Maize Yield and Nutrient Losses as Affected by Different Fertilizer Rates

This project was initiated in 2012 to fine-tune N and K fertilizer application rates for maize grown on sloping farmlands in Sichuan province. The N rates used in 2014 were adjusted downward, K rates remained constant, and P was fixed to a single rate based on results from previous years. The seven treatments included five rates of N (0, 150, 225, 300, or 375 kg N/ha), three rates of K (0, 75 or 120 kg K₂O/ha) and one P rate (150 kg P₂O₅/ha). Nitrogen was split four times (10%-20%-20%-50%) at seeding (basal), and three topdressings (seedling, elongation and tasseling stages). Fertilizer P and K were applied once at seeding.

Maize yield was boosted by the addition of N fertilizer, and the yield response leveled off at 225 kg N/ha. This confirmed the optimal N rate tested in previous years and the NPK fertilizer combinations for maize on sloping lands in Sichuan. Similar to previous results, 75 kg K₂O/ha produced the highest maize yield amongst the three K rates. The optimal fertilizer combination achieved the highest N use efficiency, which decreased with N rates above 225 kg/ha. Water loss, soil erosion and nutrient loss were all lower under the optimal treatment due to better growth, higher nutrient uptake and denser plant canopy.

Good nutrient management not only increases maize yields but also limits soil erosion and nutrient loss from sloping lands.