BALOTA, E. L.; MACHINESKI, O.; TRUBER, P. V. <b>Soil enzyme activities under pig slurry addition and different tillage systems</b&gt; - doi: 10.4025/actasciagron.v33i4.9816. Acta Scientiarum. Agronomy, v. 33, n. 4, p. 729-737, 4 maio 2011.