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.     

Economic potential for soil carbon sequestration in the Nioro region of Senegal’s Peanut Basin

This paper presents results from an analysis of the economic potential for soil carbon sequestration in the Nioro region of Senegal’s Peanut Basin. This analysis was based on the linkage of site-specific biophysical models and economic simulation models using the Tradeoff Analysis System to simulate farmers’ participation in contracts to sequester soil carbon. Available soils and climate data were used to implement the DSSAT/Century models to estimate crop yields and changes in soil carbon stocks under nine scenarios of increased fertilizer use and increased incorporation of crop residues in a peanut-millet rotation. Data from the 2001 farm survey conducted by the Ecole Nationale d’Economie Appliquée were used to parameterize a spatially explicit econometric-process simulation model for the peanut-millet production system. The economic simulation model was used to simulate a carbon-payment scheme that requires farmers to apply higher fertilizer rates and incorporate some crop residues into the soil. The results show that the combination of increased fertilizer use and crop residue incorporation could result in the supply of marketable quantities of carbon that could be sequestered in the soils of the Nioro region. However, the sensitivity of results to the levels of labor costs of incorporating crop residues, the value of crop residues, and the transaction costs of implementing carbon payment schemes, suggests the need for better data on these variables and for an accurate assessment of the capabilities of local institutions to implement carbon contracts.     

Analysis of information systems and communication networks for organic and conventional hazelnut producers in the Samsun province of Turkey

This research presents an analysis of the agricultural information systems and communication networks for organic and conventional hazelnut producers in the Samsun province of Turkey. Structured interviews were used to collect data from 64 randomly selected conventional and all 39 organic hazelnut producers living in the study area. Information systems for organic and conventional producers were found to be different. Organic producers benefited from more information sources than conventional producers. In addition, the contract farming approach to organic agriculture had initially isolated organic producers from conventional producers. Furthermore, dissatisfaction from the organic marketing company and its organic production project resulted in further separation among organic producers and led some of them to establish their own union. The lack of access to information and support from the organic project-related sources, professional institutions and mass media sources was evident. This resulted in the development of social sources to exchange information among the producers within their villages. However, this information is mainly based on traditional practices rather than scientific applications. Thus, more functional cooperation and professional communication between personal and institutional information sources are needed to enhance the diffusion of information and technology among farmers.     

Life cycle assessment of Swiss farming systems: I. Integrated and organic farming

Organic farming (OF) is considered a promising solution for reducing environmental burdens related to intensive agricultural management practices. The question arises whether OF really reduces the environmental impacts once lower yields and all the changes in farming methods are taken into consideration. This question is addressed in a comprehensive study of Swiss arable cropping and forage production systems comparing OF to integrated production (IP) systems by means of the life cycle assessment (LCA) method.The LCA study investigated the environmental impacts of two long-term farming system experiments: the DOC experiment comparing bio-dynamic, bio-organic and conventional/integrated farming and the “Burgrain” experiment encompassing integrated intensive, integrated extensive and organic production. All treatments received similar amounts of farmyard manure. The system boundary encompasses the plant production system; storage and application of farmyard manure is included in the system boundary, the animal husbandry is not included. The Swiss Agricultural Life Cycle Assessment method (SALCA) was used to analyse the environmental impacts.In the overall assessment OF was revealed to be either superior or similar to IP in environmental terms. OF has its main strengths in better resource conservation, since the farming system relies mainly on farm-internal resources and limits the input of external auxiliary materials. This results in less fossil and mineral resources being consumed. Moreover the greatly restricted use of pesticides makes it possible to markedly reduce ecotoxicity potentials on the one hand, and to achieve a higher biodiversity potential on the other. This overall positive assessment is not valid for all organic products: some products such as potatoes had higher environmental burdens than their counterparts from IP.The main drawbacks identified for Swiss OF systems are lower yields. As a consequence some production factors are used less efficiently, thus partly negating the advantages of OF. Furthermore, the different manure management strategy leads to relatively high nutrient losses in relation to yield. These two points were shown to be the main priorities for the environmental optimisation of OF systems. The differences between the bio-organic and the bio-dynamic farming systems consisted in a slightly higher input of organic matter, a few applications of mineral fertilisers and copper applications in the former.The eco-efficiency analysis led to the conclusion that the optimisation of OF is mainly output-driven, i.e. that higher yields of good quality should be achieved with the available (limited) resources. On the contrary, optimisation of IP was found to be input-driven; the inputs should be used in a quantity and manner which minimise the environmental burdens per unit produced. The study showed that despite the efforts of recent years, there is still considerable room for the environmental optimisation of Swiss farming systems.     

