HOW FARMERS CAN CONDUCT FIELD TESTS 365 



easy to fertilize a strip through the center of a field, or to leave 

 an unfertilized area for comparison. When fertilizers are used in 

 the drill for corn, for example, a few rows could be left unfertil- 

 ized (Figs. 133 and 137). 



Sometimes the problem is to determine the proper combina- 

 tion of fertilizers or which are the best to use. It then becomes 

 necessary to make a more elaborate test. Figure 225 represents a 



Muriate of potash, 200 I bs. per acre /\ 



Muriate of potash, 200 Ibs. per acre D 



Acid phosphate, 400 Ibs. per acre 



No treatment (check) C 



Muriate of potash, 200 Ibs. per acre 

 Rock phosphate, 800 Ibs. per acre 



Manure, 25 tons per acre 



FIG. 231. Diagram of a manure and fertilizer test made on a marsh soil. (See Figs. 

 132, 232, and 233.) 



test made on a marsh area in Wisconsin. Four different treat- 

 ments were compared. Each strip represents one-quarter of an 

 acre. Figure 226 shows the results secured on plots A and B. 

 Figures 232 and 233 combined, compare the results of B with no 

 treatment C. Figure 233 shows the results on plots C and D; 

 and Figure 132 shows the results on D and E. 



Similar tests may be made on sands and on other upland soils. 

 When the soils are acid, one-half of each fertilized plot or a portion 

 of each end, should be limed, so that results may be secured both 

 with and without lime. 



