Nitrogen And Phosphorus Budget And Soil Of Livestock And Poultry Manure Returning To Field

With the continuous improvement of the scale of livestock and poultry breeding in China,a large amount of breeding manure has not been effectively treated and comprehensively utilized,which has gradually become a problem of rural environmental governance.Farming manure is rich in nitrogen and phosphorus nutrients.The harmless treatment of manure into farmland can effectively improve soil fertility and increase crop yield,but excessive input will lead to a large accumulation of soil nitrogen and phosphorus,resulting in agricultural ecological environment pollution.In this study,livestock manure and chemical fertilizers were applied in different proportions to monitor the spatial and temporal distribution of nitrogen and phosphorus in soil,air,water and crops in farmland system,to test the physical and chemical properties of soil and fertility changes,and to determine the growth characteristics and yield of crops at different growth stages.The nitrogen and phosphorus income and expenditure,soil fertility changes and crop growth and development in the farmland system were studied,and the effects of different experimental treatments were compared to explore the best returning mode to provide support for the resource treatment of manure returning to the field and provide a basis for reasonable manure returning to the field.The following conclusions are drawn:The application of livestock and poultry manure significantly increased the nitrogen surplus of farmland.The CF₀M₁₀ treatment（0%chemical fertilizer combined with 100%manure）increased the nitrogen content of the topsoil by 43.46%-96.64%,and the nitrogen surplus was 61.48 times that of CF₁₀M₀ treatment（100%chemical fertilizer combined with0%manure）.The total nitrogen leaching loss of each experimental treatment was 0%～0.36%of the nitrogen application rate;there was a significant positive correlation between ammonia volatilization and chemical fertilizer application rate（P<0.01）,accounting for0.07%～0.18%of nitrogen application rate.The highest nitrogen uptake of CF₁₀M₀treatment was 493.42 g/plot,which was 2.08 times that of CK treatment（no fertilization）.Livestock manure returning to the field can increase the phosphorus content of topsoil.The total phosphorus content of CF₁M₉ treatment（10%chemical fertilizer combined with90%manure）was the highest（293.14 g/kg）,which was 48.59%～69.86%higher than other treatments.The soil phosphorus content of CF5M5 treatment（50%chemical fertilizer combined with 50%manure）was close to the balance of payments.The leaching loss of phosphorus accounted for 0.00%～0.02%of the phosphorus application.CF₇M₃ treatment（70%chemical fertilizer combined with 30%manure）had the highest phosphorus content absorbed and utilized by crops,which was 36.66%higher than the phosphorus application rate.This treatment led to a loss of phosphorus in the soil by 30.36 g/plot.Compared with CF10M0 treatment,CF0M10 treatment increased soil organic matter by 1.90～1.61 times.Soil organic matter content was positively correlated with available phosphorus and available potassium（P<0.01）,and negatively correlated with chemical fertilizer application rate（P<0.01）.Soil conductivity was negatively correlated with manure application rate（P<0.01）.The application of manure had a significant improvement effect on soil salt status.The application of livestock and poultry manure promoted the growth of crops at seedling stage,and the application of manure combined with chemical fertilizer increased crop yield.The stem diameter and plant height of CF₀M₁₀ treatment were 1.40～1.75 times that of CK treatment.The highest seed yield of CF₇M₃ treatment was 77.98%,and the highest yield was 874.20 kg/mu,which was 2.63%higher than that of local conventional tillage.In summary,CF₇M₃ treatment increased crop yield and quality,improved soil fertility and physical and chemical properties,and did not cause environmental risks such as ammonia volatilization,nitrogen and phosphorus leaching,which was suitable for popularization and application in experimental areas.