Yield of Tomatoes as Influenced by Time of Application of Municipal Biosolids

Abstract

A trial evaluating the use of municipal biosolids application in 1996 resulted in stunted transplants, delayed fruit set, season-long reduction in plant vigor, and reduced yield of `Mt. Pride' tomatoes. Hypotheses for these effects include nitrogen (N) immobilization, increased salinity, and acetic acid phytotoxicity. Subsequently, a trial was initiated in 1997 at The Univ. of Tennessee Plateau Experiment Station near Crossville to evaluate the effect of timing of biosolid application on `Mt. Fresh' tomato plant growth and fruit yield. Treatments included an inorganic control consisting of 134, 67, and 67 kg·ha-1 N, P2O5, and K2O, respectively and a municipal biosolid at a rate of 168 kg·ha-1 N applied at transplanting, 2 months prior to transplanting, or 3 months prior to transplanting. The rationale for these treatments is that time would allow for mineralization of N and leaching of salts and/or acetic acid. Stunting of transplants was observed in all treatments receiving applications of municipal biosolids, with the degree of stunting increasing as length of delay decreased. Marketable and total yields were not influenced by treatment. Municipal biosolids applied at transplanting resulted in the greatest fruiting delays and increased the amount of blossom end rot observed. Plants receiving inorganic fertilization produced the highest percentage of cracked and rotten fruit. Recommendations for municipal biosolid use include applying a rate based on N in the fall prior to production or applying a rate based on phosphorus with supplemental inorganic N in the spring.