Modelling the interactions between regional farming structure, nitrogen losses and environmental regulation

Changes in the structure of agriculture are known to affect emissions of environmental pollutants from agriculture. Such changes are often driven by structural changes in agricultural production, so structural changes are likely to have indirect effects on emissions. In a pilot study, we consider how linking two complementary simulation models might be used to explore these effects. The agent-based AgriPoliS model was used to simulate the structural dynamics of agricultural production. The results from AgriPoliS were passed via a number of intermediate models to the Farm-N model, which was used to estimate the nitrogen surplus and losses from each farm for each year.The modelling complex was exercised by simulating the effects of two plausible policy scenarios for each of 14 years. The initial sizes and types of farms were based on statistics from a region in Denmark and the farms were randomly distributed within this region. The reference scenario (REF) implemented the current area-based Common Agricultural Policy payments for Denmark. The 1 LU scenario applied the additional constraint that a minimum area of 1 ha land had to be available for the application of the manure produced by one livestock unit.Substantial changes in the structure of agricultural production were shown for both scenarios. The effect on the regional nitrogen surpluses was predicted to differ between scenarios and the contribution of the different farm types to change with time. Predicted ammonia emission changed with time and differed between the scenarios, whereas the Danish fertiliser and manure legislation meant that nitrate leaching remained fairly stable.The implementation of additional environmental legislation significantly changed the trajectory of structural adjustment processes. Results emphasize the complex interplay between structural changes, losses of nitrogen, and environmental regulation.It is concluded that the effects of structural change on environmental emissions can be usefully explored by linking agent-based models of farmers’ investment decisions with other models describing nutrient losses from the farm and that such modelling can play a useful role in designing effective environmental policies for agriculture. However, the approach demands the availability or collection of many region-specific data and this could create a barrier to its use.     

养殖场小型多杆拨齿槽式翻抛机设计

针对中小型养殖场粪便废弃物的处理需求,设计了一种双驱动小型多杆拨齿槽式翻抛机。论述了翻抛机的主要结构及工作原理,对其行走系统、翻抛系统和控制系统进行了设计研究,行走底盘采用双减速电机驱动,翻抛系统采用经结构优化的拨齿,控制系统采用PLC和传感器组合的形式。试验表明,该机运行平稳、翻抛均匀流畅和生产高效,处理能力达到150～200 m3/h,广泛适用中小型养殖场的粪便废弃物处理和有机肥生产。      

Economic analysis of integrated on-farm drainage management

The goal of integrated on-farm drainage management (IFDM) is to eliminate the discharge of subsurface drainage water from farms into waterways or evaporation ponds. Components of a typical IFDM system include improved irrigation practices, irrigation of salt-tolerant plants with drainage water, and on-farm disposal of drainage water using a solar evaporator. Costs of an IFDM system include initial investments, operation and maintenance, and the opportunity costs of land used for the solar evaporator and for irrigation of nonmarketable, salt-tolerant plants. The farm-level cost of an IFDM system increases with the proportion of farmland used to irrigate salt-tolerant plants. A conceptual framework for evaluating the farm-level costs of IFDM is presented, along with empirical analysis from California’s San Joaquin Valley.     

Machinery selection method for farms in North India

This paper describes a method of selecting farm machinery systems for farms of different sizes and categories. The annual cost equations developed determine the cost of each farm operation, as well as the total cost of the system of farm machinery. Comparison of the costs of different systems is used to select the system with the lowest costs.Computer programs were developed to handle the lengthy iteration computations. The utility of these programs is demonstrated in selecting least-cost power and machine combinations for farms of up to 20 ha growing maize and wheat in the Ludhiana district of Punjab, India.     

Egg production on cooperative farms: An economic analysis

This paper examines the economics of egg production of forty co-operative farms in South-Western Nigeria. In the paper, cost functions are analysed by the use of ordinary least squares and weighted least squares. The impact of different factors of production on revenues was computed by fitting a production function that related total revenue to inputs.Results of the analysis indicated that productive inputs appeared to be combined in fixed proportions over all sizes of co-operative farms. Feed was found to account for over two-thirds of the costs on co-operative farms.     

