Push—pull technology: a conservation agriculture approach for integrated management of insect pests,weeds and soil health in Africa

Push—pull technology (www.push-pull.net) is based on a novel cropping system developed by the International Centre of Insect Physiology and Ecology, Rothamsted Research (UK) and national partners for integrated pest, weed and soil management in cereal—livestock farming systems. Stemborers are attracted to Napier grass (Pennisetum purpureum), a trap plant (pull), and are repelled from the main cereal crop using a repellent legume intercrop (push), desmodium (Desmodium spp.). Desmodium root exudates effectively control the parasitic striga weed by causing abortive germination. Desmodium also improves soil fertility through nitrogen fixation, natural mulching, improved biomass and control of erosion. Both companion plants provide high value animal fodder, facilitating milk production and diversifying farmers' income sources. The technology is appropriate to smallholder mixed cropping systems in Africa. It effectively addresses major production constraints, increases maize yields from below 1 to 3.5t/ha, and is economical as it is based on locally available plants, not expensive external inputs. Adopted by over 30,000 farmers to date in East Africa, key factors in its further up-scaling include effective technology dissemination, adaptability of companion plants for climate resilience, capacity building and multi-stakeholder collaboration, integration with livestock husbandry, improvement in input accessibility and creation of a supportive policy framework.     

Profitability and opportunity of conservation agriculture in acid savannah grasslands of Laos

In north-eastern Laos, the savannah grasslands of the Plain of Jars cover vast areas of potentially cultivable land. However, soil acidity, low inherent fertility, and the absence of alternatives to tillage represent significant constraints to the development of sustainable smallholder agriculture. Our objective was to evaluate the potential for conservation agriculture (CA) to enhance soil productivity and farming system profitability. A three-year rotation of rice/maize/soybean was tested under three fertilization levels and four agricultural systems: one conventional tillage-based (CT) system and three CA systems based on no-tillage with cover crops. After four cropping seasons, our results show that, compared with CT, CA systems led to similar-to-higher grain production, similar-to-higher profits, higher opportunity of livestock system intensification, and higher labour productivity regardless of fertilization levels. While CA represents a relevant alternative to current practices, our results suggest that its contribution to the emergence of a sustainable smallholder agriculture is conditioned by broader institutional transformations, including the enrolment of local manufacturers and traders for deploying no-till implements and seed market channels for cover crops, long-term public support to maintain active research and technical mentoring to farmers, and possibly the integration of ecosystem services in agricultural policy.     

Gliricidia sepium Carbon Inputs and Soil Carbon Pools in a Costa Rican Alley Cropping System

Alternative land management practices, including agroforestry, help to maintain levels of soil organic matter (SOM) and can facilitate soil carbon (C) sequestration for mitigating atmospheric CO₂ emissions. This study quantified C inputs and determined the changes of the soil C pool in a 19-year-old Gliricidia sepium alley cropping system, studied at two fertiliser levels (tree prunings only [? N], and tree prunings plus chicken manure [+ N]), and was compared to a sole crop system. Carbon input from tree prunings ranged from 455 to 457 g C m^{? 2} y^{? 1}, whereas C inputs from crop residues were similar between alley- and sole crops ranging from 121 to 159 g C m^{? 2}y^{? 1}. The soil organic C (SOC) pool in the alley crop was 16–23% higher than the sole crop. In the 19th year of alley farming, SOC was significantly higher (p < 0.05) in the alley crop (3.2%) compared to the sole crop (2.4%), and was also greater compared to that at the time of establishment of the agroforestry system (2.8%). Gross SOC turnover to a 20-cm depth ranged from 12 to 14 years in the + N and ?N alley crops compared to 49 and 50 years in the + N and ?N treatments for the sole crops. Residue stabilisation efficiency in the alley crops was 39% and 55% in + N and ?N treatments respectively.     

Does mixed crop‐livestock farming lead to less diversified diets among smallholders? Evidence from Laos

Malnourishment continues to remain a challenge in developing countries. As the undernourished are largely smallholder farmers, it is widely assumed that farm diversification and mixed crop‐livestock agricultural systems can help alleviate this problem. However, empirical evidence in this context is limited. Hence, we use a two‐year panel's data from Laos to examine whether farm production diversity as well as a mixed crop‐livestock farming system improves household dietary diversity among smallholder farmer. The results from the fixed effects regression indicate that although farm production diversity does lead to a higher dietary diversity, the effect diminishes with continued farm diversification. The counterfactual analysis from the endogenous switching regression reveals that mixed crop‐livestock farming systems do not necessarily enhance dietary diversity. However, we further find that purchasing food from the markets plays an important role in enhancing the dietary diversity of rural smallholder farmers.     

