786 THE FRUIT INDUSTRY IN NEW YORK STATE 



The presence of humus in the soil has a very important bear- 

 ing upon its physical condition. When the supply of organic 

 matter becomes low, our clay soils are stiff and difficult to work, 

 and they puddle and bake easily. Those rich in humus have 

 better drainage, can be plowed earlier, remain in plowed con- 

 dition longer, and in every way are easier to handle. 



Plants utilize only the moisture which surrounds the soil par- 

 ticles. When the roots reach the level of the ground water, where 

 the air has been driven out, their activities cease. Unless the 

 soil be of such a nature as to be retentive of this moisture, plants 

 may suffer from drought, even in seasons of normal rainfall. 

 Humus is like a sponge in its power to retain moisture, and 

 its presence in the soil greatly increases the amount of water 

 available to the plant. 



Only in one way do cover crops add to the total amount of 

 any one plant food element in the soil, and that is through the 

 nitrogen-fixing activities of the bacteria which are usually found 

 on the roots of the legumes. When non-leguminous cover crops 

 are used, the available food supply may be increased, but not the 

 total amount of the food elements. 



The conservation of plant food is another valuable function 

 of cover crops. Every spring our rivers and creeks carry down 

 to the lowlands and the lake bottoms immense deposits of silt 

 which the rains have washed from the fields. These minute 

 particles of soil are the ones which are most readily acted 

 upon by the acid soil water, and hence their loss from our 

 fields is a serious loss of plant food. Nothing checks this soil 

 washing in the orchards so effectively as the mat of rootlets 

 supplied by a good cover crop. The breaking down of soil par- 

 ticles, with the resulting formation of soluble plant food, goes 

 on in the fall and spring when the fruit crops are in a dormant 

 condition. By using cover crops which remain alive through the 

 winter, much of this plant food is utilized by them and thus pre- 

 vented from washing away in the drainage water. This plant 

 food then becomes available to the fruit crops when the corn 

 crop decays. 



The intense cultivation given to orchards is a forcing process 

 which, if continued throughout the season, would result in a late 



