28 AGRICULTURE IN THE SEMIARID GREAT PLAINS. 



seven years. These crops were all produced on land that had been 

 thoroughly summer-tilled and during a period of seasons more favor- 

 able than the average. It must be remembered that each of these 

 crops required two years for its production. 



In the matter of summer tillage for the conservation of moisture there 

 is considerable variation in the practices of the best dry-land farmers. 

 The best method appears to be to double-disk the land in the summer 

 as soon as possible after the grain is cut (if a small-gram crop was 

 grown), and again in the spring as early as the ground can be worked, 

 and then disk or harrow as often as is necessary to keep down the 

 weeds and to keep the crust broken till about June; then plow as 

 deeply as the available horsepower will permit, disking or harrowing 

 each half-day's plowing before leaving the field, or, better, using a 

 revolving pulverizer attachment on the plow. After this the ground 

 must be double-disked, harrowed, or worked with some other surface 

 cultivator as often as is necessary to keep the crust broken, maintain 

 a good surface mulch, and keep the weeds down till time for seeding 

 wmter wheat. A field tilled in this way is shown in figure 3, while 

 the crop grown on an adjoining field similarly tilled the preceding 

 year is shown in figure 2. 



The depth of surface mulch required will vary somewhat with 

 different soils and other varying conditions, but will generally need 

 to be 3 or 4 inches. This should not be a dust mulch but a mulch of 

 granular soil or small clods. A dust mulch is not only less effective 

 in conserving moisture than a mulch of small clods but is a very 

 uncertain thing to hold in a region of high winds. A dust mulch of 

 3 or 4 inches might be blown off the entire field in a smgle day. In 

 maintaining the mulch it is best to vary the depth of cultivation so as 

 to prevent the formation of a crust below the mulch. 



Before time for seeding, that part of the soil between the surface 

 mulch and the bottom of the plowing should be well firmed in order 

 to reestablish connection between the furrow shce and the soil below, 

 enabling the water to rise by capillarity to within easy reach of the 

 young plants and form a firm seed bed, which is an absolute necessity 

 for the best development of the small grains and grasses. This con- 

 dition may be secured by subsurface packing immediately after the 

 plow, but tlie subsequent working will usually give the required 

 condition. When considerable rain falls between tlie time of ])lowing 

 and the time of seedmg this will serve to firm the lower part of the 

 furrow and connect it with the soil below. Packing will insure the 

 filhng of the air spaces left in the soil as it falls from the moldboard of 

 the plow and will bring the moist soil in contact witli whatever stubble 

 or trash may be turned under and hasten its decay — an important 

 point. Packing will show the greatest benefits on light soils i?i dry 



J 1.5 



