FORMS OF PLANT FOOD 89 



done, as it will prove the best and most permanent 

 way of removing the alkali. Good surface drainage 

 should also be provided. Quite frequently a quarter 

 or a third of the total alkali in the soil will, in a dry 

 time, be found near and on the surface. In such cases, 

 and if the spots are small, a large amount of alkali 

 can be removed by scraping the surface and then cart- 

 ing the scrapings away and dumping them where 

 they can do no damage. 



When preparing an 'alkali' spot for a crop, deep 

 plowing should be practiced, so as to open up the soil 

 and remove the excess of alkaline matter from the 

 surface. Where manure, particularly horse manure, 

 can be obtained these spots should be manured very 

 heavily. The horse manure, when it decomposes, fur- 

 nishes acid products, which combine with the alkaline 

 salts. The manure also prevents rapid surface evapora- 

 tion. Oats are about the safest grain crop to seed on 

 an ' alkali ' spot because the oat plant is capable of thri- 

 ving in an alkaline soil where many other grain crops 

 fail. 



'Alkali' soils are usually deficient in available 

 nitrogen. The organism which carries on the work 

 of changing the humus nitrogen to available forms 

 cannot thrive in a strong alkaline solution. In main- 

 of these soils, as demonstrated in the laboratory, nitri- 

 fication cannot take place. After thorough drainage and 

 preparation for a crop, a few loads of good soil from a 



