I+D+i

Comparison of the effects of dairy sludge and a mineral NPK fertilizer on an acid soil

Autor: M.E. López-Mosquera, V. Cascallana & S. Seoane

In the present study, the short term effects produced by a dairy sludge applied to an acid soil, at a rate of160 m3 ha–1, with or without K supplementation, were compared with those of a mineral fertilizer conventionallyused on mixed swards in northwestern Spain. The investigation was carried out under field conditions on asoil with a very low exchange capacity, a high percentage of saturated Al and a high P retention. Four differenttreatments were applied: unfertilized control, dairy sludge, dairy sludge supplemented with K and mineral fertilizer.Soils were analysed at different times up to 8 months after treatment application and forage productionwas estimated after cutting the grass for silage in spring. Results showed that, compared to the mineral fertilizer,the dairy sludge (with or without K supplementation) had a liming effect (pH and exchangeable Ca increased).The dairy sludge was also a good source of P. Although there was an initial increase in salinity (at 3 months),limiting levels were never reached and the effect had disappeared at 6 months after application of sludge treatments,due to the diluting effect of rainfall. In spite of different fertility conditions achieved by the four treatments,there were no significant differences in forage production. It is concluded that, in the short term, and atan application rate of 160 m3 ha–1, dairy sludge is as effective as the mineral fertilizer in supplying nutrients forforage production 
Comparison of the effects of dairy sludge and a mineral NPK fertilizer on an acid soil
 
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