Caracterização edafoclimática em um cultivo de mamona (Ricinus communis L.) em vale aluvial no Agreste de Pernambuco

Abstract

The aim of this study was to evaluate the potential of the castor bean culture in an alluvial valley of Pernambuco Agreste. The research was conducted in the Nossa Senhora do Rosário farm, Pesqueira-PE. It was cultivated the BRS 188 – Paraguaçu castor bean, which according to the literature is suitable to the local conditions. The cultivation experiment started up on 15/03/2007, finishing his first stage on 31/10/07. In this period, the experiment was conducted on a dry condition, with only one irrigation application of 12 mm. Therefore, the soil and climate conditions were evaluated wider which where the culture was developed, such as soil texture, electrical conductivity of the saturation extract (CEes), average soil fertility, reference evapotranspiration (ET0). Based on the Tanque Class "A" and employing crop coefficient for castor bean suggested by culture FAO, it was estimated the crop evapotranspiration (ETc). The parameters evaluated were the height of the plants, stem diameter, leaf area index and productivity. All these parameters were estimated using descriptive statistics. It has been observed mean values of 1.48 dS.m-1 for CEes, before planting, and of 0.96 dS.m-1 at the end of the cycle, at sandy-loam area. The ETo average over the cycle was 2.98 mm.day-1 and ETc of 2.08 mm.day-1, while the average soil water matric potential was -27.97 kPa. By the end of1° cycle, the plants were 3.32 m tall with a diameter of 65 mm; regarding the estimation of the leaf area, a value of 4.42 m has been obtained of highest vegetative growth, and the approximate yield was 2900 kg.ha-1. On the other hand, it was also used geoestatistics techniques to observe the degree of dependency for the attributes and the spatial variability of soil, texture and CEes, and the attributes crop stem diameter and height of the plants. All parameters adjusted to a normal distribution, except free with the exception of stem diameter, for 200 days after sowing, showing a medium to low degree of spatial dependence. None of the variables showed pure nugget effect, adjusting to theoretical models for the semivariograms. The contour maps produced isolinhas the observation of the most heterogeneous areas, where a local management strategy can be developed.