Carbon and nitrogen content in soil and microbial biomass in soils with different uses and periods of pig slurry application

The replacement of the forest by annual crops and pastures, as well as the application of pig slurry (PS), can cause changes in soil chemical and biological properties. To evaluate changes in organic carbon (OC) and total nitrogen (TN) in the soil, and carbon in the microbial biomass (CMB) and nitrogen in the microbial biomass (NBM) in the soil, a diagnosis was performed in properties of Coruja/Bonito watershed, municipality of Braço do Norte, Santa Catarina, southern Brazil. The sampled plots of corn and naturalized pasture were defined according to the period PS application, approximately 5, 10 and 20 years. Later periods were divided into ranges: short (less than 10 years) and long (more than 10 years).The attributes were evaluated in the up-to-10cm soil layer, and the OC was analyzed by the method of wet oxidation, NT Kjeldahl method, and CMB and NBM by the method of fumigation-extraction. The period of PS application did not affect the values of the parameters evaluated. The highest concentrations of OC and CMB occurred in the soil under forest, and higher values of TN and NBM occurred in pasture soil. The soil under maize had the lowest mean values for all the attributes studied. The parameters evaluated were good indicators of changes in soil properties due to use.