356 THE SMALL GRAINS 



more permanent preventive measure; (3) plowing under 

 green manure crops, such as rye, sweet clover, cowpeas, 

 and field peas, which will have the same effect as barn- 

 yard manure; (4) listing narrow strips of land at right 

 angles to the direction of the wind ; (5) planting tall 

 growing sorghum crops in long fields at right angles to the 

 wind, and sowing the following crop without removing 

 the sorghum stalks and without plowing; (6) probably 

 the most effective and permanent prevention, but one 

 requiring time to develop, is the establishment of long, 

 narrow belts of trees running east and west, and growing 

 the annual crops between these belts. To be thoroughly 

 effective, the widths of tree belts and crop belts should 

 have at least the ratio of 1 : 7, while 1 : 4 is better. Con- 

 sidering both rapidity of growth and hardiness, the best 

 trees for this purpose are osage orange, cottonwood, green 

 ash, honey locust, and Russian mulberry, with always a 

 hedge of tamarisk on the south side of the belt. Where 

 there are no borers, black locust is excellent. 



384. Cereals as nurse crops are not uncommon occur- 

 rences in the Great Plains. They serve in this way for 

 alfalfa, clover, sweet clover, and grasses. Seeding down 

 wheat or barley with clover or grass seed or both is prac- 

 ticed both in this country and in Canada. Brome-grass 

 is seeded with wheat on disked corn land, and remains 

 two years after the wheat is removed. 



GROWING THE CROP 



385. Preparation of the land for fall seeding. In 

 preparation for rye or winter wheat in this area, it is 

 generally agreed that early plowing is important, unless 

 the crop is to follow summer tillage. The early plowing, 



