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Plant availability of phosphorus in swine slurry and cattle feedlot manure
- Eghball, B., Wienhold, B.J., Woodbury, B.L., Eigenberg, R.A.
- Agronomy journal 2005 v.97 no.2 pp. 542
- pig manure, cattle manure, nutrient availability, plants, phosphorus, plant nutrition, nutrient uptake, soil temperature, soil water content, temporal variation, soil texture, runoff
- To utilize manure P for crop production, P release and plant availability needs to be quantified. An incubation study was conducted to determine P availability from swine (Sus scrofa) and cattle (Bos taurus) feedlot manure in three soils. Treatments for each manure included temperature (11, 18, 25, and 32°C), water regime [constant 60% water-filled pore space (WFPS) vs. four dry-down cycles of 60 to 30% WFPS], time, and soils (Catlin silt loam, Sharpsburg silty clay loam, and Valentine fine sand). In another study, synthetic P fertilizer was used to determine the fraction of P that becomes unavailable with time to compare with manure P. Time, soil, and manure application were factors that influenced soil test P and water-soluble P during incubation. At the low synthetic P fertilizer rate of 6 μg g-1, about 12 kg P ha-1. none of the applied P remained available in the Catlin soil while about one-third remained plant available in the Sharpsburg soil and two-thirds in the Valentine soil. At the high P rate, 68 mg kg -1, 38 to 83% of fertilizer P remained available in the three soils. Phosphorus availability was 60 to 100% of applied cattle manure P and 52 to 100% of swine slurry P in the three soils. Phosphorus availability in the Sharpsburg soil was 100% of P in both manure types. Phosphorus availability from manure is high, and manure can be used similar to inorganic P fertilizer in soils where P-based application is made in areas susceptible to P loss in runoff. In P-deficient soils, a P availability of 70% should be used.