Fertiliser use efficiency, production risks and profitability of maize on smallholder farms in East Africa

Kiwia, A and Kimani, D and Harawa, R and Jama, B and Sileshi, G W (2022) Fertiliser use efficiency, production risks and profitability of maize on smallholder farms in East Africa. Experimental Agriculture, 58. pp. 1-16. ISSN 1469-4441

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Abstract

The use of fertilisers in maize production has been the focus for many years of agronomic studies on research stations in East Africa. However, information on production risks and profitability of fertiliser use on smallholder farms is generally lacking because most of the early studies have focused on mean yields and yield components on research stations. This study applied rigorous analyses to determine conditions under which (1) production risks are low; (2) the recommended nitrogen (N) and phosphorus (P) fertiliser rates achieve a yield target of ≥3 t ha−1 believed to be a necessary condition to kick start a smallholder-led ‘green revolution’ in Africa and (3) N and P fertiliser use is profitable on smallholder farms in East Africa. Analysis of data from 464 on-farm trials in Kenya, Rwanda, Tanzania and Uganda revealed significant variations in production risks and nutrient use efficiency with season and soil type. On most sites, except in Uganda, production risks were lower with the recommended N and P fertilisers than the control during both the short and long rains. Production risks were three to four times higher with N and P fertiliser relative to the control on Lixisols and Ferralsols, but such risks were much lower on Nitisols, Leptosols, Vertisols, Plinthosols and Cambisols. The probability of exceeding grain yields of 3 t ha−1 with the recommended N and P rates was over 0.60 on Nitisols and Leptosols, but less than 0.20 on Lixisols and Plinthosols. The agronomic use efficiencies of N (AEN), P (AEP) and value cost ratios (VCR) were highest on Cambisols and lowest on Plinthosols. The VCR increased linearly with increase in AEN (R2 = 0.92) and AEP (R2 = 0.87) and less so with increase in grain yields (R2 = 0.47–0.60). Net present values indicated profitably of N and P fertiliser over the long term in only 30% of the site by season combinations in Uganda compared with 69% in Kenya, 81% in Rwanda and 84% in Tanzania. Patterns of N use efficiencies were different from P use efficiencies across soil types. Therefore, we recommend that N and P fertilisers should be appropriately targeted to soils where applied nutrients are used efficiently by maize crops.

Item Type:	Article
Divisions:	Research Program : East & Southern Africa
CRP:	UNSPECIFIED
Uncontrolled Keywords:	agronomic efficiency, downside risk, net present value, value cost ratio
Subjects:	Others > Smallholder Agriculture Others > Maize Others > East Africa
Depositing User:	Mr Nagaraju T
Date Deposited:	12 Jan 2024 05:13
Last Modified:	12 Jan 2024 05:13
URI:	http://oar.icrisat.org/id/eprint/12357
Official URL:	https://www.cambridge.org/core/journals/experiment...
Projects:	UNSPECIFIED
Funders:	Bill & Melinda Gates Foundation
Acknowledgement:	We thank all AGRA grantees for their input into the design of the on-farm demonstrations and for managing them well, and the farmers who hosted and managed the trials. We also thank the Bill and Melinda Gates Foundation for the generous funding of this work.
Links:	Google Scholar

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