1848 



ENCYCLOI'KDIA OK I'UAC'TICAL HOUTH'Ul/PUHK 



froi> is cul off ami reuiovLHl from Uie land, 

 the gain in nitrogen to the soil is slight 

 if any. It is generally estimated that for 

 most common forage cro|)s, the dry matter 

 in the root system constitutes about one- 

 fifth, and the above-ground portion tour- 

 fifths of the total growth. By coniiiaring 

 this statement with that in the iirereding 

 Ijaragraph. it will be seen tluil, under or- 

 dinary conditions, the amount of nitrogen 

 returned to the soil by the decay of the 

 roots only of the crop would be just equal 

 to the proportion of the crop's total sup- 

 ply which originally came from the soil. 

 If, however, the tops, as pastura.ge, soiling 

 crop, or hay, are fed to live stock and the 

 manure therefrom returned to the land to 

 be plowed under, nearly ninety per cent of 

 the total nitrogen of the crop will be re- 

 stored to the soil. 



If the entire crop is plowed under, all 

 of the nitrogen which it contains is re- 



stored to the soil, and as the crop de- 

 cays, becomes available to succeeding 

 crops. 



(>ain of Nitrou'en per Acre and Market 

 Value 



The gain of nitrogen per acre to the 

 soil if any one of these crops be plowed 

 under as a green manure may be cal- 

 culated by multiplying the percentage of 

 nitrogen in the whole jilant by the weight 

 of dry matter produced on an acre. This 

 wei,ght of growth will, of course, vary ex- 

 tremely in different seasons, on different 

 soils, and with different cultivation. 

 Table V shows examples of possible gains 

 which may be made, computed from the 

 yields per acre as given. The present 

 market value of nitrogen in commercial 

 fertilizers as sold in this state is about 

 twenty cents per pound. The market 

 value of the gain in nitrogen per acre by 

 plowing under the average crop as shown 

 is indicated in the last column. 



TABLE V 

 Gains in Nitrogen by Plowiny Crops I luler 



It is probable that the yields assutiied 

 in this table are higher than coulil be ob- 

 tained in actual field practice. Certainly 

 they are larger than would be obtained in 

 the dryer sections of the state. They are 

 not larger, however, than may be secured 

 under irrigation, or in those parts of the 

 state where the annual rainfall is heavy. 

 Not all of the nitrogen shown as gain, in 

 the above table, would be net gain in 

 every instance. On soils rich in nitrogen, 

 the crop takes only a part of its nitrogen 

 from the air, securing a considerable pro- 

 portion from the soil itself. Probably, 

 the poorer the soil is in nitrogen, the 

 greater the proportionate gain in nitro- 

 gen from the air. The net gain is, there- 



fore, likely to be greatest in those soils 

 which are in greatest need of nitrogen. 



R. W, Thatcher, 

 Piiector Wash. I';xi)ei'inii'nl Station. 



A BALAX'EI) (lli:.>lMM, CO.MI'OriVD 

 l\ THE S(HI, 



We know what il nieans to have a bal- 

 anced ration of human food. No matter 

 how good an article of foofl may be, if the 

 individual is compelled to eat that and 

 nothing else he not only tires of it, but it 

 is impossible for him to maintain on that 

 food alone a good degree of health. Per- 

 haps the food that contains more of all 

 the nutritive substances than any other 

 is whole wheat or Irish potatoes, but 



