Effects of pig manure-biogas slurry application on soil ammonia volatilization and maize output and quality

Pig manure-biogas slurry contains nutrients such as N, P, K, amino acid, humic acid, etc., and poses eutrophication of water bodies if not efficiently used. Using biogas slurry as a substitute for chemical fertilizers is best alternative practice. The aim of this study was to analyze the effects of pig manure-biogas slurry on soil ammonia volatilization and maize output (quantity and quality). A set of spring and summer maize field experiments were carried out to study the variations in the contents of soil available N, P and K and ammonia volatilization after application of pig manure-biogas slurry. The results showed that soil ammonia volatilization after base fertilization was higher in summer maize than in spring maize. Soil ammonia volatilization was significantly higher under biogas slurry application than under chemical fertilization. Also ammonia volatilization increased with increasing biogas slurry application rate. Ratio of N loss by ammonia volatilization to fertilizer N was 0.17%~2.16%, with an average of 0.88%. In spring maize season, treatment of 100% chemical fertilization, and treatment of 50% biogas slurry N with 50% chemical N yielded 901.55 kg·667m^-2 and 892.71 kg·667m^-2 maize, remarkably higher than the outputs from other treatments. Dissoluble sugar content under 100% chemical fertilization treatment was 103.69 g·kg^-1, much lower than that from other treatments. Also dreg ratio of 100% chemical fertilization treatment was 9.87%, significantly higher than that of other treatments. The other parameters of maize quality were not remarkably different among treatments. Summer maize output was lower than that of spring maize. Summer maize yield of 100% chemical fertilization treatment was 523.47 kg·667m^-2, the highest in all the treatments. The yield of treatment of 50% biogas slurry N with 50% chemical N was 513.41 kg·667m^-2, the second highest in all the treatments. Maize quality under 100% chemical fertilization treatment was higher than that under 100% biogas slurry treatment. However, no significant difference was noted in maize quality under treatment of 50% biogas slurry N with 50% chemical N. The results suggested that 50% chemical fertilizer N was replaceable with biogas slurry N in maize cultivation.