Nutrient Availability from a Pelletized Waste Material

The research described in this report was conducted as part of the Brown County Waste Transformation Initiative (BCWTI). The BCWTI is a public-private partnership of various stakeholders in northeast Wisconsin that is exploring methods of improved solid waste utilization through the development of commercially viable products that are appealing for public use. Many of these materials are currently being landfilled, incinerated, or landapplied in an unstable form. To date, a variety of solid waste materials have been blended and pelletized in “bench top” scale tests to create usable and more easily transportable products. Examples of waste materials that may be included are animal manure, paunch manure and other wastes from meat packing plants, papermill residuals, municipal biosolids, and other local organic waste materials. This study evaluated a material known as “Four Blend” consisting of residuals from selected municipal wastewater treatment plants and meat processing facilities. Small plot studies were established in 2009 at the Arlington Agricultural Research Station where the N and P availability of the blend was assessed. Replicated field scale strip trials were established in the Green Bay area to demonstrate the potential of blending materials with reduced rates of urea fertilizer to supply the N requirement of corn. First year results showed that the Four Blend material increased soil test P when applied to a P responsive field prior to seeding alfalfa, but only at the highest rate of application. Yield of the first cut was increased compared to the control where either P fertilizer or material was applied, however the fertilizer treatments produced higher yield than the material. The yield differences for the second cutting were not significant. The pelletized materials were found to be a source of S for the alfalfa. Corn was found to respond to the addition of the Four Blend material on a N responsive site. The pre-sidedress nitrate test demonstrated that the pelletized material supplied adequate N when somewhere between 184 and 368 lb total N/a was applied. Corn grain and silage yield increased with increasing material application rate and the highest rate of application produced grain yields that were greater than the highest fertilizer treatment. This could be due to the response to other plant nutrients in the material such as sulfur and zinc, which were not supplied in the fertilizer only treatments. An evaluation of the corn N uptake showed that the pelletized material was 40 – 45 % as efficient as corn at supplying N at this site in 2009. The final component of the study examined the response to the material when blended in proportion with reduced rates of fertilizer N. No attempt was made to totally substitute for the missing N with material, so the observed response may indeed be due to factors other than N. Sites established on different soil types in the Green Bay area showed that the treatment that utilized 90 % of the recommended N, with a small amount of pelletized material was equivalent to the 100 % fertilizer treatment. Reducing the urea N to 75 % of the recommended rate was not found to be favorable. The evaluation of the Four Blend material on alfalfa and corn shows promise as a supplier of plant nutrients. Preliminary data show that relatively high rates of application produce only a modest increase in soil test P and that when substituted for urea for corn there is promise for utilizing the material in standard agricultural production practice.