Soil chemical attributes and sunflower and maize yield according to the application of urban waste compost

Abstract

The use of composted urban waste as a source of nutrients in agriculture is an economic alternative for discarding this material. However, due to the diversity of materials that compose this waste, long term studies on its effects on soil chemical attributes and crop yield are necessary. This study aimed at evaluating the potential of urban waste compost (UWC) as a fertilizer for sunflower and maize crops, as well as its effects on the chemical attributes of an Oxisol. A field experiment, with UWC doses of 0 Mg ha^-1, 10 Mg ha^-1, 20 Mg ha^-1, 30 Mg ha^-1 and 40 Mg ha^-1 and mineral fertilization according to the recommendation for each crop, was carried out. The results showed an increase in soil pH from 6 to 6.5, with the UWC application. The soil potential acidity decreased linearly from 3.0 cmol_c dm^-3 to 2.4 cmol_c dm^-3, contributing to the SMP index increase, what reflected on the increase of the soil cation exchange capacity. The bases saturation increased from 77% to 85%, mainly due to the increase in calcium and magnesium levels. The use of UWC resulted in sunflower grain yield similar to that for mineral fertilization, at 10 Mg ha^-1, 20 Mg ha^-1 and 30 Mg ha^-1, being significantly higher at 40 Mg ha^-1. The maize grain yield at or above 20 Mg ha^-1 of UWC did not differ from the mineral fertilization. The UWC presented potential to replace the mineral fertilization for sunflower and maize crops.