夏闲期耕作对黄土高原旱地麦田土壤水稳性团聚体稳定性的影响

【目的】研究不同夏闲期耕作方式对黄土高原旱地麦田土壤水稳性团聚体稳定性的影响,为改善旱地土壤结构、提高粮食产量提供依据。【方法】于2013—2017年在山西省闻喜县邱家岭村开展免耕—免耕—免耕—免耕(4a NT)、深翻—深翻—深翻—深松(3a PT-ST)、深松—深松—深松—深翻(3a ST-PT)和深松/深翻(4a ST/PT)轮耕4种耕作处理,测定了平均重量直径(MWD)、几何平均直径(GMD)、稳定率(WSAR)、破坏率(PAD)、分形维数(D)、峰凸系数(C_E)和偏倚系数(C_S)等水稳性团聚体稳定性指标。【结果】4年轮耕处理结果表明,深松/深翻轮耕能够有效提高土壤有机质含量和旱地麦田产量。深松/深翻轮耕0—50 cm土层0.25 mm水稳性团聚体含量分别比连续免耕、深翻—深翻—深翻—深松和深松—深松—深松—深翻高40.4%—45.5%、61.8%—98.0%和39.4%—106.1%,且深松/深翻轮耕处理下的GMD、MWD、WSAR和C_S均显著高于其他耕作处理,而D、PAD和CE均显著低于其他耕作处理(P0.05)。各参数之间的相关分析结果显示,WSAR、MWD、GMD和C_S之间相互呈极显著正相关,且均与PAD、D和CE呈极显著负相关(P0.01)。【结论】夏闲期耕作会显著影响土壤水稳性团聚体的稳定性,而夏闲期深松/深翻轮耕处理能提高耕层水稳定性团聚体含量与稳定性,更好的改善旱地土壤结构,提高产量。

Stability Characteristics of Soil Water-Stable Aggregates Under Different Tillage Treatments in Summer Fallow on the Loess Plateau

【Objective】The paper studied the effects of different tillage treatments in summer fallow on the stability characteristics of soil water-stable aggregates in the Loess Plateau.【Method】The 4 rotational tillage experiments, including 4aNT (no-tillage in four experimental years), 3aPT-ST (deep plow in three years, followed subsoiling in forth year), 3aST-PT (subsoiling in three years, followed deep plow in forth year), and 4aST/PT (subsoiling in first year, deep plow in second year, again subsoiling followed by alternating the next year), were conducted in dryland wheat fields of Qiujialing Village in summer fallow period from 2013 to 2017. Based on the experiments, mean weight diameter (MWD), geometric mean diameter (GMD), aggregate stability rate (WSAR), destruction rate (PAD), fractal dimension (D), peak convex coefficient (C_E) and bias coefficient (C_S) were used to analyze and compare soil aggregates stability (＞0.25 mm).【Result】Results indicated that the treatment of 4aPT/ST improved soil organic matter content and winter wheat yield in the dry farmland, and adoption of 4aPT/ST significantly increased the soil aggregates with particles greater than 0.25 mm by 40.4%-45.5%, 61.8%-98.0% and 39.4%-106.1% than 4aNT, 3aPT-ST and 3aST-PT, respectively. In addition, GMD, MWD, WSAR and C_S of water-stable aggregates under 4aST/PT treatment was also higher than that under other three treatments, but D, PAD and C_E of water-stable aggregates under 4aST/PT treatment was lower than that under other treatments at 0-50 cm soil depth (P＜0.05). The correlation between parameters showed that there were significant positive correlation among WSAR, MWD, GMD and C_S, while these indexes had negative correlation with PAD, D and C_E (P＜0.01).【Conclusion】Tillage in summer fallow influenced the stability of soil water-stable aggregates, and adoption of 4aST/PT increased soil macro-aggregate content and stability and improved dry farmland soil structure and yield.