504 



Journal of Agricultural Research 



Vol. VI, No. 13 



Table XII. — Dry matter and phosphorus content of plant products of cowpea'i from pot 

 cultures, with tire addition of Tennessee brown rock phosphate and dextrose; series 7 



<» The plants on pots s to 10, inclusive, were all dead by Aug. 9, 1913. 



b Five cowpea seeds were planted in each pot. These contained 3.92 tngm. of phosphorus. 



Rye, clover, and cowpeas failed to thrive wherever the smallest quan- 

 tity of dextrose was present. There is but little doubt that this destruc- 

 tive influence is due to the decomposition of dextrose. If this conclusion 

 be true, a liberal use of calcium carbonate should neutralize the acids 

 developed, and a normal growth of the plants should result. Series 8 

 (Table XIII) was designed for determining what influence calcium car- 

 bonate would have in stimulating plant growth by producing an alkaline 

 medium and to ascertain Avhether calcium served as a food. 



Table XIII. — Dry matter produced in spring rye by Tennessee brown rock phosphate with 

 the addition of dextrose and calcium carbonate — series 8 



a Pots s and 6 were leached and the leachings placed on pots 7 and 8. Pots 9 and 10 were leached and 

 the leachings placed on pots 11 and 12. Pots 13 and 14 received all plant food but phosphorus. Pots 21 

 and 22 received nothing. Pots 23 and 24 were leached and drainage water taken for analytical purposes. 



