Silvopasture for reducing phosphorus loss from subtropical sandy soils

Abstract

Phosphorus (P) losses from sandy soils that are predominant in the 1.4 million ha of pastureland in Florida are a major cause of water pollution. We hypothesized that soil P loss would be lower from silvopastoral systems than from treeless pastures because soil P removal by a combined stand of trees and pasture would be more than that of treeless pasture. Four slash pine (Pinus elliottii Engelm.) + bahiagrass (Paspalum notatum Flüggé) silvopastoral systems located in Alachua, Suwannee, Manatee, and Osceola counties in Florida were selected for the study. The former two sites are on Ultisols, and the latter two on Spodosols. Soil samples were collected at different depth increments. Soil P storage capacity (SPSC), the maximum amount of P that can be safely applied to a soil before it becomes an environmental concern, was calculated. Water-soluble P concentrations in the 0-5 cm soil layer ranged from 4 to 11 mg kg −1 for the silvopasture sites and 10 to 23 mg kg −1 in the treeless pasture sites, with higher P concentrations in the treeless pasture at each location. Total SPSC in the upper 1 m depth ranged from 342 to 657 kg ha −1 in the silvopasture sites and −60 to 926 kg ha −1 in the treeless pasture sites (a negative value indicates that the soil is a P source). The results suggest that P buildup within the soil profile and therefore the chances for loss of P from soil to water bodies were less from silvopastures than from treeless pastures. Thus, silvopasture systems can be expected to provide greater environmental service in regard to water quality protection compared to treeless pastures under comparable ecological settings

Carbon Storage of Different Soil‐Size Fractions in Florida Silvopastoral Systems

“…The sand, silt, and clay content for the silvopasture and OP areas were reported as similar across all soil depths in the Alachua, Suwannee, and Osceola sites (Michel et al, 2007). In the top (0–5 cm) depth, the percent sand, silt, and clay were 87, 4, and 9% in the OP soils and 92, 3, and 5% for the silvopasture soils, respectively, for the Alachua site.…”

Native trees and shrubs for the productive rehabilitation of tropical cattle ranching lands

“…In humid regions, SPS can sequester more carbon than pastures and store it deeper and more permanently Nair et al, 2007a;Haile et al, 2010). The combination of grasses and trees also helps retain soil and water, protecting watersheds and soils from erosion (Ibrahim et al, 2006) and nutrient pollution (Michel and Nair, 2005;Michel et al, 2007). As trees mature, nutrient cycling speeds up and habitats become more wildlife-friendly (McAdam et al, 2007;Murgueitio et al, 2007).…”

Agroforestry: Practices and Systems

“…Additional benefits of silvopasture include water quality improvement (Michel et al, 2007), soil conservation, esthetics, and providing shade to cattle (Garrett, 2009). Alternative land uses including sustainable forest management, outdoor recreation, and ecotourism, and most encouragingly silvopasture, are considered highly compatible with traditional ranching and include several elements of best management practices for ranchers (Garrett, 2009).…”