Development and Dissemination of 4R Nutrient Stewardship Knowledge to Support Crop Production Intensification in Western Kenya

The lack of appropriate site-specific nutrient management recommendations is a key factor underlying low crop productivity in sub-Saharan Africa (SSA). The 4R Nutrient Stewardship Framework developed by the fertilizer industry aims to provide the context for efficient nutrient management focusing on four central components: applying the right fertilizer source, at the right rate, at the right time in the growing season, and in the right place. To assess the impact of 4R practices in smallholder cropping systems, on-farm nutrient omission trials were initiated in 2013 in 26 heterogeneous farms in Western Kenya. Although the region has a high potential for agriculture intensification, current average farmer yields are lower than 2 t/ha compared to research stations yields of up to 8 t/ha. The trials will run for a total of eight seasons through 2016. The main objective of these trials is to facilitate the development and dissemination of 4R practices for sustainable crop production intensification. The project is also using the nutrient omission trials as field demonstration sites for training farmers on best crop and nutrient management practices. In each season, maize is planted at a spacing of 75 cm by 25 cm, under five treatments comprising of: 1) no input control, 2) PK, 3) NK, 4) NP, 5) NPK.

Yield responses to N, P and K has been in the order: 2.6, 0.25 and 0.4 t/ha; 2.5, 1.3 and 0.7 t/ha; and 3, 2 and 1.2 t/ha in the long rains (LR) 2013, short rains (SR) 2013, and LR 2014 seasons, respectively. This indicates the temporal nature of nutrient dynamics in this region. Agronomic efficiencies (AE) for N, P and K over the three seasons have been in the order 15, 13 and 11, respectively in the LR 2013 season; 17, 40 and 18 in the SR 2013 season; and 20, 50 and 20 in the LR 2014 season. This illustrates the need for long term and detailed experimental studies prior to the development of fertilizer recommendations. Different from the first two seasons where yield in the control treatment was higher than that obtained following farmers’ practice in the pilot farmers’ fields, in the third season farmer practice yield was significantly higher (4 t/ha) than control treatment yield (2.2 t/ha) indicating that farmers in the study area are adopting the improved practices and benefitting from the 4R training conducted over the past two years.