Atividade microbiana de um solo sob cobertura morta e cultivado com forrageiras irrigadas com água de reuso.

Abstract

The United Nations estimates that the population will be 9.7 billion inhabitants in the next 30 years, demanding an increase in food production. A strategy to increase this demand and reduce environmental impact is the use of wastewater for irrigation in association with mulch, which can bring benefits to the soil microbiota, greater availability of nutrients and agricultural productivity. The objective of this work was to evaluate the abundance and microbial activity in soils cultivated with forage cactus, irrigated with sewage wastewater and with mulch. The experiment was at the Parnamirim Production Unit - PE, using reused water from the sewage treatment plant for irrigation of forage cactus consorted with buffel grass and sudan sorghum. The forage cactus was implanted in double rows 0.5m x 0.5m x 2.0 m, with the cultures intercalated between the double rows, with the experimental unit formed by three double rows of 4 m in length each. Four replications were used in the design in randomized blocks, in factorial arrangement 2 (intercropping with sudan sorghum and buffel grass) x 4 covers (no cover, 8 and 12 tons of corn straw per hectare and natural vegetation). We evaluated soil basal respiration, carbon and nitrogen from soil microbial biomass and metabolic quotient, at 0-10 and 10-20 cm layers. There was no significant difference in soil basal respiration, microbial nitrogen, and metabolic quotient at 0-10 and 10-20 layers. Estimating carbon from microbial biomass at 0-10 cm layer, we observed a significant difference between the intercrops without vegetation cover, however at 10-20 with buffel grass, the 8 tons mulch differed from the other treatments. Even so, further research is necessary to observe these variables over a longer period.