连作及灌溉方式对棉田土壤微生物量碳氮的影响

Effect of continuous cropping and irrigation way on soil microbial biomass carbon and nitrogen

采用野外采样与室内分析的方法,对不同连作年限及灌溉方式条件下土壤微生物量碳、氮的变化规律进行研究,结果表明:与荒地相比,棉田土壤微生物量碳氮含量均增加,且随种植年限的延长,土壤微生物量碳氮变化规律基本一致,连作2 a的微生物量碳氮含量最低,分别为16.22±0.77和13.08±0.75 mg/kg,随连作年限的延长微生物量碳氮含量不断增加,到连作15 a时达到最高点,分别为38.67±1.22和23.39±0.65 mg/kg,之后微生物量碳氮含量开始下降;相对于地面沟灌而言,滴灌使土壤微生物量碳氮含量明显提高;微生物量碳与微生物量氮呈现极显著正相关性,相关系数为0.951,与土壤全氮、速效氮呈显著正相关,相关系数分别为0.863、0.854;微生物量氮与土壤全氮、速效氮的相关系数分别为0.919、0.945,呈极显著正相关。

By field sampling and indoor analysis methods,we have surveyed soil microbial biomass carbon and nitrogen change in different duration of continuous cropping years and irrigation condition,and the results showed that： Compared with wasteland,soil microbial biomass carbon and nitrogen both increase in cotton field,and with the increase of years for cultivation,the change laws of soil microbial biomass carbon and nitrogen are basically the same.The microbial biomass carbon and nitrogen are the lowest in the two-year continuous cropping,being 16.22±0.77 mg/kg and 13.08±0.75 mg/kg respectively.With the extension of continuous cropping,microbial biomass carbon and nitrogen content continue to increase.In 15-year continuous cropping,the microbial biomass carbon and nitrogen get to the highest points of 38.67±1.22 mg/kg and 23.39±0.65 mg/kg respectively,and then the soil microbial biomass carbon and nitrogen begin to decline.Compared to furrow irrigation,drip irrigation improves obviously microbial biomass carbon and nitrogen.Microbial biomass carbon has extremely obvious positive correlation with microbial biomass nitrogen,and the correlation coefficient is 0.951.It also has obvious positive correlation with soil total nitrogen and available nitrogen,and the correlation coefficients are 0.863 and 0.854 respectively.Microbial biomass nitrogen has extremely obvious positive correlation with soil total nitrogen,available nitrogen,with the correlation coefficients being 0.863 and 0.854 respectively.