SPRING WHEAT IN THE GREAT PLAINS AREA. 21 



are not exhibited at this station in either the good or the poor years. 

 The reason for this is to be found in the shallowness of the soil that 

 functions for the growth of the crop and for the storage of water that 

 can be recovered by the crop. This shallowness makes the crop 

 dependent for its growth upon seasonal rains that fall while the crop 

 is growing. It may be that this shallowness makes it possible to 

 realize quicker results from the cumulative effect of the use of manure 

 than would be realized on deeper soils. 



The relative merits of fall or spring plowing of either wheat or oat 

 stubble seem to be a matter of season. In no case does it make 

 a great difference, and on the average the difference has been neg- 

 ligible. It should be noted that the result from the one plat of wheat 

 on spring-plowed wheat land deserves but little consideration. On 

 account of its location and of continual spring plowing, it has accu- 

 mulated blowing soil until it is now built up several inches above its 

 original level, or the present level of other plats. 



Fall-plowed corn ground has apparently had an advantage over 

 corn ground, either spring plowed or disked, in preparation for wheat. 

 The results are determined from 1 plat of fall-plowed corn as against 

 12 plats of disked corn ground, which are distributed over the whole 

 field; the advantage, therefore, may be due to a particularly favor- 

 able location of the one plat. 



With the exception of the high yield of wheat in 1914 on peas used 

 as green manure, there is little choice between them and rye similarly 

 used. Both have been better than sweet clover plowed under. The 

 average yield of wheat following peas as green manure is exactly 

 the same as the average on summer tillage. 



Summer tillage has given an average yield of 17.9 bushels per acre 

 for the eight years. This is exceeded only by the yield on fall-plowed 

 corn ground. When this is compared with a similar average yield 

 of 17.7 bushels per acre from disked corn ground and 14.2 bushels 

 from wheat under all methods following small-grain crops, it is seen 

 that summer tillage is an unnecessary practice and one not to be 

 recommended for this section. This is brought out strongly by Table 

 IX, which shows the cost of production and the resultant profit or 

 loss from each method. Disked corn ground shows an average 

 8-year profit of $7.64 per acre, spring plowing $4.76, and fall plowing 

 $4.15, while the cost of summer tillage has reduced the profit to $1.03. 

 The average loss for the green manures has been $2.92 per acre. 



HETTINGER FIELD STATION. 



The soil at the Hettinger (N. Dak.) station is a heavy clay loam. 

 The seasons during which the work has been carried on have been 

 such that the results of soil-moisture study are not yet conclusive 

 in determining the proportion of water that can be stored in the soil 



