Table 5. — Estimated construction cost per acre for benches 

 of varying widths, by slope 1 



Table 6. — Estimated alfalfa production per 100 acres 

 on level benches, by slope and width of bench 



Percent- 

 age of 



Cost 



when width of bench 



in feet is — 













slope 2 



W 



28 



42 



56 



70 





Dollars 



Dollars 



Dollars 



Dollars 



Dollars 



1 



3 25.00 



3 25.00 



25.92 



34.56 



40.00 



2 



3 25.00 



34.56 



48.00 



61.44 



77.04 



3 



25.92 



48.00 



69.36 



88.55 



105.82 



4 



34.56 



61.44 



88.55 



112.86 



141.02 



5 



40.00 



76.80 



105.82 



141.02 



176.44 



6 



48.00 



88.55 



126.94 



169.18 



211.64 



7 



56.00 



103.27 



148.06 



197.56 



246.84 



8 



61.44 



112.86 



169.18 



225.72 



282.04 



9 



69.12 



126.94 



190.52 



253.88 



317.46 



10 



76.80 



141.02 



211.64 





352.66 



1 Calculated from quantities of earth moved (table 3) at 

 the following rates per cubic yard (see text): 



Cubic yards 



Cost per 



per acre 



:ubic yara 



Under 150 



$0.27 



150 - 249 



.25 



250 - 349 



.24 



350 - 449 





450 and over 



.22 



The slope is assumed to be uniform throughout the field. 

 A lower limit of $25 per acre was assumed. 



Percent- 



Production per 100 acres 



when width of 



age of 





bench 



in feet is — 





slope 1 



14 



28 



42 



56 



70 





Tons 



Tons 



Tons 



Tons 



Tons 





Benches without contributing area: 



1 



219 



238 



245 



248 



251 



2 



215 



233 



240 



244 



246 



3 



211 



229 



236 



239 



241 



4 



207 



225 



231 



235 



237 



5 



204 



221 



227 



230 



232 



6 



200 



217 



223 



226 



228 



7 



197 



213 



219 



222 



224 



8 



193 



209 



215 



218 



220 



9 



190 



205 



211 



214 



215 



10 



187 



202 



207 



210 



212 





Benches with 1:1 contributing area: 



1 



181 



189 



192 



194 



195 



2 



180 



188 



190 



192 



193 



3 



178 



186 



189 



190 



191 



4 



176 



184 



187 



188 



189 



5 



175 



182 



185 



187 



187 



6 



173 



181 



183 



185 



186 



7 



172 



179 



182 



183 



184 



8 



170 



177 



180 



181 



182 



9 



169 



176 



178 



180 



180 



10 



167 



174 



177 



178 



179 



The slope is assumed to be uniform throughout the 

 field. 



Table 7. — Cost and returns from alfalfa on natural slopes and level benches, 

 per 100-acre field on 4-percent slope 



Land use: 



Roads and fences 



Dikes 



Turning and odd-shaped areas 



Contributing area and natural slope- 

 Benches 



Total 



Alfalfa production: 



Turning and odd-shaped areas 



Contributing area and natural slope- 

 Benches 



Total 



Gross returns 



Total investment, bench construction — 



Annual costs: 



Amortization of bench construction — 



Land and machinery cost 



Maintenance of stand (reseeding) 



Harvest cost 



Labor 



Added cost for small fields, etc. 



Total annual cost 



Net returns (gross returns minus total 

 annual costs) 



Average yield per acre (net) 



Gain in yield per acre 



Increase in cost per acre 



Gain in gross returns per acre 



Gain in net returns per acre 



Acres 

 do. 

 do. 

 do. 

 do. 

 do. 



Tons 

 do. 

 do. 

 do. 



do. 



do. 

 do. 

 do. 

 do. 

 io. 

 c. 



do. 



Tons 



do. 



Dollars 



do. 



do. 



Natural 

 slope 



42- foot bench 



With 

 contrib- 

 uting 

 area 



3.0 

 

 

 97.0 

 







116.4 







1,979 

 





 335 

 194 

 388 

 582 







2,099 



-120 

 1.16 



3.0 



5.2 

 43.0 

 43.0 



100.0 100.0 



6.2 



51.6 



129.0 



186.8 



3,176 

 4,321 



348 

 935 

 182 



- : -- 

 719 

 30 



468 



1.87 



.71 



6.09 



11.97 



5.88 



Without 

 contrib- 

 uting 

 area 



3.0 

 11.0 



6.0 

 

 80.0 



100.0 



7.2 

 

 224.0 



231.2 



3,930 

 8,058 



649 

 935 

 172 

 584 

 836 

 55 



3,231 



699 



2.31 



1.15 



11.32 



19.51 



8.19 



Table 8. — Net returns per 100 acres from alfalfa on 

 level benches of varying widths and slopes 



Percent- 

 age of 

 slope 



Net returns when width of 

 bench in feet is — 



14 



28 



42 



56 



70 





Dollars 



Dollars 



Dollars 



Dollars 



Dollars 





Bene! 



les without contributing areas 



1 



948 



1,211 



1,300 



1,287 



1,276 



2 



906 



1,091 



1,088 



1,040 



953 



3 



861 



947 



884 



792 



692 



4 



757 



809 



699 



570 



392 



5 



680 



656 



531 



325 



92 



6 



581 



529 



339 



80 



-205 



7 



490 



385 



147 



-163 



'-492 



8 



418 



279 



-40 



-400 



-781 



9 



327 



143 



-226 



-634 



-1,067 



10 



241 



9 



-413 



-866 



-1,344 





Benches with 



1:1 contributing area 



1 



613 



728 



769 



762 



755 



2 



594 



673 



664 



636 



590 



3 



576 



602 



561 



513 



461 



4 



521 



528 



468 



398 



304 



5 



482 



449 



380 



270 



143 



6 



430 



383 



278 



138 



-15 



7 



382 



308 



173 



6 



-175 



8 



345 



249 



71 



-127 



-333 



9 



295 



174 



-35 



-260 



-495 



i: 



248 



100 



-140 



-391 



-659 



20 



