SOIL AND TILLAGE. 57 



of plant food you have to buy. In my mind you should seldom 

 buy it at all, except for strawberries, garden vegetables, and 

 potatoes. Phosphoric acid will not evaporate nor leach if top 

 dressed on the land, more than two or three inches deep in the 

 hardest rain. Potash will probably not go down under similar 

 washings more than eight inches before the natural filtering 

 power of the soil will arrest it. But a hard rain will entirely 

 wash all free nitrogen from the soil, as it locks hands with water 

 almost as readily as it does with air. To be sure capillary action 

 will bring some of it back within two days after even a hard rain, 

 and earth worms deposit rich nitrogenous humus on the surface 

 every night, brought from the subsoil below. But you can 

 manufacture your nitrogen in the soil by a superior method of 

 tilling. Numerous forms of bacteria which are present in fertile 

 soil when warm and moist, produce or set it free from day to 

 day just fast enough for plant uses. To stimulate these little 

 fellows you must till every few days and aerate the land. They 

 cannot work over-time without this encouragement. Just as the 

 pig goes into the pile of rank green manure and by turning and 

 returning it oxygenates it by exposure to the air and causes it to 

 turn black — just as your silver turns black, so does your soil and 

 humus when propertly aerated. In doing this the oxygen which 

 unites with the humus surrenders the nitrogen which was locked 

 up with it in the air. 



One word more and I am done. Look out that vour land is 

 ^'sweet." It often happens that land which you little suspect car- 

 ries an acid reaction, and these lands are, by the way, very hard 

 ones in which to maintain nitrogen. If, for instance, clover or 

 other nitrifying plants, especially other legumes do not grow, 

 your land is probably sour and should be treated with a dust of 

 "biting" lime. Fifty bushels per acre will sometimes reclaim 

 land so sour that it previously would not even sod over. Use the 

 best lime, and slack it by covering for a few days with several 

 inches of moist soil. It will come out a dry powder, as fine as 

 flour. You can spread it with a shovel, soil and all, and by har- 

 rowing thoroughly, sow at once with oats or grass, with no 

 danger of the seed being killed. Sometimes green manure will 

 sour land and it is safer to sow a green crop with a few bushels 

 of lime, ashes or gypsum just before turning it under. 



Another word of warning just here. Do not plow under green 

 stuflF so late that there is not sufficient heat left in the soil to 



