EFFECTS OF CONVENTIONAL AND ALTERNATIVE MANAGEMENT-SYSTEMS ON SOIL-PHOSPHORUS CONTENT, SOIL-STRUCTURE, AND CORN YIELD

Conventional management practices have been associated with increased soil erosion and organic matter loss and the contamination of surface and ground water. Alternative agriculture systems which minimize exter nal chemical inputs and degradation of soil and water resources repres ent alternatives to conventional management practices. Four different management practices were compared on an alluvial silty loam soil cult ivated to grow corn (Zea mays L.). The effects of conventional and red uced tillage and of different chemical inputs on the distribution of p hosphorus (P) concentration and on soil porosity were investigated. Re sults showed that the highest P content was detected in the topsoil (0 -10 cm) of the minimum tilled plots even though the amount of P fertil izer added was much lower than the amount added in the conventionally tilled plots. The total porosity was significantly higher in the minim um tilled soil and was related only to the tillage technique. Since th e higher porosity was mainly due to the higher proportion of elongated and regular pores, the minimum tilled soil appeared to be more resist ant to physical stresses and characterized by a higher biological acti vity.