Evaluation of sewage sludge as an organic fertilizer in volcanic soils of agricultural and forestal use in Jalisco, Mexico

Sewage sludge applications to agricultural and forest soils represent an important alternative for reuse of materials with a high nutrient content. The effects of different application rates of sewage sludge as organic fertilizer on corn production and Pinus douglasiana development were studied. The experiments were established in a volcanic soil of the central region of Jalisco, Mexico. The application 10 and 20t(.)ha(-1) of dry sewage sludge and of sludge compost mixed with garden residues on corn yield was evaluated. The materials were homogeneously applied on the ground, using a randomized complete block design with five replications. Both the corn and fodder yield (dry matter base) increased as a result of the addition of sludge and compost in 18 and 22%, respectively. The effects of different application rates of dry sewage sludge (0, 30, 60 and 100g/tree) on the initial development of Pinus douglasiana were also evaluated. Application of sludge at the highest rate significantly improved the establishment of Pinus douglasiana (83%) after 14 months, whereas the control only reached 67%. At the highest rates of application, both height and diameter of tree steams were increased by similar to 18%. Application of sewage sludges as an organic fertilizer improved the corn production and the initial development of Pinus douglasiana on volcanic soils.