ABSTRACT

Conservation agriculture (CA) is believed to contribute to sustainable crop production. However, there are contrasting reports on its short-term effects on soil properties. An experiment was conducted to determine the effects of CA on bulk density (BD), porosity, mean weight diameter (MWD) and penetration resistance (PR) in a semiarid province of South Africa (SA). A split–split–plot design was used; the main treatment factor was allocated to tillage [(Conventional Tillage (CT) and No-Till (NT)], sub-factor of crop rotation [(Maize-Fallow- Maize (MFM), Maize–Oat–Maize (MOM and Maize–Vetch–Maize (MVM))] and sub-sub factor of residue management [(retention (R+); removal (R-) and biochar (B)]. No-tillage, significantly increased soil organic carbon (SOC) compared to CT at the 0–5 cm depth. Tillage, crop rotation and residue management significantly (P < 0.01) affected MWD at the 0–5 cm depth, but not (p > 0.05) on BD, porosity and PR. The lack of significant differences, in both NT and CT plots, between biochar applications and residue retention with respect to BD, MWD across seasons and PR, also show that biochar can potentially be used as a crop residue strategy in a CA system. However, there is a need to further tests and also explore the biochar crop residue retention combinations.

摘要

保护性农业 (CA) 被认为有助于可持续作物生产。然而，关于其对土壤性质的短期影响，有不同的报道。在南非 (SA) 的半干旱省进行了一项实验以确定 CA 对堆积密度 (BD)、孔隙率、平均重量直径 (MWD) 和抗穿透性 (PR) 的影响。使用了裂-裂区设计；主要处理因子分配给耕作[（常规耕作（CT）和免耕（NT）]，轮作子因子[（玉米-休耕-玉米（MFM），玉米-燕麦-玉米（MOM和玉米） -Vetch-Maize (MVM))] 和残留物管理的子子因子 [(保留 (R+)；去除 (R-) 和生物炭 (B)]。免耕，显着增加土壤有机碳 (SOC) CT 在 0–5 cm 深度。作物轮作和残留物管理显着（P < 0.01）影响 0-5 cm 深度的 MWD，但对 BD、孔隙度和 PR 没有（p > 0.05）。在 NT 和 CT 地块中，生物炭应用和残留物保留在 BD、MWD 跨季节和 PR 之间缺乏显着差异，这也表明生物炭可以潜在地用作 CA 系统中的作物残留物策略。但是，需要进一步测试并探索生物炭作物残留物保留组合。