Effects Of Manure Types And Application Rates On Soil Nitrogen Fractions And Nitrogen Losses Of Farmland

In order to study the impacts of the manure application rates and types on soil nitrogen fractions and nitrogen losses from farmland,a field plot experiment with three N levels and four types of manure, was carried out on corn before planted in Langfang in the years of 2008 and 2009. The three N levels were N0 (no manure), N1 (72¹55kg N/ha), N2 (195⁴63kg N/ha) respectively, and the N levels of chicken and pig manure treatment was N0, N1, N2, cow and duck manure treatment was the N0, N2. And in this study, rainfall simulation experiments were done in order to understand the change of soil nitrogen fractions after manure application influencing on N losses through runoff, leakage from different experiment plot. The main results were as follows.With the increasing of the amount of AN in manure, the mineralized N (AAN, AN) contents in the soil depth of 0⁵cm, 5²0cm are also increasing. There are significant or extremely significant positive correlations (p<0.01) between the amount of AN in manure and the content of TN, THN, AAN, AN in 0⁵cm, 5²0cm soil depth. When the amount of manure is 195⁴63kg N/ha , there are apparent differences of TN, THN, AAN, AN in 0⁵cm, 5²0cm soil depth between the N2 treatment and N0 treatment, with the increasing rates of the four N fractions contents of 92.22%, 93.81%, 108.37%, 76.01% in 0⁵cm soil depth, and 48.48%, 44.47%, 60.04%, 39.00% in 5-20cm soil depth respectively.With the increasing of the mineralized N content in 0⁵cm, 5²0cm soil depth, the concentrations of total N, total dissolved N, NO₃^--N are increasing in leakage. There are significant (p<0.05) or extremely significant positive correlations (p<0.01) between the mineralized N content in 0⁵, 5²0cm soil depth and the concentration of total N, soluble N, NO₃^--N in leakage. With the increasing of the amount of the mineralized N in manure, the amount of total N, soluble N are increasing in runoff and the concentration and amount of total N, soluble N are increasing in leakage. There are significant or extremely significant positive correlations between the amount of the mineralized N in manure and the amount of total N, soluble N in runoff, significant (p<0.05) or extremely significant positive correlations (p<0.01) between the amount of the mineralized N in manure and the amount and concentration of total N, soluble N.The NO₃^--N is the main form of N losses in leakage for the treatments of four manure types, there is different from runoff, the NO₃^--N is the main form of loss with chicken treatment, while the NH₄⁺-N is the main form of loss with the treatment of duck manure, pig and cattle manure. The manure types almost have no effect on the form and amount of N losses in runoff and leakage at the same N level.The results showed that the higher of the amount of AN in manure, the higher of the content of soil mineralizable nitrogen, which lead to the great risk of N losses from farmland.