The Physical Effects of Contrasting Tillage Treatments over Thirty Consecutive Cultivation Seasons

Abstract

Measurements of the changes in the physical properties of topsoil are reported from a I5-year factorial tillage trial in a plantation of arabica coffee. Two monsoon-type rain seasons per year gave thirty cycles of soil wetting, weed growth, tillage, and soil drying. Rainfall acceptance tests showed clean weeding to cause an average IS per cent. Reduction of infiltration from very heavy rainstorms, compared with the minimum weeding treatment. Where a grass mulch provided coarse organic matter for incorporation into the topsoil, a modified rotary hoe, described in a previous paper, proved even more successful than hand implements in maintaining soil structure. In the absence of grass mulching, the rotary hoe did more damage than the hand implements. The experiments demonstrated a sound technique for maintaining very good topsoil structure; Part III of this series showed that these methods also increase yields.