SOIL AGGREGATION CHANGES IN COFFEE PLANTA TIONS AS AFFECTED BY MANAGEMENT

Soil samples of the surface layer were collected in three long-term co ffee field experiments to evaluate the effect of the management system s on soil aggregation. The following treatments were evaluated: site 1 soil fertility management: NPK chemical fertilization, green manure, mulching with Brass straw and organic compost; site 2 weed controls: h and hosing, rototilling and mechanical cutting of weeds just above the ground; and site 3 coffee population density: 893, 2381 and 7143 tree s/ha. Treatments that contributed to maximize the residue left on soil surface, such as mulching, organic compost cutting weeds above the gr ound, and higher coffee tree population density increased soil aggrega tion. Treatments that increased the time of soil exposure, organic mat ter losses and decreased crop residue cover, decreased soil aggregatio n. A reclamation strategy for the degraded coffee soils in Parana is t o increase the use of practices that minimize soil erosion and improve residue cover.