Chemical changes of a soil under different management forms of coffee plantation

Widespread marketing technologies recomend the use of high doses of chemical fertilizers and the control of pests and diseases to maintain the productive potential of farms. This affects the sustainability of the coffee agroecosystem, creating a total dependence of industrialized products. The objective of this study was to compare the alterations of some chemical, physical, and microbiological characteristics of a Typic Hapludox from the region of Santo Antonio do Amparo (Minas Gerais State, Brazil), in agroecosystems of "organic coffee"; "in conversion"; and "conventional" coffee production, to a native forest fragment. Data were collected throughout one year on two farms, under the influence of similar climate and relief conditions, and using the same cultivar (Acaia IAC474-19) of equal age (five years). Soil samples were collected twice (July 1999 and December 1999) at a depth of 0-20 cm. The principal component analysis allowed a comprehensive visualization of the characteristics that most influenced the soil behavior in the different studied systems. In general, the management forms for the production of organic, in conversion and conventional plantations increased the soil fertility in comparison to the soil under the native forest fragment. Larger chemical characteristic alterations were observed in the agroecosystem of organic coffee production in relation to the conventional; there were increments in the values of soil pH and Ca, Mg, K, P, Zn, B, CTC, base saturation, and decrease of exchangeable Al.