146 CHEMISTRY OF FARM PRACTICE 



plant. It also seems to promote a more economical use 

 of the soil moisture. 



105. The Use of Potash on Different Soils. The potash 

 content of soils is very variable, ranging from T V of 1 per 

 cent on very light sandy soils, to as much as 2 per cent on 

 very heavy clay soils. 



The muck soils are very deficient in potash. Truck crops 

 and practically all crops grown on light sandy and muck 

 soils are improved by applications of potash salts. This is 

 true to a very marked extent with cotton. On muck soils, 

 the yields of corn are largely increased by the use of potash 

 salts. In fertilizing general farm crops, unless there is some 

 special reason that makes it objectionable, the use of muriate 

 of potash is quite satisfactory and most economical. 



Heavy clay soils contain a sufficient supply of potash for 

 general farm crops, and, if these soils are properly farmed so 

 that the conditions for bringing stored up plant food into 

 availability are accentuated, there should be such an 

 abundant supply of potash that it will not become a limiting 

 factor of plant growth. In fact, field tests show that large 

 amounts of money are expended unnecessarily each year 

 for the application of potash to such soils. 



Table XIII shows the effect of the use of potash on grass 

 lands. The yield of hay is greatly increased and the growth 

 of leguminous plants stimulated while the percentage of 

 weeds is markedly decreased through the use of a com- 

 plete mineral manure as compared with results obtained with 

 a fertilizer not containing potash or with no fertilizer at all. 



106. Selection of the Source of Potash. The cheapest 

 form of potash for sale in the United States is the muriate 

 (KC1). This is manufactured by the purification of crude 

 salts, most of the impurities being removed. While muriate 

 of potash is a cheap and effective source for general farm 

 crops, the use of a potash salt containing chlorine injures 

 the burning qualities of tobacco, lowers the starch content 

 of Irish and sweet potatoes, and hinders the crystallization 



