SOIL NITROGEN 



Table 1. — Arrangement op Plots and Subplots 

 Legume Nonlegume Legume Nonlegume 



The original plots, 5, 6, 7, 8, 9, and 10, are 8 rods long and 2 rods wide, and 

 contain Mo acre. 



The sections LW, NLW, LE, and NLE of each plot are 2 rods square and 

 contain Ko acre. 



The crops 2 chosen were annuals, with the exception of grasses and clovers. 

 Summer crops were preferred because soil organisms are more active in warm 

 soil. Seedings were planned for dates that would permit growth during June, 

 July, and August and harvesting at stages of growth before ripened seeds 

 could scatter. 



The crops on each subplot were sampled and weighed immediately after 

 being cut, except in 1932 when a sudden shower obliged several subplots to 

 lie for twenty-four hours. This part of the work has been performed by the 

 writer with few exceptions. Samples were taken at random from different 

 parts of a subplot while the crop lay flat, and were weighed when gathered. 

 They were allowed to dry under shelter until it was convenient to analyze 

 them. The air-dry samples were then weighed and run through a feed cutter. 

 Subsamples were taken by quartering and prepared for determinations of dry 

 matter and nitrogen. 3 



2 In planning the system of crops, important suggestions were received from Professor A. B. 

 Beaumont and Director S. B. Haskell. 



3 All determinations of dry matter and nitrogen have been made in the Feed Control Labora- 

 tory under the supervision of Mr. P. H. Smith, whose kindly cooperation is highly appreciated. 



