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Nitrogen Release Characteristics from Biosolids-Derived Organomineral Fertilizers

Antille, Diogenes L., Sakrabani, Ruben, Godwin, Richard J.
Communications in soil science and plant analysis 2014 v.45 no.12 pp. 1687-1698
NPK fertilizers, biosolids, coatings, field capacity, grain crops, granules, grasses, laboratory techniques, mineral content, mineralization, nitrogen, particle size, potassium, soil minerals, soil treatment, soil types, urea, England
This study investigated the availability of nitrogen (N) following soil application of a novel biosolids-derived organomineral fertilizer (OMF ₁₅—15:4:4) in comparison with urea (46% N). OMF ₁₅ is produced by coating biosolids granules (particle size range: 1.10–5.50 mm in diameter) with urea and potash [60% potassium oxide (K ₂O)], which increase the concentration of mineral N and potassium (K), respectively, resulting in a balanced fertilizer material suitable for application in cereal and grass crops. The study comprised two soil types of contrasting characteristics which were incubated over a period of 90 days at 25 °C and maintained near field capacity. Nitrogen was applied at rates equivalent to 0 (control), 150, and 300 kg ha ⁻¹, and soil mineral N measured routinely using standard laboratory techniques. Results showed that the majority of N was released from OMF ₁₅ within 30 days from application (range: 40% to 72% of total OMF ₁₅-N applied) with a further 10% to 28% in the following 60–90 days. OMF ₁₅ required an accumulated thermal time of 2250 degrees-day to release between 68% and 79% of the total OMF ₁₅-N applied. From this, it was inferred that mineralization of the organic-N fraction in OMF ₁₅ is likely to progress beyond harvest of winter cereal crops in-field conditions in England. The results of this study aided the development of fertilization strategies for the best use of OMF in winter cereal and grass crops.