Abstract:
Maize is the world’s third most important cereal after wheat and rice. It serves as a staple food to more than 1.2 billion of the world population. However, its production is threatened by declining soil fertility; mainly due to low inputs of fertilizers containing major elements to replenish lost soil nutrients and unsustainable soil tillage practices linked to mono-cropping. To examine the influence of N, P and K and residual compost on maize growth and yield, an experiment was carried out at the Hatfield Experimental Farm of the University of Pretoria. Utilizing the long-term maize trial, controls (0 and W), seven inorganic fertilizer treatments (N, P, K, NP, NK, PK & NPK) and seven organic + inorganic fertilizer treatments (WN, WP, WK, WNP, WNK, WPK & WNPK) were used. The influence of these fertilizer and residual compost treatments on maize seed viability (germination), plant growth, reproductive development, pollen performance, grain yield parameters, yield and grain yield water-use efficiency was investigated.
Higher seed viability was associated with balanced soil nutrient status (WNPK & NPK), whilst deficient soil nutrient status (0, N, P & K) resulted in lower seed viability. Plant growth (plant height, total dry mass and LAI) and reproductive development (tassel length, ear length, and days to tasseling and silking) were positively influenced by a balanced soil nutrient status and residual compost. Deficiencies in soil nutrients restricted maize plant growth and delayed reproductive development. This highlighted the importance of a balanced soil nutrient status in attaining a vigorous crop and good reproductive development.
Soil nutrient deficiencies (0, P & K treatments) enhanced the production of pollen (mass per plant), but resulted in low pollen quality (viability and germination). Balanced soil nutrient status (WNPK & NPK) resulted in the production of high quality pollen (viability and germinability), which however had a low mass. In both 2012/2013 and 2013/2014 seasons, maize grain components; cob length, number of kernel rows per cob, number of kernels per row, mass per kernel and mass of 100 kernels were positively influenced by balanced soil nutrient status. Grain yield and water use efficiency were also positively influenced by a balanced soil nutrient status (WNPK & NPK), whilst deficient soil nutrient status had a negative effect.
