Study On Nitrogen Composition Variation Characteristics In Organic Substrate Under Cucumber Cultivation

Development and application of organic substrate based on biowaste showed great significance on promoting the development of agroforestry and environmental protection. This research was aimed at studying characteristics of organic nitrogen composition in culture substrates mixed with different volume ratio of vinegar and soil, influencing of different substrates and fertilizer quantities on the changes of nitrogen components,and relationships between nitrogen components and enzyme activity in the process of cucumber cultivating.This research was also aimed at analyzing the key factors which affected nitrogen transformation and providing the basis for nitrogen managements and regulations in substrate cultivation.Research mainly had the following results:(1) Different ratios of vinegar reside had significant effects on cucumber growth. As the ratio of vinegar residue in substrates increases,the cucumber plants grow better and production gets higher. Pure vinegar reside treatment(C) has a better plant height, stem diameter and leaf number than other substrate treatments. In different substrates, different fertilizer quantities showed no obvious fertilization effects.(2) In different substrates, the greater vinegar radio, the greater contents of inorganic nitrogen, organic nitrogen in the substrates.Ammonium nitrogen accounted for a larger proportion than nitrate nitrogen in inorganic nitrogen.Organic nitrogen accounts for a proportion between 57.3% ~ 98.4% in total nitrogen.Nitrogen components in order from large to small was amino acids nitrogen > ammonium nitrogen > unknown acid solution nitrogen >amino sugar nitrogen. Ratio of different vinegar residue and different growth stage of the cucumber had significant effects on nitrogen components contents. With the increase of fertilizer amount, each of nitrogen components in substrate performed a first reduce and then rising trend.Unknown nitrogen component in acid solution showed a higher content in medium fertilizer treatment than in other treatments.(3) The different substrates had obvious influence on urease and catalase activity and microbial diversity. The greater accounts of vinegar reside for the volume ratio, the greater urease and catalase activities,while the lower microbial diversity index. Urease and catalase activity and microbial diversity index were affected by the cucumber growth and different fertilizer amounts,Urease and catalase activities in tendril period and flowering period were higher than which in the early and late periods of cucumber growth.Medium-amount fertilizer could obviously promote catalase enzyme activity.(4) Correlation between nitrogen components and enzyme activity,other physical andchemical properties showed, the nitrogen composition content and plant nitrogen absorption showed no significant correlation.Ammonium nitrogen showed significant correlation with EC,C/N, total nitrogen and nitrate acid solution.Nitrate nitrogen with all nitrogen components except amino sugar,and pH, EC, C/N, organic matter content, activity of urease and catalase were significantly correlated.In addition to the ammonium nitrogen and amino sugar nitrogen,total nitrogen and other various nitrogen components, urease and catalase activity, and physical and chemical properties indexes showed significant correlation; Amino sugar nitrogen and pH showed a significant correlation with total nitrogen in acid solution; Amino acid nitrogen and ammonium nitrogen showed significant correlation with all the other substrate properties except for ammonia nitrogen and amino sugar nitrogen.Total nitrogen in acid solution showed a significant correlation with various physical and chemical indicators as well as enzyme activity.The correlation between nitrogen components and pH and C/N were negative significant while it was positively significant with other indexes.(5)The significant correlation between nitrogen component showed closely relation between each link of nitrogen transformation, pH, C/N, organic matter content as well as urease and catalase activity were important factors which affect nitrogen transformation.