耕作方式对长期免耕农田土壤微生物生物量碳的影响

以华北冬小麦-夏玉米两熟区长期免耕土壤为研究对象, 研究不同耕作方式(免耕、翻耕和旋耕)对长期免耕土壤微生物生物量碳(SMBC)的影响, 为制定合理的轮耕制度提供依据。试验结果表明: 长期免耕土壤进行耕作处理后SMBC 的时空分布和稳定性产生显著变化。不同耕作处理SMBC 含量在0~5 cm 和5~10 cm 土层变化明显, 小麦起身期含量最低, 收获期最高; 深层SMBC变化不明显。免耕处理SMBC 随土壤层次明显降低, 且各土壤层次SMBC 差异达显著(P<0.05)水平; 翻耕、旋耕处理0~5 cm 和5~10 cm 土层间SMBC 无明显差异, 其他层次间差异显著(P<0.05)。从生育期平均值看, 0~5 cm 土层免耕处理SMBC 含量较高, 翻耕和旋耕处理则分别比免耕降低6.7%、6.1%; 与免耕相比, 5~10 cm 土层SMBC 翻耕、旋耕处理分别增加30.2%和20.7%(P<0.01),10~20 cm 土层SMBC 翻耕、旋耕处理比免耕增加48.1%(P<0.01)和10.5%(P<0.05)。在冬小麦生育期内, 0~20 cm土层SMBC 稳定性表现为翻耕>旋耕>免耕, 20~30 cm 土层SMBC 稳定性表现为免耕>翻耕>旋耕。

Effect of tillage practices on soil microbial biomass carbon in the field with long-term non-tillage

In order to provide a reasonable basis for the rotational tillage system, the effects of different tillage practices on soil microbial biomass carbon (SMBC) were determined in double maturation of wheat-corn cropping fields with long-term non-tillage in North China Plain. The results showed that tillage managements significantly influenced spatio-temporal variations and stability of SMBC in long-term non-tillage soil. SMBC in the 0~5 cm and 5~10 cm soil layers exhibited obvious seasonal variations in different treatments. While the lowest value was at double ridge stage, the maximum was at harvest stage of wheat. In deep soil layers, there were insignificant seasonal variations in SMBC. SMBC significantly decreased (P<0.05) with soil depth under non-tillage and straw mulch (NT) treatment. In the 0~5 cm and 5~10 cm soil layers, SMBC was insignificantly different under conventional tillage (CT) and rotary tillage (RT). Among all other soil layers, however, SMBC was significantly different (P<0.05). Compared with NT treatment, CT and RT dropped average SMBC by 6.7% and 6.1% in the 0~5 cm layer. However, CT and RT significantly increased SMBC by 30.2% and 20.7% (P<0.01) in the 5~10 cm layer. Also average SMBC under RT and CT increased significantly by 10.5% (P<0.05) and 48.1% (P<0.01) in the 10~20 cm layer. The trend of the effects of different treatments on SMBC stability in the 0~20 cm soil layer was as follows: CT > RT > NT. That in the 20~30 cm soil layer was NT > CT > RT.