Agroecologgy is climate smart

Agroecology is climate smart; but this is not equivalent to say that climate smart agriculture (CSA) is synonymous with agroecology. CSA has been defined as an approach to addressing food insecurity and climate challenges through: (1) sustainably increasing agricultural productivity and incomes; (2) adapting and building resilience to climate change; (3) reducing and/or removing greenhouse gases emissions. The first priority is perhaps the most controversial one, as it is subject to the way in which ‘sustainability’ is defined and measured. In climate-dominated debates both sustainability and environmental impacts tend to be assessed almost exclusively in terms of global warming potential. Rather reductionist indicators such as CO2 emission equivalents per unit of agricultural produce are often used, masking (i) the actual performance of systems in terms of resource efficiency or generalised resilience, and (ii) non-climate related environmental impacts such as water pollution with agrochemicals or biodiversity loss. The impression is that almost anything, any technology or practice could be justified, as long as its CO2 emission equivalent per unit of produce is low. Agroecology, on the other hand, is defined as the use of ecological principles for the design and management of sustainable food systems. Agroecology is not only a scientific discipline or set of practices; social organization is the key to the spread of agroecology among family farmers around the world. Agroecological systems follow the principles of diversity, resource efficiency, recycling, natural regulation and synergies. There is no prescription or certification standard, just principles, that translate into management practices adapted to specific contexts. I will present documented examples from around the world to show how agroecology contributes to the three priorities of CSA, particularly in the context of smallholder family agriculture, and discuss the potential of agroecological principles to guide the design and management of large scale farming as well. (Texte intégral

Sustaining soil productivity of cotton-based cropping systems in the savannahs of West and Central Africa : challenges and opportunities

The production of cotton (#Gossypium# spp.) is one of the major economic activities in many countries of West and Central Africa. Traditionally, cotton production was seen as 'engine for development' in rural Africa, but deregulation and the dismantling of commodity boards, and severe fluctuations in international fibre prices led to a considerable decrease in the areas under cotton in the region and declining cotton yields. Food crops such as maize or sorghum are increasingly replacing cotton on the land cultivated by smallholders. This poses an important threat to the maintenance of soil productivity, since cotton is often the sole entry point of nutrients to the cropping system when fertilisers are provided by the industry. Te consequences of this are examined through analysis of existing agronomic and experimental evidence from cotton-based agroecosystems in the region, and ways forward for agricultural research for development are outlined. (Résumé d'auteur

Translating farmers' objectives and preferences into scenario sets for the design and assessment of (smallholder) crop-Iivestock systems

Dairy farmers of the South use a diversity of feed resources, cultivated or not, together with crop residues and different types and amounts of supplements. Feed requirements may be met by purchasing concentrated dairy meals, allocating land to fodder production or making use of the natural vegetation in communally or privately owned grazing lands. All these strategies entail different degrees of economic and environmental risks and impacts, depending on the nature of the biophysical resource base, the livelihood strategy and market orientation of the household, and the broader socio-economic context. Livelihood strategies are driven by the objectives and preferences of the decision-maker, his or her attitudes towards risks and the resulting resource allocation pattern. We examined examples from smallholder crop-livestock systems in Latin America and Africa where competing uses for financial, land and labour resources make it difficult to find an optimum design (e.g., through allocation of land to crop vs. fodder production) of the crop-livestock system. We propose the use of companion modeling to assist co-innovation processes thereby formalizing opportunities and constraints for the production systems and encompassing the decision maker objectives and preferences. This methodology is being used in two case studies in the highlands of Central Kenya and in Central Mexico. Objectives and preferences were derived through participatory work. These were used together with a dynamic simulation tool to analyse plausible pathways for intensification. The modelling tool (NUANCES-FARMSIM) includes relatively simple crop-soil, livestock, and organic resource management sub-models, a labour and a cash balance. The analytical tool includes a decision making module, equipped with a MGLP (multiple goal linear programming) model which combines stepwise the results from the dynamic simulations with prices for inputs and outputs, and objectives and preferences, making the decision making dynamic at a different temporal scale. The results of the modelling exercise are presented to the farmers and other stakeholders to stimulate discussions on alternative management of their systems. Lessons learnt from the companion modelling exercises show that most dairy farmers making non-optimal tactical decisions and are willing to stay in the sector at lower profit levels and the model selects using the objectives and preferences reported by the farmers. According to the simulations, strategic decisions such as planning replacements and balancing the herd structure results in the largest biophysical productivity and profit at a large range of prices of inputs and outputs. (Résumé d'auteur

Food sovereignty and consumer sovereignty: two antagonistic goals?