Farm-level adaptation to climate change in Western Bangladesh: An analysis of adaptation dynamics,profitability and risks

Using long-term district-level climate data and a case study from a drought-prone village in western Bangladesh, this research explored trends in climate change, and analysed farmers’ adaptation dynamics, profitability and risks. This is the first study of its kind for drought-prone areas in Bangladesh.Farmers perceived climate changes included increases in temperature and decreases in rainfall which were as consistent with the trends of Chuadanga climate records. Farmers’ adaptation measures included changes in cropping systems, cropping calendars, crop varieties, agronomic practices, crop diversification and improved animal husbandry. Reducing environmental stress, ensuring self-sufficiency in staple crops (mainly rice) and other crop production practices, and enhancing economic viability of farm enterprises have underpinned these adaptations. Off-farm and non-farm wage employment, temporary migration, self-employment and educating children, constituted the core non-farm adaptation strategies.Emerging cropping systems like maize/cucumber and maize/stem amaranth/rice were economically more viable than the traditional rice/rice and rice/maize systems. Despite some uncertainties, farming was preferred to off-farm work, generating higher returns to labour for all cropping systems. Limited access to stress-tolerant varieties, extension services and affordable agricultural credit, combined with high production costs, variability in crop yields and output prices, are the main barriers to adaptation. Stronger agricultural research and support services, affordable credit, community-focussed farming education and training are critically important for effective adaptation to climate change.     

Enhancing ecosystem services in vineyards: using cover crops to decrease botrytis bunch rot severity

Botrytis bunch rot is a disease that causes loss of yield and quality in many fruit and vegetable crops in temperate climates worldwide. The rot is caused by the fungus Botrytis cinerea, a saprophytic necrotroph. In grapes, the presence of the fungus can reduce yield, taint wine and increase its sensitivity to oxidation. In the current work, inter-row phacelia and ryegrass were mulched in situ in winter 2005 and compared with a bare ground control. The mulches were applied under 10-year-old Chardonnay vines in a 10-replicate randomized block design in New Zealand. Functional soil biological activity increased by 1.5–4.5 times in the two cover crop treatments compared with the control, an effect related to elevated soil moisture in these treatments. This increase in soil moisture and a higher rate of soil biological activity increased vine debris degradation, reduced B. cinerea primary inoculum on the debris and decreased B. cinerea severity at flowering (December 2005) and harvest (April 2006). These results show the potential of mulched cover crops to enhance soil ecosystem services, reduce variable costs and improve the sustainability of viticulture and potentially other agricultural systems, in temperate climates worldwide.     

Soil and cropping system research in semi-arid West Africa as related to the potential for conservation agriculture

Semi-arid West Africa faces challenges to increase sorghum and pearl millet production to meet food needs for a growing human population while increasing soil carbon (C), nutrient levels, and water holding capacity that are documented benefits of conservation agriculture. This review focuses on the wealth of research on cropping systems, tillage, crop residue, nutrient, and weed management as related to conservation agriculture. It also identifies needs for multidisciplinary, integrative research to assist the transition from current production systems to conservation agriculture. Crop residue use as livestock feed, or fuel are major constraints to adoption of conservation agriculture, which could be reduced by wood production in agroforestry systems, alternate energy sources, and increased forage supply. Crop residue and grain yields are related, thus improved crop, soil, water, nutrient, and weed management to increase grain yield would also increase the supply of crop residue with potential for ‘left over’ crop residue being available for soil mulching. Incorporating indigenous shrubs and/or cover crops could also increase crop residue supply. Species diversity can be increased through crop rotation, agroforestry, cover crops, and intercrops. Higher grain and stover yields and increased profit potential for resource-poor farmers in West Africa will be required before wide-scale adoption of conservation agriculture will be possible.     

Input subsidies and crop diversity on family farms in Burkina Faso

Since their independence, many countries in sub-Saharan Africa have used input subsidies to increase agricultural productivity and improve food security. We analyse the effects of both a fertiliser and a seed subsidy on farming households' land allocation among crops and crop diversity in Burkina Faso. Although previous studies investigated either the impact of a fertiliser or a seed subsidy on targeted crops, few examined the effects of both subsidies combined. Applying a correlated random-effects model with a control function approach to nationally representative, 2-year panel data collected from farming households, we find that those with access to the fertiliser subsidy allocate more land to the crops it targets (rice, maize and cotton) than non-targeted crops. Focusing on a minor crop with key agronomic and nutritional attributes, we conclude that land allocation to cowpea as the primary crop and intercrop declined with the fertiliser subsidy. The fertiliser subsidy also negatively affects crop diversity. However, we find that the cowpea seed subsidy offsets the bias of fertiliser subsidy toward fertiliser-targeted crops and enhances diversity.     

