Fertilizer Use Issues for Smallholder Agriculture in Tropical Africa

Fertilizer is an essential input for wide-scale sustainable intensification of crop productivity in tropical Africa, but its use by smallholders is often financially constrained. Four fertilizer use issues are addressed. Smallholders need high net returns from their investments, with acceptable risk, which can be achieved with good crop-nutrient-rate choices made in consideration of the farmer’s financial and agronomic context. Soil acidification, which is affected by crop N supply, is best managed with the use of slightly more acidifying but less costly common N fertilizer, e.g., urea, coupled with lime use compared with the use of more costly but less acidifying N fertilizer such as calcium ammonium nitrate. This chapter addresses the feasibility of tailored fertilizer blends for maximizing farmer profit with respect to the nutrient supply cost, the need for flexibility in nutrient application according to the farmer’s context, and the weak justification for tailoring blends based on soil test results. The use of a well-formulated blends is justified in some cases, e.g., for some crops in Rwanda, but the supply of blends does not justify restricting the supply of common fertilizers. Farmers need to be aware that unregulated nontraditional products very often fail to provide the claimed benefits. Fertilizer use, sometimes with timely lime application, can be highly profitable with modest risk with good crop-nutrient-rate choices, adequate free-market fertilizer supply, and avoiding products with unsubstantiated claims

Water and nitrogen use of pearl millet and grain sorghum in Nebraska

Pearl millet [Pennisetum glaucum (L.) R. Br] and grain sorghum [Sorghum bicolor L. Moench] are drought tolerant crops that may serve as possible alternative summer crops in rotation with winter wheat [Triticum aestivum L.] in western Nebraska and may add to the diversification in cropping systems of eastern Nebraska. Two types of field experiments were conducted. The first experiment evaluated pearl millet and grain sorghum yield, water use, and yield components and their interrelation in determining yield across environmental conditions. The range of environmental conditions included the 2000 and 2001 growing seasons, a silt loam soil at Sidney and a silty clay loam soil at Mead, and four water regimes. The latter consisted of (1) no irrigation, (2) single irrigation at boot stage, (3) single irrigation at mid-grain fill, and (4) multiple irrigations. The second experiment evaluated the response of two pearl millet hybrids to N fertilizer rates of 0, 45, 90, and 135 kg N ha−1 , and N uptake and use efficiency under different environmental conditions at Mead and Sidney. Across environmental conditions, pearl millet grain yields of 1.9 to 5.1 Mg ha−1 were 60 to 80% that of grain sorghum with yields of 4.1 to 6.1 Mg ha−1. Pearl millet and grain sorghum used 330 to 374 mm of water, and their grain yield increased linearly with increase in water use. Grain sorghum, with greater yields, had greater water use efficiency than pearl millet. Yield increase from irrigation was attributed to kernel weight and kernels panicle−1 at Mead, and kernel weight, kernels panicle−1 and panicles m−2 at Sidney. Stepwise regression and path analysis indicated that kernel weight was the major contributor for grain yield of both crops, except for pearl millet at Sidney where kernels panicle−1 was the largest yield contributor. Pearl millet, with lower and less stable yields, does not currently have the potential to be a substitute for grain sorghum in Nebraska. The two pearl millet hybrids used had similar responses to N fertilizer and their yields, N uptake, and nitrogen use efficiency (NUE) increased with increased N rate. Maximum grain yield was reached with 90 kg N ha−1 in most environments. However, based on the different NUE components, the optimum N rate for pearl millet was 45 kg N ha−1 in all environments

Yield Components of Pearl Millet and Grain Sorghum across Environments in the Central Great Plains

