122 MISSOURI AGRICULTURAL REPORT. 



that the stockman and dairyman may have the grain which they feed in 

 addition to that which they raise. 



Among the first essentials to successful grain farming so far as 

 present knowledge goes, is the adoption of, and the close adherence to 

 a rotation adapted to the local conditions. The injurious effects of con- 

 tinous grain cropping are known not only to those who have followed 

 the development of agriculture through history but even to those who 

 •have seen the development of the corn belt in the last quarter of a cen- 

 tury. The rotation not only effects the physical condition of the soil, but 

 it furnishes a very practical means of combating insect ravages and 

 fungous diseases which prey upon any particular crop, and it may also 

 bring about favorable changes in the plant food content, in fact by the 

 use of a legume, as clover ar cowpeas, in the rotation, the supply of one 

 element of plant food, nitrogen, may be actually increased. 



There are necessary for the development and growth of every plant 

 ■ten of these elements of plant food ; some of these are in the air about 

 the plant, others are in the water, and still others are in the soil in such 

 large proportions that they do not limit the yield. There are three of 

 •the ten, however, which, on account of their limited supply in some soils 

 •and because they are removed in comparatively large quantities by all 

 crops, must be considered in connection with the crop producing power 

 of soils. These three are nitrogen, phosphorus, and potassium. In 

 •the atmosphere over every acre of land there is, if valued at fifteen 

 cents a pound, more than $10,000,000 worth of nitrogen. Most plant 

 life, however, cannot draw upon this inexaustable supply, but must de- 

 pend upon the liberation of nitrogen from the organic matter of the 

 soil. Nature has, however, given us one class of plants called the le- 

 gumes (to which class the clovers, vetches, alfalfa, peas, beans, the locust 

 tree, and several others belong), which, through the bacteria living in the 

 nodules upon their roots, can obtain nitrogen from the air. 



Those scientists, who some years ago proved beyond a doubt that 

 through legumes we can draw at will upon the inexhaustable supply of 

 nitrogen in the air, settled forever the nitrogen question so far as exten- 

 sive farming is concerned. Nitrogen on the market in the form of dried 

 blood, sodium nitrate, and other commercial fertilizers, costs fifteen cents 

 per pound, and there is one pound of it in every bushel of corn, and more 

 than a pound in every bushel of wheat. This means that the corn 

 grower and the wheat grower cannot afford to buy nitrogen, but must 

 depend upon a rotation in which occurs one or more of these legume crops 

 as full crops and as catch crops to be plowed under in order to maintain 

 the supply of nitrogen in the soil. To be assured of success in the growing 



