Soil physical properties and soybean (Glycine max, Merrill) root abundance in conventionally- and zero-tilled soils in the humid Pampas of Argentina
Soil physical properties and soybean (Glycine max, Merrill) root abundance in conventionally- and zero-tilled soils in the humid Pampas of Argentina
复制标题
阿根廷潮湿的潘帕斯草原传统和零耕土壤的土壤物理特性和大豆（Glycine max、Merrill）根丰度
DOI：
10.1016/j.still.2005.02.004
复制
发表时间：
2006
影响因子：
6.5
通讯作者：
M. Taboada
中科院分区：
文献类型：
--
作者：
Federico Guillermo Micucci;M. Taboada
在阿根廷潮湿的潘帕斯草原，大豆种植在不同的土壤类型中，在过去的十年里，这些土壤类型从传统的耕作系统改为免耕系统。关于大豆根系对这些不同土壤物理环境的反应知之甚少。2001年2月至3月，在一个桑迪粘壤土和两个粉质粘壤土软土和一个粘变性土中，对种植大豆（R1和R2个体发育阶段）的pageli、常规耕作和零耕作田间批次进行了取样。在0-0.05m土层中，常规耕作和免耕土壤有机碳占牧草地土壤有机碳的53-72%，连续免耕4-11年后土壤有机碳开始恢复。土壤团聚体稳定性在常规耕作区比放牧区低10.1-46.8%，在免耕区完全恢复。土壤相对紧实度为60.8- 83.6%，低于作物产量的阈值（>90%）。在变化中，>50μm的土壤孔隙度范围为0.91-5.09%土壤体积，远低于根系通气和伸长的最低临界限值（> 10%，v/v）。在诱导犁盘中，仅常规耕作的Bragado土（5.9MPa）、常规耕作的Ramallo土（3.7-4.2MPa）超过土壤阻力阈值（约2- 3 MPa）。然而，无论是低孔隙度还是高土壤阻力都不会阻碍大豆根系的生长。根丰度与土壤粘粒含量呈显著负相关（R2=0.84，P<0.001）。大豆的根只在桑迪粘壤土的下层土壤中大量存在，而这层土壤的粘粒含量小于350 gkg − 1。结果表明，底土性质和免耕制度是影响大豆根系生长的主要因素。
In the humid Pampas of Argentina soybean is cultivated in different soil types, which were changed from conventional- to zero tillage systems in the last decade. Little is known about the response of soybean roots to these different soil physical environments. Pasture, and conventionally- and zero-tilled field lots cropped to soybean (R1 and R2 ontogenic stages) were sampled in February–March 2001 in a sandy clay loam and two silty clay loam Mollisols, and in a clayey Vertisol. In the 0–0.05m layer of conventionally- and zero-tilled lots soil organic carbon represented 53–72% of that in pasture lots, and showed an incipient recovery after 4–11 years of continuous zero tillage. Soil aggregate stability was 10.1–46.8% lower in conventionally-tilled than in pasture lots, and recovered completely in zero-tilled lots. Soil relative compaction ranged 60.8–83.6%, which was below the threshold limit for crop yields (>90%). In change, soil porosity>50μm ranged 0.91–5.09% soil volume, well below the minimum critical limit for root aeration and elongation (>10%, v/v). The threshold of soil resistance (about 2–3MPa) was only over passed in an induced plough pan in the conventionally-tilled Bragado soil (5.9MPa), and in the conventionally- and zero-tilled Ramallo soils (3.7–4.2MPa, respectively). However, neither the low macroporosity nor the high soil resistances impeded soybean roots growth in any site. According to a fitted polynomial function, root abundance was negatively related to clay content in the subsoil (R2=0.84, P<0.001). Soybean roots were only abundant in the subsoil of the sandy clay loam Mollisol, which had <350gkg−1clay. Results show that subsoil properties, and not tillage systems, were the primary effect of root growth of soybean.