14 



IMPROVEMENT OF THE WHEAT CROP IN CALIFORNIA. 



soil to allow the planting of green-manure crops by December 1 , 

 though in some sections and in exceptional seasons the planting may 

 be necessarily later. It is not advisable, however, to sow later than 

 December 15, for unless the early spring rains are so delayed as to 

 facilitate late plowing the green-manure crop will not be of much 

 value. This crop should be turned under during early March before 

 the soil is too dry for deep plowing. In other words, in order to 

 give green-manure crops the maximum period of growth it is nec- 

 essary to sow as early as the ground can be worked in the fall and to 

 turn under as late as possible in the spring. 



The length of the growing period is regulated very largely by the 



Fig. 3. — Wheat growing on plat cm which Canadian field peas were grown and plowed under in 1908. (See 



figure 1, D.) 



length of the rainy season. The dry condition of the wheat fields 

 in the fall permits a plowing of only 4 to 5 inches in depth when 

 getting the stubble land in shape for the early planting of green- 

 manure crops. The stubble should be double-disked, where possi- 

 ble, immediately after the wheat crop is harvested. The disking 

 prepares the land to retain the moisture already present and to 

 receive the light precipitation coming during the fall months, thus 

 putting it in shape for an early shallow plowing and a good seed 

 bed. In the spring the land should be plowed deep in order to get 



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