A stochastic simulation model for evaluating forage machinery performance

The selection of machinery on a dairy farm is the focus of the study. A simulation model is constructed that evaluates alternative forage machinery complements on New York State dairy farms. Attention is focussed on the machinery use, forage crop production and concentrate purchase. The key measure of performance is the total cost of acquiring feed for the dairy herd. The total cost includes the machinery investment and operating costs and the cost of feeds required to supplement that produced on the farm.The simulation model, written in Fortran, utilises a daily timestep. Each day the feasibility of machinery operation is determined, machinery operations are scheduled and the end of day status is determined.     

Dairy farm nutrient management model: 2. Evaluation of different strategies to mitigate phosphorus surplus

To reduce (P) surpluses on dairy farms and thereby the risk of P losses to natural waters we studied different management alternatives by a nutrient balance model described in the companion paper. The strategies evaluated mitigating the P surpluses were: mineral P fertilisation, dietary mineral P supplementation, replacement rate, animal density, production level, feeding intensity, dietary P concentration and nutrient efficiency in crop production. Responses to several interventions (e.g. mineral P fertilisation, purchased feed P, replacement rate) were similar to those observed in Finnish field studies. Reducing or completely giving up the use of purchased mineral P fertilisers was the most efficient measure to reduce P surplus. The slope between the amount of mineral fertilisers and P surplus was 0.98-0.99 (in the field data 1.0). Increased animal density resulted in a greater P surplus, but the slope between P input from purchased feed and surplus was considerably smaller (0.65) than that of P fertilisation. Increasing milk yield with improved genetic potential of the cows would have minimal effects on P surplus per unit of product, but it would increase P surplus per hectare. When the intensity of energy and protein feeding was increased, P surplus rose markedly both per unit of product and hectare. This is (1) due to increased dietary P concentration and (2) due to smaller marginal production responses than those calculated from feeding standards. Reducing dietary P concentration by constraining P excess per kg milk in least-cost ration formulation improved P efficiency in milk production and dairy farming system. However, feed cost increased as low P energy (sugar-beet pulp) and protein (soybean meal) supplements are more expensive than cereal grains or rapeseed feeds. Improving the nutrient use efficiency in crop production had a strong influence in the whole-farm efficiency and P surplus. The modelling results showed that Finnish dairy farms have a great potential to improve P efficiency and reduce P losses to the environment, even by increasing production intensity (milk/ha). It is concluded that the most cost-effective scenario to mitigate P surpluses at a dairy farm would be to reduce or give up the use of mineral P as fertilisers and supplements, and to improve the use of present soil P reserves.     

Farm types for beef production and their economic success in a mountainous province of northern Vietnam

The objective of this study was to compare the management and economic success of beef production by three types of farm in northwestern Vietnam. The potential of household farms to supply beef for the market and their competition with large farms were examined.The fieldwork was done in 2007 on 73 farms consisting of 58 small mixed farms (small farms), 10 medium mixed farms (medium farms) and 5 specialised large-scale beef farms (large farms) in Son La province. The three types of farm differed in ethnicity (Thai, H’mong, and Kinh), remoteness (lowland, highland), production objectives (subsistence, market output), degree of specialization (mixed farm, specialised beef farm) and integration of production (single farmers, cooperative). Data on biological productivity, inputs and outputs, and the social contribution of cattle production were collected by household and key person interviews, participatory rural appraisal tools and cattle body measurements. Economic values were derived by assessment of market or replacement costs. Quantitative data analysis was done with linear models (PROC GLM) in the SAS software (version 9.1).Lowland small farms had higher costs for cattle production than the highland farms (0.8 Mill. VND head⁻¹ year⁻¹ compared with 0.02 Mill. VND head⁻¹ year⁻¹, respectively). The large farms had high production costs, with an average of 2.5-3.6 Mill. VND head⁻¹ year⁻¹. Cattle brought high benefits of non-cash values to the household farms. The total revenue from cattle was in the range 4.5-11.5 Mill. VND head⁻¹ year⁻¹, which depended on the use of non-market functions of cattle on the household farm. The value of net benefit/kg live weight (LW) of lowland small farms with an average of 39,000 VND/kg LW was significantly higher than that of the medium and small farms in the highlands (26,000 VND/kg LW). However, the small farms kept fewer cattle than the medium farms (average of 2-4 cattle/farm compared with 9 cattle/farm, respectively) because of forage and labour shortages and have no option to further develop cattle production. Keeping larger numbers of cattle based on available natural pasture brought high benefit from stock value as farm liquidity to only the medium farms. This was the most promising type of farm for future development of beef production, given its actual success and the availability of underutilised resources. Large-scale farms suffered high economic losses of 0.3-1.4 Mill. VND cattle⁻¹ year⁻¹, due to the lack of professional management, high feed costs and low animal performance, and showed no potential for developing cattle production.     

