195 



Paqe 4 



The question of "why" became fairly Important to the Nutrient 

 Management Task force. By examinini^ nitrate levels In tile water 

 under different forms of vegetation and cultivation, it became clear 

 that row crop agriculture has a very definite part of the 

 responsibility for the surface water nitrate problem, we learned 

 that Iowa's organic soils have an average of 3000 pounds of nitrogen 

 per acre tied up in organic matter. This nitrogen Is released as 

 microbial activity digests the organic matter, when Iowa was drained 

 and our vegetation changed from prairie grass to corn and soybeans, 

 we moved from a vegetation that consumed nitrogen seven to eight 

 months out of the year, to nitrogen use only 4 1\2 months of the 

 year. A logical question is If there is 3000 « of nitrogen in every 

 acre of Iowa soil, why should I want to apply another 100* before I 

 plant corn? The answer Is, that organic nitrogen is not available 

 for plant uptake. Some of that organic nitrogen is available every 

 year, but as of now researchers do not know how to predict how much 

 nitrogen will be available from the soil. 



The bottom line is, regardless of how good a 3ob I do managing 

 nitrogen Inputs, I can not guarantee any improvement In surface water 

 nitrogen levels. I have not said anything about potassium or 

 phosphate because the soils I work with hold these elements so 

 tightly, that they are not a pollutant. 



1 do not envy the responsibility of writing a Clean Water Act 

 that will be meaningful and still attainable. This would not be easy 

 In Iowa with Its different soil areas, but for the entire country to 

 include the problems of sand soils, of irrigation, and some of the 



