140 BOARD OF AGRICULTURE. [Pub. Doc. 



Professor Brooks. This basic slag is a new thing among 

 the farming community, and we find that this material 

 contains a high percentage of lime, and also contains from 

 8 per cent to 9 per cent of free lime. It is being imported 

 by some large fertilizer manufacturers, and will be used in 

 the future more than in the past. 



Mr. Parmentee. I would like to ask in regard to po- 

 tatoes, being a large grower, and making this a money crop. 

 We have an elevation of something like 1,900 feet, where we 

 propose to rotate potatoes, oats, or barley and hay, with 

 nothing to supply the food but commercial fertilizers. Is it 

 possible to keep ujd indefinitely the fertility of that soil along 

 practical lines with commercial fertilizers ? What we have 

 been using is one that has 5 of nitrogen, 8 of phosphoric acid 

 and 11 of potash from sulphate. 



Dr. VooRHEES. I do not think there would be any ques- 

 tion but that you could continue it. After a while you will 

 have to use a good deal more fertilizer than now to get a crop, 

 because of the depleted condition due to the growing of 

 potatoes and growing two crops, either hay, oats, timothy or 

 grass. Therefore you are not getting into your soil any 

 organic matter at all, and after a while the physical condi- 

 tion will not be so good as it is now. You will have to use 

 a larger amount of commercial fertilizer. I would suggest 

 that you have a cover-croj) in between these, or substitute a 

 cover-crop, preferably leginne, for the barley; so that you 

 keep up your sup23ly of organic matter. That helps a whole 

 lot in the absorption and distribution of the fertilizer, and 

 will prevent any possible bad results that come from the 

 continuous application of large quantities of fertilizer. In 

 our State they will grow potatoes for three years, and some- 

 times even longer, but they have their fields in crimson 

 clover in the spring, and sometimes red clover; they have 

 their land covered all the time, and with a leguminous crop, 

 which helps to keep up the supply of vegetable matter. I do 

 not see any particular reason in your case why potato grow- 

 ing should not be continued by large ajoplications of com- 

 mercial fertilizer. After a while the conditions might be- 