Modelling the fate of water and nitrogen in the mixed vegetable farming systems of northern Tasmania, Australia

A combination of high input management systems, high annual rainfall and deep, permeable soils in northern Tasmania create conditions that are conducive to high drainage and nitrogen losses below the root zone. An understanding of the extent and mechanism of such losses will enable farm managers and their consultants to identify and implement more sustainable management practices that minimise potential adverse financial and environmental consequences. Analysing the fate of water and nutrients in farming systems is complex and influenced by a wide range of factors including management, soil characteristics, seasonal climate variability and management history of the paddock/farm in question. This paper describes a novel farm system modelling approach based on the model APSIM, for analysing the fate of nitrogen and water in mixed vegetable-based farming enterprises. The study was based on seven case farms across the Panatana catchment in northern Tasmania. Substantial simulated drainage losses (>100 mm average seasonal loss) were apparent for all crop and rotation elements across all farms in response to the surplus between crop water supply and crop water use. Crop nitrogen demand was found to be close to crop nitrogen supply for all crop and pasture rotation elements with the exception of potato, which had an average surplus nitrogen supply of 89 kg N/ha. This resulted in potato having much higher nitrate nitrogen leaching losses (32 kg N/ha) compared to other crops (<10 kg N/ha). Simulations suggest that practicable management options such as deficit-based irrigation and reduced N fertiliser rates will maintain current levels of productivity while reducing potential offsite N loss and generating significant financial savings via reduced input costs.     

Efficiency differentials in the traditional agriculture of Northern Nigeria

It is generally accepted that farmers operating in traditional agricultural systems are highly efficient, given the resources and technology available to them. This has led to farm policies in third world countries which place a high emphasis on capital investments.This paper uses a frontier production function analysis to generate firm specific efficiency indices for traditional farms in three different areas in northern Nigeria. Computed indices are then employed in identifying both inter- and intra-area efficiency differentials. The relationships between technical efficiency and commonly used farm performance measures are also examined.The results indicate that efficiency scores range between 0·67 and 1·00. This implies that least efficient farmers could have obtained gross value of output 24–36% above their actual output. Thus, the results reported in this paper are not in total support of the conventional belief that no increase in traditional agricultural output is possible by a more efficient use of factors at the disposal of farmers. One implication of these findings is that extension programmes based on the experience of more successful farmers, even with traditional practice, can yield modest dividends.     

Dairy farm nutrient management model. 1. Model description and validation

Intensive dairy farming results in significant phosphorus (P) emission to the environment. Field data indicates that farm-gate P surplus is highly positive in Finland and strategies to mitigate the surplus are needed. The objectives of this study were to build a P cycle model for dairy farms (1) and to validate the model with independent field data (2). The dairy farm nutrient management model (“Lypsikki”) described in this paper includes three sub-models: (1) soil and crop, (2) dairy herd and (3) manure management. The model is based on empirical regression equations allowing estimations of crop and milk yields in response to increased fertilisation and nutrient supply, respectively. In addition, the model includes a dynamic simulation model of the dairy herd structure and calculation of the farm-gate nutrient surplus. The model was validated with independent annual (average for 1-4 years) farm-gate P surplus data from 21 dairy farms. Model simulations were conducted using two levels of soil productivity, mean (M) and low (L). The model validation indicated a strong relationships between model-predicted and observed farm-gate P surplus: (M: R² = 0.77 and L: R² = 0.80). The line bias between the model-predicted and observed data was negligible and insignificant (P > 0.6) suggesting a robustness of the model. The mean biases were relatively high and significant (M: 4.7 and L: 1.8 kg/ha, P < 0.001), but evidently related to overestimation of crop yields that has to be taken into account when using the model on a single farm. The prediction error of the model (observed minus predicted P surplus) was significantly correlated to the difference between simulated and observed P import in feeds (M: R² = 0.55 and L: R² = 0.51). This suggests either that all the dairy farms did not fully exploit the possibilities in the crop production or that all the model assumptions are not correct. The effects of purchased feed and fertiliser P and exported milk P (per cow or cropping area) on farm-gate P surplus were of the same magnitude in both observed and simulated data. This implies that the model developed can be used as a management decision tool to find strategies to mitigate P surplus on dairy farms.     

