90 'FIELD CROPS FOR THE COTTON-BELT 



remain green and thrifty through periods of drouth. 

 Duggar suggests that potash probably reduces the amount 

 of water necessary to keep the plants in health.^ 



100. A fertilizer test for cotton. — Soils differ in their 

 requirements for fertilizers even when growing the same 

 crop for two important reasons. (1) The natural plant- 

 food content of soils is very variable. (2) The past treat- 

 ment of a soil is important in determining its fertilizer 

 needs. The continuous growth of one crop may exhaust 

 one plant-food element more rapidly than others. For the 

 above reasons the farmer should make tests of different 

 fertiUziag mixtures with the view of determining those 

 most profitable for his particular soil. The soil on which 

 this test is conducted should be level, of uniform pro- 

 ductiveness, and representative of the soU type upon 

 which the general crop of cotton is to be grown. A con- 

 venient and satisfactory size of plot for each fertilizer 

 treatment is one-tenth of an acre. Eight rows, 136 feet 

 long and 4 feet apart, represent an area of approximately 

 one-tenth acre. In order that the adjacent conditions 

 of all plots be similar, the various plots should be sep- 

 arated from each other by an unfertilized row of cotton, 

 known as the "guard row." To one making this test 

 the following treatment of the various plots is recom- 

 mended, it being assumed that the plots are of the size 

 recommended above: 



Plot 2 1. No fertilizer. 



Plot 2. 20 pounds of cotton-seed meal. 



Plot 3. 20 pounds of 14 per cent acid phosphate. 



Plot 4. 8 pounds of kainit. 



1 J. F. Duggar, "Southern Field Crops,'' p. 333. 



2 The term "plot" in this outline has reference to 8 rows, 136 feet 

 long and 4 feet apart. 



