Impacts of mulching measures on crop production and soil organic carbon storage in a rainfed farmland area under future climate

Abstract

Mulch planting techniques are used widely to increase the crop yield in the Loess Plateau region of China. However, the impacts of long-term mulching measures on crop productivity and soil organic carbon (SOC) storage under climate change are still unclear. In this study, the denitrification-decomposition (DNDC) biogeochemistry model was calibrated based on field test data from 2013 to 2018, and the downscaling predicted climate data from 33 Global Climate Models (GCMs) were used to assess the future trends in spring maize yield and soil organic carbon storage changes under different mulching tillage measures (i: conventional tillage without mulching as the control (CK); ii ridge–furrow planting with half plastic film mulching (R); iii: straw mulching (S); iv: dual mulching of the ridge (film) and furrow (straw) (RS)) in the Loess Plateau region. The results showed that the precipitation and temperature will increase in the future (2021–2100), especially under RCP8.5. Similarly, crop productivity has been more substantial increase under RCP8.5. Under both scenarios, the predicted yield increase under each treatment was greater in the early period than the later period, and the RS treatment obtained the largest increase. However, when the annual precipitation exceeded 600 mm, the yield increase was not significant under R. Sensitivity analysis showed that ridge and furrow mulching measures reduced the sensitivity of the yield to precipitation changes. In the future, SOC storage increased slightly with both CK and R under RCP4.5, but both showed a downward trend under RCP8.5, respectively. R treatment showed a lower temperature threshold, and when the temperature was increased above 9.60 °C, the carbon loss rate accelerated. Under S and RS, the SOC storage tended to increase due to straw mulching. All these results indicated that in the future period, when the annual precipitation exceeded 600 mm and the annual average temperature exceeded 9.60 °C, ridge-furrow plastic film mulching was not suitable in this area, dual mulching of the ridge with film and furrow with straw may help to achieve sustainable high maize yields in the Loess Plateau region.