Compactação de um planossolo após sete anos sob sistema de integração lavoura-pecuária-floresta no agreste paraibano

Abstract

Compaction is considered one of the main causes of soil degradation in pastures, especially due to the use of machinery. Allied to this, soil conservation systems provide the path to sustainable agricultural advancement, as they reduce soil disturbances and diversify the activities carried out. Therefore, studies that evaluate soil quality are important, with mechanical resistance to penetration being one of the most effective indicators to indicate the physical properties of the soil, through the use of penetrometers. The objective of the present study was to evaluate the mechanical resistance of the soil to penetration into Planosol after seven years of implementation of the Crop-Livestock-Forest Integration system in the Agreste of Paraíba. The experiment has been conducted since July 2015 in an experimental area of the Paraibana Research, Rural Extension and Land Regularization Company (EMPAER), in the municipality of Alagoinha, Paraíba. The experimental design adopted was randomized blocks (DBC) with five treatments and four replications (5 x 4). The treatments were composed of the following consortia: T1) Brachiaria decumbens Stapf. + Gliricidia (Gliricidia sepium); T2) Brachiaria decumbens Stapf. + Sabiá (Mimosa caesalpiniifolia Benth.); T3) Brachiaria decumbens Stapf. + Ipê (Tabebuia alba (Chamiso) Sandwith); T4) Annual Crop and T5) Brachiaria decumbens Stapf. The experimental plots had a total area of (38 x 20 m) and were 4 meters apart between blocks, totaling 760 m2 . To this end, a specific assessment of resistance to penetration was carried out in the plots, in different types of crops, with soil samples collected using the impact penetrometer. The layer evaluated was at a depth of 0.00 – 0.30 cm, in order to obtain the current gravimetric humidity in field conditions. The results show that after seven years of planting the crops, the mechanical resistance to penetration varied in “low” among all treatments. Furthermore, in depth, it is observed that for all treatments, the surface layer showed lower resistance. Furthermore, it is noted that the Brachiaria decumbens + Sabiá (Mimosa caesalpiniifolia Benth.) treatment presented the highest MPa values, especially in the deeper layers.