34 GARDEN FARMING 



easy matter to determine the exact increase of area over this plot, 

 and it will surprise one to find how much more surface of the land 

 is actually exposed under these conditions than when it lies per- 

 fectly flat. In fact, it is possible almost to double the surface 

 exposure of land by throwing it into such narrow ridges. Since the 

 object of surface cultivation is the preservation of moisture, the 

 more nearly the area can be made to approach a perfect plane 

 the better. 



Artificial means of modifying the soil. Beside the mechanical 

 benefits derived from culture and drainage, quite as important 

 physical modifications can be produced by the addition of organic 

 matter to the soil through turning under heavy crops for green 

 manure. In those districts where cowpeas, crimson clover, vetch, 

 and clover can be used for this purpose the fertility of the soil can 

 be decidedly increased at the same time that its physical character 

 is modified by plowing under these crops. Under conditions which 

 permit the use of soil-improving crops only during the winter, 

 crimson clover or rye will serve a useful purpose ; while the rye 

 adds no fertility, it will prove of great value as a means of in- 

 creasing the humus content of the soil. 



The effect of turning under large quantities of green manure or 

 coarse stable manure is to modify the physical character of the soil. 

 Heavy soils become more friable, more easily worked, and some- 

 what darker in color. Light sandy soils are equally benefited by 

 such treatment. The addition of organic matter makes them more 

 retentive of moisture, less liable to erosion, and better able to hold 

 and withstand injurious effects of heavy applications of chemical 

 manures. In fact, decaying vegetable matter or humus seems to be 

 Nature's great restorative for all soil ills. In cases where continuous 

 heavy applications of high-grade chemical fertilizers have produced 

 injurious effects on crops, the plowing under of green crops and the 

 use of lime quickly restore the soil to its normal cropping capacity. 



Requirements for germination. There are three necessary fac- 

 tors for the germination of seed : heat, moisture, and air (or oxy- 

 gen). Given any two of these without the third, seeds will not 

 germinate. In any humid region these three factors are usually 

 present during the growing period. The one which is most apt to 

 be lacking is a proper amount of moisture, and this leads to the 



