Assessment of nutrient flows in maize-based farming system by smallholder farmers for sustainable production in Ikara, Kaduna State

Nutrient depletion is one of the major causes of decreased crop yield, and a threat to food security and sustainable crop production. NutMon- toolbox was used to determine nutrient flows and partial nutrient balances of maize-based smallholders’ farming system. Data was collected using structured questionnaire from 15 randomly selected farmers, with five farmers each in three villages. Composite soil samples were also taken from each of the three plots. At crop maturity, samples of crop products and residues were randomly taken from the selected fields. Nitrogen, P and K contents in soil and crop material was used to calculate nutrient flows and partial balances. Results obtained revealed that mineral fertilizer flow, averaged 349.20kg N yr-1 and 81.45kg K yr-1 and were lower than 376.65kg N yr-1 and 431.44kg K yr-1 organic input. However, phosphorus in mineral fertilizer (55.78kg P yr-1) was higher compared to phosphorus (51.06 kg P ha-1 yr-1) in organic input. Nitrogen, phosphorus and potassium for maize seeds and crop residue were all negative. The partial nutrient balances were positive 53.45kg N ha-1 yr-1 and 79.40kg K ha-1 but negative 1.10kg P ha-1 yr-1. Harvesting of crops for food, without incorporation of crop residue into the soil, were the most important sources of nutrient mining in smallholder production system. Integrated soil fertility management practices that favour the buildup of soil organic matter and use of animal manure should be encouraged through effective extension services at Ikara, Kaduna State, Nigeria.