Soil Fertility Replenishment in Africa: An Investment in Natural Resource Capital

Sánchez, Pedro A.; Shepherd, Keith D.; Soule, Meredith J.; Place, Frank; Buresh, R. J.; Izac, Anne-Marie N.; Mokwunye, A. U.; Kwesiga, Fred R.; Ndiritu, C. G.; Woomer, Paul L.

doi:10.2136/sssaspecpub51.c1

Cited by 310 publications

(171 citation statements)

References 48 publications

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“…A critical effect is the ongoing reduction in the soil's N r capital (soil 'nitrogen mining'), where the labile pools of soil organic N (SON) seem to be well correlated with N release rates, such as particulate organic N and N in the light fraction of soil organic matter (SOM). While such soil N r mining will maximize 'service flows' (usable outputs) and the value of crop production for several years (Sanchez et al 1997), it is not sustainable in the long term. In low-input smallholder systems, soil nitrogen stocks have reduced due to escapes into the environment as a result of over-farming, erosion and leaching (Stoorvogel and Smaling 1990) if the systems are not managed for sustainability.…”

Section: N R Intensification In Low Input Systems and Integrated Soilmentioning

confidence: 99%

Synthesis and review: Tackling the nitrogen management challenge: from global to local scales

Reis

Bekunda

Howard

et al. 2016

Environ. Res. Lett.

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One of the 'grand challenges' of this age is the anthropogenic impact exerted on the nitrogen cycle. Issues of concern range from an excess of fixed nitrogen resulting in environmental pressures for some regions, while for other regions insufficient fixed nitrogen affects food security and may lead to health risks. To address these issues, nitrogen needs to be managed in an integrated fashion, at a variety of scales (from global to local). Such management has to be based on a thorough understanding of the sources of reactive nitrogen released into the environment, its deposition and effects. This requires a comprehensive assessment of the key drivers of changes in the nitrogen cycle both spatially, at the field, regional and global scale and over time. In this focus issue, we address the challenges of managing reactive nitrogen in the context of food production and its impacts on human and ecosystem health. In addition, we discuss the scope for and design of management approaches in regions with too much and too little nitrogen. This focus issue includes several contributions from authors who participated at the N2013 conference in Kampala in November 2013, where delegates compiled and agreed upon the 'Kampala Statement-for-Action on Reactive Nitrogen in Africa and Globally'. These contributions further underline scientifically the claims of the 'Kampala Statement', that simultaneously reducing pollution and increasing nitrogen available in the food system, by improved nitrogen management offers win-wins for environment, health and food security in both developing and developed economies. The specific messages conveyed in the Kampala Statement focus on improving nitrogen management (I), including the reduction of nitrogen losses from agriculture, industry, transport and energy sectors, as well as improving waste treatment and informing individuals and institutions (II). Highlighting the need for innovation and increased awareness among stakeholders (III) and the identification of policy and technology solutions to tackle global nitrogen management issues (IV), this will enable countries to fulfil their regional and global commitments.

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Section: N R Intensification In Low Input Systems and Integrated Soilmentioning

confidence: 99%

Synthesis and review: Tackling the nitrogen management challenge: from global to local scales

Reis

Bekunda

Howard

et al. 2016

Environ. Res. Lett.

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“…Low soil fertility in SSA is often characterized by low available phosphorous (P), nitrogen (N), organic matter (C org ), and soil acidity, among others [21]. Such parameters must be corrected as they are an integral part of the interaction of legume genotype, rhizobia strain, environment, and crop management, which determines the performance of BNF in particular and legume productivity in general [22-25].…”

Section: Introductionmentioning

confidence: 99%

Variability of soybean response to rhizobia inoculant, Vermicompost, and a legume-specific fertilizer blend in Siaya County of Kenya