规模化养猪场粪水处理和资源化利用关键技术

随着我国畜禽养殖业的迅猛发展,养猪场粪污集中排放对环境的影响越来越大,有效处理和合理利用猪场粪污迫在眉睫。通过对目前规模化养猪场污水处理工艺、技术、进行总结分析,为规模化畜禽养殖场粪污处理提供参考。      

农业机械化适度规模经营模糊分析研究

利用模糊理论，对与机械化家庭农场适度规模经营有关的因素－－劳力纯收入、公顷投入资金、机械化综合水平、化顷纯收入、化顷粮食产量、化顷用肥量及用工进行模糊综合评判，找出目前农村家庭农场最佳土地智谋规模经营的范围。     

Co-evolutionary scenarios of intensification and privatization of resource use in rural communities of south-western Niger

Agricultural production in the semi-arid agro-ecosystems of the Sahel centres on cereal staple crops and pastoralism with increasing crop–livestock integration. Animals mobilize soil fertility through manure production, graze crop by-products, and transfer nutrients from distant pastures to cropped areas. Yet in these systems various interacting factors, i.e. climate variability, poor soil fertility, poverty, and institutional constraints limit the capacity of agriculture to keep pace with the growing needs of an increasing human population.The major trends associated with population growth are (1) increasing area cropped at the expense of rangelands; (2) reduced availability of and access to good quality grazing resources, and (3) seasonal migration of labourers and transhumance of herds. These trends lead to co-evolution of farming systems towards increased privatisation of resource use.This study examines the implications of the development processes where farming systems co-evolve with their surroundings. It explores the impact of integrated management of livestock and crops in rural communities on both the livelihoods of differently endowed farms, and on the agro-ecosystem. Different scenarios explored the co-evolution of three sites situated in Western Niger with their environment. The sites differ in relative area cropped. The scenarios simulate the different future outcomes for varying socio-economic and biophysical criteria with either current or more intensive management.Explorative bio-economic models are used to compare a range of farm, livelihood and ecological indicators, and to reveal social and ecological trade-offs.If current agro-ecosystems and their environments co-evolve towards increased privatisation of grazing resources, then soil fertility is likely to deteriorate on the lands managed by the agro-pastoral groups. Soil fertility may improve on lands managed by the livestock-scarce farmers settled in villages, at the cost of declining farm incomes. The agro-pastoral groups are likely to resort to more distant pastures for feed. The village-based, livestock-endowed farms will resort to feeding on on-farm crop residues. Intensification, though associated with relative decreases in real incomes, will enhance food security in these new systems, except for the poorer settled farmers.     

Characterising rice-based farming systems to identify opportunities for adopting water efficient cultivation methods in Tamil Nadu, India

Efficient water use in rice cultivation is a prerequisite for sustaining food security for the rice consuming population of India. Novel rice production practices, including water-saving techniques, modifications in transplanting, spacing, weeding and nutrient management, have been developed and shown to be effective on farm, but adoption of these techniques by farmers has remained restricted. Potential constraints include technical difficulties with new practices, and labour and gender issues which differ between farms. On the basis of a rapid survey of 100 rice-based farms, four farm types were identified based on their socio-economic and biophysical characteristics. Detailed farm surveys were conducted on three representative farms of each farm type to evaluate land use patterns, use of inputs such as water, labour, nutrient, capital and machinery, income from crop and animal production and off-farm activities. Opportunities exist for one or more new rice cultivation techniques to be adopted in all the four farm types. For all farm types, however, the opportunities for use of water-saving irrigation were the least promising. In general, adoption of water-saving irrigation will not improve farmers’ livelihoods despite its importance in reducing water scarcity problems at regional scale. At farm scale, the potential for adoption of water-saving irrigation depends on the season, location of fields and the irrigation source. Changes in government policies such as rules and regulations, pricing, institution building and infrastructure development, as well as training and education of farmers are needed to improve the adoption of modified methods for rice cultivation.     