Perennial grain crops in the West Soudanian Savanna of Mali: perspectives from agroecology and gendered spaces

Perennial grain crops may play an important role in environmentally sound and socially just food systems for Africa. We study the future possibility of integrating perennial grains into Malian farming systems from the perspective of agroecology, and more specifically using a gendered space approach. We interviewed 72 farmers across the sorghum-growing region of Mali. We found that perennial grains offer a vision for transforming human relations with nature that mirrors the resource sharing of customary land tenure, including patterns of extensive and intensive land use in time and space. Women interviewees identified a broad set of potential advantages and challenges to perennial grain production. Advantages include reduced labour, saving seed, and improving food security. Women farmers were concerned about livestock, water access, and resource limitations. We argue that perennial grains may increase access to land and natural resources for women farmers. Perennial grains may improve soil quality, reduce labour early in the rainy season, and provision more resources from fallow lands. Pastoralists stand to benefit from improved pastures in the dry season. We conclude that investments are needed to develop viable crop types in consideration of the complexity of West African farming systems and the local needs of women farmers and pastoralists.     

“一带一路”背景下新疆农业水土资源配置研究

[目的]新疆作为"一带一路"发展战略的核心区,为新疆地区经济的发展带来了新的机遇。但如何提高农产品在国际市场上的竞争力,如何处理全区的水土等资源的合理配置是目前新疆地区面临的首要问题。[方法]文章以新疆农产品对中亚5国比较优势为背景,以2015年全区的农业投入产出情况作为基础数据,采用线性规划模型,借助Matlab软件进行求解,对新疆地区的水土资源进行有效分配,以全区的农业结构优化方案作为表现形式。[结果]新疆地区应减少小麦、玉米、棉花等效益较低、耗水较高、用工较多的作物种植面积,增加大豆、马铃薯等可套种、可抗旱且收益较高的作物种植面积,增大葵花、蔬菜、果用瓜、苜蓿等经济作物种植面积。同时,该地区应扩大畜牧业的养殖数量,并增加饲草的来源。[结论]基于"一带一路"倡议,新疆需充分利用地缘优势,以经济效益最大化为发展目标,对全区农业结构进行优化调整,以达到水、土等资源的合理配置,最终推动新疆地区与中亚5国的农产品贸易良好发展。     

Integration of conservation agriculture in smallholder farming systems of southern Africa: identification of key entry points

A component-omission experiment based on the principle of conservation agriculture (CA) was established on smallholder farms for three seasons in Murehwa and Hwedza districts, Zimbabwe; Barue district in Mozambique; Balaka district and Chitedze Research Station in Malawi, and Monze district in Zambia to identify strategies for improving crop productivity and livelihoods for smallholder farmers. The objective of the experiment was to evaluate the effect of tillage, residue retention, fertiliser application and weed control on maize yield. In addition, the study analysed possible combinations of these factors that could provide a sustainable entry point for intensification through CA. Results showed that fertilisation had the strongest effect on crop yield in both tillage systems; adequate fertilisation is therefore key to success in CA. Retention of crop harvest residues increased yield in no-tillage systems; no-tillage without residues depressed yield by 50% when compared with yields of conventional tillage. A step-wise integration of CA into the smallholder farming systems is proposed as a possible strategy to avoid new constraints on smallholder farms. If resources are limiting, farmers may apply all principles on small areas to overcome the initial demand in resources (labour, fertiliser and residues), and once productivity is raised, they can expand.     

Conservation agriculture practices adopted in southern Brazil

The adoption of conservation agriculture (CA) practices are essential for soil and water conservation. In CA, farmers must adopt no-tillage (NT) with crop rotation to maintain a permanent soil cover. In Brazil, mainly in the South region, for CA to be more efficient, practices such as contour farming and agricultural terraces should also be adopted. Thus, the objective of this study is to determine the extent to which NT has been adopted with crop rotation and others soil and water conservation practices. Data from the Agricultural Census in Paraná State, southern Brazil, were used. For the data analysis, the relationship between the level of adoption of NT and the use of crop rotation, contour farming and agricultural terraces was analyzed. A factor and cluster analysis were performed to distinguish regions in terms of soil and water conservation practices. The results show good overall soil and water conservation practices, although heterogeneity has been observed in the adoption practices between regions. Adoption of NT is high in almost all the studied regions. The conservation practice most widely used with NT is contour farming, whereas the least used is agricultural terraces. Conservation practices for runoff control are being neglected by farmers.     

