Ito  Kumiko

Nanzyo  Masami

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Nanzyo, Masami

Ito, Kumiko

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Phosphates in the Air-dried Residues of Water or Dilute Acid Extracts from Compost

紀要類 (bulletin)Poster Sessiondepartmental bulletin pape

Tohoku University Repository (TOUR) / 東北大学機関リポジトリ

Phosphates in the Air-dried Residues of Wateror Dilute Acid Extracts from Compost著者 Nanzyo  Masami, Ito  Kumikojournal orpublication titleJournal of Integrated Field Sciencevolume 11page range 68-68year 2014-03URL http://hdl.handle.net/10097/57396Poster Session Phosphates in the Air-dried Residues of Water or Dilute Acid Extracts from Compost Masami Nanzyo and Kumiko Ito Tohoku University, Japan The content of P in compost is reported to be 4.43-48.6 g kg-I and P is mostly inorganic (Yokota et ai., 2003). With a rise in prices of chemical P fertilizers, P in the composts is expected to playa role of P fertilizer. So far, chemical forms ofP in the compost have been estimated to be CaHP04.2H20 or MgNH4P04.6H20 (Tanahashi et ai., 2010). However, it is not very facile to observe and detect these crystalline phosphates directly in cattle ma-nure compost (CMC) using an electron microscope or X-ray diffraction. The objective of the present study was to examine chemical forms of P in the air-dried residue of water or dilute-acid extracts of compost. Air-dried CMC, a product of Kawatabi Field Science Center, Graduate School of Agricultural Science, To-hoku University and commercially available fermented chicken manure pellets (FCMP) were ground to pass a 2 mm sieve. To 15 g each of these composts, 50,49.25,45,40,30 mL of pure water and 0,0.75,5, 10,20 mL of 1 mol L-I HCI, respectively, were added, and shaken by hand. Regarding FCMP, 20 mL of 2 mol VI HCI was used instead of 20 mL of 1 mol VI HCI because of its high carbonate content. Then, the mixtures were allowed to stand at room temperature for 24 h with occasional swirling. After measurement of suspension pH, solutions were separated by filtration using Toyo No.5C filter paper. After measuring electric conductivity of the solutions, Ca, Mg, Na and K were analyzed by atomic absorption spectrometry and P concentration was determined by the molybdenum blue method. The remaining solutions were air-dried. After removing highly soluble salts from the air-dried residues with small amount of water, the residual precipitates were examined by X-ray diffraction, scan-ning electron microscope observation and energy dispersive X-ray analysis. The amounts ofCa, Mg, K and Na extracted from two composts were greater than those ofP. Among these, the amounts of Ca, Mg and P increased with decreasing pH of the extracting solution, compared with those of K and Na. Crystalline phosphates found in the air-dried residues from CMC were MgKP04.6H20, MgHP04.3H20, and CaHP04.2H20, depending on extracting pH. Non-crystalline Ca phosphate was included in the precipitates from acidic extracts. In the air-dried residues from FCMP, non-crystalline phosphates were found as major compo-nents, and small amounts ofMgNH4P04.6H20 and CaHP04.2H20 were also detected. 68 

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Phosphates in the Air-dried Residues of Water or Dilute Acid Extracts from Compost

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