Nitrogen release from air-dried biosolids for fertilizer value

• Published in: Soil use and management Vol. 27; no. 3; pp. 294 - 304
• Main Authors: Rouch, D. A., Fleming, V. A., Pai, S., Deighton, M., Blackbeard, J., Smith, S. R.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.09.2011; Wiley-Blackwell
• Subjects: Agricultural chemicals; Agronomy. Soil science and plant productions; Biological and medical sciences; fertilizer application; Fertilizing; Fundamental and applied biological sciences. Psychology; Management; mineral-N; Moisture; N-mineralization; Pans; phosphate; Physical properties; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil (material); soil moisture; Soil science; Stability; Stockpiles; tenosol; Water and solute dynamics; Phosphates; Tenosols; Inorganic element; Sewage sludge; fertilizer application; N-mineralization; mineral-N; Mineralization; Soil science; Release; Macronutrient(mineral); Fertilization; Soil moisture; Air drying; Property of soil; phosphate; Immature soil; Physical properties; Soil management; Fertilizers; tenosol; Soil water properties; Nitrogen cycle; Inorganic nitrogen; Phosphorus compound
• ISSN: 0266-0032; 1475-2743
• DOI: 10.1111/j.1475-2743.2011.00338.x

Mineral‐N production by air‐dried biosolids was measured in an Australian tenosol type soil with two moisture conditions over 70 days, using a controlled laboratory incubation procedure. The biosolids were from both air‐drying pans and stockpiles. Inorganic‐N components (NH4‐N, NO3‐N and NO2‐N) were present in all biosolids, with higher concentrations in samples from air‐drying pans compared with stockpiles of 1 yr age. Nevertheless, significant production of NO3‐N occurred in moist soil amended with all air‐dried biosolids. In contrast, saturated soil amended with air‐dried biosolids generally showed a net loss of inorganic‐N compounds during incubation, presumably owing to denitrification. In the saturated soil, only biosolids from air‐drying pans provided NO3‐N production from existing NH4‐N. The results indicated that biosolids from air‐drying pans provided the most robust production of NO3‐N, compared with aged material from the stockpiles, owing to the reduced N content and increased stability of the organic fraction in stored biosolids. However, the rates of N‐mineralization in the tenosol soil were substantially lower than reported for more fertile soil types and most of the organic‐N content of the biosolids remained undegraded by day 70. The biosolids thus may substantially remain to provide improved properties of soil, such as structure and water‐holding capacity. The results suggest that anaerobically digested biosolids from air‐drying pans are potentially highly consistent products that could be effective replacements for inorganic‐N fertilizer in agricultural production.