18 FOOD FOR PLANTS 



percentage of Nitrogen, and only in organic form, 

 such as cotton-seed or "tankage," it will be of great 

 advantage to use one hundred pounds per acre of 

 Nitrate of Soda in addition to it. No fertilizer is 

 really complete without Nitrate of Soda. 



It is now known that the Nitrogen in organic 

 matter of soil or manure is slowly converted into the 

 available form by a minute organism. This cannot 

 work if the soil is too cold, or too wet, or too dry, or 

 in a sour soil. As a general rule, soils must be kept 

 sweet and the other conditions necessary for the con- 

 version of the Nitrogen into the form are warm 

 weather and a moist soil in good physical condition. 



In the early spring the soil is too wet and too cold 

 for the change to take place. We must wait for warm 

 weather. But the gardener does not want to wait. 

 He makes his profits largely on his early crops. 

 Guided only by experience and tradition, he fills his 

 land with manure, and even then he gets only a mod- 

 erate crop the first year. He puts on seventy-five 

 tons more manure the next year, and gets a better 

 crop. And he may continue putting on manure till 

 the soil is as rich in Nitrogen as the manure itself, 

 and even then he must keep on manuring or he fails 

 to get a good early crop. Why? The Nitrogen of 

 the soil, or of roots of plants, or manure, is retained 

 in the soil in a comparatively inert condition. There 

 is little or no loss. But when it is slowly converted 

 into Nitrate during warm weather, the plants take it 

 up and grow rapidly. 



How, then, is the market gardener to get the 

 Nitrate absolutely necessary for the growth of his 



