有机肥对黑土不同粒级有机碳、氮的影响

Effect of manure application on distribution of organic C and total N in bulk black soil and particle-size fractions

采集公主岭市长期定位监测基地不施肥和施用不同用量有机肥的黑土,通过超声波分散-离心分离得到细黏粒(<0.2μm)、粗黏粒(0.2～2μm)、粉粒(2～53μm)、细砂粒(53～250μm)、粗砂粒(250～2000μm)5个颗粒级别,分析全土及不同粒级中土壤有机碳、总氮并进行含量与分布的比较。结果表明,有机质多集中在粉+黏粒中,碳氮比随着粒级的减小而逐渐降低;与粗黏粒相比,细黏粒有机质的转化更快。长期施用有机肥后,除细砂粒级外,全土及各粒级有机碳、氮库大小和浓度均有显著增加;粗砂粒中有机碳、总氮的富集系数升高,黏粒(尤其是细黏粒)中富集系数降低;粉粒和砂粒中的C/N显著降低。施肥量的变化对全土和各粒级中有机碳、总氮浓度的影响较大,对C/N比的影响不显著。

The black soil fertilized with different amount of pig manure for 21 years was sampled from Gongzhuling long-term station. Fine clay(<0.2μm), coarse clay (0.2-2μm), silt(2-53μm), fine sand(53-250μm) and coarse sand (250-2000μm) fractions were obtained by ultrasonic dispersion, centrifugation and wet sieving separation. Soil organic carbon(SOC) and total nitrogen(TN) were detected in bulk soil and particle-size fractions. The results show that soil organic matter mostly exist in the silt plus clay, and the ratios of carbon to nitrogen become narrow with particle size decreasing. Soil organic carbon in fine clay fraction is characterized by a more rapid turnover than in the coarse clay fraction. Except for the fine sand, the SOC, TN concentrations in bulk black soil and other size fractions increase significantly with the increase of pig manure application. The application of pig manure resulted in the increase of the enrichment coefficients of SOC and TN in coarse sand, while the decrease in clay fraction, especially in coarse clay. Moreover, C/N ratios in silt and sand fractions narrowed markedly. Change of pig manure application amount affected the concentrations of SOC, TN significantly, while C/N ratios slightly in both bulk soil and particle-size fractions