施用有机物料对沙化土壤碳氮含量、酶活性及紫花苜蓿生物量的影响

为探讨施用有机物料对宁夏沙化土壤的改良效果,以当地易得的杨树(Populus alba var.pyramidalis)枝条、玉米(Zea mays)秸秆、牛粪为原料,通过桶栽方法研究了有机物料单施和配施对宁夏沙化土壤碳氮含量、酶活性及紫花苜蓿生物量的影响。结果表明,与无添加对照相比,单施和配施有机物料(除牛粪外)均使土壤的碳、氮组分含量(除无机氮外)有不同程度的增加;单施牛粪处理增加了土壤的无机氮,土壤有机碳、易氧化有机碳、全氮和水解氮含量均最高,但是土壤C/N(有机碳/全氮)及微生物C/N(土壤微生物生物量C/微生物生物量N)较低;杨树枝条+玉米秸秆+牛粪配施处理的土壤微生物生物量碳和微生物生物量氮含量,土壤酶活性(纤维素酶、过氧化氢酶、蔗糖酶、磷酸酶、脲酶)以及紫花苜蓿(Medicago sativa)生物量(是对照的3.33倍)最高,而单施牛粪却出现抑制紫花苜蓿生长的现象。土壤肥力水平综合得分显示,杨树枝条+玉米秸秆+牛粪处理对土壤肥力水平的提高效果最佳。该研究为宁夏及其它类似地区沙化土壤改良提供了参考的依据。

Effects of fertilizing organic materials on contents of carbon and nitrogen,enzyme activity of desertified soils and alfalfa biomass

Poplar branch,corn straw,and cow manure were selected from a local site in order to study the effects of these amended materials on desertified soil in Ningxia.Further,a microcosm experiment was set up to test the effects of individual material or mixed materials on contents of carbon and nitrogen,enzymatic activity of desertified soil,and alfalfa biomass.Results showed that both individual material (except cow manure) and mixed materials increased all fractions of soil carbon and nitrogen,except inorganic nitrogen,compared with control.Cow manure increased inorganic nitrogen,soil organic carbon (SOC),oxidized organic carbon,total nitrogen (TN),and available nitrogen of the soil relative to other treatments.However,cow manure decreased soil C/N (SOC/TN) and microbial biomass C/N (MBC/MBN).Mixed materials with poplar branch,corn straw,and cow manure were the best in increasing microbial C and N contents,and also showed the best tendency for increasing enzyme activity,including the activities of cellulase,catalase,sucrase,phosphatase,and urease.Mixed materials with poplar branch,corn straw,and cow manure was also the best in increasing alfalfa biomass.Individual treatment with cow manure resulted in lower alfalfa biomass compared with the control.In conclusion,mixed materials with poplar branch,corn straw,and cow manure showed the most significant effect on improving soil fertility in desertified soils according to principal component analysis.The study will be an example for desertified soil amendment in Ningxia and other similar sites in China.