MANURE, YIELD AND SOLUBLE SALTS IN SOILS. 



10 



Mean increase in yields on 8 soil types due to differences in fertili- 

 zation with stable manure. 



(1) It appears from this table, as an average of all trials on 

 8 soils with corn and potatoes, that 1 ton of stable manure has 

 increased the yield at the mean rate of 62.283 Ibs. of dry mat- 

 ter in the form of grain and tubers alone. If the dry matter 

 in stalks and vines were included, the increase would not be far 

 from 100 Ibs. per ton. 



(2) The relative increase of dry matter, in the form of 

 grain and tubers, has been in the ratio of 59.56 for corn to 

 65.01 Ibs. for potatoes, taking the dry matter in the potatoes at 

 21.1 per cent, and 60 pounds per bushel as the weight for pota- 

 toes and 56 pounds per bushel for corn. 



(3) The average increase on the four 1 poorer soils, as com- 

 pared with that on the four stronger soils, has been as 58.417 

 to 66.149, the increase being greater on the stronger soils; but, 

 as has been pointed out, the true relation is probably the re- 

 verse, as it was with the corn. The "tip-burn" on the potatoes 

 grown on the four poorer soils did have a relatively greater 

 effect in reducing the yield there. 



(4) The mean increase in dry matter per ton of manure as 

 grain and tubers alone, where 5' tons were applied, was at the 



