The Bulletin 37 



For Phosphoric Acid. — This constituent is generally low in the 

 Durham, Granville, Cecil, and Wehadkee series of soils of the county. 

 It is also low in the silt loam type of the Alamance series. The other 

 types are fairly well provided potentially with this constituent. 



With the farmer it is generally necessary, in order that his profits 

 may be greatest, for him to use the source of phosphoric acid that is 

 going to give him the highest net returns per acre. Taking everything 

 into consideration, the two commercial forms that will largely have to 

 be depended upon at the present time to supply phosphoric acid are 

 acid phosphate and basic slag. Of course, there will be added to the 

 soil a considerable amount of phosphoric acid when liberal amounts of 

 manure, cotton-seed meal, and soybean meal, and ground bone used 

 alone or in such materials as tankage and fish scrap, are added to the 

 soil. Where large amounts of organic matter are being turned back 

 into the soil in many cases it may be profitable to add finely ground 

 phosphate rock at the time the material is being turned. The organic 

 matter in rotting will tend to bring into available form some of the 

 phosphoric acid contained in this material. Again, a plan that in many 

 cases would appear to be practical would be to add this material to the 

 manure in the stable as the manure is being formed, using the finely 

 ground phosphate rock at the rate of 1 to 2 pounds per day broadcast 

 over the manure, making the applications twice per week. 



For Potash. — With soils of this county, as well as with Piedmont 

 soils generally, the least important of the main plant-food constituents 

 at the present time has been found to be potash. As a matter of fact, 

 from the standpoint of potential plant food it would appear, even from 

 this standpoint, that potash is of far less importance than is phosphoric 

 acid and nitrogen, i^one of the soils contain less than 0.23 per cent, 

 while the Congaree Silt Loam and the Georgeville Slate Loam contain 

 over 1.8 per cent of this constituent. Speaking generally, the soils of 

 the county contain enough potash in them for the growth of maximum 

 crops for a goodly number of years to come, but it is not usually present 

 apparently in large amounts in soluble form. It is generally with the 

 soils of this county, as with most other Piedmont counties, more of a 

 l>roblem of making the supply present available than of increasing it 

 by the addition of materials supplying this constituent; particularly is 

 this so with the nonleguminous crops. 



When the price of potash is as high as it is at the present time its 

 use will not usually pay with ordinary crops such as corn, cotton, and 

 small grains grown in the county. 



For Lime. — When the main crops of the county, like corn, cotton, 

 and small grains, are grown continuously on the land, as is frequently 

 done, without the turning in of leguminous crops or the addition of 

 organic matter in other Avays, lime will not usually be found to be of 

 primary necessity at the present time. However, when cover crops are 

 used, as they should be, on all of the soils, especially on soils low in 

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