Effects of Organically Enhanced Biofertilizer and Fertilizer Briquettes on Mineral Nutrition, Quality, and Yield of Corn and Soil Health

Interest in alternate fertilizers has increased in recent years in order to improve crop nutrition and soil health. The efficacy of these fertilizers on corn (Zea mays L.) production and quality has been scarcely documented. Two alternative fertilizers, organically enhanced NPSFe Unity biofertilizer (Unity) manufactured from sterilized organic additives extracted from municipal wastewater biosolids and NPKZn briquettes (briquettes) produced by compacting solid fertilizers into a super-granule between 1-3 grams, were evaluated for nutrient concentrations, growth, quality, and yield of corn, residual soil nutrient levels, and soil microbial community structure relative to the conventional fertilizers ammonium sulfate and urea at Jackson and Ames, TN from 2011 to 2013. Unity, briquettes, ammonium sulfate, and urea, and four N rates of 0, 85, 128/170, and 170/255 kg ha^-1 [hectare] were assigned to the main and sub plots, respectively, in a split plot randomized complete block design with four replicates. Unity sometimes had lower N and P concentrations in plant biomass and grain, but resulted in greater Zn concentrations in plant biomass at higher N rates. Plant Fe concentration was not increased by the application of Unity. The briquettes did not consistently improve N, P, K, and Zn nutrition in the plant. Unity and ammonium sulfate resulted in higher plant S concentrations than the briquettes and urea. Unity increased soil organic C levels, but decreased diversity of soil microbes. The briquettes produced lower soil NO₃^--N [nitrate] concentrations particularly under wet soil conditions. Unity and ammonium sulfate generally maintained stronger plant growth through early to middle season of corn than the banded briquettes and split-applied urea. Physiological defects were fewer under briquette fertilization at lower N rates. Unity and the briquettes at lower N rates had greater grain yields; at higher N rates they were only comparable in grain yield to ammonium sulfate and urea. Unity and the briquettes also had greater grain yields under wet soil conditions. In conclusion, the agronomic benefits with the briquettes are not consistent compared to the conventional prilled fertilizers. Unity biofertilizer is a viable source to increase plant S nutrition and soil C sequestration.