DRY FARMING CONGRESS. 



127 



cluctiveness may be due in part to an improvement of tillage method-., 

 but there are indications which should not be overlooked, that some of 

 these fields are actually more fertile than they were at first. In anv 

 event, it seems true that the productiveness of these lands has been 

 maintained to a surprisingly high degree. In the great wheat belt of 

 the vallej^ of the Red River of the North, it is a matter of common 

 knowledge that after 12 or 15 consecutive crops of wheat have been 

 grown on the land, it is no longer profitable to grow this crop except in 

 a rotation. 



In the Cache Valley, however, indications are that the equivalent 

 conditions have not yet been reached. If this be true, it is important to 

 dis<:over the causes involved and to determine if the tillage methods 

 used are largely responsible for the present condition, and, if so, what 

 features are the most important and need greater emphasis. In the first 

 place, it must be kept in mind that the soils which have given the best 

 results under this system of tillage have been those sufficiently heavy to 

 retain without leaching all of the annual rainfall. As a result, all of the 

 soluble mineral matter, the product of centuries of weathering to which 

 the soil has been subjected, is held in the surface layers and is available 

 for the use of the plants. Furthermore, the methods of tillage followed 

 give conditions that enormously accelerate this weathering process, so 

 that so far as the mineral salts are concerned, the indications are that 

 summer fallowing and alternate year cropping can be depended upon to 

 keep up the supply of mineral plant food. It is necessary, however, to 

 provide for a continuous supply of nitrogen in soil being continuously 

 cropped with grain. Grain crops require a considerable nitrogen supply, 

 and they require that it be in an immediately available form and at a 

 very definite period in the life of the plant. The available nitrogen 

 of the soil is drawn partly from the organic matter, which contains 

 nitrogenous compunds, and partly from the air by micro-organisms capa- 

 ble of utilizing nitrogen gas. Since these organisms must have organic 

 matter of some sort to live on, it becomes doubly important to provide 

 a continued supply of organic matter in soils being continually cropped. 

 By a fortunate coincidence, this result has been achieved probably with- 

 out conscious design. It has been the custom in farming the dry land 

 of this region to use headers instead of binders in harvesting grain. As 

 a result, a large amount of loose straw is annually plowed under, and 

 the amount of organic matter in the soil is probably increased at a more 

 rapid rate than it was under virgin conditions. If this custom is, as 

 it now appears to be, an important factor in maintaining the productive- 

 ness of these dry farms, it should most certainly be preserved. It would 

 be a misfortune, indeed, if this continued supply of organic matter should 

 be reduced, which would be the case, for instance, if it became the custom 

 to burn over these wheat fields after harvest instead of plowing under 

 the straw, or if the straw should be cut close to the ground and hauled 

 away and not returned to the land in the form of manure. 



