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On-Site Assessment of Extractable Soil Nutrients after Long-Term Biosolid Applications to Perennial Forage
- Haney, Richard L., Jin, Virginia L., Johnson, Mari-Vaughn V., White, Michael J., Arnold, Jeffrey G.
- Communications in soil science and plant analysis 2015 v.46 no.7 pp. 873-887
- Cynodon dactylon, application rate, biosolids, forage, forage production, magnesium, mineralization, nitrates, nitrogen, orthophosphates, phosphorus, pollution load, potassium, recycling, soil nutrients, soil profiles, Texas
- The objective of this study was to evaluate soil nutrient loading and depth distributions of extractable nitrogen (N), phosphorus (P), and potassium (K) after long-term, continuous annual surface applications of anaerobically digested class B biosolids at a municipal recycling facility in central Texas. Commercial forage production fields of coastal bermudagrass (Cynodon dactylon L.) were surface applied at 0, 20, 40, or 60 Mg dry biosolids ha ⁻¹ y ⁻¹ for 8 years. Application duration was evaluated in fields treated with 20 Mg dry biosolids ha ⁻¹ y ⁻¹ for 0, 8, or 20 years. Total soil loads of extractable inorganic N and P increased linearly with application rate, but only extractable P increased with duration. Neither total load nor soil distribution of extractable K was affected by biosolid applications. Mineralization of biosolid-derived organic N and P likely contributed to elevated concentrations of nitrate throughout the soil profile (0–110 cm) and orthophosphate in surface soils (0–40 cm).