Detecting near-surface Urochloa ruziziensis (Braquiaria grass) effects on soil physical quality through capacity and intensity indicators

Abstract

In Brazil, no-tillage is the most widely used soil conservation system (on more than 32 million hectares). However, intensification of the mechanisation of agricultural operations with larger and heavier machines increases the pressure on the soil, which, together with the reduced diversity of crops, results in compaction and physical degradation of soils under no-tillage systems. In this context, strategies to reduce soil compaction have been employed and the use of Braquiaria grass (Urochloa ruziziensis) (hereafter urochloa) as a cover plant is one promising strategy. The objectives of this study were to quantify, using physical indicators of capacity and intensity processes, the effects of cultivating urochloa sown in the interrow between corn (Zea mays L.) on storage and transmission of air and water in the surface layer of the soil and to evaluate the sensitivity of these indicators at detecting such effects. The results indicated that urochloa cultivation in the interrow produced an increase in storage capacity of air and water, and transmission of air and water, compared with the treatment in which the interrow was without urochloa. Cultivation of urochloa also alleviated compaction through an 18% reduction in soil bulk density and an increase of up to 490% in pore system continuity, in addition to improving the relationship between water and air storage, creating an environment that facilitates access to water and air. These results suggest that the use of urochloa as an interrow cover plant in corn improves the physical functions of the topsoil, producing a physical environment more favourable to development of crops. The use of intensity process indicators of physical properties was ~10 times more sensitive at detecting the effects of urochloa than the properties indicating capacity processes.