PROBLEM TO BE SOLVED: To provide a soil conditioner for field crops that achieves a well-balanced absorption of nutrients in soil into field crops and the like for appropriate growing of field crops and the like and exhibits a bactericidal action against pathogenic bacteria and virus by scattering a fertilizer including not only minerals as a major element but also a trace metal element and an ultratrace metal element in a good balance and permitting field crops and flowers to ingest the fertilizer and to provide a soil conditioning method using the soil conditioner for field crops.SOLUTION: The soil conditioner for field crops is used by mixing into soil for cultivating field crops and flowers and uses lava powder composed mainly of lava powder formed into a fine powder by pulverizing lava stones collected in a volcanic area. The soil conditioner for field crops uses the lava powder 95% or more of which has a particle size of less than 1.0 &mu；m. The soil conditioning method comprises mixing the soil conditioner for field crops in an amount of 13-20% by weight ratio based on a fertilizer and scattering the soil conditioner for field crops in an amount of 2-3 kg per are of soil.【課題】多量要素のミネラルのみならず、微量金属元素・超微量金属元素をもバランスよく含んだ肥料を散布し農産物や花きに摂取させることにより、農産物等がバランスよく土壌中の養分を吸収させて好適な育成をすることを図るとともに、病原菌やウイルスに対する殺菌作用を発揮させる農産物用土壌改良剤及びこれを用いた土壌改良方法の提供。【解決手段】農産物花きの栽培用の土壌に混入して用いる農産物用土壌改良剤であって、火山地帯で採取される熔岩石を粉砕して微粉末状にした熔岩粉末を主成分とする熔岩粉末を用いた農産物用土壌改良剤。前記熔岩粉末の９５％以上が粒径１．０μｍ未満である熔岩粉末を用いた農産物用土壌改良剤。肥料に対して重量比で１３％～２０％の前記農産物用土壌改良剤を混ぜ、土壌１ａ当りに前記農産物用土壌改良剤を２～３ｋｇを散布する土壌改良方法。【選択図】なし
