WATER RETENTION, COMPACTION AND BEAN YIELD IN DIFFERENT SOIL MANAGEMENTS UNDER A CENTER PIVOT SYSTEM

摘要

The southwestern region of the state of S?o Paulo, Brazil presents significant area of annualrncultures basically composed of cereals under central pivot system irrigation. The bean culture isrnpart of crop rotation used by irrigators from this region, who perform no-tillage management as arnform of sustainable soil use. The objective of this work was to compare two soil managementrnsystems: conventional management and no-tillage management systems in relation to theirrneffects on the soil physical-hydric properties, compaction and production components of beanrnculture under central pivot system irrigation. The experiment was conducted at the Buriti-MirimrnFarm, Km 223.5 of the Raposo Tavares Highway, Angatuba, SP, Brazil, during the secondrnsemester of 2003 using an area irrigated through center pivot system divided into two types ofrnsoil managements: conventional management and no-tillage management. Although no-tillagernmanagement presented higher water retention capacity at the most superficial soil layers as wellrnas lower compaction, the soil managements did not present significant differences in relation tornculture productivity. Since conservationist management cycles are short, it was verified that thernno-tillage management practice generated indirect benefits; however, time was not enough tornpromote structural changes in the soil and hence significant alterations in the physical-hydricrnproperties that would lead to higher root development and culture productivity.