SOIL AND MICRONUTRIENT ACIDITY AVAILABILITY AS AFFECTED BY SOIL MANAGEMENT

Abstract

The acidity is an important characteristic of the main soils of Brazilian Savanna as Latosol (56%) and Quartzpsemment (20%). This study was carried out at Três Irmãos farm, in Santa Helena, state of Goiás, Brazil, with soybean, corn, rice and common bean crops under four soil management: 1) no-till; 2) deep moldboard plowing; 3) shallow harrow plowing and 4) deep stirring, using a chiseling plow and three levels of fertilization: 1) Check; 2) State recommendation and 3) Fertilizers to cover the nutrients extracted by grain exportation. The distribution of exchangeable aluminum was influenced by soil management in function of machines and implements demanded by each system. The areas submitted to no-till management presented higher aluminum concentration in the superficial layer after the first crop, but the same was observed in the areas submitted to deep stirring only after the last crop. The areas submitted to shallow harrow plowing showed similar results of those obtained by deep moldboard plowing , even so in smaller degree. In the area where deep moldboard plowing was used, aluminum concentration was similar in all soil layers. Higher pH values were observed on the superficial layer of soil submitted to deep moldboard plowing in relation to no-till shallow harrow plowing and deep stirring. Uniform distribution of iron and manganese was observed in areas submitted to deep moldboard plowing. No variation was observed in relation to fertilizer application.

KEY-WORDS: Soil fertility; micronutrients; no-till; crop systems.