Soil structure modifications were studied in a coffee crop, growing in a "Latossolo Roxo", at Analandia, State of São Paulo, Brazil. The effects of mechanical, chemical and hand hoeing methods of weed control were compared. Soil structure modiftcations were evaluated by the distribution of classes of aggregates and by the average diameter of soil particles. Also the soil compaction was considered and determined through the bulk density determinations. After nine years of experintentation, between 1973 and 1982, signifcant differences among the effects of the rotary shredder and the other treatments were observed, concerning the average diameter of soil particles. This result was confirmed by the average distribution percentages of particles in the classes of aggregates. Higher values for the average diameter of soil aggregates were observed when the rotary shredder was used, and lower values when the disc harrow was used. An evaluation of the several treatments effects was not possible, due to the dispersion of the bulk density values.
agricultural mechanization; agricultural machinery; tillage machines; mechanical tillage; tillage system; coffee crop