138 FIELD CROPi< 



if it is han'owed smooth in the fall. In the semiarid regions 

 where the soil must be thoroughly cultivated in one season 

 and enough moisture stored in it to grow a crop the following 

 year, the plan just given would not be advisable, for it is 

 necessary' to harrow after heavy rains in order to retain the 

 moisture which falls. 



To prepare fall-plowed land for wheat in the spring, thor- 

 ough disking and harrowing are necessary. Spring-plow^ed 

 land is prepared for spring wheat in the same manner as fall- 

 plowed land for winter wheat. 



176. Preparing Seed for Planting. Wheat grown in the 

 vicinity, graded to maximum weight and quality, and free 

 from foul seed, has been shown by numerous experiments to 

 be the best that is possible to obtain for the main crop. On 

 many farms, a great many weed seeds and seeds of grain of 

 inferior quality are sown with the seed wheat. It is not rea- 

 sonable to expect better grain in the harvested crop than is 

 sown. Wheat grown continuously in one community is 

 often said to run out, and frequently the practice of chang- 

 ing seed grain every few years is followed. This is not the 

 best practice, for it has been shown beyond any question of 

 doubt that if the home-grown grain is carefully graded each 

 year and the best used for seed, it will not run out, but may 

 be gradually improved. 



On the general farm, there is not sufficient time to permit 

 the careful breeding and selection of grain as practiced by 

 careful plant breeders; but it is entirely practical to select 

 a small proportion of the best grain by running a quantity 

 of it through a common fanning mill, and in this wa^^ to 

 select the heaviest and plumpest kernels. 



177. Fanning Mill Selection. Fanning mills separate 

 grain by size and shape of kernel, and by weight of kernel. 

 In some makes of mills one of these methods is employed, 

 and in others both are used. The mill which separates by 

 only one of these means cannot do as satisfactoiy work as 



