No. 6. DEPARTMENT OF AGRICULTURE. 483 



Sand, or Winter Vetch. 



This vetch is an annual, and is a native of western Asia. It 

 has been recently grown wih success in the middle, eastern and 

 southern States. It is a trailing plant, thus making it ddflficult 

 to harvest for forage, unless seeded with some small grain, as wheat, 

 oats or rye, to serve as a support. It may be i)lanted either in spring 

 or fall, at the rate of about one and one-half to two bushels per acre. 

 It grows much better upon light, poor soils than cow peas or soy 

 beans, and for such conditions is much superior as a green manure 

 crop. The cost of seed thus far has practically prohibited its use, 

 except in cases where small areas are grown. 



Soil Inoculation. 



The superior advantages of the leguminous crops as green ma- 

 nures, are due in large part to the fact, as already pointed out, 

 that they are capable of obtaining their nitrogen in part, at least, 

 from the air, a source inaccessible to the other class of plants. It 

 must be remembered, however, that in order that this function may 

 be exercised it is necessary that there shall be present in the soil 

 certain organisms which attach themselves to the roots of the 

 plants; their presence in the soil is indicated by the formation of 

 tubercles or nodules on the roots, which range from a pin-head to 

 a pea in size. Where these nodules are not present on the roots it 

 is an indication that the proper organisms are not present and that 

 the legumes, in common with other plants, must derive their nitro- 

 gen from the soil, and thus from the standpoint of accumulation 

 of nitrogen they are, under these conditions, no more useful than 

 the cereal crops. 



Methods of Inoculation. 



In view of these facts it becomes necessary in order to obtain 

 the full benefit from the growth of the leguminous crops, to see to 

 it that the proper organisms are present in the soil. This may be 

 readily accomplished by inoculation, or introducing the specific or- 

 ganism into the soil. That is, soils in which these ofganisms are 

 not present may be supplied with them by using a portion of the 

 soil where they are present to introduce them. Experiments that 

 have been conducted show that a small quantity only is necessary 

 to accomplish the purpose, for example, a peck or one-half bushel 

 of soil taken from different parts of a field which contains the 

 organisms will, if sown broadcast over an acre which does not con- 

 tain them, introduce the organisms, which multiply and dis- 

 tribute rapidly, and be prepared to do their work for the crop. Once 



