines from 1998 to 2006. While local practices and standardized government recommendations had included applying N, P, and K, the application of lime to correct soil acidity had not been practiced locally and lime was not commercially available in local markets. Based on data from 39 field trials on 13 different farms over four years, we calculate that liming increased maize grain yield on the average by 1.5 t/ha. A farmer purchasing and applying lime would realize a single-season marginal rate of return on investment of about 160%. Because of the positive results of the on-farm trials of the NuMaSS, and in particular the positive result of liming acid soils, the Philippine Department of Agriculture began a lime promotion program in four provinces in Region II in 2006. The program includes field days, farm-level demonstrations, and distribution of subsidized lime to farmer-cooperators. We estimate the economic value of the NuMaSS and lime promotion program to have an NPV of $8 million or an IRR of 25%. We base our calculations on the costs for the research program itself, the costs of the extension program, the costs of the subsidized inputs for the first four years, and the benefits of improved maize production over a 40 year horizon over 12,000 ha (out of a potential 90,000 ha of acid soils in maize production). Our calculations show that the NPV of the lime promotion increases with increasing adoption but the program has a positive NPV even if adoption is negligible after the initial promotional program ceases. Our results document the adoption and farm level and regional economic impact of a decision aid. As agriculture in the Philippines and other developing countries expands with increasing food prices and other demands such as bioenergy production, farmers will need better decision tools such as the NuMaSS to manage crop production on problem soils and marginal sites.     

Spatially targeting the distribution of agricultural input stockists in Malawi

Developing the rural agricultural input markets in sub-Saharan Africa can improve the current low productivity of smallholder farmers. Malawi has seen significant efforts in addressing the availability of agricultural inputs at village level in the last few years; for example, the improvement of rural agro-dealer networks. Nevertheless inputs are still difficult to obtain for many remote smallholder farmers. Spatial analysis can help in the expansion of input stockists, especially agro-dealer networks, by assessing the coverage of existing input outlets and deriving optimum locations for village-level input stockists.We address three research questions. First, what is the locational efficiency of the current village-level stockists of inputs (Citizens Network for Foreign Affairs – Rural Agricultural Market Development Trust trained network of agro dealers and public sector)? Secondly, how many village-level stockists of markets are needed to reach 60% of the population in the central region of Malawi within one hour? Finally we address the potential spatial components of the sustainability of input stockists relating to the potential demand from smallholder farmers and the access to bulk supplies. The problem of finding the optimum location for village-level stockists of markets is addressed in two stages, using spatial analysis in conjunction with location–allocation models. First, the locational efficiency of the existing network of stockists of inputs is determined, followed by the establishment of a set of optimal sites for village-level stockists of inputs. A final step explores the viability of stockists and calculates the population surrounding the stockists taking into account competition from other sources of inputs and the accessibility of the selected stockists to potential wholesalers who are bulk distributors of farm inputs.Our results show that locational efficiency can be assessed in terms of the differential access of households to resources and transport. Often, these differences are not considered in covering problems and can have a large effect on the physical access to inputs. The results can be used to define which areas are inherently difficult to serve with agricultural inputs and could inform efforts to provide incentives to remote areas. Further implications for input policies in Malawi are that improvements in road infrastructure might not directly benefit the poorest farmers (if they are walking) but could serve to reduce the wholesale prices and therefore the retail price. In addition, the improvement in roads might increase the number of potential customers of any particular stockist, with economies of scale allowing the reduction of prices while ensuring a satisfactory profit margin for the stockist. The results of our models imply that Citizens Network for Foreign Affairs may need to train stockists over a wider area to increase the access to inputs of those smallholder farmers with least resources.     

