Soil fertility :  slide-tape instructional unit SR-4/  
The International Rice Research Institute 
 - Los banos, Laguna :  The International Rice Research Institute,  [Date of publication not identified] 
 - [18] pages :  illustrations ;  22 cm 
 - Rice production training series .
 - Rice production training series .
<br/><br/><label>Subjects--Topical Terms: </label><br/>Soil fertility<br/>Soil science
<br/><br/><label>LC Class. No.: </label>S591 S65