Analysis of nitrogen input and soil nitrogen load in orchards of Hebei province

It is important to study and analyze the input and load characteristics of orchard nitrogen for orchard nitrogen nutrient management. Based on data collected from survey of orchard soil fertility, farmer interview and agricultural statistics database, the characteristics of N application and its surplus were studied among different fruit trees and regions through N balance method. The results showed that the average application rate of N fertilizer was 438.0 kg/ha, with common types being urea, and compound fertilizers. The N input rate through manure application was 181.6 kg/ha, using common animal waste and manures. However, poultry manure proportion accounted for 25.5% of organic manure. In different regions, the rates of N input, surplus in the orchards of the East Tangshan-Qinhuangdao region in Hebei and central-south districts of Hebei plain were relatively higher than other regions. It was found that peach and grape had higher rate of N fertilizer application compared with other fruit trees. Positive correlation was found between N surplus and applied N rate in the surveyed orchards. Excessive N fertilizer input led to the increase of N surplus and soil N load. Further, soil total nitrogen and the ratio of soil C/N increased with higher N surplus. The influence of nitrogen surplus on soil total nitrogen was higher than soil organic matter.