Affordable Nutrient Solutions for Improved Food Security as Evidenced by Crop Trials

Abstract

The continuing depletion of nutrients from agricultural soils in Sub-Saharan African is accompanied by a lack of substantial progress in crop yield improvement. In this paper we investigate yield gaps for corn under two scenarios: a micro-dosing scenario with marginal increases in nitrogen (N) and phosphorus (P) of 10 kg ha 21 and a larger yet still conservative scenario with proposed N and P applications of 80 and 20 kg ha 21 respectively. The yield gaps are calculated from a database of historical FAO crop fertilizer trials at 1358 locations for Sub-Saharan Africa and South America. Our approach allows connecting experimental field scale data with continental policy recommendations. Two critical findings emerged from the analysis. The first is the degree to which P limits increases in corn yields. For example, under a micro-dosing scenario, in Africa, the addition of small amounts of N alone resulted in mean yield increases of 8% while the addition of only P increased mean yields by 26%, with implications for designing better balanced fertilizer distribution schemes. The second finding was the relatively large amount of yield increase possible for a small, yet affordable amount of fertilizer application. Using African and South American fertilizer prices we show that the level of investment needed to achieve these results is considerably less than 1% of Agricultural GDP for both a micro-dosing scenario and for the scenario involving higher yet still conservative fertilizer application rates. In the latter scenario realistic mean yield increases ranged between 28 to 85% in South America and 71 to 190% in Africa (mean plus one standard deviation). External investment in this low technology solution has the potential to kick start development and could complement other interventions such as better crop varieties and improved economic instruments to support farmers.

Human-induced nitrogen–phosphorus imbalances alter natural and managed ecosystems across the globe

“…Phosphorus fertilizer continues to be overused in croplands of developed countries, causing eutrophication of downstream ecosystems, but it is not applied in sufficient amounts in developing countries, where food security is a challenge 16 . In contrast to the global tendency for an enhancement of the N:P ratio, intensely used pastoral areas and areas where animal slurry is used as fertilizer 17 are being polluted with excess phosphorus; this phosphorus decreases the N:P ratio of water in soil, lakes and streams.…”

Remote sensing data for managing climate risks: Index-based insurance and growth related applications for smallhold-farmers in Ethiopia

“…To establish the relationship we focus on the so-called Mitscherlich-Baule crop response function (see e.g. Van der Velde et al, 2013), defined as:…”

“…The parameters a 2 , a 3 , a 4 , and a 5 are usually obtained via field trials. In our case-study (see below), we use FAO trials conducted in Ethiopia between 1988 and 1993 as part of the FAO's Fertilizer Programme (for data see: http://www.fao.org/ag/agl/agll/nrdb/; for details on the methodology also see Van der Velde et al (2013)). To simplify the methodology, only the application of nitrogen based fertilizer is considered (the input of phosphorus, as well as of potassium and micro-nutrients is therefore ignored).…”

“…The specific parameters were obtained by minimizing the sum of squared errors for all applications in each trial which are located near North Shewa. In more detail, the Nelder-Mead multidimensional unconstrained nonlinear minimization algorithm was used to minimize the objective function (Van der Velde et al, 2013).…”

Climate Strategic Soil Management

“…Agronomic regeneration of soil fertility in Asian smallholder uplands is essential to sustainable food production [147]. Affordable nutrient solutions have to be developed for improving food security [148] and eliminating nutrient imbalances [149]. Regeneration of soil fertility, through integrated nutrient management (INM), is critical to improving the agronomic productivity of smallholder farmers of Asia [147] and elsewhere in developing countries, including SSA.…”