施用玉米秸秆生物质炭对黑土腐殖质组成和胡敏酸结构特征的影响

Effects of maize stalk biochar on humus composition and humic acid structure in black soil

为探究不同施加量生物质炭对黑土中腐殖质组成和胡敏酸(Humic acid,HA)结构的影响,进行了盆栽试验研究,设置4个处理,分别为空白,生物质炭施加量为6、12、24 t·hm^(-2)。结果表明:施加生物质炭3年能明显提高土壤有机碳(Soil organic carbon,SOC)含量,SOC随施加生物质炭量增加而提高,不同处理SOC含量较空白分别上升3.61%、13.40%和30.64%;不同处理水溶性物质(Water-soluble substances,WSS)中有机碳含量较空白分别上升30.88%、86.29%和116.18%;不同处理胡敏素(Humin,Hu)中有机碳含量较空白分别上升5.44%、19.46%和51.16%;不同处理HA中有机碳含量较空白分别上升7.89%、13.60%和25%;不同处理富里酸(Fulvic acid,FA)中有机碳含量较空白降低13.11%、24.60%和45.90%。施加生物质炭3年,能使HA分子结构发生变化。相较于空白,不同处理H/C摩尔比值分别降低0.01%、0.03%和0.05%;相对于空白,不同处理O/C摩尔比值分别降低0.05%、0.11%和0.17%,不同处理在2920 cm^(-1)处相对强度分别提高0.38%、0.41%和0.49%,在1620 cm^(-1)处相对强度分别提高0.94%、0.24%和0.39%。施用生物质炭能提高HA缩合度,降低HA的氧化度,增加HA的脂族性和芳香性,使HA结构复杂化。

Biochar has showed to increase soil organic matter content. However, how biochar influences soil humus composition and humic acid（HA ） structure is not well understood. Here a pot experiment was conducted to examine the effects of applying maize stalk biochar on humus composition and humic acid structural characteristics in black soil. Four treatments, namely CK and three rates of maize stalk biochar （equivalent to 6 t·hm-2,12 t·hm-2 and 24 t·hm-2） were employed. Results showed ： （ 1 ） Applying maize stalk biochar greatly improved soil organic carbon（SOC） at the third year. At the third year, biochar at 6, 12 and 24 t·hm-2 increased SOC by 3.61%, 13.40% and 30.64%, enhanced water-soluble substances（WSS） by 30.88%, 86.29% and 116.18%, and elevated humin content by 5.44%, 19.46% and 51.16%, respectively, compared with CK. The content of HA was 7.89%, 13.60% and 25% greater, whereas that of fulvic acid（FA） was 13.11%, 24.60% and 45.90% lower than that of CK, respectively, in 6 t ＂hm-2, 12 t ＂hm-2 and 24 t ＂hm-2 biochar treatments.（2） Compared with CK, applying maize stalk biochar for three year reduced H/C mole ratio by 0.01%, 0.03% and 0.05%, and O/C mole ratio by 0.05%, 0.11% and 0.17%, respectively, in 6 t ·hm-2,12 t·hm-2 and 24 t·hm-2 biochar treatments. The relative intensity of 2920 cm-1 increased by 0.38%, 0.41% and 0.49%, while that of 1620 cm-1 increased by 0.94%, 0.24% and 0.39%, respectively, in 6 t ·hm-2,12 t ·hm-2 and 24 t ·hm-2 biochar treatment, compared with CK. Maize stalk biochar applications improved HA degree of condensation, lowered HA oxidation, in- creased HA aliphatic and aromaticity, complicated the structure of HA.