Mathenge¹,

Thuita²,

Masso³

et al. 2018

Preprint

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2 11 Abstract 12 Rhizobia inoculation can increase soybean yield, but its performance is influenced by soybean 13 genotype, rhizobia strains, environment, and crop management among others. The objective of 14 the study was to assess soybean response to rhizobia inoculation when grown in soils amended 15 with urea or Vermicompost to improve nitrogen levels. Two greenhouse experiments and one 16 field trial at two sites were carried out. The first greenhouse experiment included soils from sixty 17 locations, sampled from smallholder farms in Western Kenya. The second greenhouse 18 experiment consisted of one soil selected from soils used in the first experiment where 19 inoculation response was poor. The soil was amended with Vermicompost or urea. In the two 20 greenhouse experiments, Legumefix® (inoculant) + Sympal (legume fertilizer blend) were used 21 as a standard package. Results from the second greenhouse experiment were then validated in the 22 field. In the first greenhouse trial, soybean response to inoculation was significantly affected by 23 soil fertility based on nodule fresh weight and shoot biomass. Soils with low nitrogen had low to 24 no response to inoculation. After amendment, nodule fresh weight, nodule effectiveness, nodule 25 occupancy, and shoot dry biomass were greater in the treatment amended with Vermicompost 26 than those amended with urea (Legumefix® + Sympal + Vermicompost and Legumefix® + 27 Sympal + urea). Under field conditions, trends were similar to the second experiment for 28 nodulation, nodule occupancy, and nitrogen uptake resulting in significantly greater grain yields 29 (475, 709, 856, 880, 966 kg ha -1 ) after application of Vermicompost at 0, 37, 74, 111, and 148 kg 30 N ha -1 , respectively. It was concluded that soybean nodulation and biological nitrogen fixation in 31 low fertility soils would not be suppressed by organic amendments like Vermicompost up to 148 32 kg N ha -1 . 33 Keywords: Rhizobia inoculation, nodule occupancy, nodule effectiveness, Vermicompost, grain 34 yield. 3 36 Introduction 37 Soybean (Glycine max L. Merr) is one of the world's most important legumes in terms of 38 production and trade and has been a dominant oilseed since the 1960s [1]. The crop is well 39 known for its high protein content (about 40%) [2]. Additionally, it can improve soil properties 40 and soil biological health by soil nitrogen enrichment through N 2 fixation and subsequent 41 mineralization of shoot and root biomass [3]. It therefore represents a significant opportunity in 42 sub-Saharan Africa (SSA), where over 80% of the soils are nitrogen deficient [85], and over 39% 43 of the children under 5 years are stunted because of malnutrition caused by nutrient deficiency, 44 particularly proteins [4], contributing to over one third of child deaths [5]. Integration of soybean 45 in smallholder farming systems would thus not only improve human nutrition when the crop is 46 included in diets but also soil productivity. Such benefits would materialize when good 47 agronomic practices...

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“…Subsistence farming, which is still practiced by the vast majority of farmers, is often confronted with low and declining soil fertility (Bationo and Mokwunye, 1991;Sanchez et al, 1997). Traditional soil fertility restoration practices are no longer sufficient to maintain soil fertility.…”

Section: Introductionmentioning

confidence: 99%

Millet response to microdose fertilization in south–western Niger: Effect of antecedent fertility management and environmental factors

Bielders

Gérard²

2015

Field Crops Research

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a b s t r a c tSoil fertility is a major constraint to agricultural development in most of the Sahel, with P being the most limiting nutrient for millet production on acid sandy soils. To address this issue, microdose applications of P fertilizer have been widely advocated in recent years. However, little is known regarding the effect of farmer management practices and environmental factors on millet's yield response to this technique. For this purpose, 276 farmer demonstrations were setup across a 3-year period in the Fakara region, western Niger. Five strata were considered based on antecedent organic manure management (corralling or transported manure). At each demo site, conventional management was compared to basal microdose fertilizer application of DAP (2 g hill −1 ), NPK (6 g hill −1 ), or DAP (2 g hill −1 ) with urea (1 g hill −1 ) applied at tillering. Millet grain yields on control plots were low (84% < 400 kg ha −1 ), reflecting the unfavorable environmental conditions of the area. On average, the application of DAP, NPK and DAP + urea increased grain yields by 43, 46 and 69 kg ha −1 (2001)(2002). A positive response to microdose fertilization was observed for 92% of the sites where yields on control plots were <100 kg ha −1 but only for 32% of the sites where yields on control plots were >500 kg ha −1 . In particular, the positive response to microdosing increased with later sowing given that late sowing tended to reduce yields on control plots. Higher rainfall during the early growing season favored a positive response to microdosing. On average over DAP and DAP + urea, 36% of the demonstrations had value-cost ratios (VCR) < 1. However, for low yielding control plots (<200 kg grain ha −1 ), 26% of the demonstrations had VCR < 1, whereas for high yielding plots (>400 kg grain ha −1 ), 55% had a VCR < 1. Not accounting for labor, DAP and DAP + urea had similar economic returns. The use of NPK could not be recommended as the cost per unit P is 3 times higher than DAP. It appears that, for the Fakara study area, microdosing may best be targeted to areas with low expected yields. In particular, it may serve as a famine mitigation strategy in case of late sowing. Nevertheless, for poorly endowed areas such as the Fakara, the economic risk associated with microdosing (2 g DAP hill −1 ) appears higher than has hitherto been reported and widespread adoption may not be warranted without institutional support.

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Soil Fertility Replenishment in Africa: An Investment in Natural Resource Capital

Cited by 310 publications

References 48 publications

Synthesis and review: Tackling the nitrogen management challenge: from global to local scales

Synthesis and review: Tackling the nitrogen management challenge: from global to local scales

Variability of soybean response to rhizobia inoculant, Vermicompost, and a legume-specific fertilizer blend in Siaya County of Kenya

Millet response to microdose fertilization in south–western Niger: Effect of antecedent fertility management and environmental factors

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