Carbon stocks of a degraded soil recovered with agroforestry systems

Abstract

The use of agroforestry systems (AFS) for the recovery of degraded lands allows the diversification of biomass production and can increase the ecological, economic and social resilience of the restored areas. We evaluated a degraded soil 5 years after the establishment of three AFS with different managements using the carbon stored in the soil and tree biomass as quality indicators. In the AFS we used 33 species. Thirty were native trees interspersed with three cropped species: Hevea brasiliensis, Malpighia glabra L. and Bixa orellana. The AFS treatments were: AFS1 (Mower, trees planted in hollows, spacing 3 m × 2 m, 300 g hollow−1 of limestone + 36 g hollow−1 of P2O5, no plantation between rows); AFS2 (Herbicide, trees in hollows, 3.5 × 2 m, maize (Zea mays) between lines, 2 Mg ha−1 of limestone + 2 Mg ha−1 of filter cake + 300 kg ha−1 of NPK 8-28-16); AFS3 (Plough, harrow, scarifier, trees in furrows, 3.5 × 2 m, maize between lines, fertilization similar to the AFS2). As reference, we used a soil under a forest fragment nearby the main experiment. In 5 years, there was an increase of 10 Mg ha−1 of the soil C stocks under the AFS, which represents an average accumulation rate of 2 Mg ha−1 year−1. The carbon stocks in the biomass in AFS were lower than in the forest. The different management practices used in the implementation of the AFS do not directly affect the total carbon stocks in the 0–100 cm soil layer.