【Paper】
Possibility of Using Sludge from Water Purification Plants in Animal Manure Composts to Suppress Phosphate and Potassium Dissolubility and Organic Matter Decomposition
Tsuyoshi Yokota*, Masahiko Saigusa* and Toyoaki Ito*
* Experimental Farm of the Graduate School of Agricultural Science, Tohoku University
† Correspondence should be addressed to Masahiko Saigusa:
（232-3 Ohkuchi Yomogida Narugocho Tamatsukuri-gun, Miyagi, 989-6711 Japan）


Abstract
The effects of sludge treatment in animal manure composts on both carbon mineralization patterns, and the reduction of potassium and phosphate dissolution were examined in comparison with untreated composts and composts treated with poly-aluminum chloride.
1）　Almost all of the potassium was dissolved by water out of the non-aluminum treated composts whereas, about 75％ of the potassium was dissolved out of the aluminum treated ones.
2）　The amounts of easily soluble phosphates in the sludge treated composts were 24-35％ lower than those of untreated control composts. Similarly, those amounts in the poly-aluminum chloride treated composts were 38-42％ lower.
3）　The potentially decomposable carbon in proportion to the total carbon in the control composts, in the sludge treated composts and in the poly-aluminum chloride treated composts were 26.1-26.3％, 22.6-22.8％ and 17.4-21.1％, respectively.
The amounts of water-soluble potassium and of easily dissoluble phosphate, and the carbon mineralization of composts were reduced by the addition of poly-aluminum chloride, but this addition tended to result in incomplete fermentation. On the other hand, the addition of sludge also reduced the amounts of water-soluble potassium and easily dissoluble phosphate, and the carbon mineralization of composts, but without any significant effect on the fermentation.


Key words: animal manure compost, carbon mineralization, phosphate, sludge from water purification plants, poly-aluminum chloride