Influence of Amendments Added to Acid Soils on Biochemical Properties, Nitrogen Uptake and Hybrid Maize Yields in Nakuru County, Kenya

Aim: The current study investigated effect of soil amendments; lime (L), manure (FYM) and minjingu phosphate rock (PR) added to soils on soil microbial biomass carbon and nitrogen (SMB-C and SMB-N), available soil nitrogen (N), crop N uptake and grain yields of two maize hybrids (H513 and H614).
Study Design: Two experiments, one for each maize hybrid as test crop, were laid out in a randomized complete block design with a 23 factorial arrangement. The factors each at two levels were L (0 and 3 t ha-1), PR (0 and 60 kg P ha-1) and FYM (0 and 5 t ha-1) giving a total of eight treatments; L, RP, FYM, L+RP, L+FYM, RP+FYM, L+RP+FYM and control (nothing applied).
Methods: Soil and plant samples for the determination of SMB-C and SMB-N, available soil N, and crop N uptake were collected at maize seedling, tasseling and physiological maturity.
Place and Duration of the Study: The experiment was conducted in Molo district of Nakuru County, Kenya during the long rain seasons of 2009 and 2010.
Results: SMB-C and N levels were higher in 2010 than 2009, with lower levels obtained at maize tasseling for both maize hybrids. Available soil N and crop N uptake were higher at maize seedling and declined towards maturity. Statistically significant (P<.05) increases in SMB-C and SMB-N and available soil N and uptake were obtained with the application of soil amendments over the control. In all treatments, H513 had lower N uptake than H614 at tasseling and maturity stages of maize growth and correspondingly higher available N in soil. Maize yields (t ha-1) were higher in 2010 than 2009 and in H614 than H513. The H614 yields were significantly higher (P<.05) in L+PR+FYM (3.9) and, L+PR+FYM (4.1) and L+PR (3.9) treatments in 2009 and 2010, respectively. For H513, yields were significantly higher in L+PR+FYM (2.1 and 2.4) and L+PR (1.9 and 2.1) treatments in 2009 and 2010, respectively.
Conclusion: The L+PR+FYM treatment is a feasible acid soil amendment for its superiority in the measured soil and crop parameters. The H513 matured faster than H614 and because of this attribute, is a viable option in response to the diminishing rainfall amounts and unpredictable weather patterns experienced in the County.