82 FIELD CROPS FOR THE COTTON-BELT 

 TABLE 5. SHOWING PLANT-FOOD REMOVED BY COTTON 



The cotton plant requires much more nitrogen than 

 either phosphoric acid or potash. Of the total nitrogen re- 

 quired, approximately 98 per cent is in the stalks and seed 

 and only 2 per cent in the lint. Approximately 99 per cent 

 of the phosphoric acid and 95 per cent of the potash is in 

 the stalks and seed. When it is remembered that in ordi- 

 nary farm practice the stalks are returned to the soil and in 

 some cases the seed used as a fertilizer, or its equivalent in 

 cotton-seed meal purchased and returned to the soil, the 

 fact becomes clear that the cotton crop does not remove ex- 

 cessive amounts of plant-food as compared with other field 

 crops. The gradual decline in the organic content of the soil, 

 the leaching and erosion during the winter months, and 

 the poor physical condition of the soil, all of which result 

 from the continuous cultivation of cotton, are the primary 

 reasons why cotton soils become poor. 



90. Maintenance of fertility. The ideal practice 

 is to return to the soil, either directly or in farm manure, 

 all plant-food not sold from the farm. However, sound 

 fertilizer practice does not mean that the plant-food 

 constituents must be purchased and returned to the soil 

 in the proportions in which they are removed by crops. 

 Many clay soils contain large quantities of potash. Here 