An economic analysis of irrigation systems

Summary An array of irrigation systems are available which can be broadly classified as being gravity flow or pressurized. Pressurized irrigation systems provide better control on the amount of applied water and, in most cases, better irrigation uniformity than gravity flow systems. They also have a higher initial capital cost than gravity flow systems and an analysis is required to determine whether the improved performance of pressurized systems justifies the additional costs. An economic analysis was done on several irrigation systems which included consideration of farm management costs associated with a given irrigation system, shifts in crop yield and drainage volumes associated with the optimal management of each irrigation system, and costs associated with disposal of drainage waters. Cotton was selected as the crop for analysis. Irrigation uniformity is a significant determinant to the results. Although irrigation uniformities can be highly variable based on design, maintenance and management, a typical uniformity for each irrigation system was selected. For the conditions of the analysis, gravity flow systems were calculated to be more profitable than pressurized systems if there was no constraint on the amount of drainage water generated or cost for its disposal. Imposition of costs for drainage water disposal induced a shift whereby pressurized systems became more profitable than gravity flow systems.     

The impact of agriculture on ground water quality in Slovenia: standards and strategy

Ground water and water from springs are sources used for water supply in Slovenia. The quality of these waters has been monitored since 1987. Among 12 main ground water aquifers in Slovenia the amount of nitrate exceeds the allowable level (50 mg/l) for drinking water in areas with more intensive agricultural production with higher concentrations of animals (two livestock unit – LU/ha) and where drainage of sewage water is not excellently arranged or where quality of river water that effluent ground water is not well. The identification of nitrogen surpluses has been done on regional and farm level (using normative approach). This method is taking into account nitrogen input from mineral fertiliser, animal wastes and the deposition from the atmosphere minus nitrogen uptake of harvested crops and ammonia losses to the atmosphere. On an average nitrogen input from mineral fertiliser is low, while input from organic manure is rather high – 90 kg/ha. Average net-balance surplus for Slovenia is about 56 kg N/ha. The differences between regions are relatively high. In the most intensive arable region with high intensity of animal husbandry (2 LU/ha) nitrogen surplus is about 90 kg/ha. This region can be identified as vulnerable for nitrogen leaching into ground water. In regions with limited growing conditions for agriculture plants (climate, soil depth) just small increase of livestock density can cause high nitrogen surpluses. Our Slovenian legislation, which almost entirely corresponds to EC Nitrate Directive and Code of Good Agricultural Practice intends to reduce mineral surpluses in agriculture and meet the standards of nitrate in drinking water.     

Poverty and biodiversity trade-offs in rural development: A case study for Pujiang county,China

Both, poverty reduction and preservation of biodiversity are high on the global agenda on sustainable development. The relationships between poverty, biodiversity of agro-ecosystems and agricultural development are complex and poorly understood. In this paper, we present an integrated framework for analysis of agricultural development and natural resource management options at agro-ecosystem level, using Pujiang county, in Zhejiang province, China as a case study area to perform the analysis. A regional linear programming (LP) model is applied, maximizing regional economic surplus, given production and labour market conditions in Pujiang. We use the model to examine the consequences for a set of regional poverty and biodiversity indicators, of four so-called poverty reduction strategies, i.e., (i) intensification of production, (ii) diversification towards livestock production, (iii) land expansion, and (iv) an exit from agriculture. The analysis indicates that diversification is the most promising poverty reduction strategy, but requires efficient use of animal manure in cropping systems to avoid environmental problems. Improved nutrient management in cropping systems is effective in reducing the regional nitrogen surplus, but less effective in increasing per capita income. The exit strategy is effective in reducing poverty and achieving biodiversity goals, but may have important social consequences that are not addressed in this study. Further reduction in rural poverty is hampered by labour constraints during the harvesting period in high value crops such as vegetables and fruits, which calls for research and development in the field of agricultural mechanization.     

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.