Location, year, and water supply influence the relationship between grain yield and yield components of pearl millet [Pennisetum glaucum (L.) R. Br] and grain sorghum Sorghum bicolor (L.) Moench]. Field experiments were conducted in 2000 and 2001 on a silt loam soil in semiarid western Nebraska and on a silty clay loam soil in subhumid eastern Nebraska to determine how environment (location, year, water regime) influences number of panicles per square meter, kernel weight, and kernels per panicle in determining grain yield of pearl millet and grain sorghum. Grain yield components were examined by analysis of variance, correlation, and path analysis. Four water regimes were used: (i) no irrigation, (ii) single irrigation at boot stage, (iii) single irrigation at mid-grain fill, and (iv) multiple irrigations. Grain sorghum produced from 109 to 212 g m-2 greater yield than pearl millet in all environments in western Nebraska and 52 to 150 g m-2 greater yield in eastern Nebraska. Correlation and path analysis direct effects indicated that the number of kernels per panicle (R from 0.36–0.93; P from 0.21–0.45) and kernel weight (R from 0.46–0.89; P from 0.46– 0.73) were associated with grain yield for both crops at both locations, but in the path analysis, kernel weight was more highly associated with grain yield for grain sorghum (P from 0.65–0.73) than the number of kernels per panicle (P from 0.21 and 0.32). Plant breeding and production research to increase pearl millet and grain sorghum yield should consider all yield components, but increased emphasis on kernel weight is merited for grain sorghum

Data from: Pearl millet and cowpea intercrop response to applied nutrients in West Africa

In the Sahel, crop production is dominated by pearl millet [Pennisetum glaucum (L.) R. Br.] cropping systems including intercropping with cowpea [Vigna unguiculata (L.) Walp]. The research objectives were to determine pearl millet sole crop (PMSC) and intercrop nutrient response functions, profit opportunities from fertilizer use, and a means of relating intercrop to PMSC response. Pearl millet–cowpea trials were conducted in Niger and Mali. The treatment structure was an incomplete factorial with five, four, and four levels of P, N, and K, respectively. Response functions were determined for intercropping with cowpea yield converted to a pearl millet grain yield equivalent for ratios of cowpea to pearl millet grain value (CpPm) ranging from 1 to 5 kg kg–1. Response functions were also determined in consideration of fodder value. A method of adjusting PMSC response coefficients with CpPm as the independent variable was developed for determination of intercrop response functions. Yields and responses to nutrients were low but adequate for profitable N and P use. Value of intercrop production ranged from 50 to 125% more compared with PMSC for CpPm of 2 and 4, and the respective response to 10 kg ha–1 P was 28 and 135% more with intercrop. Consideration of fodder added 23% to the yield value. Application of N and P for intercrop compared with PMSC production has much more profit potential. The ability to apply PMSC functions in determination of pearl millet–cowpea responses to applied nutrients offers a means to improve fertilizer use for the intercrop

Adoption of and farmers’ exposure to soil and Water Management (SWMGT) Practices in the Sahel Savanna of West Africa: Average Treatment Effect (ATE) Estimations.

This paper approaches the soil and water management (SWMGT) adoption estimation from the perspective of the modern evaluation theory. As a result, the analytical procedure adopted for the study follows the Average Treatment Effect (ATE) estimation framework. The data gathered for the analysis are part of the baseline data collected from a sample of 572 households in 20 villages in Maradi (Niger Republic) and katsina (Nigeria). Results show that about 45 percent of the respondents have adopted the soil and water management (SWMGT) practices, out of 398 (70%) households that had knowledge or were aware of the SWMGT options. The joint exposure and adoption rates from three different models have been estimated at 39%. Results for joint exposure and adoption (within the SWMGT exposed sub-population) rate are also similar for the three models (59%) with similar range of 95% confidence interval (between 52% and 65%). With the intervention of the SSACP through the 2 IAR4D, it is expected that the adoption rate could be increased by at least 14% if an effective awareness of these SWMGT practices through the Innovation Platform system is undertaken. Key words: Adoption, Exposure, Average treatment Effect, Innovation Platform, Integrated Agricultural Research for Development

Biofortification through fertilizer nutrient application in Tropical Africa

Data from 70 crop-nutrient response trials conducted in Mali, Niger, Nigeria and Tanzania were used to evaluate nutrient application effects on nutrient concentrations for grain of five pulse and five cereal crops and for storage roots of cassava

Data from: Fertilizer application effects on grain and storage root nutrient concentration

