1854 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



whatever. The growing of peas and 

 vetches aids greatly in keeping up the fer- 

 tility of the soil, but will not add to the 

 humus supply of the soil like a clover sod, 

 unless the tops are plowed in. 



Where the system of farming does not 

 include the growing of a hiennial or per- 

 ennial crop, like clover and grasses, some 

 quick-growing crop must be plowed in oc- 

 casionally. Rye or vetches, sown in the 

 fall after an early crop is removed, will 

 be ready to plow under for a late spring 

 crop. In almost any system a humus-pro- 

 ducing crop may be sandwiched in some- 

 where occasionally. 



(2). By the use of barnyard manure. 

 This is preeminently the best means for 

 keeping soil in a high state of fertility. 

 In all countries and in all localities where 

 dairying has become well established and 

 where thorough tillage has accompanied 

 the use of the manure, high average 

 yields are secured, and nothing will op- 

 erate faster for the building up of West- 

 ern Washington soils than the develop- 

 ment of the dairy industry, accompanied 

 with careful saving and use of the ma- 

 nure produced. 



Excellent examples are scattered all 



over Western Washington, showing that 



conformity to the foregoing principles 



will bring the majority of our Western 



Washington soils into a very high state 



of fertility. Nearly all our soil contains 



stored plant food enough for a great many 



bumper crops. 



George Severai^ce, 



Superintendent Western Washington Experi- 

 ment Station, PuyaUup, Washington 



HEAT AlVD SOIL FERTILITY 



The Rothamsted experiments have re- 

 cently thrown great light on the earlier 

 known fact that heating the soil, thus ac- 

 complishing something approaching ster- 

 ilization, results in a heightening of the 

 "fertility" of the soil. The experiences 

 of Stone of Amherst and others show that 

 the general fact has come under observ- 

 ation- The experience that carbon bisulfid 

 used for killing the Phylloxera increases 

 the growth of the vines, even though the 



Phylloxera was not previously present, 

 and the practice of the ancients of "firing" 

 the soil, are other examples. 



The reason for this is that heating the 

 soils may improve their fertility. It ap- 

 pears that, in addition to the bacteria in 

 the soil which have to do with the prepa- 

 ration of those nitrogenous substances 

 which can be taken up by the plant, there 

 are numerous animal forms called proto- 

 zoa, similar to the white corpuscles or 

 phagocytes of the blood. As these destroy 

 bacteria which gain entrance to the body 

 through wounds, so the protozoan forms 

 in the soil devour and thus destroy the 

 bacteria which are so useful in the prep- 

 aration of materials for the plant. If, 

 therefore, there are many protozoa in the 

 soil this will be a poor soil, since the bac- 

 teria are destroyed. Heating may be ar- 

 ranged so as to destroy all the protozoa, 

 and, while the numbers of bacteria are 

 reduced, they may not be totally de- 

 stroyed. Thus, the bacteria remain to 

 start afresh the nitrifying processes, and 

 their recovery and multiplication is very 

 rapid. In this way the "fertility" of a 

 soil treated is very much increased. 



It will appear that the method of heat- 

 ing the soil by steam will be of great 

 practical importance, especially in green- 

 houses and hotbeds and cold frames in 

 which vegetables and seedlings are raised, 



EXTEKT OF SOIL EEOSIOIf IN THE 



UMTED STATES 



Investigations by the United States Geo- 

 logical Survey of the erosion of numerous 

 drainage basins of the United States show 

 that the surface of the country is being 

 removed at the average rate of about an 

 inch in 760 years. Though this amount 

 seems trivial when spread over the sur- 

 face of the country, it becomes stupen- 

 dous when considered as a total, or even 

 in separate drainage basins. Mississippi 

 river, for instance, carries annually to the 

 sea 136,400,000 tons of dissolved matter 

 and 340,500,000 tons of suspended matter, 

 and of this total Ohio river carries 83,- 

 350,000 tons and Missouri river contrib- 

 utes more than twice as much. Colorado 

 river, which has built up for itself a vast 



