Integrated Management of Soil Fertility and Land Resources in Sub-Saharan Africa: Involving Local Communities

The soils of sub-Saharan Africa are characterized by their poverty in nutrients along with low clay and organic carbon content and low exchange capacity. There is high pressure on land resources with the quick growth of population and demand for food. Maintaining the fertility of cultivated soils and land resources is a challenge. Since the paradigm of “external input” in the 1960s and 1970s, to the latest concept of integrated soil fertility management, most of the approaches remain crop oriented or livestock oriented with less attention to local communities (LC), which are at the heart of land resource management. This chapter suggests a new integrated and holistic approach involving LC for land resources management, including cultivated soils and rangelands. A global framework is proposed for development of management options of land resources with LC. It is a dynamic process of participative management of lands as providers of services for the entire community

Developing fertilizer recommendations for rice in Sub-Saharan Africa, achievements and opportunities

Improving agricultural productivity to keep pace with the fast-growing food demand is a huge challenge for sub-Saharan Africa (SSA). Fertilizer is a powerful productivity-enhancing input; nevertheless, farmers of SSA use only 5–9 kg ha−1 of fertilizer, which is ten times lesser than Latin America and Asia (50 and 80 kg ha−1, respectively). Rice (Oryza sativa) is one of the most important food crops of SSA, and its consumption is growing faster than any other commodity in Africa. Rice-based systems have high potential for improving food production through an efficient management of fertilizers. The biophysical environment, cropping systems and socio-economic status of farmers including market opportunities are the main factors for developing appropriate fertilizer recommendations. Many research efforts have been invested in different countries to develop fertilizer recommendation for rice. However, the diversity of rice ecologies, the type and the cost of fertilizers available on local market are the main constraints for development of blanket recommendations of fertilizer usually applied in many countries. Here, we make a reviews of the progress made on the development of fertilizer recommendations for rice-based systems in SSA. The utilization of the new concepts and decisions support tools for development of fertilizer recommendation and the main achievements and weakness are discussed. The opportunities offered by the new concepts, modeling and decision support tools are discussed in a regional strategic approach for better management of fertilizers in the diversified ecologies of rice-based systems

Effect of nitrogen fertilizer on yield and nitrogen use efficiency of four aromatic rice varieties

The objective of this study was to optimize nitrogen fertilizer for higher yield and nitrogen use efficiency of four aromatic rice varieties. Field experiments were conducted at Ndiaye and Fanaye (Senegal) during the hot and dry season 2012 and the wet season 2012 to evaluate the effect of nitrogen on rice yield and nitrogen use efficiency under phosphorus and potassium omission management. Five rates of nitrogen (0, 60, 90, 120 and 150 kg/ha) were associated with P (26 kg P/ha); or P-K (26 kg P/ha and 50 kg K/ha). Four aromatic rice varieties Pusa Basmati, Sahel 329, Sahel 177 and Sahel 328 and a non-aromatic variety Sahel 108 were evaluated. Results showed that across genotypes, rice yield varied from 3.3 to 8.6 Mg/ha under N-P fertilizer and from 3.5 to 8.8 Mg/ha under N-P-K fertilizer at Ndiaye. At Fanaye, rice yield varied from 3.7 to 8.6 Mg/ha under N-P fertilizer and from 3 to 10.3 Mg/ha under N-P-K fertilizer. The highest grain yield was obtained by Sahel 177 among the aromatic rice varieties. The optimum nitrogen dose varied with rice genotype and location. The PFPN and the ANUE were influenced by genotype and varied from 161 to 28 kg grain/kg N and from 105.9 to 0.9 kg grain/kg N, respectively. The highest PFPN was obtained by Sahel 108 followed by Sahel 177. K addition to N-P significantly increased ANUE from 6.4 to 20.78 kg grain/kg N. The aromatic rice variety Sahel 177 is the performing alternative to the non-aromatic rice Sahel 108 in Senegal

Evaluation of the feed quality of six dual purpose pearl millet varieties and growth performance of sheep fed their residues in Niger

Pearl millet (Pennisetum glaucum) is a staple food popularly cultivated by small farmers in Niger. The stover are also used as feeds for livestock (small ruminant) as basal diet, especially during the cold dry season. ICRISAT has developed many dualpurpose millet varieties that aim to increase feeds for livestock while providing grain as food to farmers. But the nutritional quality of Stover of these varieties for livestock are not known. This research aims to assess the quality of residues of the dual-purpose varieties and their effect on feed intake and live weight changes of young sheep

Restoration of Degraded Lands in West Africa Sahel: Review of experiences in Burkina Faso and Niger

