Plant Production in Semiarid Shrubland Communities Amended with Biosolids in Central Mexico

Abstract

Biosolids application in semiarid rangelands has been proposed as a viable alternative for the rehabilitation of degraded soils. We analyzed the effect of rate, time, and number of applications of biosolids per year on the growth of herbaceous vegetation. Summer and winter single applications and a dual application (summer + winter) of biosolids were tested in two soils (calcareous and igneous) of the southern Chihuahuan desert at four rates (0, 3.5, 7, and 10.5 Mg/ha). A single period of vegetation growth occurs in the summer in this region. No major net changes in biomass were recorded with one application of biosolids in the summer or winter applications on both soil types. Winter biosolids application increased the annual species cover on igneous soil. However, annual species cover decreased in the second year on both soil types with one application (summer) or two applications (summer + winter) of biosolids. The lack of synchrony between the availability of NO3-N and moisture may have been the reason for the highly variable response of vegetation growth on calcareous soil. The igneous soil had better soil moisture retention, probably allowing for increased uptake of nitrate by plants. The largest increases in both biomass and plant cover were obtained for perennials with the dual strategy of biosolids application on igneous soil at higher rates. The patterns of plant biomass and cover responses to biosolids application were different on each functional group and soil type. Biosolids application rate and timing are important for enhancing plant productivity in semiarid areas; overall biosolids should be considered as a viable amendment for rangeland restoration.