The diversity of rural livelihoods and their influence on soil fertility in agricultural systems of East Africa - A typology of smallholder farms

Technological interventions to address the problem of poor productivity of smallholder agricultural systems must be designed to target socially diverse and spatially heterogeneous farms and farming systems. This paper proposes a categorisation of household diversity based on a functional typology of livelihood strategies, and analyses the influence of such diversity on current soil fertility status and spatial variability on a sample of 250 randomly selected farms from six districts of Kenya and Uganda. In spite of the agro-ecological and socio-economic diversity observed across the region (e.g. 4 months year⁻¹ of food self-sufficiency in Vihiga, Kenya vs. 10 in Tororo, Uganda) consistent patterns of variability were also observed. For example, all the households with less than 3 months year⁻¹ of food self-sufficiency had a land:labour ratio (LLR) < 1, and all those with LLR > 1 produced enough food to cover their diet for at least 5 months. Households with LLR < 1 were also those who generated more than 50% of their total income outside the farm. Dependence on off/non-farm income was one of the main factors associated with household diversity. Based on indicators of resource endowment and income strategies and using principal component analysis, farmers’ rankings and cluster analysis the 250 households surveyed were grouped into five farm types: (1) Farms that rely mainly on permanent off-farm employment (from 10 to 28% of the farmers interviewed, according to site); (2) larger, wealthier farms growing cash crops (8-20%); (3) medium resource endowment, food self-sufficient farms (20-38%); (4) medium to low resource endowment relying partly on non-farm activities (18-30%); and (5) poor households with family members employed locally as agricultural labourers by wealthier farmers (13-25%). Due to differential soil management over long periods of time, and to ample diversity in resource endowments (land, livestock, labour) and access to cash, the five farm types exhibited different soil carbon and nutrient stocks (e.g. Type 2 farms had average C, N, P and K stocks that were 2-3 times larger than for Types 4 or 5). In general, soil spatial variability was larger in farms (and sites) with poorer soils and smaller in farms owning livestock. The five farm types identified may be seen as domains to target technological innovations and/or development efforts.     

Distribution of soil water-stable aggregates and organic carbon content affected by tillage systems: a meta-analysis

A better understanding of soil carbon( C) distribution within aggregate fractions is essential to evaluating the potential of no-till for sustaining productivity and protecting the environment. A metaanalysis on 744 comparisons from 34 studies was conducted to determine the effects of three different tillage treatments( conventional mouldbould ploughing tillage( CT),reduced tillage( RT) and no tillage( NT)) on water-stable aggregate size distribution,soil C concentration in aggregate fractions.The meta-analysis indicates that compared with CT treatment, NT/RT significantly( P 0. 05)increases macro-aggregate above 20 cm by 20. 9%-82. 2%( 2. 00 mm) and 5. 9%-19. 1%( 0. 25-2.00 mm),whereas NT/RT significantly reduces micro-aggregate and silt clay fractions above 20 cm.NT/RT significantly( P 0. 05) increases the SOC in macro-aggregate( 0. 25 mm) and microaggregate( 0. 25 mm) size classes above 20 cm soil depth compared with CT. The results suggest that soil sampling depth should be considered to evaluate the influence of tillage systems on the distribution of soil aggregate,and the content of aggregate-associated C content.     

Communicating complexity: Integrated assessment of trade-offs concerning soil fertility management within African farming systems to support innovation and development

African farming systems are highly heterogeneous: between agroecological and socioeconomic environments, in the wide variability in farmers’ resource endowments and in farm management. This means that single solutions (or ‘silver bullets’) for improving farm productivity do not exist. Yet to date few approaches to understand constraints and explore options for change have tackled the bewildering complexity of African farming systems. In this paper we describe the Nutrient Use in Animal and Cropping systems - Efficiencies and Scales (NUANCES) framework. NUANCES offers a structured approach to unravel and understand the complexity of African farming to identify what we term ‘best-fit’ technologies - technologies targeted to specific types of farmers and to specific niches within their farms. The NUANCES framework is not ‘just another computer model’! We combine the tools of systems analysis and experimentation, detailed field observations and surveys, incorporate expert knowledge (local knowledge and results of research), generate databases, and apply simulation models to analyse performance of farms, and the impacts of introducing new technologies. We have analysed and described complexity of farming systems, their external drivers and some of the mechanisms that result in (in)efficient use of scarce resources. Studying sites across sub-Saharan Africa has provided insights in the trajectories of change in farming systems in response to population growth, economic conditions and climate variability (cycles of drier and wetter years) and climate change. In regions where human population is dense and land scarce, farm typologies have proven useful to target technologies between farmers of different production objectives and resource endowment (notably in terms of land, labour and capacity for investment). In such regions we could categorise types of fields on the basis of their responsiveness to soil improving technologies along soil fertility gradients, relying on local indicators to differentiate those that may be managed through ‘maintenance fertilization’ from fields that are highly-responsive to fertilizers and fields that require rehabilitation before yields can improved. Where human population pressure on the land is less intense, farm and field types are harder to discern, without clear patterns. Nutrient cycling through livestock is in principle not efficient for increasing food production due to increased nutrient losses, but is attractive for farmers due to the multiple functions of livestock. We identified trade-offs between income generation, soil conservation and community agreements through optimising concurrent objectives at farm and village levels. These examples show that future analyses must focus at farm and farming system level and not at the level of individual fields to achieve appropriate targeting of technologies - both between locations and between farms at any given location. The approach for integrated assessment described here can be used ex ante to explore the potential of best-fit technologies and the ways they can be best combined at farm level. The dynamic and integrated nature of the framework allows the impact of changes in external drivers such as climate change or development policy to be analysed. Fundamental questions for integrated analysis relate to the site-specific knowledge and the simplification of processes required to integrate and move from one level to the next.     

