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TOTAL WATER AVAILABLE - INCHES 



Figure 6.— Relationship of alfalfa production and value to total water available. 



3 inches of water in addition to the water nor- 

 mally available on a nonbenched slope. As 

 mentioned earlier, benches located favorably 

 in relation to wind direction averaged about 

 7 inches more soil water in the spring than 

 a nonbenched slope. 



Other Crops 



So far in this analysis, alfalfa has been 

 the only crop considered. A few rough cal- 

 culations, plus some careful reasoning, sug- 

 gest that benches might be profitable for other 

 crops, particularly grass, and to a lesser 

 extent for wheat. No yield increases for corn 

 have been demonstrated in the experimental 

 work. 



Grass 



The increase in grass production was 

 less than for alfalfa, but if grazed, costs 

 would be reduced considerably. There is, how- 

 ever, the added cost of nitrogen fertilizer, 

 which is necessary for most efficient grass 

 production. Investment cost would be less 

 because narrow benches could be used through- 

 out, and there would be no harvesting costs. 

 There is a question, however, as to whether 

 animals grazing on the benches might make 

 paths over the dikes and eventually break them 



down at irregular intervals. A new experiment 

 has been set up to test the use of benches on 

 pastureland, and to determine whether mainte- 

 nance problems are likely to develop. 



Wheat 



With wheat, the maximum gain in produc- 

 tion from benches was 6 bushels per acre for 

 the benched area. When the reduction in acre- 

 age for dikes is taken into account, the gain in 

 yield is reduced substantially, even on the 

 gentlest slopes. Large machinery is more 

 commonly used for wheat than for alfalfa, 

 so it would be especially advantageous to con- 

 sider benches 56 or 70 feet wide. 



Results of preliminary calculations show 

 that for wheat the additional returns from the 

 construction of benches without contributing 

 areas exceeded the increased fixed costs on 

 1 -percent slopes but not on 2-percent slopes 

 (table 9). For benches on 1- and 2-percent 

 slopes with contributing areas, there were 

 increased net returns on all benches except 

 the 70-foot width with 2-percent slope. For 

 both types of benches, operating costs would 

 increase more for wheat than for alfalfa be- 

 cause cultural operations require more "times 

 over." With wheat, heavy tillage machinery 

 would be used on the benches, so maintenance 

 of the end dikes might be more costly. 



13 



