12 BULLETIN 268, U. S. DEPABTMENT OF AGBICULTUBE. 



Perhaps the first thing that impresses one in viewing the average 

 yields from all stations is the much greater adaptation of oats to 

 the northern than to the southern section of the Plains. There is an 

 almost constant decrease in yields from the northern, cooler, shorter 

 season stations to the southern, warmer, longer season ones. This 

 decrease is about the same for the heavier yielding as it is for the 

 lighter yielding methods. This decrease in yield from north to south 

 for all methods proves that the problem is one of adaptation of crops 

 to conditions rather than one that can be overcome by cultural prac- 

 tices. 



General averages for all of the stations mean little, as differences in 

 yield obtained at one station by the combination of factors that 

 determine yield may be balanced by differences in an opposite direc- 

 tion, as a result of a different combination of factors, at another 

 station. With the trifling exception of a fraction of a bushel at 

 Edgeley, spring plowing at all stations north of Hays has given higher 

 average yields than fall plowing. At Hays and the stations south 

 of it, fall plowing has been in about an equal degree better than spring 

 plowing. The greater number of stations represented in the northern 

 group makes the general average of averages show a small margin 

 in favor of spring plowing. The general average, however, is of little 

 value. It should not influence the practice at those stations whose 

 results show fall plowing to be for them the best practice. 



At all of the stations north of North Platte, disking has been pro- 

 ductive of higher average yields than either fall or spring plowing. 

 At North Platte, Dalhart, and Amarillo, it has been between the two 

 in yield. At Hays it has yielded the same as fall plowing and higher 

 than spring plowing. At Garden City it has yielded higher than 

 either. In the general average of all the stations reported it has 

 given a yield of 28.3 bushels per acre against 25.8 bushels for spring 

 plowing and 24.4 bushels for fall plowing. The great bulk of the 

 land disked is corn ground. 



With the exception of a sharp decrease from subsoiling at Akron 

 and a similar increase from listing at Garden City, the yields from 

 each of these practices have not departed far from the yields of 

 ordinary plowing. 



Green-manured land has been productive of higher yields than either 

 fall or spring plowed or disked corn ground at 9 of the 13 stations 

 from which results from it are reported. At Dickinson it has given 

 lower yields than disked corn ground. At Hettinger, Akron, and 

 Dalhart it has yielded less than any of the three methods mentioned. 

 At Amarillo fall-plowed land has exceeded it in yield. 



Summer tillage has produced higher yields than any of the methods 

 under trial at every station except Hettinger, where it has been ex- 

 ceeded only by disking corn ground. Averaged for all the stations, 



