Biomass productivity in poor soils is limited by several factors, among which are climatic conditions and nutrients. The most important limiting nutrients in plant productivity are nitrogen and phosphorus, even in regions receiving <200 mm precipitation. In this study, we evaluated the improvement in pasture and soil quality using different fertilization management procedures over 2 years in phosphorus-deficient soils. Three different fertilizers were used: urban solid waste (USW), ecofertilizer (EF) and calcium superphosphate (SP). The hypothesis that fertilization management significantly improves the quality of the soil and forage for cattle was also tested.
Results showed that biomass change depended on the year but not on the treatment. Different percentages of functional groups (graminoids, leguminoids and others) were compared by year and treatment. The results were similar for the three groups. In general, the sampled year was more important than the treatments. Soil composition did show some changes, e.g. higher levels of phosphorus in soils fertilized with USW than in the soils under other treatments. As for plant nutrient composition, control plots revealed lower levels of nutrients for graminoids and leguminoids, while the results were irregular in the case of the other species group. For the fertilized plots, USW and SP revealed better results in graminoids, whereas for leguminoids, EF was more nutrient effective in 2004. In 2003, the three fertilizers led to improvements in soil and forage quality compared with the controls.
Given the dependence of the local population on goat produce, we suggest a restoration of degraded native pasture areas using these treatments. In particular, USW increases productivity but has minimal effects on functional group composition and soil nutrient cycles.