Deep Soil Water Content and Forage Production in a Tropical Agroforestry System

Marcos Vinicius Mansano Sarto,Wander Luis Barbosa Borges,Charles W Rice,Márcio Renato Nunes,Ciro Antonio Rosolem,Doglas Bassegio

doi:10.3390/agriculture12030359

Abstract

Agroforestry systems integrating tree and forage growth are important for maintaining soil health but may change the soil’s physical-hydric properties. Our goal was to investigate the impact of introducing Eucalyptus trees into a pasture on the soil water content throughout the soil profile. The study was conducted in a 6-year-old agroforestry system where two species of Eucalyptus were introduced into a palisade grass pasture. Soil moisture was sampled at 0.0 (planting row), 2.0, 4.0, and 6.0 m (midpoint between tree rows) from the Eucalyptus tree rows. A monoculture palisade grass pasture was used as a control. The soil water content down to a depth of 50 cm was lowest in the tree row and increased with distance from the trees. In the Eucalyptus row, the soil water content in the 0–50 cm layer was lower than in the monoculture pasture. Agroforestry systems decreased the water content in the superficial layers of the soil in the rainy months; in the dry season, the soil water contents in all layers were similar between the Eucalyptus inter-rows. In most seasons, the agroforest systems reduced the forage production close to the Eucalyptus tree rows, up to 2 m from the trees, likely due to the soil water content decrease. Overall, this study showed that in tropical regions with sandy soils, the grass and trees’ competition must be considered when establishing integrated agroforestry systems in order to maximize the advantages and benefits of the diversified agroecosystem.

Highlights

Agroforestry improves soil quality, carbon sequestration, and water quality in cropping systems [1–3] and reduces runoff and nutrient losses [4]
The 0–10 and 10–20 cm soil layers, the soil water content was significa6ntolfy1h4 igher (p < 0.05) in the monoculture pasture compared to the soil water content close to the Eucalyptus tree rows
Under tropical conditions and coarse-textured soils, Eucalyptus trees altered the soil water content in an agroforestry system compared with a monoculture pasture

Summary

Introduction

Agroforestry improves soil quality, carbon sequestration, and water quality in cropping systems [1–3] and reduces runoff and nutrient losses [4]. This land-use system promotes the efficient use of resources (e.g., nutrients, light, and water) compared with traditional soil and crop management practices [5]. An important factor limiting the adoption of agroforestry systems by farmers is the competition between trees and crops for solar radiation, water, and nutrients [11,12]. The soil water content in agroforestry systems is influenced by microclimatic conditions such as solar radiation, wind speed, and rainfall [13]. The competition for water is affected by root distribution [19] and decreases in crop or forage root length due to the fact that proximity to tree rows could result in a reduced capacity to compete for resources [20]. Gomes et al [22] found that morphologic composition and sward characteristics were affected up to 3 m from the trees

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Conclusion