Phosphorus compounds and their solubility in swine manure compost

• Published in: Soil science and plant nutrition (Tokyo) Vol. 59; no. 3; pp. 419 - 426
• Main Authors: Komiyama, Teppei, Niizuma, Seiichi, Fujisawa, Eiji, Morikuni, Hiromasa
• Format: Journal Article
• Language: English
• Published: Kyoto Taylor & Francis 01-06-2013; Taylor & Francis Ltd
• Subjects: ammonium nitrogen; Brassica rapa subsp. nipposinica var. perviridis; composts; Indexing in process; magnesium ammonium phosphate; phosphorus; phosphorus solubility; pig manure; scanning electron microscopes; scanning electron microscopy; solubility; spinach; struvite; Swine manure compost; X-ray diffraction
• ISSN: 1747-0765; 0038-0768; 1747-0765
• DOI: 10.1080/00380768.2013.789397

Swine manure compost (SMC) contains a significant amount of phosphorus (P). In this study, the characteristics of P compounds in SMC were investigated by the nondestructive X-ray diffraction (XRD) method, chemical extraction, and a cultivation experiment. Only magnesium ammonium phosphate hexahydrate (MAP or struvite, MgNH ₄PO ₄·6H ₂O) was detected as crystal P compound by XRD in most SMC. Furthermore, MAP crystal was observed by scanning electron microscope (SEM) image. The amount of ammonium nitrogen in MAP (MAP-NH ₄-N) was 3.38 ± 2.24 mg-N g ⁻¹ on average, equivalent to 54% of total NH ₄-N (hydrochloric acid-extractable NH ₄-N) in SMC. The content of P in MAP (MAP-P) in SMC calculated backward from MAP-NH ₄-N was 7.5 ± 4.5 mg-P g ⁻¹. Sequential water extraction demonstrated that MAP in SMC was dissolved in water. The ratio of MAP-P to water-extractable P (WEP) was 66%, indicating that the amount of WEP was controlled by MAP existence in SMC. The amount of P uptake by the Japanese mustard spinach (Komatsuna; Brassica rapa var. perviridis) plant accorded with WEP content in SMC.