MACRO AND MICROMORPHOLOGIC INDICATORS OF PHYSICAL CLAYEY RED LATOSOL CULTIVATED WITH SUGARCANE

Abstract The southwest of Goiás stands out in the process of the recent expansion of sugarcane plantation, especially in micro-region of Quirinópolis, where previously areas of annual crops were replaced, especially soybeans, and then pasture areas on clayey dystroferric Red Latosol (LVdf) which has a high potential for compaction. The aim of this work was to evaluate the process of compaction such soils cultivated with sugarcane, considering the selected profiles were decompressed, corrected and fertilized before planting sugarcane. Such profiles have along with the current use of sugarcane varying in relation to previous use (soybean/sugarcane, pasture/sugarcane and pasture succession/soybean/sugarcane), and the management with and without fertigation with vinasse, and an area of remaining natural vegetation as control. Macro and micromorphological indicators, followed by tests evaluated in laboratory as penetration resistance and physic-hydric analysis. The results indicated surface and subsurface compaction of the soil profile studied, regardless of previous uses, being the main indicators the presence of structure tending to laminar few porous in compaction levels, and increased of soil density and of penetration resistance.

摘要 戈亚斯州（Goiás）西南部在近期甘蔗种植扩张进程中优势显著，尤以基里诺波利斯微区域（Quirinópolis）为典型。该区域此前以一年生作物（多为大豆）种植为主的用地相继被改造，后续又涉及黏质暗色铁铝性红砖红壤（LVdf）上的牧草地，此类土壤具备极高的压实潜在风险。本研究旨在评估种植甘蔗的该类土壤的压实过程，试验所选土壤剖面均在甘蔗种植前完成了疏松处理、改土作业与施肥操作。试验剖面结合当前甘蔗种植模式，其前茬利用方式存在三类差异：大豆→甘蔗、牧草地→甘蔗，以及牧草地连作→大豆→甘蔗；同时设置了施加与不施加糖蜜废液滴灌肥的两种管理模式，并以原生自然植被区作为空白对照。本研究采用宏观与微观形态学指标，并结合实验室测定的土壤穿透阻力（soil penetration resistance）及理化水文特性分析开展综合评估。结果显示，无论前茬利用方式如何，供试土壤剖面均出现了表层与亚表层压实现象，核心表征为土壤结构趋于层状且孔隙匮乏，同时伴随土壤容重与穿透阻力的显著升高。