Pedotransfer functions to estimate water retention and availability in Planosol under integrated agricultural production systems in the Agreste of Paraíba

Abstract

The objective of this work was to generate and obtain Pedotransfer Functions (PTFs) to predict the moisture retained at specific potentials in Planosol under integrated agricultural production systems in the Agreste of Paraíba, three years after implementing the system. The research was conducted at EMPAER, Alagoinha, PB. The experimental design used was in randomized blocks with five integration systems and four replications The treatments were: 1) Gliricídia + Brachiaria decumbens (GC+BD); 2) Sabiá + Brachiaria decumbens (SB+BD); 3) Purple Ipê + Brachiaria decumbens (IP+BD); 4) Corn + Brachiaria decumbens (ML+BD); 5) Brachiaria decumbens (BD). Soil water retention was determined in the following matrix potentials: Ψm = 0, -6, -10, -33, -100, -300, -500, -1000 e -1500 kPa. Pedotransfer functions (PTFs) were also generated and validated for each point of the retention curve. The PTFs generated to estimate the points of the water retention curve in the studied soil were validated through the 1: 1 ratio between data observed in the soil and those estimated. Existing FPTs in the literature were also applied. The results showed an increase in available water content in all treatments at depth, being related to soil granulometry. The points of the soil water retention curve were estimated with reasonable precision (R² ≈ 0.88) from the generated FPT, and these functions can be used in soil water retention simulation models, considering the soil under study and the characteristics of the region. The tested FPT from the literature showed low predictive efficiency.