不同培肥措施下种植制度及撂荒对土壤微生物量碳氮的影响

以黄土高原南部半湿润易旱区已进行17年的田间定位试验为研究对象,研究了不同培肥措施(不施肥、施用氮磷钾及氮磷钾与有机肥配合施用)下两种种植制度(一年1熟及一年两熟)和撂荒对土壤微生物量碳、氮(SMBC、SMBN)及可溶性有机碳、氮(SOC、SON)等含量的影响.结果表明,与一年1熟的小麦一休闲种植制度相比,一年两熟小麦一玉米轮作提高了0～10 cm土层SMBC、SMBN、有机碳(TOC)、全氮(TN)和土壤SOC、SON的含量,而对10～20 cm土层上述测定指标影响不大.与不施肥(CK)或单施化肥处理(NPK)下小麦-休闲和小麦-玉米轮作方式相比,撂荒处理显著提高了0～10 cm土层各测定指标的含量.不同培肥措施相比,氮磷钾配施有机肥显著提高了0～10 cm、10～20 cm土层SMBC、SMBN含量;NPK处理0～10 cm土层SMBN含量显著增加,10～20 cm土层SMBN和0～10 cm、10～20 cm土层SMBC含量增加但未达显著水平.不同培肥措施和种植制度对SMBC/TOC和SMBN/TN的比例无明显影响.

Effect of different crop rotation systems and continuous fallow on soil microbial biomass carbon and nitrogen under different fertilizer treatments

Crop rotation affects the amount and quality of crop residue returned into the soil. In this study, a 17-year long-term field experiment was conducted to study the effect of different crop rotation systems continuous fallow(CF), wheat and summer fallow (WF), and wheat and maize rotation (WM)] under various fertilization treatments on the contents of soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), soluble organic carbon (SOC) and soluble organic nitrogen (SON). Compared with WF rotation, WM rotation increases SMBC, SMBN, SOC, SON, total organic carbon (TOC) and total nitrogen (TN) contents in the 0~10 cm layer soil, but this is not so obvious in the 10~20 cm soil layer. CF also significantly increases SMBC, SMBN, SOC, SON, TOC and TN contents in the 0~10 cm soil layer in comparison with treatments without fertilizer (CK) or with chemical fertilizer (NPK) under both WF and WM rotations. The effect of different fertilizer treatments on the level of SMBC, SMBN, SOC and SON is in the following order: MNPK>NPK>CK. Crop rotation systems and fertilizer treatments have insignificant effect on SMBC/TOC and SMBN/TN ratios in the soil.