　水田での野菜栽培において，家畜ふん堆肥を化学肥料の代替として活用する場合の適正な施用方法を明らかにするために，豚ぷん堆肥の肥料成分および窒素無機化特性を明らかにし，冬出しリーフレタス栽培においてその施用方法を検討した。

　７種類の豚ぷん堆肥の全窒素含量，全炭素含量，加里およびリン酸含量には差が認められ，また，反応速度論的に予測したリーフレタス冬出し栽培期間の窒素の無機化率も14～34％と差が認められた。

　加里含量をもとに豚ぷん堆肥の施用量を決定し，不足する窒素量を硝安で施用した堆肥施用区と，窒素，リン酸，加里をすべて化学肥料で施用した化学肥料区ではリーフレタスの収穫物の生育に差が認められず，堆肥施用区の生産経費を削減できた。

　以上の結果から，堆肥を化学肥料の代替として適正に施用するためには，加里，リン酸含量，および栽培期間の窒素無機化率が堆肥の種類で異なるため，これらを分析，予測する必要があること，また，堆肥の施用で加里およびリン酸を供給し，不足する窒素量を化学肥料で補うことで，冬出しリーフレタスの栽培が可能であることが示唆された。

　Fertilizer Component Characteristics of Pig Feces Compost Produced in Fukuoka Prefecture and Method for Applying the Compost to Cultivate Leafy Lettuce. SUEYOSHI Takayuki, Shinichi FUJITOMI, Toshihiko HIRANO and Masato ARAKI (Fukuoka Agricultural Research Center, Chikushino Fukuoka 818-8549, Japan) Bull. Fukuoka Agric. Res. Cent., 23: 42 - 47 (2004)

　In order to establish a suitable method of applying livestock feces compost in vegetable cultivation in paddy fields as an alternative to chemical fertilizer, fertilizer nutrient and nitrogen mineralization characteristics of pig feces compost were studied for the winter cultivation of leafy lettuce.

　Of the seven kinds of pig feces compost that were studied, differences were found in the total nitrogen content, total carbon content, potassium and phosphoric acid contents and their nitrogen mineralization rates ranged from 14% to 30% which are to be applied during leafy lettuce winter cropping period, according to predictions by kinetic analysis.

　At the compost application plot, we manured pig feces compost, at a rate decided on the basis of the potassium content, and where there is a shortage of nitrogen we manured ammonium nitrate. At a chemical fertilizer plot we added nitrogen, phosphoric acid and potassium all using chemical fertilizer. There was no difference between the compost application plot and the chemical fertilizer plot in growth and development of leafy lettuce, and production cost of the compost application plot could be reduced.

　From these results, it may be induced that in order to utilize suitably the compost for alternative chemical fertilizer, it is necessary to analyze potassium and phosphoric acid contents and predict the nitrogen mineralization rate of the compost because there are differences in the rate depending on the kinds of compost. Leafy lettuce winter cultivation is made possible by supplementing the shortage of nitrogen with ammonium nitrate.