Ramadjita Tabo

Fertilizer Microdosing and “Warrantage” or Inventory Credit System to Improve Food Security and Farmers’ Income in West Africa

The fertilizer microdosing technology deals with the application of small quantities of fertilizers in the planting hole, thereby increasing fertilizer use efficiency and yields while minimizing input costs. In drought years, microdosing also performs well, because larger root systems are more efficient at finding water, and it hastens crop maturity, avoiding late-season drought. Recent research found that solving the soil fertility problem unleashes the yield potential of improved millet varieties, generating an additional grain yield of nearly the same quantity. Recognizing that liquidity constraints often prevent farmers from intensifying their production system, the warrantage or inventory credit system helps to remove barriers to the adoption of soil fertility restoration. Using a participatory approach through a network of partners from the National Agricultural Research and Extension Systems (NARES), non-governmental organizations (NGOs), farmers and farmer groups and other international agricultural research centres, the microdosing technology and the warrantage system have been demonstrated and promoted in Burkina Faso, Mali, and Niger during the past few years with encouraging results. Sorghum and millet yields increased by up to 120%, and farmers’ incomes went up by 130% when microdosing was combined with the warrantage system. This chapter highlights the outstanding past results and the ongoing efforts to further scale up the technology using Farmer field schools (FFS) and demonstrations, capacity and institutional strengthening, private sector linkages and crop diversification amongst other approaches.

Building Capacity for Modeling in Africa

The use of models in decision support is important as field experiments provide empirical data on responses to only a small number of possible combinations of climate, soil, and management situations. Yet, crop modeling by African scientists so far has been limited. Therefore, to build the capacity of African scientists in the use of decision support systems, a provision was made for training within two main projects: Water Challenge Project (WCP) and Desert Margins Programme (DMP), jointly led by TSBF-CIAT (Tropical Soil Biology and Fertility Institute of the International Centre for Tropical Agriculture) and International Centre for Research in the Semiarid Tropics (ICRISAT). A unique approach to training on modeling was developed and was based on four main pillars: (a) learning by doing, (b) integrated follow-up, (c) continuous backstopping support and (d) multi-level training embedded in a series of three training workshops. Although crop models are useful they have limitations. For instance, they do not account for all of the factors in the field that may influence crop yield and inputs must be accurate for simulated outputs to match observations from the field. Thus it is imperative that these issues are carefully considered and weighted before attempting to evaluate the predictability of a crop model. However, the use of crop models and decision support systems in concert with experiments can provide very useful alternative management options for resource-poor farmers in Africa and other regions across the globe.

Estimation of nitrogen flow within a village-farm model in Fakara region in Niger, Sahelian zone of West Africa

To determine the efficiency of utilization of organic matter in agricultural production, nitrogen flow was estimated within a village-farm model in the west of Niger, West Africa. Nitrogen was focused on in this study as it is known to be a major nutrient component of organic matter and one of the limiting nutrients in Sahelian soil. Local practices regarding the use of organic matter and pertinent information on traditional practices for soil fertility management were determined by interviews with local farmers. To estimate nitrogen flow in farmlands and consumption in the village through various activities, quantitative measurements of crop yield and organic amendment were carried out. Data on human and livestock excreta were taken from published reports. The size and classification of farmlands were as follows: 0.5xa0ha adjacent farmland, 1.6xa0ha threshing farmland, 6.0xa0ha transported-manure farmland, 5.5xa0ha corralling farmland, and 86.5xa0ha extensively managed farmland (EMF). Levels of nitrogen flow from these farmlands to the studied villages were 0.9, 2.9, 9.6, 15.2, and 94.2xa0Mg, while the flows to these farmlands were 14.6, 6.3, 13.7, 17.5, and 26.3xa0Mg, respectively. Upon calculation of nitrogen balance −8xa0kgxa0ha−1xa0year−1 was estimated in EMF, but there was a positive balance in other types of farmland, which ranged from 4 to 262xa0kgxa0ha−1xa0year−1, indicating inefficient use of nitrogen in the study area for crop production. The results indicated that nutrient flow in the study site was unequally distributed and nitrogen was not recycled. Therefore, efforts should be made to establish efficient utilization of available nutrients by reducing the loss from livestock feed and human consumption. At the same time, more research is needed to improve the management of EMF.

Rothamsted carbon model reveals technical options to maintain soil organic carbon under semi-arid climate

Soil organic matter in the Sahel is severely reduced by continuous cultivation. Reductions of soil organic matter decrease in turn soil productivity. Nonetheless, reports show that organic matter application in the Sahel improves crop yield. However, long-term effects of organic matter application on soil fertility have not been fully studied. In particular, it is essential to get information on organic matter decomposition and annual carbon requirement. Model simulation is suitable for evaluating long-term sustainability. The Rothamsted carbon model is convenient and has been recently validated for use in Sahelian conditions. Here, we studied the annual carbon requirement for sustainable soil organic carbon management in the Sahelian zone using datasets of short-term trials conducted in the Sahel. We estimated the long-term effect of various agricultural managements on soil organic carbon dynamics as one of the soil fertility indices. The 10-year soil organic carbon value changes were predicted by the Rothamsted carbon model for 59 treatments. Results show that, contrary to previous short-term experiments that indicated crop yield enhancement, these technical options also cause a decline in soil organic carbon if enough organic resource is not applied. Soil productivity should therefore decrease. The annual carbon requirement to maintain the soil organic carbon level is approximately 0.8xa0tons of carbon per hectare.

Effect of Integrated Soil Fertility Management Technologies on the Performance of Millet in Niger: Understanding the Processes Using Simulation

Low soil fertility and erratic rainfall are the most limiting factors to crop production, in the Sudano-Sahelian zone of West Africa. The region is the home of the world’s poorest people, 90% of whom live in villages and gain their livelihood from subsistence agriculture. However, yields of cereals in general, and millet in particular that constitute the staple food of rural people, are very low (300–400 kg/ha). Research has developed technologies of integrated soil fertility management, but resource poor farmers have not adopted them. DSSAT (Decision Support System for Agrotechnology Transfer) is a tool incorporating models of 16 different crops with software that facilitates the evaluation and application of crop models for different purposes. Its use requires a minimum data set on weather, soil, crop management and experimental data. The simulations from these data can help scientists to develop promising management options to improve farmer’s conditions. However, requirements for such model use is to evaluate its capabilities under farming xadsituations, soils, and weather that are characteristic of the area where it will be used. This study was conducted to evaluate the DSSAT millet model capabilities for xadsimulating the interactions between soil fertility and millet yields in three sites (Banizoumbou, Bengou and Karabedji) of Niger over 5 years (2001–2005) and xaddifferent nitrogen management.