Abstract: Full plastic film mulched ridge-furrow tillage (FMRF) and straw incorporation (S) are two effective strategies for managing soil fertility in semiarid areas. However, the effect of these two practices in combination (FMRF_S) and the key mechanisms by which FMRF_S positively modifies soil fertility characteristics, especially following application of cellulose-decomposing microbial cultures has not been well studied. To address this lack of information, a three-year field experiment with six treatments [conventional planting (CP), conventional planting with straw incorporation (CP_S), conventional planting with straw incorporation plus decomposer (CP_SD), FMRF, FMRF_S, and full plastic film mulched ridge-furrow tillage with straw incorporation (FMRF_SD)], and using a randomized block design with three replications, was conducted from 2015-2017. Soil organic matter (SOM), soil total and available nitrogen, phosphorus and potassium (TN, TP, TK and AN, AP, AK), soil bulk density (BD) and pH values of the 0-30 cm soil profile were examined. Soil organic carbon (SOC) content, SOC and TN accumulation as well as straw sequestration efficiency (CSE) were calculated. Results indicated that FMRF_SD considerably accelerated SOC and TN accumulation in topsoil, significantly (P<0.05) increased the content of SOC, total and available N, P and K, especially the AP and AK content, in 0-30 cm soil profile, via enhanced straw decomposition and nutrient release that more than offset the loss of SOC by mineralization and replenished soil nutrients consumed by crop growth uptake, simultaneously enhancing crop growth and vigor, resulting in increased organic matter (litter and roots, etc.) returned to the soil to complement the soil nutrient reservoir through the synergistic effects of modified soil hydrothermal conditions and the added cellulose-decomposing microbial culture. Measurement results showed that, compared to CP, FMRF_SD cumulatively sequestrated 41.17% of the straw carbon added over 3 years, which led to SOC and TN accumulation being increased by 0.79 mg C·ha^-1 and 0.04 mg N·ha^-1,respectively. This in turn increased the content of TN, TP and TK by 0.05, 0.03 and 3.05 g·kg^-1, respectively, and the contents of AN, AP, and AK by 10.80, 8.90 and 101.50 mg·kg^-1, respectively. These increases corresponded to elevations, respectively, of 6.87%, 6.94%, 15.28%, 10.24%, 56.69%, 55.34%. In addition, the soil BD was lowered by 3.9%, and the soil pH by 0.004 units. With the increase of soil carbon and nitrogen storage, nitrogen, phosphorus and potassium nutrient content and the decrease of soil BD and pH values, the ability of soil to supply plant nutrients was increased, the soil structure and properties were improved, and thus the fertility was significantly improved. Therefore, FMRF_SD is a highly effective management regime for improving soil carbon-nitrogen status and fertility characters in dryland.

Key words: straw incorporation, full plastic film mulched ridge-furrow tillage, decomposer, carbon and nitrogen accumulation, soil fertility character