等碳量玉米秸秆及其腐解、炭化材料还田对黑土腐殖质的影响

本文通过在高型塑料桶施加等碳量的玉米秸秆、腐熟秸秆和生物质炭的盆栽试验,以不施加有机物料作对照,研究不同还田材料对土壤腐殖质组成和胡敏酸结构性质的影响,为施用不同秸秆产品提供科学支持。试验共设4个处理,分别是不施加有机物料的对照(CK)、施加玉米秸秆(CS)、施加腐熟玉米秸秆(HCS)和施加玉米秸秆生物质炭(Bc),每个处理3次重复。结果表明:3种有机物料处理有利于增加土壤有机碳含量,改善腐殖质组成。Bc、HCS和CS处理SOC分别增加了18.20%、17.36%和1.45%,Bc和HCS处理差异显著;水溶性物质(WSS)含碳量分别增加36.36%、36.36%和18.18%,差异显著;胡敏素(HM)含碳量分别增加28.91%、24.69%和1.25%,Bc和HCS处理差异显著;胡敏酸(HA)含碳量分别增加21.64%、19.65%、8.46%,差异显著;富里酸(FA)含碳量显著减少;PQ值显著增加,从CK的62.86%分别增加到74.16%、69.86%和67.47%。不同材料对HA分子结构的影响不同,CS和HCS 2种秸秆处理的HA分子H/C和2920/1620比值增大(分别从1.056增加到1.075和1.107;从0.262增加到0.333和0.380),高温/中温放热比和失重比显著降低(分别从1.95降低到1.75和1.57;从1.56降低到1.50和1.41),说明施加玉米秸秆和腐熟秸秆使得HA分子缩合度和芳香性下降,脂族性增强,有利于HA分子向简单化方向发展;而Bc与秸秆处理相反,HA分子H/C和2920/1620比值减小(分别从1.056减少到1.025;从0.262减少到0.223),高温/中温放热比和失重比增加(分别从1.95增加到2.19;从1.56增加到1.65),说明施加生物质炭使得HA分子脂族与芳香碳比例下降,缩合度和芳香性增强,更有利于HA分子的稳定。秸秆和腐熟秸秆还田有利于增强HA的活性,而生物质炭还田更有利于土壤有机碳的固定。

Effects of corn straw and its humified and carbonized materials applying to the black soil with an equal mass of carbon on soil humus

In this study, pot experimentation was conducted to investigate the differences in carbon sequestration on humus composition and humic acid (HA) structure under applications of three different forms of corn straw (original, humified, and carbonized) to black soil with an equal mass of carbon. The four treatments were non-organic material amendment as control (CK), corn straw (CS), humified corn straw (HCS), and biochar (Bc). Each treatment material was fully mixed with the soil in triplicate. The following results were found. The Bc, HCS, and CS treatments increased the SOC contents by 18.20%, 17.36%, and 1.45%, respectively; the water soluble substance (WSS) contents had significant increases of 36.36%, 36.36%, and 18.18%, respectively, and the humin (HM) contents increased by 28.91%, 24.69%, and 1.25%, respectively. In addition, the HA contents with the Bc, HCS, and CS treatments significantly increased by 21.64%, 19.65%, and 8.46%, respectively. In contrast, the FA contents significantly decreased for all treatments, compared with that of the CK. The values of PQ were 62.86%, 67.47%, 69.86%, and 74.16% for CK, CS, HCS, and Bc, respectively. Great difference was observed in the HA molecular structure with the addition of different materials. The ratio of H/C and 2920/1620 of CS and HCS treatment increased, and the exothermic heat ratio of high temperature/moderate temperature and weight loss significantly decreased. These results indicated that corn straw and humified corn straw applications to the soil facilitated the simplification of the soil humic structure by decreasing the HA condensation, aromaticity, hydrophobicity, while simultaneously increasing the HA molecular aliphaticity. In contrast, the ratio of H/C and 2920/1620 of Bc treatment decreased, and the exothermic heat ratio of high temperature/moderate temperature and weight loss significantly increased. These results indicated that biochar application to the soil was helpful in promoting HA molecular condensation and aromaticity and the soil HA molecular tends to be complicated and stable. These results suggested that the CS and HCS treatments had the highest HA activities, whereas Bc treatment was beneficial to increase soil organic carbon.