COMBINATION OF ORGANIC AMENDMENTS AS A SOIL RECOVERING STRATEGY AT A DESERTIFICATION HOTSPOT IN THE BRAZILIAN SEMIARID

The use of manure, organic mulch and legume-based fertilizers can increase soil fertility in semiarid regions. However, the effects of such practices on soils prone to desertification are unknown. This study aimed to evaluate soil fertility and herbaceous stratum yield on soils amended with different organic inputs in the desertification hotspot of Irauçuba, Ceará state, Brazil. The experiments were performed in two areas with different soils (Planosol and Cambisol), in randomized blocks with a 2x2x3+1 factorial design. The factors consist of (i) mulch (presence or absence of Copernicia prunifera [carnauba palm] straw), (ii) manure (sheep or cattle), and (iii) legume-based fertilizer ( Mimosa tenuiflora [jurema], M. caesalpiniifolia [sabiá] and Leucaena leucocephala [leucena]), in addition to an untreated control, with three replicates. Soil chemical attributes and herbaceous stratum yield were assessed in the two areas. Positive effects of the combined use of carnauba palm straw, manures and legume-based fertilizers on soil fertility were more evident for Planosol than for Cambisol. The combination of sheep manure with sabiá-based fertilizer on Planosol, and cattle manure and leucena-based fertilizer on Cambisol increased herbaceous stratum yield. Herbaceous stratum yield on Planosol is more responsive to the input of great amounts of soil nutrients (especially P) and to increases in soil organic matter levels, while on Cambisol, herbaceous stratum yield is more associated with the ability of inputs to make nutrients readily available. The use of organic amendments can reverse, in the short-term, degradation and desertification processes of soils in the Brazilian semiarid region.