Abstract

Injection of pig slurry (PS) into soils under no-tillage system (NTS) is more efficient for improving soil chemical and physical attributes, and reducing C and N emissions, than surface applications. This study evaluated the effect of using injection and surface application of PS, compared to NPK and control treatments, on the soil aggregate, C and N contents, and isotopes ¹³C and ¹⁵N. The NTS consisted of rotations of summer (maize) and winter (black oat and wheat) grasses from 2011 to 2015. The treatments were PS injected into the soil (PS_I), PS applied on the soil surface (PS_S), chemical fertilization (NPK), and control (CTRL). The following soil properties were evaluated in the 0–5, 5–10, and 10–20 cm layers: aggregate stability (geometric mean diameter – GMD; aggregate mass distribution); total organic carbon (TOC) and total nitrogen (TN) in macroaggregates (8.0–0.25 mm), microaggregates (<0.25 mm), and bulk soil (<2.0 mm); and isotopes ¹³C and ¹⁵N in macro and microaggregates. The application of PS_I improved the soil physical attributes, presenting higher GMD (0–5 cm) than the PS_S, NPK, and CTRL treatments. In the 5–10 cm layer, the PS_I treatments were more efficient in increasing the GMD and macroaggregate mass than the NPK. PS_I also was more efficient in increasing TOC and TN when compared to PS_S, and generated a higher GMD, which are protectors of these elements in the soil. The natural abundance of ¹⁵N denoted the lower soil organic matter decomposition in the PS_I treatment when compared to the PS_S. The natural abundance of ¹³C showed less-negative values in macroaggregates than in microaggregates, denoting that the soil management practices and crops used (grasses) affected positively the abundance of ¹³C. After seven applications of PS in maize-oat-wheat rotation in NTS, the application of PS_I was more efficient in improving the soil physical and chemical attributes than the application of PS_S.

摘要

在免耕系统 (NTS) 下将猪粪 (PS) 注入土壤中，在改善土壤化学和物理属性以及减少碳和氮排放方面比地表施用更有效。本研究评估了与 NPK 和对照处理相比，注射和表面施用 PS 对土壤团聚体、C 和 N 含量以及同位素¹³ C 和¹⁵ N 的影响。 NTS 包括夏季（玉米）和2011 年至 2015 年冬季（黑燕麦和小麦）牧草。处理方法是将 PS 注入土壤（PS _I），PS 施用于土壤表面（PS _S)、化学施肥 (NPK) 和对照 (CTRL)。在 0-5、5-10 和 10-20 cm 层中评估了以下土壤特性：团聚体稳定性（几何平均直径 - GMD；团聚体质量分布）；大团聚体（8.0-0.25 毫米）、微团聚体（<0.25 毫米）和大块土壤（<2.0 毫米）中的总有机碳 (TOC) 和总氮 (TN)；以及宏观和微聚集体中的同位素¹³ C 和¹⁵ N。PS _I的应用改善了土壤物理属性，表现出比 PS _S、NPK 和 CTRL 处理更高的 GMD（0-5 厘米）。在 5-10 cm 层中，PS _I处理在增加 GMD 和大团聚体质量方面比 NPK 更有效。PS_我与 PS _S相比，在增加 TOC 和 TN 方面也更有效，并产生更高的 GMD，这是土壤中这些元素的保护者。与 PS _S相比，¹⁵ N的自然丰度表明PS _I处理中土壤有机质分解较低。¹³ C的自然丰度在大团聚体中的负值小于微团聚体中的负值，表明土壤管理实践和使用的作物（草）对¹³ C的丰度产生了积极影响。 在玉米-燕麦-小麦轮作中施用七次 PS 后NTS，PS _I的应用与施用PS _S相比，在改善土壤理化属性方面更有效。