The Bulletin 41 



what experiments have shown to be the chief needs 



of the soils 



Experiments which have been conducted in this county on the Cecil 

 clay, in Iredell on Cecil clay loam, and in Gaston on Cecil sandy loam, 

 have shown for several years that nitrogen and phosphoric acid are the 

 constituents chiefly needed. Potash has not generally shown to be essen- 

 tial except for such crops as tobacco and potatoes, which are heavy users 

 of this constituent. 



Field tests on the Iredell loam type have shown unmistakably that 

 nitrogen is of the greatest importance for profitable returns to be secured 

 in growing crops on this soil as it occurs on an average in the county. 

 Potash has been found to give moderate returns when applied, but phos- 

 phoric acid has not shown to be at all profitable. As a matter of fact 

 the yields have not been increased by the use of acid phosphate which 

 carried phosphoric acid in the experiments. 



For cotton and corn, lime has not shown to be of pressing need. Espe- 

 cially is this so where these crops are grown without intervening cover 

 crops in the rotation. The soil is very high in this constituent, as shown 

 by analyses, and it would probably not be as essential to use lime on this 

 soil as on others like the Cecil soils which contain this constituent in 

 nuich smaller quantities. It is of interest to knoAv that the surface 6% 

 inches of the Iredell loam type of soil as it occurs in this county con- 

 tains enough phosphoric acid for about 137 100-bushel corn crops, pot- 

 ash for 381 crops, and only enough nitrogen for less than 11 crops of 

 this size, when the grain is removed and the stalks and leaves are plowed 

 in each year. 



It might be that when nitrogen is added in sufficient quantities to the 

 Iredell loam soil to produce maximum crops that applications of phos- 

 phoric acid would show an influence upon the yield. Notwithstanding 

 the high potash content, when it is selling at moderate prices, applica- 

 tions in moderate quantities has generally paid. This may be due to 

 an indirect effect rather than as a direct plant food. On this particular 

 type the application of potash-bearing materials like kainit, which con- 

 tain a high percentage of common salt, beneficial results may be due to 

 the salt contained rather than the potash contained. There is no ques- 

 tion but that the use of materials like kainit on soils of this character 

 reduce the amount of cotton rust. Experiments have shown that the use 

 of ordinary refuse meat salt at the rate of 300 to 500 pounds per acre 

 also will greatly lessen this trouble on soils of this character. 



Results on the Durham sandy loam type of soil have shown that 

 nitrogen, at the present time, is the chief need. Next in importance is 

 l)hosphoric acid and potash— potash being the least essential at the 

 present time on the crops like corn, cotton and small grains. When a 

 proper system of rotation of crops is practiced, lime will be found to be 

 essential on soils of this series. 



The Mecklenburg clay loam has been shown to be chiefly benefited by 

 applications of nitrogen. Phosphoric acid and potash do not seem to 