Characteristics and economic viability of milk production in the smallholder farming systems in The Gambia

Domestic milk production has been for a long time hindered by many factors including lack of interest from decision makers, distorted economic policy and biotechnical constraints. For the last 20 years, many developing countries have been attempting to develop the domestic milk production sector. However, research on the basic realities and the viability status of enterprises within this sector remain largely unproved in many developing countries. This study focuses on the characteristic of smallholder milk producers in The Gambia. Data were collected from 90 smallholder farm households to characterise milk producers and evaluate the profitability and viability status of this activity. Based on current typology of farms and gross margin analyses at farm level, the study identified two resource-based types of smallholder farms. The current milk production system is surely viable. Constraints to increased productivity include lack of improved technology at farm level and weak institutional support. Despite the low viability status, it is shown that milk production generates reliable incomes, which could be a departure for most farmers to intensify farming systems, particularly in areas where no loan schemes exist for purchasing agricultural inputs.     

The value of climate information when farm programs matter

Predictability of seasonal climate variations associated with ENSO suggests a potential to reduce farm risk by tailoring agricultural management strategies to mitigate the impacts of adverse conditions or to take advantage of favorable conditions. Federal farm policies may enhance or limit the usefulness of this climate information. A representative peanut–cotton–corn non-irrigated North Florida farm was used to estimate the value of the ENSO-based climate information and examine impacts of farm programs under uncertain conditions of climate, prices, and risk aversion levels. Yields from crop model simulations and historical series of prices were used to generate stochastic distributions that were fed into a whole farm model, first, to optimize crop selection and planting dates, and then, to simulate uncertain outcomes under risk aversion, with and without the use of climate information, and with and without the inclusion of farm programs. Results suggest that seasonal climate forecasts have higher value for more risk averse farmers when La Niña or El Niño ENSO phases are forecast. Highly risk averse farmers could benefit from the forecast by taking advantage of potential favorable conditions (offensive responses). The inclusion of Commodity Loan Programs (CLP) and Crop Insurance Programs (CIP) decreased the overall value of the forecast information even to negative levels. However, more risk averse farmers could still benefit moderately from El Niño and marginally from La Niña forecasts when they participate in CLP and CIP.     

Comparison of two pasture growth models of differing complexity

Two pasture growth models that shared many common features but differed in model complexity were refined for incorporation into the Integrated Farm System Model (IFSM), a whole-farm model that predicts effects of weather and management on hydrology, soil nutrient dynamics, forage and crop yields, milk or beef production, and farm economics. Major differences between models included the explicit representation of roots in the more complex model and their effects on carbon partitioning and growth. The simple model only simulated aboveground processes. The overall goal was to develop a model capable of representing forage growth and ecosystem carbon fluxes among multiple plant species in pastures while maintaining a relatively simple model structure that minimized the number of required user inputs. Models were compared to observed yield data for 12 site-years from three experiments in central Pennsylvania, USA. Both models underestimated observed yield by 6% when averaged across site-years. However, the simple model provided a better fit to the one-to-one line between observed and simulated yield than did the complex model. The models also showed similar relationships between yield and gross primary productivity (GPP), despite the fact that the complex model was specifically developed to optimize simulation of GPP. The simple model predicted much greater shoot respiration and carbon partitioning to above ground plant tissues, but less shoot senescence than the complex model. Published data on the proportion of GPP consumed in aboveground or total plant respiration exhibit a wide range of values, making it impossible to determine which model provided the best representation of respiration rates and, thus, of the entire carbon budget.     

农机大户经营中面临的困境及解决对策

农机大户在农业机械化发展中发挥着主导作用,为我国农业现代化的发展做出了积极贡献。随着农机大户的纷纷涌现和作业管理规范的缺失,农机大户在经营过程中遇到了很多困难,如何破解这些难题,找到发展对策是值得研究的新课题。分析了当前农机大户经营面临的困境,提出了几点解决对策。      

揭膜拔杆技术试验分析

地膜覆盖技术,以其保温、保土、保墒、增产等显著特点,在农业生产中得到了广泛应用,对农业增产、农民增收起到了巨大的推动作用,给农业生产带来巨大经济效益。然而,由于过度使用地膜难以被完整回收,造成土壤耕层的白色污染十分严重。强调了治理残膜污染、保护农田生态环境和保持农业可持续发展的重要性,以及研制、推广先进适用的残膜回收机械的紧迫性。