Evaluation of paper mill biosolid as a soil amendment

Field trials in Truro and Afton Hills, N.S., and four greenhouse experiments were conducted in 2002--2003, to evaluate paper mill biosolid as a soil amendment for corn, soybean and forage. The initial estimate of 50% available nitrogen from the biosolid in the first year appears to be too high, since a beneficial response only occurred in the second year after the biosolid further decomposed. The high C:N ratio of the biosolid (∼40:1) appears to have immobilized nitrogen in year 1; decomposition in year 2 may have offset this. The biosolid supplied adequate phosphorous to meet crop requirements, but was limiting in potassium. Biosolid improved organic matter and phosphorous content, mainly in low fertile soils. There was no evidence that the biosolid caused environmental concern. Land application of biosolid may be of low agronomic value in the short term, but long term effects may prove positive.