Effect of micronutrients on production of maize (Zea mays L.) in the acid soils of Chitwan Valley.

Field experiments were held during the summer and winter seasons of 2003 and 2004 respectively in the acid soils of the National Maize Research Programme’s (NMRP) farm. The objectives of the study were to identify which micronutrients were deficient in the soils and the effect on grain production, and to recommend micronutrients that would improve the quality and quantity of the produce. No significant yield advantage was found between the recommended amounts of major plant nutrients nitrogen (N), phosphorous (P2O5) and potash (K2O) at a rate of 120:60:40 kg per hectare and the various combinations of micronutrients: sulphur (S), boron (B), zinc (Zn), molybdenum (Mo), iron (Fe), and copper (Cu). The same was found for stover yield and thousand grain weight of maize. The productivity of maize was found to be somewhat higher in winter than in summer with the same treatment and variety of maize. Response to micronutrients was not consistent in the two seasons. In the summer season all micronutrients demonstrated a response except for sulphur. The crop yield decreased in the absence of B, but there was no significant difference from the treatment without micronutrients. In the winter season, there was an indication of deficiency of S only and there was no response to other micronutrients. Nitrogen (N) and potassium (K) uptakes by maize grains were higher with the application of major and micronutrients but there was no significant difference except with the control plot. The treatment without sulphur also gave a significantly lower uptake of N and K, but phosphorous (P) uptake was not significant compared to the control plot. Nitrogen was recorded as deficient in leaf samples in the summer season, whereas P and K were adequate. During the winter season N, P, and K were adequate in the leaf samples. Diethylene triamine penta acetic acid (DTPA) extractable Zn was found to be below the critical level while Fe and manganese (Mn) were adequate. Zinc content in maize leaf was deficient, whereas Cu and Mn were in the normal range and Fe was in excess. A significant relationship was found between Zn and Mn content in the leaf and soil test, but not for Fe.