WATER AVAILABILITY IN A PLANOSOL UNDER INTEGRATED CROP-LIVESTOCK-FORESTRY SYSTEM IN THE AGRESTE REGION OF PARAIBA, BRAZIL

ABSTRACT Integrated agricultural production systems, involving agriculture, livestock, and forest are strategies that improve soil quality. The objective of this work was to evaluate the effect of the integrated crop-livestock-forest system (ICLF) on water availability of a Planosol in the Agreste region of the state of Paraíba (PB), Brazil. The experiment was conducted at the experimental site of the Agricultural Research Company of Paraíba (EMEPA), in Alagoinha, PB. The soil evaluated was a Eutric Planosol, with a moderate A horizon. The following intercrops (treatments) were implemented in June 2015: I. Gliricidia sepium + Brachiaria decumbens; II. Mimosa caesalpiniifolia + Brachiaria decumbens; III. Tabebuia alba + Brachiaria decumbens; IV. Zea mays + Brachiaria decumbens; and V. Brachiaria decumbens. A randomized block experimental design was used, with five treatments. The analyzed variables were field capacity, permanent wilting point, soil available water, granulometry, degree of flocculation, total porosity, macroporosity, microporosity, saturated hydraulic conductivity, resistance to penetration, and aggregate stability index. The results showed that the water availability in the ICLF implemented in the Agreste region of Paraíba had no significant variation after three years. After the three-year period, the ICLF promoted no significant physical improvement in the attributes of the evaluated Planosol.

摘要：涉及种植业、畜牧业与林业的综合农业生产系统，是改善土壤质量的有效策略。本研究旨在评估农林牧复合系统（integrated crop-livestock-forest system, ICLF）对巴西帕拉伊巴州阿格里斯特地区某平原土（Planosol）有效含水量的影响。实验于帕拉伊巴州阿拉洛因哈的帕拉伊巴州农业研究公司（EMEPA）试验基地开展。供试土壤为富铁平原土（Eutric Planosol），其A层发育中等。实验于2015年6月设置了如下间作处理：I. Gliricidia sepium + Brachiaria decumbens；II. Mimosa caesalpiniifolia + Brachiaria decumbens；III. Tabebuia alba + Brachiaria decumbens；IV. 玉米（Zea mays）+ Brachiaria decumbens；V. Brachiaria decumbens。本实验采用随机区组实验设计，共设置5个处理组。测定指标包括：田间持水量、永久萎蔫点、土壤有效含水量、颗粒组成、絮凝度、总孔隙度、大孔隙度、小孔隙度、饱和导水率、抗穿透阻力及团聚体稳定性指数。研究结果显示，在帕拉伊巴州阿格里斯特地区构建的ICLF系统中，土壤有效含水量在三年后未出现显著变化；且三年周期结束后，该系统未对供试平原土的物理属性带来显著改善。