[Effects of Straw Return from Different Crop Rotation Systems on Soil Nutrients and Carbon Pool Management Index in...

To investigate the impact of straw incorporation from different preceding crops on soil nutrient and carbon pool management indices in wheat field， a 13-year study was conducted in the Guanzhong Plain area. The study measured and analyzed the soil contents of total nitrogen （TN）， total phosphorus （TP）， soil organic carbon （SOC）， microbial biomass carbon （MBC）， soluble organic carbon （DOC）， and easily oxidizable organic carbon （ROC） in the 0-10， 10-20， and 20-40 cm depths. Moreover， the stability of SOC was evaluated comprehensively using a soil carbon pool management index method. The research aimed to clarify the effects of straw return from various preceding crops on wheat field nutrient and carbon pool stability. Four treatments were established： winter wheat-summer corn + no straw return （as control， CK）， winter wheat-summer soybean + straw return （TS）， winter wheat-summer soybean + no straw return （NS）， and winter wheat-summer corn + straw return （TM）. The results showed that straw return from different rotation crops had significant effects on soil nutrients. Compared with CK， the TS and TM treatments significantly increased the contents of TP， TN， SOC， ROC， and MBC in 0-10 cm soil layer by 13.33%， 18.31%， 28.26%， 107.80%， and 42.25% and 5.09%， 17.22%， 26.45%， 83.06%， and 29.43%， respectively （P < 0.05）. In the 10-20 cm soil layer， the contents of TN， TP， SOC， MBC， ROC， and DOC were significantly increased under TS and TM compared with CK （P < 0.05）， and the increase was greater under the TS treatment. In the 20-40 cm soil layer， the TP， SOC， and MBC of TS were significantly increased by 9.05%， 15.09%， and 55.83% （P < 0.05） compared with CK， and the TN， TP， and MBC of TM were significantly increased by 4.03%， 5.11%， and 56.42% （P < 0.05） compared with CK. In addition， the effects of different previous stubble return on the soil carbon pool management index were significant. Compared with CK， TS significantly increased the soil carbon pool management index of the 0-10 cm and 10-20 cm soil layers （P < 0.05）. The soil carbon pool management index was highest under the NS treatment in the 20-40 cm soil layer， although there were no significant differences among the different treatments. At the same time， straw return significantly increased the yield of winter wheat. Compared with CK， the winter wheat yield was significantly superior under the TS and TM treatments， with significant increases of 37.65% and 28.93%， respectively （P < 0.05）. Correlation analysis showed that CPMI was significantly correlated with MBC， DOC， TP， and TN in the 0-20 cm soil layer （P < 0.05）. In the 20-40 cm soil layer， the yield was significantly positively correlated with TN and MBC （P < 0.05）. In conclusion， adopting a planting pattern of winter wheat， summer soybean， and straw return can enhance soil nutrient levels （0-40 cm） and improve active organic carbon components in the soil， thereby promoting the soil organic carbon management index and winter wheat yield. Therefore， this recommended scheme is beneficial for improving both soil nutrients and the potential for sequestering carbon in the Guanzhong Plain of China.