玉米地土壤微生物量碳、氮及微生物熵对不同物料还田的响应

在四川丘陵区紫色土上进行田间试验,以无物料还田为对照,对比分析了蚕豆秸秆、油菜秸秆、猪粪3种物料还田对夏玉米吐丝期和收获期0—20,20—40cm土层土壤有机碳、全氮、微生物量碳氮含量及微生物熵的影响,以期为农业废弃有机物料的综合利用及四川丘陵区土壤质量的提升提供理论参考。结果表明:(1)尽管有机物料还田于0—20cm土层中,0—20,20—40cm土层土壤有机碳(SOC)、全氮(TN)、微生物量碳(SMBC)、微生物量氮(SMBN)含量均受到有机物料的深刻影响。各处理0—20cm土层SOC、TN、SMBC、SMBN含量均显著高于20—40cm土层,且上下2层土壤SOC、TN、SMBC和SMBN含量在生育时期间均表现为吐丝期>收获期。(2)在2个生育时期,3种物料还田均能提高0—20,20—40cm土层SOC、TN、SMBC、SMBN含量。与对照相比,物料还田处理的SOC、TN、SMBC、SMBN含量分别提高2.6%~141.2%,1.9%~33.0%,5.1%~114.7%,41.5%~98.7%,其中收获期各处理0—20,20—40cm土层SOC、SMBC、SMBN均表现为油菜秸秆>蚕豆秸秆>猪粪>对照,TN表现为蚕豆秸秆>猪粪>油菜秸秆>对照。(3)各处理SMBC/SMBN、qMB、SMBN/TN分别为3.74~10.53,0.86%~2.19%,1.01%~3.41%,且物料还田降低SMBC/SMBN,提高土壤qMB和SMBN/TN值。相关分析表明,SMBC、SMBN与SOC、TN之间均存在极显著正相关关系。因此,农业生产中可通过物料还田提供给微生物足够的碳氮营养,提高土壤SMBC、SMBN、SOC、TN含量和qMB值,维持较高的农田生产力,提升土壤质量,但具体施用物料时还需寻求土壤肥力提升、玉米产量增加以及环境效益之间的平衡。

Responses of Soil Microbial Biomass Carbon, Nitrogen and Microbial Entropy to Different Materials Returned to Corn Fields

In order to study the effects of different materials returned to field on soil microbial biomass carbon, nitrogen and microbial entropy of 0-20 cm and 20-40 cm soil layers in summer maize silking and harvesting period, a field experiment was conducted on the purple soil in Sichuan Hilly area. This study was expected to provide a theoretical reference for the comprehensive utilization of agricultural waste organic materials and the improvement of soil quality in hilly areas of Sichuan. Four treatments with different materials returned to field were designed in this experiment, including control (no material returned to the field), faba bean straw, rape straw and pig manure. The results showed that:(1) Although the organic materials were returned to the 0-20 cm soil layer, the soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon (SMBC), microbial biomass nitrogen (SMBN) contents in both 0-20 cm and 20-40 cm layers were significantly affected. The contents of SOC, TN, SMBC and SMBN in the 0-20 cm soil layer were significantly higher than those in 20-40 cm. Soil SOC, TN, SMBC and SMBN in both soil layers appeared as silking stage>harvest stage during the growth period. (2) In the two growth periods, the three materials returned to the field could increase the SOC, TN, SMBC and SMBN contents of 0-20 cm and 20-40 cm soil layers. Compared with the control, the contents of SOC, TN, SMBC and SMBN in the treatments with materials returned were increased by 2.6%~141.2%, 1.9%~33.0%, 5.1%~114.7% and 41.5%~98.7%, respectively. The contents of SOC, SMBC and SMBN in both soil layers appeared as rape straw > faba bean straw > pig manure > control, while TN contents as faba bean straw > pig manure > rape straw > control. (3) In this study, SMBC/SMBN, qMB and SMBN/TN varied from 3.74 to 10.53, 0.86% to 2.19% and 1.01% to 3.41%, respectively. The materials returned to the field reduced SMBC/SMBN and improved soil qMB and SMBN/TN values. Correlation analysis indicated that there were significantly positive relationships between SMBC, SMBN, SOC and TN. Therefore, we could improve the contents of SMBC, SMBN, SOC, TN and qMB value by returning materials to the field in agricultural production, and then we could maintain high farmland productivity so as to improve soil quality. However, during returning the specific types of materials, the balance among higher soil fertility, maize production and environmental benefits should also be considered.