香蕉茎秆及其生物炭对珠江三角洲土壤团聚体特征的影响

为了探究施用香蕉茎秆(蕉秆)及其制备的生物炭对珠江三角洲农田土壤肥力的影响,本文通过土壤培养和盆栽试验,研究了施用0.5%、1.0%和2.0%蕉秆和水稻秸秆(稻秆)及其生物炭后,土壤中不同粒级水稳性团聚体的组成,并采用团聚体平均重量直径(MWD)、几何平均直径(GMD)、分形维数(D)和平均重量比表面积(MWSSA)等评价团聚体的稳定性。结果表明:1)珠江三角洲农田土壤水稳定性团聚体以0.25 mm微团聚体为主,占团聚体比例29.80%～52.52%;1～0.5mm团聚体次之,占18.19%～20.08%。2)施用1.0%、2.0%蕉秆和2.0%稻秆显著增加0.25 mm土壤团聚体总量,并显著提高土壤团聚体水稳定性;与不施用有机物料对照相比,团聚体MWD分别增加45.60%、62.37%和65.50%,GMD分别增加43.45%、55.34%和60.66%,D分别降低2.23%、2.32%和2.78%, MWSSA分别降低18.14%、20.09%和23.01%。3)MWD、GMD与 5mm、5～2 mm和2～1 mm团聚体所占比例呈极显著或显著正相关,与0.25 mm微团聚体所占比例呈极显著负相关; D、MWSSA与0.25 mm微团聚体所占比例呈极显著正相关,与5 mm、5～2 mm和2～1 mm团聚体所占比例呈极显著或显著负相关。4)综合主成分和差异显著性分析结果表明,施用2.0%和1.0%蕉秆提高土壤团聚体稳定性效果佳,均与施用2.0%稻秆没有显著差异,而施用蕉秆生物炭和稻秆生物炭短期内不能提高土壤团聚体稳定性。研究结果可为蕉秆废弃物资源化利用、提高土壤肥力提供参考依据。

Effects of banana stem and its biochar application on soil aggregate characteristics in the Pearl River Delta

Here, to investigate the effects of banana stem and its biochar application on soil fertility in the Pearl River Delta, the effects of applying 0.5%, 1.0%, and 2.0% banana stem, rice straw, and their biochar on the composition of soil water-stable aggregates were evaluated in soil culture and pot experiments. The mean weight diameter (MWD), geometric mean diameter (GMD), fractal dimension (D), and mean weight specific surface area (MWSSA) were used to evaluate soil aggregate stability. The results revealed the following:1) Water-stable aggregates in the studied soil was dominated by <0.25-mm micro-aggregates, followed by 1-0.5-mm aggregates, accounting for 29.80%-47.55% and 18.19%-20.08% of the aggregates, respectively. 2) Applying 1.0% and 2.0% banana stem and 2% rice straw significantly increased >0.25 mm macro-aggregate content and soil aggregate stability. Compared with the control treatment, the soil aggregate MWD increased by 45.60%, 62.37%, and 65.50%, respectively; GMD increased by 43.45%, 55.34%, and 60.66% respectively; D decreased by 2.23%, 2.32%, and 2.78% respectively; and MWSSA decreased by 18.14%, 20.09%, and 23.01% respectively. 3) The MWD and GMD significantly positively correlated with >5 mm, 5-2 mm, and 2-1 mm soil aggregate percentages, and significantly negatively correlated with <0.25-mm soil micro-aggregate percentage. The D value and MWSSA significantly positively correlated with <0.25-mm soil micro-aggregate percentage, and significantly negatively correlated with >5 mm, 5-2 mm, and 2-1 mm soil aggregate percentages. 4) The results of principal component analysis and difference significance test indicated that applying 2.0% and 1.0% banana stem had a better effect in improving soil aggregate stability, and this effect was not significantly different from that of 2.0% rice straw application; however, the application of biochar did not increase the stability of aggregates in the short term. This study provides a reference for effectively utilizing banana stem waste and improving soil fertility.