A review of the Current State of Soil Infertility and Management Options in Kenya: The Case of Maize Growing Regions

Abstract

Inappropriate soil fertility management has caused fertility to decline considerably over the years leading to low maize yields despite the growing human population with high food demand in Kenya. Despite high nutrient mining, fertilizer use and adoption of soil fertility improvement practices have remained low among maize farmers in the country. At the current yield levels, maize crops extract over 40, 8, 40.6, and 5.4 kg of N, P, K, and S per growing season, respectively. These extracted nutrients must be replaced to avoid nutrient depletion. Maize crop response to secondary macronutrients (S, Ca, and Mg) and micronutrients (Zn and B) is evidenced, signifying that these nutrients have also reached critical levels in Kenya soils. The rate of replenishing these lost nutrients is still low, farmers apply an average of 43.25 kg of fertilizer per hectare per season. The situation is worsened further by increasing soil acidity-currently below pH 5.5 in most maize-growing regions. Poor agronomic practices applied by farmers directly reduce yields and facilitate other factors leading to nutrient losses. For example, farmers across the country recycle seeds, apply low fertility rates, and rarely keep their fields weed-free. These practices lower the capacity of the crops to tolerate the impact of other production constraints including infertility.To realize yield improvement and return on investments, farmers must adapt and adopt crucial practices under integrated soil fertility management. Managing soil acidity should be the first approach to unlocking fixed nutrients. Fertilizer application should follow the right rate, right source, right time, and right placement approach. Also, improved cropping systems such as maizelegume rotation and intercropping should be considered for sustainable soil fertility management and crop production.

Review of the Current State and Potential Benefits of Using Herbicides by Smallholder Farmers in Sub-Saharan Africa

“…Legume yields are also low; dry bean yields are less than 1 t/ha compared to over 2.5 t/ha under well-managed farmers (Otieno et al, 2020). These lower yields are due to several factors, mainly soil infertility, soil acidity (Otieno et al, 2018;Otieno, 2021), pest and disease infestations (Okeyo et al, 2019;Otieno, 2019a), weed infestation (Bedry, 2007;Monteiro et al, 2011;Amare, 2014;Olayinka & Etejere, 2015), drought (Mathobo et al, 2017), and use low yielding varieties (Nkonya & Mwangi, 2004;Japhether et al, 2006). All these constraints must be addressed if the region has to be food self-reliant through best-crop agronomy.…”