Field evaluation of a mechanical topdresser for solid wastes

An applicator for topdressing (or sidedressing) row crops with solid waste materials was evaluated. The apparatus can meter and deliver animal manures and other raw solid waste materials between rows of a growing crop without the material contacting the crop. Results from a 3-year field study clearly indicate that new poultry litter management strategies, using this litter topdressing equipment and improved soil and plant nitrogen tests, should improve the agronomic and environmental efficiency of maize (corn) Zea mays L. production in the mid-Atlantic region of the USA. Economically optimum yields were obtained with starter fertilisers and moderate topdress N rates, and poultry litter as a topdress material was found to be as effective as topdressing with a commercial fertiliser. Comparison of total application costs revealed that topdressing with poultry litter is about US $10 ha−1 more expensive than conventional methods, which can be attributed to the lower concentrations of N in poultry litter, requiring significantly more applications and greater operator time per hectare.