8 BULLETIN 268, U. S. DEPARTMENT OF AGRICULTURE. 



Subsoiling, as compared with fall plowing similar wheat stubble 

 without subsoiling, has been of doubtful utility as a means of increas- 

 ing yields. As a means of overcoming drought it is without value. 

 At Judith Basin and Scottsbluff it has shown a small increase in 

 yield over a comparable plat fall plowed without subsoiling, but the 

 increase was hardly sufficient to pay the extra labor costs. The evi- 

 dence from eight stations, some of which have eight years' records, 

 indicates that working the soil to a greater depth than is reached by 

 the ordinary plow is not essential. This indication is strengthened 

 by data from other work not yet published on deep plowing and 

 dynamiting. 



Listing wheat stubble instead of plowing it in the fall has resulted 

 in a small increase in yield at seven of the eight stations where it has 

 been tried. At Amarillo it has increased the yields in the years of 

 heaviest wheat production. At the same station it shows a slight 

 loss in the average for all years when compared with a comparable 

 plat fall plowed. As it is a somewhat cheaper method of preparation 

 than fall plowing it has been a more profitable one. 



Except at Judith Basin and Akron, wheat after summer tillage 

 has given the highest average yields at each station of any method 

 under trial. At Akron the yield of wheat on summer-tilled land has 

 been exceeded by that on spring-plowed corn ground by 0.3 of a 

 bushel per acre. The average of spring plowing is, however, below 

 the average of summer tillage. The reason for the departure at 

 Judith Basin is doubtless that of the depth and type of soil at that 

 station. For the whole 14 stations under study the average increase 

 in yield over disked corn ground has been 3.1 bushels per acre. Sum- 

 mer tillage requires the use of the land for two years to produce a 

 crop and requires an extra amount of cultivation to keep it free from 

 weeds in the fallow year. It consequently has the highest acre cost 

 of any method under trial except its modification — -green manuring. 

 A study of the relative profits and losses from different methods, as 

 given in Table II, shows that the increase in cost of production by 

 summer tillage has been relatively greater than the increase in yields 

 resultant from it. It has not at any station been the most profitable 

 when a profit was realized, nor has it been the source of the least 

 loss where wheat has been raised at a loss. At six stations it shows 

 a profit, but a smaller one than was realized from some other method 

 or methods. At four other stations it has resulted in a loss, while 

 some other methods have resulted in profit. At the remaining four 

 stations its practice has increased the loss attending the use of less 

 expensive methods. 



Green manuring is the most expensive method under trial. It 

 resembles a fallow in that it requires the use of the land two years 

 to produce one crop, but it has the added expense of seed and seeding. 



