Effect of standing and shattered stalk residue mulching on soil respiration during growing-season of maize (Zea mays L.)

Abstract: Cropland soil respiration (Rs) is an important part of global CO2 cycling. The growing-season Rs has great influence on the crop yield, and Rs can be affected by crop residue mulching. Two prevailing crop residue mulching methods, which were shattered residue mulching (SH) and standing residue mulching (ST) were applied after harvesting in this study since 2000. The measurement was initiated in the year of 2013, and the measurements included the soil frost depth, snow accumulation, CO2 fluxes, soil temperature and soil moisture. Total Rs are divided into heterotrophic respiration (HR) and rhizospheric respiration (RR). Radiocarbon signature technology combining with mathematical equations were utilized to calculate the CO2 fluxes of HR and RR. The experimental results showed that average snow accumulation increased by 44%, maximum soil-frost-depth reduced by 18% and the frozen soil thawing completely hastened by about 10 to 27 d of ST compared that with SH. The average CO2 fluxes were 16.55 and 14.02 mmol/m2h for ST and SH, respectively. In terms of the growing season, the Rs difference between SH and ST was relatively small at the introductory and final stage, while the Rs difference was relatively larger in the middle stage. The average Rs of ST was 3.3 mmol/m2h larger than that of SH. The HR was the dominant contributor to Rs in ST treatment, while RR only contributed about 10% to the total Rs. Redundancy analyses revealed that the Rs and HR were positively correlated with soil temperature and snow accumulation, but they were negatively correlated with the soil frost depth. These results indicated that applying ST can result in higher growing-season Rs compared with SH, the higher Rs means the higher CO2 supplement to maize for photosynthesis, which is benefit for crop yield improvement.