THE MOST IMPORTANT PURPOSE 109 



over the surface will certainly accomplish wonders in preventing 

 washing of the soil. 



Check Fall Growth. — The cover crop serves to check the 

 growth of the trees in the autumn and thus force them to ripen 

 up their wood for winter. This is often the most important func- 

 tion of the cover crop and is accomplished by its appropriating 

 water and plant food that would otherwise go to the trees. When 

 this purpose is of importance, as in sections with rather trying 

 winter climates, one should select a crop that will develop a rank 

 growth about the time that the trees ought to "sober down," 

 which is at least as early as the first of September. The date of 

 sowing the crop must of course be varied to suit its rapidity of 

 growth and the needs of the trees. If the owner is using buck- 

 wheat, which comes on with a rush, he can afford to delay sow- 

 ing much later than if he is using soybeans, which require a 

 considerable time to develop. Another very important point in 

 this connection is the question of whether the cover crop is hardy 

 or is killed by frost. If it is hardy, the date of seeding may 

 be considerably delayed, which is sometimes very desirable where 

 the trees are carrying a large crop of fruit. 



The cover crop adds humus to the soil, and where bam manure 

 is not to be had for the orchard, which is frequently the case 

 on special orchard farms, this purpose becomes an all-important 

 one. With both light and heavy soils it is particularly important 

 to keep up the supply of humus because they are both damaged 

 much more than intermediate types when the humus content runs 

 low. For these soils therefore one ought to select some large 

 growing crop and be careful to secure a good growth of it. 

 This latter is by no means as simple a matter as it might seem. 

 Weather conditions, soil conditions, the shade of the trees, and 

 various other factors come in to influence the result, and unless 

 the owner looks out for all the details he is likely to find his 

 orchard going into the winter with very little material to either 

 prevent wash or make humus. A plan which has been tried with 

 considerable satisfaction, on lands where it was difficult to get a 

 good growth of cover crop, is to reserve a part or even all of the 

 fertilizer that is intended for that block and apply it just previous 

 to sowing the cover crop. A little nitrogen in particular applied 



