TENTH ANNUAL YEAR BOOK -PART X 549 



range area is decreasing. There is a serious shortage of live stock in that 

 section, and this shortage must be met by raising more young stock on 

 the farms of the East. 



EFFECT OF LIVE STOCK ON SOIL FERTILITY. 



The effect of live stock on the fertility of the soil needs no demonstra- 

 tion. It is well known to every intelligent farmer. Up to the present 

 time, at least, no system of agriculture has been permanently profitable 

 without the use of dordestic animals as a means of maintaining the pro- 

 ductiveness of the soil. Whether such systems are possible remains to be 

 seen. It may be that the use of legumes and other crops producing hu- 

 mus, combined with the judicious use of commercial fertilizers, may serve 

 to maintain high yields, but the supply of commercial fertilizers is not un- 

 limited, and ultimately these soil amendments will have to be dispensed 

 with. 



EFFECT OF LEGUMES. 



In addition to increasing the number of domestic animals on Ameri- 

 can farms, our farmers must pay more attention to leguminous crops 

 and to other crops which provide a supply of humus for the soil. Le- 

 gumes, such as clover, peas, alfalfa, etc., are especially important because 

 of the fact that with the aid of certain soil bacteria they are able to draw 

 their supply of nitrogen from the air. Having thus an unlimited supply 

 of this valuable plant-food constituent, they become very rich in nitrogen. 

 The stubble and roots of a leguminous crop frequently leave in the soil 

 sufficient nitrogen for the need of the crop that follows. Recent investi- 

 gations by this Department in Kansas and Nebraska show that the aver- 

 age increase in the yield of corn grown after alfalfa, compared with corn 

 grown after nonleguminous crops, is 75 per cent. A good crop of clover 

 has a similar effect on the yield of crops which follow it. Instances are 

 known where the practice of sowing bur clover in cotton fields in the 

 fall of the year and turning it under in spring in time for another crop 

 of cotton has, in three years, doubled the yield of cotton. Crimson clover 

 sown in a similar manner between crops of corn has, in a few years, in- 

 creased the yield of corn 50 per cent or more. 



The reason these leguminous crops have such a marked effect on fer- 

 tility in many cases on depleted soils lies in the fact that nitrogen is not 

 a constituent of the soil proper, but only of the decaying plant and animal 

 matter in the soil. - "When soils are farmed for many years without any 

 attention to their fertility this organic matter is rotted out and the ni- 

 trogen disappears. Hence nitrogen is nearly always the first plant-food 

 constituent to become deficient in the soil. 



The fact has already been referred to that we export a large propor- 

 tion of our cotton-seed meal, oil meal, and other rich nitrogenous feeding 

 stuffs. In 1908 we exported linseed-oil meal to the amount of 696 million 

 pounds, cotton-seed meal 929 million pounds, and corn-oil cake 66 million 

 pounds. These materials are all exceedingly rich in nitrogen. They 

 should be kept at home, fed to live stock, and the manure returned to the 

 land. 



