192 STATE HORTICULTURAL SOCIETY. 



Where the largest amount of green manure is desired in the 

 shortest time, without reference to the hay crop, mammoth or sapling, 

 clover should be selected. If the land has not been too fully depleted 

 of its humus by long cultivation and cropping, and hay is desired as- 

 well as manure, the common red clover is preferable. In the southern 

 half of the State it is quite likely that the cow-pea would prove quicker 

 and more certain than either of the clovers named. At the Experiment 

 Station in Boone county this plant has done well, yielding this year 

 three tons of field-cured hay, cut before the pods opened. This crop 

 returned to the soil 117 pounds of nitrogen, 31 pounds of phosphoric 

 acid and 88 pounds of potash, disregarding the stubble and roots. This 

 plant food would have produced several maximum crops of apples, 

 peaches, grapes or pears, as will be shown a little later. 



In any section at all adapted to the cow-pea, crimson clover should 

 do well and will be of great value as a winter cover for the soil and for 

 furnishing a fair supply of rich, green manure early in the spring. 



The reason for selecting the clovers and cow-peas for green 

 manures will be apparent when we consider that they have the power 

 of gathering from the air at least a portion of the large quantity of 

 nitrogen they contain. No other agricultural plants have this power 

 so far as we know, and they are obliged to depend upon the soluble 

 supply of food already in the soil. If nitrogen exists there in soluble 

 forms in abundance there is little need of manures of any kind. But 

 with the burning out of the vegetable matter we have already learned 

 there is almost certain to be a depletion of the available nitrogen sup- 

 ply. Common red and sapling clovers have the power of drawing a 

 portion, at least, of their supply of manurial food from the subsoil, 

 where it has been leached by the percolation of rain water. Bringing,, 

 as we do, these valuable mineral elements to the surface in consider- 

 able quantities and storing them in their tops and fleshy roots, they 

 are, in a short time, in the best possible form to feed the fruit trees. 



Again it appears that these particular plants have a great power 

 of gathering and organizing into growth the desirable mineral ele- 

 ments, potash and phosphoric acid, than have most agricultural plants. 

 In other words, it appears from recent experiments that these plants 

 are able to use certain soil compounds of potash and phosphoric acid,, 

 which are not available to wheat, and possibly but slowly available to- 

 fruit trees. If this is true the clovers have the power to draw upon 

 supplies of these valuable elements of plant food that are not available^ 

 to other agricultural plants, except to a very limited degree. 



