I02 



pense with the need of purchasing nitrogen in commercial ferti- 

 lizers. This, therefore, is one of the strong features in the use of 

 cover crops, provided we use cover crops that will add nitrogen to 

 the soil. 



The deterioration of cultivated land which I mentioned a few 

 moments ago, is due more to the lessening of the supply of avail- 

 able plant food rather than to the lessening of the supply of the 

 total plant food. 



Now, there is a point which most of us are likely to overlook. 

 The soil of this portion of Pennsylvania contains, I should say, at 

 least 2% of potash. You see that you have a very great accumula- 

 tion of potash in these soils, and yet it often happens that the pro- 

 gressive fruit grower will use commercial fertilizers containing 

 potash, and by adding 50 or 60 or 100 lbs. of potash will often get 

 a return from this small amount of fertilizer. There are differ- 

 ences in the quality of the potash in commercial fertilizers and in 

 the soil, but if we found means for making that potash in the soil 

 available, is there any objection to our dispensing with the use of 

 potash in commercial fertilizers? None at all. So far as the soil 

 is concerned, the supply of potash is practically inexhaustible. 



There is no claim that could be made as to the possible deter- 

 ioration of the soil because of the removal of potash. 



When we come to study the methods of "Farmers of Forty 

 Centuries" that Prof. King refers to in his book, we are surprised 

 at the cheapness of human effort. Farmers in China will take the 

 soil off an acre of land to the depth of two or three inches, and 

 grow a rice crop on the sub-soil. They will then return the surface 

 •soil which they had meanwhile comforted and will grow something 

 else on it. 



In the addition of nitrogen and vegetable matter to the soil, 

 the two great functions of cover crops are before us, of adding and 

 transforming plant food, aside from the function of conserving 

 plant food in so far as the cover crop prevents leaching of soluble 

 plant food during the Fall or early Spring. I will refer presently 

 to the kind of cover crops we use and how they accomplish the pur- 

 poses that we are considering, but I want to point out, before I pass 

 on, that there are certain purposes in the use of cover crops in fruit 

 growing that are a disadvantage rather than an advantage in other 

 types of farming. 



In looking at the apples on the stage this morning my attention 

 was called to some spots on the apples which are supposed to be 

 due not to any fungous, but to the physical condition in the tissue 

 of the fruit itself caused by something in the soil on which that 

 fruit was produced. The statement was made by someone that 

 there was too much nitrogen in the soil. It is an old belief that 

 when too much nitrogen is present in the soil the tissues will be 

 more tender and the vegetation will be more rank and very much 

 more subject to the attack of fungous diseases, and furthermore, 

 that there may be a breaking down of the tissues. The fruit grow- 



