关于植物生长对免耕土壤特性和功能的确切影响的现有知识有限,尤其是在热带和亚热带地区。这项工作的初始假设是长期活跃的植物生物量输入-APBI(地上植物枝条生物量)将通过在先前退化的亚热带 Acrisol 中发挥不同的互补作用来改善表层和地下土壤层中的孔隙系统功能。通过检查涉及五种不同种植系统的 34 年田间试验的结果,即裸土(BS)、多年生牧场(PAST)、燕麦/玉米(O/M)、燕麦 + 紫云英/玉米( O + V/M) 和燕麦 + 紫云英/玉米 + 豇豆 (O + V/M + C)。向土壤提供 APBI,范围从 0.13 到 1.48 千克干物质 ha -1年-1。每个种植系统的 APBI 分别为非常低 (BS)、低 (O/M)、中等 (O + V/M)、高 (O + V/M + C) 和非常高 (PAST)。分析了表层(0-5 厘米)和地下(5-15 厘米)土壤层的孔隙系统的静态和动态特性,包括体积密度;总孔隙率、宏观孔隙率和微孔隙率;系统传导空气和水的能力;土壤孔隙的连续性;和植物可用水容量。土壤的微观形态图像揭示了一个复杂的孔隙网络,其结构和功能都因植物的作用而得到改善。在表层土壤层中,来自牧场的非常高的 APBI 和来自 O + V/M + C 的高输入分别使总孔隙率增加了 11% 和 14%;孔隙连续性 ( N cont) 分别减少 11 % 和 40 %;和微孔隙率分别为 31% 和 23%——均相对于裸土。在地下土壤层中,牧场和 O + V/M + C分别使氮含量降低了44 % 和 40 %,但增加了透水性 ( k w) 分别为 6.5 倍和 7 倍。此外,相对于 BS,非常高的 APBI 增加了大孔中空气的连续性和渗透性。地下土层中有组织的大孔隙有效地从土壤表面引导水和空气,并充当表层和地下土层之间的桥梁。总的来说,我们的研究结果表明,APBIs 通过长期自组织帮助开发了一个具有差异特性和互补功能的孔隙系统,影响了表层土壤层中的水分渗透和空气通量,以及地下土壤层中作物的水分可用性。系统。建议进行进一步的研究,以了解物种丰富度和根系对免耕土壤物理质量的影响。
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Active plant biomass inputs influence pore system functioning in no-till soils
Available knowledge about the exact impact of plant growth on the properties and functioning of no-till soils is somewhat limited, especially in tropical and subtropical regions. The starting hypothesis for this work was that long-term active plant biomass Input-APBI (aboveground plant shoot biomass) would improve pore system functioning in surface and subsurface soil layers by playing different, complementary roles in a previously degraded subtropical Acrisol. The hypothesis was checked by examining the results of a 34-yr field experiment involving five different cropping systems, namely: bare soil (BS), perennial pasture (PAST), oat/maize (O/M), oat + vetch/maize (O + V/M) and oat + vetch/ maize + cowpea (O + V/M + C). The soil was supplied with APBIs varying from 0.13 to 1.48 kg dry matter ha−1 yr−1. The APBIs for each cropping system were very low (BS), low (O/M), medium (O + V/M), high (O + V/M + C), and very high (PAST). The surface (0–5 cm) and subsurface (5–15 cm) soil layer were analyzed for static and dynamic properties of the pore system including bulk density; total, macro, and microporosity; the ability of the system to conduct air and water; continuity in soil pores; and plant-available water capacity. Micromorphological images of the soil revealed a complex pore network whose structure and functioning were both improved by the action of plants. In the surface soil layer, very high APBIs from pasture and high inputs from O + V/M + C increased total porosity by 11 and 14 %, respectively; pore continuity (Ncont) by 11 and 40 %, respectively; and microporosity by 31 and 23 %, respectively —all relative to bare soil. In the subsurface soil layer, pasture, and O + V/M + C decreased Ncont by 44 and 40 %, respectively, but increased water permeability (kw) by a factor of 6.5 and 7, respectively. In addition, very high APBIs increased continuity and permeability to air in macropores relative to BS. Organized large macropores in the subsurface soil layer efficiently conducted water and air from the soil surface and acted as bridges between the surface and subsurface soil layer. Overall, our findings suggest that APBIs helped develop a pore system with differential properties and complementary functions that influenced water infiltration and air fluxes in the surface soil layer, and water availability to crops in the subsurface soil layer, through long-term self-organization in the system. Future research with a view to understanding the influence of species richness and roots on physical quality in no-till soils is recommended.