The concept of food sovereignty is becoming an element of everyday parlance in development politics and food justice advocacy. Yet to successfully achieve food sovereignty, the demands within this movement have to be compatible with the way people are pursuing consumer sovereignty, and vice versa. The aim of this article is to examine the different sets of demands that the two ideals of sovereignty bring about, analyze in how far these different demands can stand in constructive relations with each other and explain why consumers have to adjust their food choices to seasonal production variability to promote food sovereignty and so secure future autonomy

Carbon and nutrient losses during manure storage under traditional and improved practices in smallholder crop-livestock systems - evidence from Kenya

In the absence of mineral fertiliser, animal manure may be the only nutrient resource available to smallholder farmers in Africa, and manure is often the main input of C to the soil when crop residues are removed from the fields. Assessments of C and nutrient balances and cycling within agroecosystems or of greenhouse gas emissions often assume average C and nutrient mass fractions in manure, disregarding the impact that manure storage may have on C and nutrient losses from the system. To quantify such losses, in order to refine our models of C and nutrient cycling in smallholder (crop-livestock) farming systems, an experiment was conducted reproducing farmers’ practices: heaps vs. pits of a mix of cattle manure and maize stover (2:3 v/v) stored in the open air during 6 months. Heaps stored under a simple roof were also evaluated as an affordable improvement of the storage conditions. The results were used to derive empirical models and graphs for the estimation of C and nutrient losses. Heaps and pits were turned every month, weighed, and sampled to determine organic matter, total and mineral N, P and K mass fractions. Soils beneath heaps/pits were sampled to measure mineral N to a depth of 1 m, and leaching tube tests in the laboratory were used to estimate P leaching from manure. After 6 months, ca. 70% remained of the initial dry mass of manure stored in pits, but only half of or less of the manure stored in heaps. The stored manure lost 45% of its C in the open air and 69% under roof. The efficiencies of nutrient retention during storage varied between 24–38% for total N, 34–38% for P and 18–34% for K, with the heaps under a roof having greater efficiencies of retention of N and K. Laboratory tests indicated that up to 25% of the P contained in fresh manure could be lost by leaching. Results suggest that reducing the period of storage by, for example, more frequent application and incorporation of manure into the soil may have a larger impact on retaining C and nutrient within the farm system than improving storage condition

Talking soil science with farmers

When agricultural researchers visit farms in order to gather information for their research programmes, farmers rarely get proper feedback. Research information on scientific concepts such as soil fertility and nutrient balances is often considered too abstract for them. Researchers in Kenya returned to farmers to discuss their results in the context of Farmer Field Schools. Through the workshops that ensued, they managed to find a common language to bridge the communication gap

Towards understanding factors that govern fertilizer response in casave: lessons from East Africa

Information on fertilizer response in cassava in Africa is scarce. We conducted a series of on-farm and on-station trials in two consecutive years to quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda and to evaluate factors governing the responses. Average unfertilized yields ranged from 4.2 to 25.7 t ha-1 between sites and years. Mineral fertilizer use increased yields significantly, but response to fertilizer was highly variable (-0.2 to 15.3 t ha-1). Average yield response per kg applied nutrient was 37, 168 and 45 and 106, 482 and 128 kg fresh yield per kg of applied N, P and K, respectively in 2004 and 2005. Fertilizer response was governed by soil fertility, rainfall and weed management, but was not influenced by variety, pest and disease pressure and harvest age. Relative N and K yields were positively correlated to SOC and exchangeable K, while response to fertilizer decreased on more fertile soils. Still, fertilizer response varied widely on low fertility soils (e.g. on soils wit