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United States Department of Agriculture

Agricultural Research Service

Research Project: NUTRIENT CYCLING AND UTILIZATION ON ORGANIC DAIRY FARMS

Location: New England Plant, Soil and Water Research Laboratory

Title: Phosphorus forms in conventional and organic dairy manure identified by solution and solid state P-31 NMR spectroscopy

Authors
item He, Zhongqi
item Honeycutt, Charles
item Griffin, Timothy
item Cade-Menun, Barbara - AGRI-AGRI FOOD CANADA
item Pellechia, Perry - UNIV OF SOUTH CAROLINA
item Dou, Zhengxia - UNIV OF PENNSYLVANIA

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 26, 2009
Publication Date: August 1, 2009
Citation: He, Z., Honeycutt, C.W., Griffin, T.S., Cade-Menun, B.J., Pellechia, P.J., Dou, Z. 2009. Phosphorus forms in conventional and organic dairy manure identified by solution and solid state P-31 NMR spectroscopy. Journal of Environmental Quality. 38:1909-1918.

Interpretive Summary: Organic dairy production has increased rapidly in recent years. Organic dairy cows generally eat different diets than conventional dairy cows. Although these differences could impact the turnover and availability of plant nutrients in manure, little information is available to aid organic dairy farmers in making nutrient and manure management decisions. In this study, we evaluated the different forms and quantities of phosphorus (P) in organic and conventional dairy manures. We found that organic dairy manure contained less organic P than conventional dairy manure. Conventional dairy manure contained more inorganic P. These results indicate that P availability from manure should be expected to differ between organic and conventional dairy production systems.

Technical Abstract: Organic dairy production has increased rapidly in recent years. Organic dairy cows generally eat different diets than their conventional counterparts. Although these differences could impact availability, utilization, and cycling of manure nutrients, little such information is available to aid organic dairy farmers in making nutrient and manure management decisions. In this study, we comparatively characterized P in organic and conventional dairy manure by solution and solid state 31P NMR spectroscopic techniques. Phosphorus in both types of dairy manure was extracted with water, Na acetate buffer (100 mM, pH 5.0) plus 20 mg Na dithionite/ml, or 0.025 M NaOH with 50 mM EDTA. Solution NMR analysis revealed that organic dairy manure contained about 10% more inorganic phosphate than conventional dairy manure. Whereas organic dairy manure did contain slightly more phytate P, it contained 30-50% less monoester P than conventional dairy manure. Solid state NMR spectroscopy revealed that mono-, di-, and trivalent metal P species with different stabilities were present in the two dairy manures. Conventional dairy manure contained relatively higher contents of soluble inorganic P species and stable metal phytate species. In contrast, organic dairy manure contained more Ca and Mg species of P. These results indicate that P transformation rates and quantities should be expected to differ between organic and conventional dairy manures.

Last Modified: 7/22/2014
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