Long-term maize stalk retention reduces seedtime soil respiration

摘要

ABSTRACT Cropland soil respiration (Rs) is a major part of CO2 transportation between the atmosphere and terrestrial ecosystems. Stalk retention is an effective method to conduct sustainable agricultural development. However, the relationship between long-term maize (Zea mays L.) stalk retention and seedtime Rs is not yet fully understood; two experimental zones with the same management history were therefore chosen to conduct the comparative study. Rainfed maize monoculture was the only crop cultivated in the study site. One zone (CZ) was covered by 5639 kg ha-1 maize stalk residue (MSR) after harvesting, and the other zone (BZ) has been left bare since autumn 2000. Annual measurements with 10 replicates were conducted at seedtime in 2015, 2016, and 2017. Results showed that mean Rs was 4.11 and 4.99 (g CO2 g-1 soil h-1 for CZ and BZ, respectively. Compared with BZ, CZ soil moisture was higher, but its soil temperature was lower. Although soil microbial abundances in CZ and BZ had decreasing trends between two adjacent seedtimes, there was a nonsignificant decrease of actinomycetes (p > 0.1) and fungi (p > 0.1) in BZ. The mean percentages of alkyl-carbon (Alkyl-C) were 25.6% and 35.0% for CZ and BZ, respectively. Redundancy analyses (RDA) showed that decreasing soil temperature, soil fungi, Alkyl-C as well as increasing soil moisture could explain reduced Rs in CZ. Maize stalk retention reduces seedtime Rs, thus maize stalk retention might contribute to soil C sequestration.