Improvement of degraded grasslands withbiosolids application in a semiarid region ofChihuahua, Mexico

Resumen

Objective: to evaluate the effects of surface-applied anaerobic biosolids on forage yield and grass basal cover in degraded semiarid grasslands of Chihuahua, Mexico.

Design/methodology/approach: The study was conducted in a degraded semiarid grassland in Chihuahua, Mexico, to assess the short-term effects of biosolid application. Six biosolids rates (0 to 50 Mg ha^-1) were evaluated in a completely randomized design, with field plots serving as experimental units and six replications per treatment. Anaerobic biosolids from Chihuahua City were applied to field plots in March 2005. Soil properties were analyzed during the first year, while plant height, basal cover, and forage standing crop were monitored annually. Vegetation responses were measured during the summer and at the end of the growing season of four consecutive years. Statistical analysis included mixed models with repeated measures to detect treatment and temporal effects.

Results: Biosolid application improved soil organic matter, plant available nitrogen, height of blue grama (Bouteloua gracilis), and associated grasses. Total forage and blue grama forage yield increased, while forage production of other grasses declined throughout the four years. The basal cover of perennial grasses remained stable during the first two years, but decreased under higher application rates in the final two years.

Limitations on study/implications: The high initial investment required for the transportation and field application of biosolids may hinder large-scale implementation.

Findings/conclusions: Biosolids application improved soil organic matter, plant-available nitrogen, and total forage standing crop. Grass basal cover was unaffected at low application rates, but decreased under high rates.