00309nam a2200109Ia 450000500170000000800410001708200150005810000200007324500600009326000380015330000080019120260225051121.0260224s9999||||xx |||||||||||||| ||und||  a631.51 LOG  aTerry J. Logan  0aEffects of conservation tillage on groundwater quality   aUSA: Lewiss Pblishing Inc. c1987  a292