短語詞組短語improve soil tilth 改良土壤耕性soil with good tilth 有良好耕性的土壤National Soil Tilth Laboratory 實(shí)驗(yàn)室suitable soil tilth 土壤適耕性tilth soil 適耕土壤tilth top soil 耕層;熟化土壤 返回 soil tilth