Data_Sheet_1_Effect of Straw and Wood Ash on Soil Carbon Sequestration and Bacterial Community in a Calcareous Soil.docx

Soil fertility can be improved by effectively utilizing agricultural waste. Straw can supply energy and wood ash adds nutrients to improve soil quality. However, few kinds of research have investigated the effect of wood ash and straw on soil carbon sequestration and the soil bacterial population, particularly in calcareous soils. The main goal of this current study was to quantify the impact of a combination of wood ash and straw on the indicators described above using stable δ13C isotope analyses by applying wheat straw to calcareous soil under a long-term C4 crop rotation. The incubation experiment included four treatments as follows: (i) no amendment (Control); (ii) amendment with wood ash (W); (iii) amendment with straw (S); and (iv) a combined amendment of straw and wood ash (SW). Our results showed that sequestration of soil inorganic carbon (SIC) in the SW and W treatments was higher (an average of 7.78%) than that in the S and Control treatments. The sequestered soil organic carbon (SOC) in the SW treatment was 1.25-fold greater than that in the S treatment, while there was no evident effect on the SOC content compared with straw alone. The microbial biomass carbon increased under SW by 143.33%, S by 102.23%, and W by 13.89% relative to control. The dissolved organic carbon increased under SW by 112.0%, S by 66.61%, and W by 37.33% relative to the control. The pH and electrical conductivity were higher in the SW and W treatments than in the S treatment and the control. The SW was conducive to maintaining soil enzymatic activities and bacterial diversity. Bacteroidetes and Actinobacteriota were dominant in SW, while the Acidobacteria phyla were dominant in the S treatment. The diversity of bacteria in the soil and community composition of the bacteria were predominantly assessed by the levels of water-soluble K, pH, and electrical conductivity. The incorporation of straw and wood ash is probably more effective at improving SIC and SOC sequestration and ameliorates the soil microhabitat.

高效利用农业废弃物可提升土壤肥力。秸秆可提供能量，木灰则通过补充养分改善土壤质量。然而，目前鲜有研究探讨木灰与秸秆配施对土壤固碳（soil carbon sequestration）及土壤细菌群落（soil bacterial population）的影响，尤其是在石灰性土壤（calcareous soils）中。
本研究以长期C4作物轮作（C4 crop rotation）模式下的石灰性土壤为研究对象，施加小麦秸秆（wheat straw）并结合稳定δ13C同位素分析（stable δ13C isotope analyses），旨在量化木灰与秸秆配施对上述指标的影响。
本次培养试验（incubation experiment）共设置4组处理：(i) 不施加改良剂（amendment，对照组，Control）；(ii) 施加木灰（W处理）；(iii) 施加秸秆（S处理）；(iv) 秸秆与木灰配施（SW处理）。
研究结果显示，SW与W处理的土壤无机碳（soil inorganic carbon, SIC）固存量较S处理与对照组平均高出7.78%。SW处理的土壤有机碳（soil organic carbon, SOC）固存量较S处理提升1.25倍，而单独施加秸秆对SOC含量无显著影响。与对照组相比，SW处理的微生物生物量碳（microbial biomass carbon）提升143.33%，S处理提升102.23%，W处理提升13.89%；可溶性有机碳（dissolved organic carbon）则分别较对照组提升112.0%、66.61%与37.33%。SW与W处理的pH值与电导率（electrical conductivity）均高于S处理与对照组。SW处理利于维持土壤酶活性（soil enzymatic activities）与细菌多样性（bacterial diversity）。SW处理中优势菌门为拟杆菌门（Bacteroidetes）与放线菌门（Actinobacteriota），而S处理的优势菌门为酸杆菌门（Acidobacteria）。土壤细菌多样性与群落组成主要受水溶性钾（water-soluble K）、pH值与电导率调控。综上，秸秆与木灰配施可更有效地提升SIC与SOC固存能力，并改善土壤微生境。