Evolution of physical properties of soils according to tillage systems on annual crops

Abstract

Soil management must keep the soil physical properties next to the original conditions in natural systems to assure the sustainability of agricultural systems. This review synthesizes the effects of conventional tillage, minimum tillage and no-tillage systems of annual crops, on soil physical properties as bulk density, porosity, soil resistance to root penetration, infiltration speed, hydraulic conductivity,compressibility, organic matter level, soil aggregate size and stability. No-tillage presents advantages on organic matter level, size and stability of aggregates, compressibility and hydraulic conductivity but has limitations on bulk density and resistance to root penetration. Minimum tillage with chisel plow is specially efficient in relation to infiltration speed and hydraulic conductivity, and intermediate between conventional and no-tillage in other aspects. Conventional tillage with total pulverization of soil surface,mainly on tropical conditions, presents the less favorable scores on soil physical properties, close to minimum tillage and no-till only in few circumstances, and frequently the most different from the natural conditions. The conservation systems by their side, despite of similarities in some aspects with natural conditions, are not able to reproduce the conditions of natural forests, savannas or natural pastures, but are in the sustainability direction.