耕层增减对作物产量、养分吸收和土壤养分状况的影响

试验于2012—2015年在淮北平原中部的濉溪县展开,设原始耕层(TS)、在原始耕层厚度上人工削减5 cm(TS-5)和在原始耕层厚度上人工增加5 cm(TS+5) 3个处理。在玉米和小麦成熟期采样分析和田间测产,在3季小麦收获后分别采集0~20 cm土层土样进行分析,明确耕层厚度变化对玉米–小麦轮作体系作物产量、养分积累的影响和土壤养分含量的变化规律。结果表明,耕层减少5 cm处理明显降低玉米–小麦轮作体系作物产量和N、P2O5、K2O积累量,与原始耕层处理相比,分别下降了5.61%和8.31%、5.65%、18.38%;耕层增加5cm后作物产量和各养分积累量均未出现显著变化。第1个轮作周期结束时,耕层减少5cm处理的土壤有机质、全氮和速效钾含量明显低于原始耕层处理;而经过3个轮作周期,土壤有机质含量仍处于较低水平,全氮和速效钾含量逐渐回升,与原始耕层对应指标已无显著差异。耕层增加5cm处理明显提高了土壤有机质和各养分含量,并在3个轮作周期后仍处于较高水平。综上,耕层厚度减少5 cm会降低玉米–小麦轮作体系作物产量、各养分积累量和土壤有机质含量,并在短期内难以恢复;增加5 cm耕层虽然能改善土壤养分状况,但对作物产量和养分积累量的提高没有明显效果。

Effects of Topsoil Thickness on Crop Yields and Nutrient Uptake as well as Soil Nutrients

A field experiment was conducted in Suixi County in the middle of Huaibei Plain from 2012 to 2015, three treatments of topsoil thickness were designed: original topsoil (TS), 5 cm topsoil removed artificially (TS-5) and 5 cm topsoil increased artificially (TS+5), plant samples of maize and wheat were collected at the mature stages and soils in 0-20 cm depths were sampled after quarterly wheat harvest. Crop yields of maize-wheat rotation and nutrient accumulation were analyzed, and the variation of soil nutrient contents were discussed. The results showed that compared with TS treatment, TS-5 treatment significantly reduced crop yields and N, P₂O₅ and K₂O accumulation in maize-wheat rotation, decreased by 5.61% and 8.31%, 5.65%, 18.38%, respectively, while crop yields and nutrient accumulation of TS+5 treatment showed no significant change. At the end of the first rotation, the contents of SOM, total nitrogen and available potassium of TS-5 treatment were obviously lower than TS treatment. After the third rotation, the contents of total nitrogen and available potassium increased gradually and had no significant difference with those of TS treatment, while the content of SOM was still at a low level. TS+5 treatment significantly increased SOM and nutrient contents, they were maintained at high levels after the third rotation. In summary, TS-5 treatment can reduce crop yields and nutrient accumulation of maize-wheat rotation and the contents of SOM and nutrients are difficult to recover in the short term. Although TS+5 treatment can improve soil nutrient status, but such improvement has no significant effect in increasing crop yields and nutrient accumulation.