This is a comprehensive literature review of land restoration activities in West Africa Sahel. Water constraints and the inherent soil poverty are the major factors that limit crop yields and productivity of cropping systems in West Africa Sahel (WAS). Livestock is not well integrated with agricultural activities and crop residues are usually exported from the farm for household needs and animal feeding. In traditional systems, soil fertility maintenance was based on a relatively long fallow period (10-15 years) followed by a short cropping period of 3 to 5 years. But the increased population pressure has resulted in significant changes of the traditional bushfallow system. Lands are now continuously cultivated for long period with low external inputs, leading to soil fertility decline over time (Bationo and Mokwunye 1991; Bekunda et al. 2010). In addition to biophysical aspects, a wide range of socio-economic factors such as the low financial capacities of poor farmers to invest in agricultural inputs, high pressure on ecological resources for food, fodder or energy, also add to the stress on the systems. Failure by the smallholder farmers to intensify agricultural production in a manner that maintains soil productivity is the main cause of land degradation, particularly in the fragile ecosystems of WAS. Land degradation is defined as a process that leads to the reduction of land productivity for useful purposes, and is typically a result of soil, wind, or water erosion; soil salinization; waterlogging; chemical deterioration; or any combination of these factors (Adeel 2003). Land degradation is a global problem, particularly in the dry areas, home to a large population of poor farmers, where land degradation and water scarcity are major threats to food security. The impacts of land degradation are severe on both human society and ecosystems. Desertification is often wrongly attributed solely to droughts, but it is the deadly combination of continued land abuse during periods of deficient rainfall that results in unproductive land, and ultimately desertification (UNESCO 2003). Combating desertification by rehabilitating degraded lands can be done successfully, using existing, often traditional techniques. Land restoration involves restoring the fertility of degraded lands. The social syndrome where diminishing availability of lands, inherent low fertility, continuous soil erosion, and continuous nutrient removal without replenishment, results in a spiraling downfall in productive capacity and a diminished resilience of the soil system to provide a suitable medium for crop growth needs to be addressed. Smallholder farmers are at the center of both soil fertility decline and restoration process. Their decisions to manage, to utilize technologies and to improve or restore soil fertility are guided by the socioeconomic conditions and the overall benefits that will accrue from production (Sanginga and Woomer, 2009; Bekunda et al. 2010). A sustainable management of lands under cultivation and the restoration of degraded lands could be achieved by affordable strategic management innovations; taking into account the socioeconomic conditions of farmers. While individual technologies can contribute; a more integrated systems that combines technologies, crops, and trees such as the agroforestry systems could better contribute for sustainable management of natural resources. Many efforts have been invested to developing strategies and approaches for both sustainable management of natural resources and restoration of degraded lands in WAS. In some cases, farmer communities have developed sound, sustainable approaches to land rehabilitation and management but there is insufficient information on successful restoration in the context of WAS, particular with regards to policy, institutions and socioeconomic conditions under which specific approaches could be adapted and applied successfully (Bunning 2003). The main objective of this review was to investigate the main experiences of regenerating degraded landscapes (RDL) in Niger. Going through the documentation, we found many similarities in experiences across the two countries of Niger and Burkina. Some interesting experiences were found in Burkina, Niger or at the same time in the two countries. We finally decided to extend the review to the two countries as a representative zone of the WAS. The critical issue in taking restoration to scale is that ecological, economic and institutional context varies at fine scales. The main goal of this review is to identify the specificities and the context of the most efficient experiences of RDL that could be widely scaled in the WAS

Soil organic carbon dynamics and crop yield for different crop rotations in a degraded ferruginous tropical soil in a semi-arid region: a simulation approach

In recent years, simulation models have been used as a complementary tool for research and for quantifying soil carbon sequestration under widely varying conditions. This has improved the understanding and prediction of soil organic carbon (SOC) dynamics and crop yield responses to soil and climate conditions and crop management scenarios. The goal of the present study was to estimate the changes in SOC for different cropping systems in West Africa using a simulation model. A crop rotation experiment conducted in Farakô-Ba, Burkina Faso was used to evaluate the performance of the cropping system model (CSM) of the Decision Support System for Agrotechnology Transfer (DSSAT) for simulating yield of different crops. Eight crop rotations that included cotton, sorghum, peanut, maize and fallow, and three different management scenarios, one without N (control), one with chemical fertilizer (N) and one with manure applications, were studied. The CSM was able to simulate the yield trends of various crops, with inconsistencies for a few years. The simulated SOC increased slightly across the years for the sorghum–fallow rotation with manure application. However, SOC decreased for all other rotations except for the continuous fallow (native grassland), in which the SOC remained stable. The model simulated SOC for the continuous fallow system with a high degree of accuracy normalized root mean square error (RMSE)=0·001, while for the other crop rotations the simulated SOC values were generally within the standard deviation (s.d.) range of the observed data. The crop rotations that included a supplemental N-fertilizer or manure application showed an increase in the average simulated aboveground biomass for all crops. The incorporation of this biomass into the soil after harvest reduced the loss of SOC. In the present study, the observed SOC data were used for characterization of production systems with different SOC dynamics. Following careful evaluation of the CSM with observed soil organic matter (SOM) data similar to the study presented here, there are many opportunities for the application of the CSM for carbon sequestration and resource management in Sub-Saharan Africa

