Microbial biomass-c, evolved CO 2 -C, mycorrhizal colonization, soil fertility and corn yield under different soil management and liming Martha Regina Lucizano Garcia 1 , Luiz Malcolm Mano de Mello 2 and Ana Maria Rodrigues Cassiolato 2 * 1 Pós-graduação em Produção Vegetal, Universidade Estadual Paulista (Unesp). 2 Departamento de Fitossanidade, Engenharia Rural e Solos, Universidade Estadual Paulista (Unesp), Av. Brasil, 56, Cx. Postal 31, 15.385-000, Ilha Solteira, São Paulo, Brasil. *Author for correspondence. e-mail: anamaria@bio.feis.unesp.br ABSTRACT. The objective of this research was to quantify the microbial biomass carbon (MBC) and evolved CO 2 -carbon (CO 2 –C), mycorrhizal colonization, soil fertility and corn production under different soil managements and surface-limestone application. For that, an experiment was carried out consisting of four treatments, as follows: two soil managements - no-tillage (NT) and minimum tillage (MT) and two limestone treatments (0 and 2 t ha -1 ), with four replications. Soil managements affected the soil chemical attributes in the 0-0.10 m depth layer: the highest P values were observed in MT and the lowest Al levels in the NT-treatments. Once no significant differences were found among treatments for the evaluated microbial variables and corn yield, it allowed affirming that it is possible to avoid disruption of the no- till sequence by applying lime on the soil surface, once the incorporation of organic matter and limestone caused little changes to the system stability. Key words: no-tillage, minimum-tillage, arbuscular mycorrhizal fungi, Brazilian savannah. RESUMO. Carbono da biomassa microbiana e do CO 2 liberado, micorrização, fertilidade e produtividade do milho sob diferentes manejos do solo e calagem. O objetivo deste trabalho foi quantificar o carbono da biomassa microbiana (CBM) e do CO 2 (C-CO 2 ) liberado, a micorrização, fertilidade e a produtividade do milho em razão do manejo do solo e da calagem aplicada à superfície. Para tanto, instalou-se um experimento com quatro tratamentos constituídos de dois manejos do solo, plantio direto (PD) e cultivo mínimo (CM), com e sem calcário (0 e 2 t ha -1 ), com quatro repetições. Os manejos afetaram os atributos químicos do solo na camada 0-0,10 m: o maior valor de P foi observado no CM e o menor de Al no PD. Uma vez que não foram observadas diferenças significativas entre tratamentos para as variáveis microbiológicas e produtividade de milho, isto permite afirmar que é possível evitar a interrupção do PD com aplicação de calcário na superfície, visto que a incorporação do material de cobertura e a calagem pouco alteraram a estabilidade do sistema. Palavras-chave: plantio direto, cultivo mínimo, fungos micorrízicos arbusculares, cerrado. Introduction There is a worldwide increasing concern about the preservation of natural soil attributes and properties. Activities related to the so-called conventional agriculture, associated with intensive and/or inadequate soil management, might exhaust the soil over the years. An uncovered soil surface, overheated by the sun, loses rapidly water content, which hinders conditions for organic matter maintenance (important in soil erosion protection) and is detrimental for development of crops and yield, while requiring more fertilizers, correctives and pesticides which are responsible for the physical, chemical and biological degradation of the soil (Sá, 1997; Silva e Resck, 1997). In Brazil, several soil conservationist management systems have been studied looking toward a minimum soil disturbing. In the cerrado (Brazilian savannah), the no-tillage system has been extensively used. It consists of soil mobilization only in the planting row and the sowing is done over a partially or totally plant residue-covered soil (Furlani, 2000). The layers of plant residues accumulated on the soil surface minimize the erosion effect of intensive rainfalls, which usually occurs in tropical regions. They also reduce soil temperature oscillations, keeping it mild, and maintain the humidity during the hot and dry seasons (Colozzi-Filho, 2000). Moreover, it contributes to improve soil structure and preserve nutrients for the following crops, increasing yield (Sá, Acta Sci. Agron. Maringá, v. 28, n. 1, p. 23-28, Jan./March, 2006