Abstract

LOPEZ, Marisol; ALFONZO, Nidia; FLORENTINO, Adriana  and  PEREZ, Mercedes. PHOSPHORUS DYNAMICS AND EXCHANGEABLE ALUMINUM REDUCTION IN A HAPLUSTULTS ON THE CONSERVATIONIST HANDLING. INCI [online]. 2006, vol.31, n.4, pp.293-299. ISSN 0378-1844.

The effects of conservationist procedures such as minimal tillage, acid resistant cultivars, rotation of cultures and combinations of organic and inorganic fertilizers upon the dynamics of P availability and the sustainability of a cereal-legume rotation system were evaluated on a Typic haplustults acid soil of very low productive capacity. The treatments were: sorghum crop remains (RG), Indigosphera lespedicioides (RN) and Crotalaria juncea (RL), which were compared with a control with no residue (SR). Organic fertilizer parcels were supplemented with inorganic sources: T1 (N+0P+K), T2 (N+P-RFR+K), T3 (N+P-RFRA+K) and T4 (N+P-FDA+K), where RFR: "Riecito" phosphoric rock, RFRPA: partly acidulated "Riecito" phosphoric rock and FDA: diammonium phosphate. On each Sorghum bicolor tillage 100, 80 and 60kg·ha-1 of N, P and K, respectively, were applied, and on those of Cajanus cajan 15, 60, 45, 5,7 and 0,2kg·ha-1of N, P, K S and Mo, respectively, were applied. After 2 years of conservationist handling, increment in P availability and Al+3 reduction were observed. Available P ranged between 10 y 40mg·kg-1, being significantly higher where RN and RL were applied with any of the P sources. Subsoil exchangeable Al (Al+3) was reduced (<0,7cmol·kg-1) with P-FDA. With FDA the was no P mobilization down to 40cm in depth, where the percentage of aluminium saturation is high.

Keywords : Abonos Verdes; Aluminio; Fósforo Disponible; Manejo Conservacionista; Suelos Ácidos.