Appropriate straw incorporation has ample agronomic and environmental benefits in the North China Plain, but most studies are limited to straw mulching or incorporation on the soil surface. To determine the effect of depth of straw incorporation on crop yield, soil organic carbon (SOC) and total nitrogen (TN), a 3-year field experiment was established with the following four treatments: (i) no straw incorporation (CK); (ii) straw incorporation at 15 cm (S15); (iii) straw incorporation at 25 cm (S25) and (iv) straw incorporation at 40 cm (S40). The results showed that straw incorporation significantly increased SOC, TN and C:N ratio (P < 0.05). Compared with CK, substantial increases (P < 0.05) in SOC and TN were observed at the 0-20 cm layer under S15, at all depths under S25 and at the 40-60 cm depth under S40. Under S25 (20-40 cm) in particular, the SOC and TN levels considerably (P < 0.05) exceeded those under CK (8.83˜17.26% of SOC and 6.28˜10.25% of TN), S15 (3.66˜9.25% of SOC and 2.13˜4.70% of TN) and S40 (4.74˜8.23% of SOC and 3.21%˜4.27% of TN). The average SOC and TN at 0-60 cm under S25 was also significantly higher (P < 0.05) than those under S15 and S40. Straw incorporation also increased the C:N ratio and the response of C:N ratio to straw incorporation differed by the depth of straw incorporation and the soil layer. Compared with S15 and S40, S25 had a significant effect on the C:N ratio at each soil layer. Both S25 and S40 decreased the stratification ratio (SR) of SOC, TN and C:N ratio and promoted a uniform distribution of SOC and TN within the 0-60 cm depth. Compared with CK, straw incorporation also significantly increased (P < 0.05) crop yields, especially under S25, by 10.83% in 2014, 13.25% in 2015 and 7.68% in 2016. The grain yields of wheat and maize were positively correlated with SOC and TN (0-20 cm and 20-40 cm). Thus, in the North China Plain, straw incorporation at the 25 cm depth would boost soil fertility and crop yield.

在华北平原，适当的秸秆掺入在农业和环境方面具有充分的效益，但是大多数研究仅限于覆盖土壤或在土壤表面掺入秸秆。为了确定秸秆掺入深度对作物产量，土壤有机碳（SOC）和总氮（TN）的影响，建立了一项为期三年的田间试验，采用以下四种处理方法：（i）不掺入秸秆（CK）；（ii）在15厘米处合并秸秆（S15）；（iii）在25厘米处合并吸管（S25），以及（iv）在40 cm处合并吸管（S40）。结果表明，秸秆还田可显着提高土壤有机碳，总氮和碳氮比（P <0.05）。与CK相比，在S15下的0-20 cm层，S25下的所有深度和S40下的40-60 cm的深度处，SOC和TN均显着增加（P <0.05）。特别是在S25（20-40 cm）下，SOC和TN含量（P <0.05）大大超过CK（8.83〜17.26％SOC和6.28〜10.25％TN），S15（SOC的3.66〜9.25％）分别为TN的2.13％〜4.70％和SOC的4.74％〜8.23％以及TN的3.21％〜4.27％。S25下0-60 cm处的平均SOC和TN也显着高于S15和S40下（P <0.05）。秸秆还田还增加了C：N比，并且C：N比对秸秆还田的响应因秸秆还田深度和土壤层而有所不同。与S15和S40相比，S25对每个土壤层的C：N比有显着影响。S25和S40均降低了SOC，TN和C：N比的分层比（SR），并促进了0-60 cm深度内SOC和TN的均匀分布。与CK相比，秸秆掺入量也显着增加（P < 0.05）的作物产量，特别是在S25条件下，分别在2014年，10.83％，2015年的13.25％和2016年的7.68％。 。因此，在华北平原，在25 cm深度的秸秆掺入将提高土壤肥力和农作物产量。