CPSP模型在华北井灌区农业水管理中的应用

为研究不同农业水管理措施对区域水平衡的影响,选择北京市大兴区为华北井灌区代表性研究区,以CPsP模型为技术支持,研究了提高灌溉水利用率、采用亏缺灌溉、改善农业种植结构及利用区外水源等不同水管理措施影响下区域水平衡、区域耗水、区域取水及用水指标的变化规律.结果表明,在资源型缺水区域,提高灌溉水利用率、采用非充分灌溉及改善农业种植结构在一定程度上能缓解区域水资源紧缺的压力,特别是采用非充分灌溉及改善作物种植结构能显著减少区域取水及耗水总量,并能减少地表水及地下水的补给量中回归水所占比例,在缓解区域水资源紧缺压力的同时也降低了区域水质遭受回归水污染风险.另外,在未来情景中,因经济快速发展及人口持续增长,工业及居民生活用水量增加,区域水资源供需矛盾将会加剧,为确保区域水资源良性循环,势必采取积极有效的水资源管理模式.     

Managing natural resources of watersheds in the semi-arid tropics for improved soil and water quality: A review

Soil, water and production systems constitute the most important natural resources of a watershed in the rainfed agro-ecosystem; and for sustainability of the production systems they need to be in harmony with the environment. To learn from the past research, a review is made of literature on the impact of natural resource management practices on soil and water quality in the semi-arid tropical regions of India. The results from long-term on station field experiments show that an integrated use of soil and water conservation practices with balanced plant nutrition can not only sustain increased productivity but also maintain soil quality at the watershed or catchment level. Natural resource management practices that conserve soil and water also help to maintain surface and groundwater quality. The changes in soil and water quality, as impacted by natural resource management practices, need to be monitored and assessed on a continuing basis as the outcome of such research offers valuable opportunity for the implementation of corrective management practices, as and when needed.     

Modernization of irrigation systems: A case of research,oriented to improve management

In recent years, the traditional concept of an irrigation project has been changing. From just a physical structure for the storage, conveyance and distribution of water, it is now being regarded as a more complex system, including farmers' participation. This implies an improved management in all phases, from reservoir operation to farm management, and therefore the change from simple operation and maintenance to operation, maintenance and management.To face this new challenge, existing projects must be modernized. The Sorraia Irrigation Project is one of those projects. In this paper major problems are identified and it is showed how research (namely through modelling) can be oriented towards an improved management, regarding the conveyance and distribution systems as well as the on-farm systems.Finally it becomes evident that beyond the technical problems to be solved, the involvement and participation of farmers must be improved at all levels of management. Hence, there is also a need for implementing programs on education, training and extension.     

GIS tools applied to the sustainable management of water resources: Application to the aquifer system 08-29

The sustainable exploitation of water resources requires planning and control methods that allow the incorporation of a great number of spatial and temporal variables. Because of its features, a Geographic Information System (GIS) seems the most suitable tool to aid in the management of available hydric resources. In this study, we have developed a specific GIS within the GESMO Project in order to better manage the 08-29 aquifer system (Mancha Oriental). This tool is intended for use by the JCRMO: Junta Central de Regantes de la Mancha Oriental (General Board of Irrigation Users of Eastern La Mancha), the organism responsible for aquifer management.This system is designed to integrate information from different sources, such as remote sensing, fieldwork data or administrative files with the cadastral subplot as a common reference. One of its functions is to expedite the control and monitoring, in real time, of the exploitation plans, which constitute the legal instrument to regulate water extractions. It will allow us to estimate the spatial and temporal distribution of water extractions needed for crops and their irrigation systems. These estimates will be highly valuable for aquifer modelling. The system also permits display of information on maps for easy handling. This visualisation allow users to more readily participate in decision-making processes.