Crop rotation with plastic mulching increased soil organic carbon and water sustainability: A field trial on the Loess Plateau.

Appropriate crop rotations are beneficial for food security and carbon sequestration. In cool and semiarid rain‐fed areas, however, the effect on carbon sequestration in soil and the soil–crop system is not clear. In this study, a crop rotation field experiment was carried out on the Loess Plateau, China, involving (1) wheat continuous cropping (WCC), (2) maize continuous cropping (MCC), (3) potato continuous cropping (PCC) and (4) wheat–maize–potato rotating cropping (RC). All treatments were tilled once, and then, plastic mulched immediately to inhibit evaporation. We found that the rotating cropping system improved water storage in the 0–300 cm soil profile by 65.8 mm through the 6 years, while MCC depleted deep soil moisture. In a drought year, total dry matter (DM) for the rotating cropping was greater by 23.9% and 79.3% and harvested carbon quantity (HCQ) by 0.6 and 1.8 Mg ha−1 compared with WCC and MCC systems, respectively. Total evapotranspiration significantly decreased by 14.5% compared with MCC, with no significant change compared with WCC and PCC. The soil organic carbon (SOC) concentration at 20–30 cm depth in the rotating cropping system was 36.0%, 28.0% and 30.3% greater than those of WCC, MCC and PCC, respectively. Similarly, the SOC sequestration rate at this depth was higher by 3.8, 3.2 and 3.4 Mg ha−1, respectively. The pure carbon accumulation (PCA) of the rotating cropping system significantly increased compared with WCC and PCC, resulting in increased water use efficiency of pure carbon accumulation (WCP) by 11.1, 2.2 and 3.1 Mg ha−1 mm−1 compared with the WCC, MCC and PCC systems, respectively. Overall, the rotating cropping (RC) system maintained better soil water conditions, sustained crop development and SOC sequestration, especially optimizing the relationship between crop water utilization and SOC sequestration in soil–crop system in the cool semiarid rain‐fed area. [ABSTRACT FROM AUTHOR]