Parâmetros de solo e de planta em diferentes configurações de espaçamentos entre linhas da cana-de-açúcar.

Abstract

he sugarcane is a renewable energy source that plays an important role in Brazil. Strategies such as the use of combined row spacing have been cited to mitigate soil compaction. However, there are few studies evaluating these row spacing of the behavior of soil physical properties and the relationship with the attributes of the plant. The objective of this study was to evaluate the soil-plant relationships in three row spacing configurations of sugarcane in first growth cycle. The experiment was established in Porto Xavier - RS in August 2012 where three types of row spacing were evaluated: one row spacing (LS), dual combined (LD) and triple combined (LT). Soil samples were collected from the 0-0.20 m layer in January 2013 during the first growth cycle of sugarcane along a 50 m transect located on the line of culture at the three row spacing types. The following attributes were determined Bulk density (BD), total soil porosity (TP), soil macro (Ma) and microporosity (Mi), soil penetration resistance (PR), volume based humidity at field capacity (θCC) and at permanent wilting point (θPWP), available water capacity (AWD), particle density (PD), soil particle size (clay, silt, sand), dispersed clay (DC) and the total organic carbon content (TOC). At each point of the transect, plant attributes were also evaluated: stalk height (H), stalk diameter (DC), ºBrix, the number of stalk (NCM) and stalk mass (MC). To evaluate the structure of spatial correlation, autocorrelogramas and crosscorrelogramas were built. The MC variable was spatially correlated with clay, sand, TP and AWD in LD row spacing and with Ma in LT row spacing, while not cross-correlating with any attribute in the LS row spacing. The ºBrix showed crosscorrelation with AWD in LD row spacing, but not with any variable in LS and LT row spacing. In row spacing LS, the MC was related to HC, DC and NCM. Soil variables did not influence the MC in LS row spacing. In LD row spacing, the plant attributes did not affect MC, with its variability explained by clay, sand, TP, and AWD through state space analysis, and by Ma and θPWP through multiple regression analysis. In LT row spacing, HC and NCM contributed to the MC and among soil attributes, Ma was related to the MC through the state-space approach. ºBRIX was not influenced by any plant or soil attribute in LS row spacing, being influenced in the LD row spacing by HC, DC, θPWP and AWD (the latter evaluated by state space approach). In the LT row spacing, plant attributes were not associated with º BRIX and among the soil attributes, only by the TOC. The contribution of soil variables in the mass of stalk and °Brix is more expressive in the row spacing LD and LT, mainly variables related to water availability.