Flexible adoption of conservation agriculture principles: practices of care and the management of crop residue in Australian mixed farming systems

This paper applies concepts from the sociological literature on ‘practices of care’ to investigate why flexibility is important for farmers in the adoption of conservation agriculture (CA) principles, and, crucially, how farmers integrate CA principles into their existing practices. Drawing on qualitative data from six mixed farming regions in South Eastern Australia, the paper discusses how a specific dimension of CA – crop residue retention – is integrated in the context of biophysical and material challenges, and practices of stubble burning. Farmers viewed burning as increasingly incompatible with their desire to be recognised as good land managers. Yet, shifting to full crop residue retention was perceived as posing challenges for their farming system and compromising farmers’ capacity to manage seasonal variations in pests, weeds and crop residue loads. As a consequence, farmers used burning as a key practice of care to deal in a flexible way with an uncertain and variable farming environment, and to make crop residue retention workable in the context of their farming system. In concluding, the paper argues that the significance of flexibility in farm-level integration of CA principles requires a shift in analytical focus from adoption barriers to practices of care.     

An African success: the case of conservation agriculture in Zimbabwe

This paper highlights the limiting factors of agricultural production in Zimbabwe and presents conservation agriculture (CA) as a potential solution to address many of these challenges. CA, based on the three principles of minimum soil disturbance, crop residue retention and crop rotations, targets low soil fertility, moisture deficits and low management standards through the use of soil-fertility-enhancing technologies (precision fertilizer application, crop rotations, sequencing and interactions), improved moisture use efficiency and higher standards of agronomic management practices. The paper also explains the role of CA in natural resource conservation as increasing productivity will reduce the land under crop production and increase the area under natural vegetation. Trends in the development of CA in the past five years and its current status in the country are explained, with the roles of different stakeholders outlined. Evidence on the impact of CA on both food security and the environment is presented. In conclusion, the paper looks at the various factors that may affect the spread of CA to different agro-ecological zones in the country.     

Improving the productivity of vertisols in the Accra plains of Ghana using leguminous cover crops

The productivity of the Vertisols of the Accra plains is low, in spite of its high potential fertility. This could be attributed to physical constraints and low organic matter content. A study was conducted at the Agricultural Research Centre, Kpong, to assess the suitability of Mucuna pruriens, Mimosa invisa and Stylosanthes guianensis, in short fallows, for improving the fertility, physical properties, moisture conservation and weed control in the case of these soils. Mucuna had the highest biomass of 5.3tha^?1, as opposed to 4.1tha^?1 under natural fallow. The mucuna and stylosanthes biomass had comparatively higher total N values (240.75 and 203.51kgha^?1, respectively) than mimosa and natural fallow (152.46 and 162.74kgha^?1, respectively). Soil organic carbon, one year after the incorporation of cover crops, was found to be relatively higher under the cover crops (mucuna, stylosanthes and mimosa) than it was under natural fallow. Bulk densities were thus lower under the cover crops than they were under natural fallow. Also, soils under the cover crops had higher total porosity, water infiltration rates and moisture storage than they did under natural fallow. Weed cover, 115 days after planting maize, was significantly lower in plots previously under Mucuna pruriens than it was under natural fallow, Stylosanthes guianensis and Mimosa invisa. There was a negative linear correlation between cover crop biomass and weed density (R ² = 0.593–0.805). Grain and stover yields of maize were higher under Mucuna pruriens than they were under natural fallow (138 and 70 per cent higher, respectively). Burning of the natural fallow resulted in greater weed growth than when the material was worked into the soil (41 and 8 per cent, respectively). Grain yield was significantly greater under mucuna than it was under natural fallow (3.1 and 1.3tha^?1, respectively).     

Identifying agroecological mixed farming strategies for local conditions in San Antonio de Los Baños,Cuba

Building on previous research at the experimental and national scales, this study was carried out at the local scale over a four-year period on three farms of reference: one specialized dairy farm ‘Vaquería 10’ (33.7 ha) and two mixed farms, ‘Remedio’ (9.4 ha) and ‘La Sarita’ (47 ha). All three farms are located in the San Antonio de Los Baños municipality, Havana, Cuba. This study illustrates the application of the Ecological Framework for the Assessment of Sustainability (ECOFAS). This methodology consists of a cyclical structure of six steps, aimed at guiding the process of implementing innovative mixed (crop–livestock) farming strategies. Local stakeholders (farmers, researchers, extension officers and representatives of the ministry of agriculture in the municipality) identified alternative strategies for agriculture in the region, based on the critical technological, environmental and socio-economic factors constraining the current performance of farming systems. The results show that implementation of ‘best practice’ mixed farming systems management strategies in the region potentially can lead to a strong positive impact on land productivity, food self-sufficiency as well as improve socio-economic performance.     