Fertilizer application can affect nutrient concentrations of edible plant products. Data from 70 crop-nutrient response trials conducted in Mali, Niger, Nigeria, and Tanzania were used to evaluate nutrient application effects on nutrient concentrations for grain of five pulse and five cereal crops and for storage roots of cassava (Manihot esculenta L.). Treatments per trial were ≥12 but this study was limited to: no fertilizer applied; macronutrients applied (NPK or PK); and the macronutrient treatment plus Mg, S, Zn, and B applied (MgSZnB). Dried grain or cassava flour samples were analyzed for concentrations of all essential soil nutrients except for Ni and Cl. Concentrations of N and K were positively correlated with concentrations of most other nutrients. The concentrations were relatively low overall for cowpea (Vigna unguiculata L.) and pigeonpea (Cajanus cajan L.) compared with other pulse crops and for maize (Zea mays L.) compared with other cereal crops. Application of NPK or PK had little effect on nutrient concentrations except for increased mean cereal grain concentrations for N, Ca, Mg, S, Zn, Cu, and B. Bean (Phaseolus vulgaris L.), maize and rice (Oryza sativa L.) grain concentrations were reduced by MgSZnB for N, K, S, Cu, Mn, and B. There were no or inconsistent effects of MgSZnB on other crop-nutrient concentrations. Nutrient concentrations are not reduced by NPK for non-legumes or PK for pulses but MgSZnB often reduced bean and cereal nutrient concentrations with greater reductions for immobile compared with mobile nutrients

West Africa Pearl Millet data set

Research was conducted in Burkina Faso, Mali and Niger for the Sahel and Sudan Savanna agroecological zones. Trials had similar basic treatment structures for determination of response functions for N, P, and K, and a diagnostic treatment for resposne to Mg, S, Zn and B. Most treatments in Niger were intercroped with cowpea and with 2.5 Mg ha-1 yr-1 manure applied but had additional treatments for determination of the effect of manure and/or intercropping on yield and response. Most treatments in Mali were sole crop pearl millet with added treatments determination of the effect of intercropping on yield and response, all with no manure applied. In Burkina Faso, trials were conducted at Dori in 2014-2015 and all treatments were with pearl millet sole crop with or without 5 Mg ha-1 manure applied in 2014 and evaluating the residual effect of manure in 2015

Data from: Diagnosis of crop secondary and micro-nutrient deficiencies in sub-Saharan Africa

Crop production in sub-Saharan Africa has numerous biotic and abiotic constraints, including nutrient deficiencies. Information on crop response to macronutrients is relatively abundant compared with secondary and micronutrients (SMN). Data from 1339 trial replicates of 280 field trials conducted from 2013 to 2016 in 11 countries were analyzed for the diagnosis of SMN deficiencies. The diagnostic data included relative yield response (RYR) and soil and foliar test results. The RYR to application of a combination of Mg, S, Zn, and B (Mg-S-Zn-B) relative to a comparable N-P-K treatment was a >5% increase for 35% of the legume blocks and 60% of the non-legume blocks. The frequencies of soil test Zn, Cu, and B being below their critical level were 28, 2 and 10% for eastern and southern Africa, respectively, and 55, 58 and 89% for western Africa, while low levels for other SMN were less frequent. The frequency of foliar results indicating low availability were 58% for Zn, 16% for S and less for other SMN. The r2 values for relationships between soil test, foliar test and RYR results were <0.035 with little complementarity except for soil test Zn and B with cassava (Manihot esculenta L. Crantz) RYR in Ghana, and foliar Zn with cereal RYR in Uganda. Positive RYR is powerful diagnostic information and indicative of good profit potential for well-targeted and well-specified SMN application. Geo-referenced RYR, soil analysis and foliar analysis results for diagnosis of SMN deficiencies in 11 countries of sub-Saharan Africa were generally not complementary

Tropical Africa Crop Nutrient Diagnosis data set Jan 2019

The data are from 1339 trial replicates of 280 field trials conducted from 2013 to 2016 in 11 countries of tropical Africa. The data were analyzed for the diagnosis of secondary and micronutrient deficiencies. The diagnostic data included relative yield response to application of a combination of Mg, S, Zn, and B (Mg-S-Zn-B) relative to a comparable N-P-K treatment. Soil and foliar sample data is also included. The data is in an Excel file with seven worksheets plus a ReadMe worksheet