Phosphorus Speciation and Sorption‐Desorption Characteristics in Heavily Manured Soils

Abstract

Managing heavily manured soils for decreased P loss to waters requires improved understanding of the chemical and sorption-desorption characteristics of P in these soils. We used soils from agricultural fi elds receiving ≥8 yr of dairy, poultry, swine manure or spent mushroom compost for the determination of P functional groups in NaOH-EDTA extracts by solution 31 P nuclear magnetic resonance (NMR) spectroscopy, degree of P saturation (DPS), and P sorption-desorption isotherms. The 31 P NMR results show that inorganic orthophosphate was the primary form of P in manure treated (79-93% of total extract P) and untreated soils (33-71%). Pyrophosphate and phosphate monoesters were identifi ed in all soils, whereas phosphate diesters were present in small proportions (<3%) in only a few soils. Polyphosphate, a more condensed form of inorganic P, was present in seven out of nine manured soils (9-47 mg P kg −1 , <2%) but absent in untreated soils. Concentrations of inositol hexakisphosphate (IHP), mostly myo-IHP plus some scyllo-IHP, were similar in manured soils (52-116 mg P kg −1 , 2-8%) and untreated soils (43-137 mg P kg −1 , 6-22%), suggesting a lack of IHP accumulation despite long-term manure applications, including poultry manures that are typically rich in IHP. Most of the treated soils had DPS ≈ 80 to 90% compared with 11 to 33% for the untreated samples. Results from P sorption isotherms showed that potential P release was 3 to 30 times greater from treated than untreated soils. The lack of IHP accumulation in soils receiving long-term manure applications implies that manure-derived IHP may not be biologically and environmentally benign.

Spectroscopic quantification of soil phosphorus forms by 31p-nmr after nine years of organic or mineral fertilization

“…Likewise, some kinds of monoester Po, especially inositol hexaphosphate (myo and scyllo), are also accumulated in soils because of their high residual charge, promoting stabilization of the soil mineral components (Anderson et al, 1974). The P forms detected by 31 P-NMR in this work were similar of those described by Koopmans et al (2003), Hansen et al (2004), He et al (2008) and Dou et al (2009) in soils treated with long-term fertilization or animal manure applications.…”

Organic matter and pH affect the analysis efficiency of 31 P-NMR

“…The Yellow River sediment samples were composed of fine sand, which had low Po. The same results were also discovered in soil samples, but not in sediments at the regional scale (McDoell and Stewart, 2006;Dou et al, 2009). Turner et al (2003a) suggested that higher adsorptive surface area and lower microbial activity are beneficial for the existence of Po.…”

Solution Phosphorus-31 Nuclear Magnetic Resonance Spectroscopy of Soils from 2005 to 2013: A Review of Sample Preparation and Experimental Parameters

“…Some researchers also filter the supernatant through 0.2-mm membrane filters (Lehmann et al, 2005), 0.45-mm membrane filters (Backnäs et al, 2012), Whatman no. 41 or 42 filter paper Dougherty et al, 2007;Doolette et al, 2009Doolette et al, , 2011aDoolette et al, , 2011bDou et al, 2009;Ohno et al, 2011), or Whatman GF/F filters (McDowell et al, 2007a(McDowell et al, , 2007bKoopmans et al, 2007). Lehmann et al (2005) and Bol et al (2006) dialyzed their extracts (12,000-14,000 Da molecular weight cut-off ) to concentrate organic P forms and remove orthophosphate.…”