Economic analysis of different options in integrated pest and soil fertility management in maize systems of Western Kenya

The major biotic constraints to the production of maize, the major staple food in Western Kenya, are field pests such as Striga and stem borers, and low soil fertility. To counter these constraints, new cropping systems have been developed, including “push‐pull,” rotations with promiscuous soybean varieties and green manure crops, and imidazolinone resistant‐ (IR‐) maize. To analyze the technical and economic performance of these technologies, both with and without fertilizer, on‐farm researcher‐managed long‐term trials were implemented over six seasons in two sites each in Vihiga and Siaya districts of Western Kenya. The economic results, based on marginal analysis using a multioutput, multiperiod model, show that the new cropping systems with fodder intercropping (push‐pull) or soybean rotations were highly profitable. Push‐pull is more profitable but requires a relatively high initial investment cost. Green manure rotation, IR‐maize, and fertilizer all increased yields, but these investments were generally not justified by their increased revenue. We argue that research on rotation and cropping systems to tackle pest and soil fertility problems in Africa deserve more attention. This will require increased collaboration between agronomists and economists to set up long‐term experiments with new cropping systems to develop proper economic models.     

Soyabeans and sustainable agriculture in southern Africa

Maize is the dominant staple crop across most of southern Africa—it is so dominant in some areas that more than 80 per cent of the smallholder land area is planted with maize. Soyabean was identified as the crop with a potential to address the need for diversifying the cropping systems, which could assist in overcoming the pervading soil fertility constraints and could provide smallholder farmers with an opportunity to earn income while also addressing the nutritional security of households. An initiative was launched in the 1996/97 cropping season in Zimbabwe, to test soyabean as a potential smallholder crop. From an initial 55 farmers in the first year, soyabean production expanded rapidly to an estimated 10,000 farmers three years later. Since then, soyabean has diffused spontaneously to most smallholder farming areas in the higher rainfall zones of Zimbabwe. Thus, the initiative has assisted a large number of smallholders to grow soyabean, and exploded a long-held belief in Zimbabwe that soyabean is not a suitable crop for smallholders.     

基于Shift-Share模型的“镰刀弯”地区食增产结构变动分析——兼论玉米种植结构调整

[目的]"镰刀弯"地区玉米种植面积大幅度增加,粮食种植结构单一,为确保粮食安全稳定、多元化发展,需要明确该地区粮食生产结构中不同作物的变化特点和竞争优势.[方法]文章运用Shift-Share模型对"镰刀弯"地区的粮食作物生产结构和竞争力优势进行比较,分析了水稻、玉米、薯类、豆类以及其他作物的结构和竞争力优势差异.[结果]"镰刀弯"地区内部不同区域之间不同作物的结构优势和竞争力优势差异明显,其主要原因在于不同作物的播种面积和单位面积产量增长变动速度不同.[结论]"镰刀弯"地区粮食种植结构的调整,尤其是玉米种植面积的调减,应当充分考虑不同作物之间的优势差异,在满足可持续发展和市场需求且不形成过度供给的情况下,增加优势作物的种植,最终形成合理的种植结构和区域布局.     

Participatory trials and farmers' social realities: understanding the adoption of legume technologies in a Malawian farmer community

This article presents results from a study exploring the reasons for low adoption of legume technologies to improve soil fertility by farmers from a community in central Malawi who took part in participatory trials. This study explores the influence of gender roles in agriculture and land ownership and socio-economic differentiation in the community. Because most women do not own land and are traditionally responsible for legume crops, they have little interest in managing soil fertility for maize crops. Men are not interested in using legumes in maize-cropping systems. Some are too poor: this group needs to complement their subsistence maize production with paid labour on the farms of better-off farmers; restricting the labour availability for their own farming activities. Wealthier farmers have access to, and prefer to use chemical fertilizer and cattle manure. Take-up rates among the middle group of farmers were also low. This study discusses how these (and other) factors influence the (non-)adoption of maize-legume technologies in Malawi and the effectiveness of participatory research. It emphasizes how differentiated farmer-realities affect the uptake of technologies identified as promising in participatory field evaluations.