Partial substitution of chemical fertilizer with aerobic fermented pig manure increases nitrogen use efficiency of summer maize and soil fertility

Objectives Unreasonable use of fertilizers and livestock manure not only restricts crop yields, but also seriously threatens soil health and environmental safety. The effects of pig manure composts and its combining application with chemical fertilizer on nitrogen use efficiency and soil fertility were studied, to provide a theoretical basis for the rational use of large-scale pig farm manure.

Methods The summer maize cultivar of Xianyu 335 was used as the test material in a field experiment conducted in the Fengning Animal Experimental Base of China Agricultural University. Five treatments included, no fertilization (CK), 100% chemical fertilizer nitrogen (CF), 100%-natural pig manure compost nitrogen (PM), 100% aerobic fermented pig manure nitrogen (PC), 50% aerobic fermented pig manure compost nitrogen + 50% chemical fertilizer nitrogen (FM). The yield and nitrogen uptake of summer maize, and the soil carbon and total nitrogen contents in 0–40 cm soil after harvest were analyzed.

Results Compared with CF treatment, FM treatment had the highest yield, grain number per ear and 1000-grain weight, and the yield of FM treatment significantly increased by 13.2%. There was no significant difference in yield, grain number per ear and 1000-grain weight among PC, PM and CF treatments. FM treatment had the highest nitrogen accumulation (304.6 kg/hm²) in maize, which was 15.5% higher than that of CF, while PC and PM treatments had no significant difference with CF in N accumulation of maize. Compared with CF treatment, the N recovery rate, N agronomic utilization rate and partial productivity in FM treatment were significantly increased by 85.9%, 59.5% and 13.2%, respectively; while those of PM, PC and CF did not have significant difference. During the key growth period of maize, the inorganic N content in the 0–40 cm soil of FM treatment reached the highest, but did not have significant difference with others. At the maturity stage, the inorganic N content of FM treatment significantly was increased by 41.8%, compared with CF. There was no significant difference in inorganic N content among PC, PM and CF treatments. The application of organic fertilizer increased the soil organic C and total N contents in different degrees. Compared with CF treatment, PC and FM treatments increased the organic C content by 13.3% and 9.8%, respectively and the total soil N content of FM treatment was increased by 33.4% significantly.

Conclusions Under the same N application rate, compared with single application of chemical fertilizer nitrogen, combined application of organic and inorganic fertilizers (50% aerobic fermented pig manure compost nitrogen + 50% chemical fertilizer nitrogen) could significantly increase summer maize grain yields, N accumulation, and soil total N and organic C contents in 0–40 cm layer. Completely organic nitrogen fertilizer has similar effect in maize yield and nitrogen accumulation with pure chemical fertilizer, but has higher soil total N and organic C contents, and aerobic fermented pig manure compost performs better than natural compost does.