Effects of controlled-release compound fertilizer on peanut yield and nitrogen loss in sloping farmland

Objectives Nitrogen loss through erosion is inevitable in slope farmland, causing non-point source pollution, and decreasing crop utilization. We studied the nitrogen runoff losses under different rates of controlled release compound fertilizers by basal application at one time, to provide a theoretical basis for efficient peanut production and low nitrogen ecological risks.

Methods A field experiment was conducted in Linyi, Shandong Province, the tested peanut variety was ‘Huayu 25’. The N–P₂O₅–K₂O ratio of the controlled-release compound fertilizer (CRF) and ordinary compound fertilizer (CF) was 15–15–15. Five treatments included no fertilizer control (CK) and the two compound fertilizer application rate 800 and 560 kg/hm² (100%CRF, 70%CRF, 100%CF, and 70%CF). All the fertilizers were basal applied in one time. Fertilizer N release characteristics, plant biomass and nitrogen content at the main growing stages were determined, and the peanut yield and kernel rate were investigated at harvest.

Results The peanut kernal yield in 100%CRF was 13.8% higher than 100%CF, and that in 70%CRF was not significantly different from 100%CF. The 100%CF treatment was recorded similar shelling rate with 70%CF, but 70%CF was recorded significantly lower shelling rate than two CRF treatments. 100%CRF increased nitrogen absorption amount by 5.9%, dry matter accumulation at mature period by 7.1% than 100%CF, and 70%CRF increased by 6.0% and 8.3% than 70%CF, respectively. There was no significant difference between 70%CRF and 100%CF treatment in dry matter accumulation. CRF reduced the runoff nitrate and ammonium nitrogen content on the first and second runoff monitoring, not on the followed monitoring, and the total nitrogen loss amount were similar in all the fertilization treatments. The fertilizer N contribution to peanut yield in 100%CRF treatment was 19.45%, which was 102.6% higher than in 100%CF, and the fertilizer N contribution rate in 70%CRF was 14.65%, 74.4% higher than in 70%CF treatment.

Conclusions In sloping farmland, the basal application of controlled-release compound fertilizer releases nitrogen slowly, so significantly increases the nitrogen uptake and yields of peanut, effectively reduces surface runoff losses of NO₃⁻-N and NH₄⁺-N, and ensures stable peanut production even with a 30% reduction in fertilizer application.