Scaling up Land Restoration Approaches to Reclaim the Hardpans of Niger for Agriculture using Sentinel 2 Imagery

Degraded lands, widespread across sub-Saharan Africa, are used mainly for grazing and firewood harvesting and have low agricultural production potential. Such areas have become degraded through overuse and removal of surface cover and associated erosion processes and are termed hardpans. Hardpans with high clay content, high cation exchange capacity (CEC) and water holding capacity have productive potential. ICRISAT has developed and scaled a gender sensitive approach Bioreclamation of Degraded Land” (BDL) that combines water harvesting technologies (planting pits, half-moon and trenches), application of compost and plantation of high value fruit trees and annual drought tolerant indigenous vegetables. In partnership with CRS in Niger, BDL was scaled to over 3000 villages (2014-18) which led to many benefits in food security and income generation for the local population. To scale further multi-spectral remote sensing based imagery of high resolution (10 m) can identify and map hardpans and differentiate higher potential sites for the BDL approach. These maps will be used to quantify the area under hardpans and the potential area in which the interventions can be scaled up

Manuel de formation sur la récupération biologique des terres dégradées

Dans le cadre du projet d’appui à la sécurité alimentaire des ménages (PASAM-TAI) au Niger, l’ONG CRS et ICRISAT ont conçu ce manuel de formation destiné aux femmes engagées dans la restauration biologique de terres dégradées. Cette approche intégrée combine techniques traditionnelles de conservation de l’eau (zaï, demi-lunes) avec la culture de légumes et arbres à haute valeur nutritive et commerciale. La technique BDL permet de produire entre autres okra, oseille, senne, pomme de Sahel, moringa sur des sols latéritiques en cours de désertification. L’impact sur les revenus, la nutrition familiale et l’indépendance économique des femmes est significatif

Biological Nitrogen Fixation by Local and Improved Genotypes of Cowpea in Burkina Faso (West Africa): Total Nitrogen Accumulated can be used for Quick Estimation

Biological nitrogen fixation (BNF) by legumes is an indicator of their potential contribution to recycling nitrogen in cropping systems. Many techniques exist for the quantitative measurement of legume BNF. The isotopic dilution (ID) methods are the most accurate but are too expensive, time-consuming and require technical expertise. There is a gap between the simple but less accurate Total Nitrogen Difference (TND) method and the Isotopic Dilution (ID) methods. By measuring the BNF of 11 cowpea (Vigna unguiculata) genotypes, this study aimed to develop a simple model as an improved tool for the quick estimation of BNF. Total N accumulated by traditional genotypes from Burkina Faso varied from 23 to 41 kg ha−1. Approximately 40 to 65% of this was nitrogen derived from the atmosphere (Ndfa) when the TND method was used (Ndfa-TND), while the ID method indicated that 29 to 37% of N accumulated was derived from the atmosphere (Ndfa-ID). The TND method overestimated the BNF of high N-yielding genotypes but underestimated the BNF of low N-yielding genotypes (N-accumulated below 31 kg N ha−1). The relationship between N-accumulated and Ndfa-ID was described by a polynomial regression: = 0.0127 - 0.5354 + 17.44, where and represent Ndfa-ID and N-accumulated, respectively (P<0.05, R2 =0.92). The model was validated and could be used for quick estimation of BNF directly from the N accumulated

Suitable management options to improve the productivity of rice cultivars under salinity stress

Growing rice in saline soils by minimizing damage on growth and yield remains a challenge. We conducted field experiments in the Africa Rice research field located in the Senegal River delta (16° 11ʹ N, 16° 15ʹ W) to study the effects of three management options of fertilization e.g. (i) nitrogen, phosphorus, and potassium fertilization: NPK; (ii) NPK combined with zinc: NPK-Zn, and (iii) NPK combined with gypsum: NPK-gypsum on the soil salinity level, the nutrient uptake and the productivity of different rice cultivars. The whole objective of this study is to determine how zinc or gypsum associated to NPK fertilizer can improve the growth and productivity of rice crop in saline soil. Results showed that the initial soil salinity level was reduced rapidly in plots treated with gypsum. The leaf-K/Na ratio, agronomic nitrogen use efficiency (ANUE), and grain yield of rice cultivars under the salinity stress were improved by the NPK-gypsum and NPK-Zn options relatively to the NPK option, suggesting that NPK-gypsum and NPK-Zn are suitable management options in reducing adverse effect of low K/Na, low ANUE as well as to improve rice yield under salinity stress