Long‐term Effects of Mesquite Removal on Soil Characteristics: II. Nutrient Availability

Abstract

AbstractPreviously we reported differences in nutrient availability of desert grassland soils under mesquite [Prosopis juliflora (Schwartz) DC] trees and adjacent open areas. In a related study conducted at that same time (1967), several mesquite trees were removed to measure shading effects. Since then about half of the harvested trees have sprouted and regrown. Now after 13 yr, we report the long‐term effects of mesquite removal on nutrient availability of these soils. In a greenhouse pot test, dry weight yield of shoots plus roots of Arizona cottontop [Digitaria californica (Benth.) Chase] and barley (Hordeum vulgare L. var. gustoe) was used to measure availability of nutrients. Variables in the pot test were mesquite history (mesquite intact, mesquite removed‐sprouted, mesquite removed), location (canopy, open), and nutrients (N, P, S, K). In the analysis of variance, the main effects and all interactions were significant. Yield responses confirmed results of our earlier study that nutrient availability of mesquite canopy soils was significantly greater than that of adjacent open areas. Removal of mesquite resulted in a significant decline in nutrient availability. For sites where mesquite had been removed but then sprouted and regrew, nutrient availability of soils was intermediate between that of mesquite‐intact and mesquite‐removed sites. Removal of mesquite resulted in a large decline in available soil N; smaller losses of available P, K, and S were noted.