Soil properties as influenced by soil fertility management in small scale maize farms in Njoro, Kenya

Abstract

Most farmers are aware of soil fertility gradients within their farms which influence their management decisions and further accentuate these variations. The purpose of this study was to assess the effect of soil amendments on soil properties under farmers management. Soil sampling was done in 37 small scale maize farms in Njoro Division of Nakuru District at 0-20 cm depth. Results of a structured questionnaire showed that 65% of the farmers used inorganic fertilizers predominately diammonium phosphate (DAP), 15% used only farmyard manure, 15% used both organic and inorganic fertilizer, while 6% did not use any soil amendments. Most of the farms had a pH (CaCl2) of less than 5.2, 27% of the farms had a pH lower than 4.0. Organic carbon (C) ranged from 1.6 to 5.8%, with a median value of 2.6%. Most of the farms were phosphorus (P) deficient with an Olsen-P of less than 10 mg kg-1. All farms had sufficient amounts of extractable potassium (K). Total nitrogen (N) ranged from 0.12 to 0.33% with 97% of the farms with N content (>0.12%). Farms amended with farmyard manure had higher organic C and total N levels in Kikapu with correspondingly lower C: N ratios. Soil pH and total N were higher for farms with gentle and undulating slopes. Overall most of the farms were acidic and of moderate fertility. Liming increased maize biomass production in Njoro. This study underscores the need for organic inputs and regular soil testing for small scale farmers © 2009 Asian Network for Scientific Information.