Qualidade física do solo e produtividade da cana-de-açúcar sob sistemas de preparo do solo

Abstract

Advances in soil science have enabled the development of different approaches to assess the soil physical quality related to sugarcane (Saccharum spp.) growth in a more critical way. The present study aimed to evaluate the effects of conventional tillage practices on soil physical quality and the response of sugarcane under rainfed conditions in the State of Pernambuco, Brazil. A randomized block design with for replications was conducted. The experiment was laid down in a randomized block design with four replications, where each block contained two experimental units (plots) and the treatments consisted of two tillage systems: no-tillage and conventional tillage. In the laboratory (ex situ), some soil physical attributes were determined, such as: bulk density, aggregate stability (wet-sieving), total porosity and pore-size distribution, saturated hydraulic conductivity, as well as the soil water retention and penetration resistance curves. In the field (in situ), soil penetration resistance was also determined. In addition, based on the laboratory data, the following models were calculated: Available Water, Least Limiting Water Range, Integral Water Capacity, Integral energy, Sindex and H-index. Furthermore, sugarcane biometrical (productivity) and technological (quality) parameters were assessed. After 17 months of its execution, no evidence was obtained that the soil tillage improved structural properties such as bulk density and aggregation. However, such system promoted an increase in soil porosity and modified its distribution. Concomitantly, there was an increase in the soil hydraulic conductivity, which reduced its storage capacity, compromising the water availability for sugarcane, evidencing and increasing the hardsetting behavior of this soil. On the other hand, the soil tillage increased the Least Limiting Water Range of the studied soil, but not enough to indicate a good physical quality, being the soil penetration resistance the main restriction. Additionally, the values of Integral energy were similar between treatments. Regarding the crop, the soil tillage did not influence the productivity of the sugarcane nor its quality.