Know your soil 

 - US Department of Agriculture  Washington  1970 
 - 16p.  ill. 
<br/><br/><label>Nat. Bib. No.: </label>4025 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Agriculture
<br/><br/><label>Universal Decimal Class. No.: </label>631.4  / KNO