INDIANA HORTICULTURAL SOCIETY, " 271 



our crops and orchards as well. Potassium, phosphorus and nitrogen 

 are the only elements, say the chemists, that may be short of the require- 

 ments of the orchard. The potassum and phosphorus exist in the soil in 

 large quantities as compared with what any crop needs, yet small quan- 

 tities, as compared with the entire makeup of the soil. The surface soil 

 of an acre to the depth of twelve inches, where perfectly dry, weighs 

 about 5,000,000 pounds. These two elements vary from one-tenth per 

 cent, to one per cent, in the soil. Then we have in the first foot, at the 

 lowest rate, 5,000 pounds of each, and the second foot probably as rich, 

 and the third as good, and so on, and in some of our better soils many 

 times these figures. The phosphorus in the form of phosphoric acid is 

 several points ahead of the potash. These elements are not available as 

 plant food but in small quantities at any one season. 



Nitrogen exists in the form of nitrate throughout the soil for many 

 feet in depth, but as ammoniates, form as plant food mainly in the upper 

 portion of five to ten inches. These elements are needed in both tree 

 growth and fruit growth, yet in different proportion. 



The problem for the orchardist is to assist nature in rendering avail- 

 able sufficient amounts of these year after j^ear to meet the demands of 

 the orchard. 



What are the forces to be used to accomplish this work? Namely. 

 Sunlight and heat, air and water, freezing and thawing, cultivation, 

 vegetable growth, chemical changes produced by vegetable and mineral 

 additions, and work of animal life. The sunlight and heat renders avail- 

 able phosphoric acid and potash. The air, by means of that active agent 

 oxygen, disintegrates the particles of soil and renders them into plant 

 food. The water dissolves, forms solvent liquids and renders its share 

 of prepared food. Freezing and thawing take their turn at the same gi'eat 

 labor and contribute no small result. Cultivation assists these named 

 forces and in an auxiliary way renders its power. The growing vegeta- 

 tion, by its root growth attacks the particles of soil and renders them 

 available for a growing plant and for those that may come after, and may 

 gather valuable plant food from the air as well. The chemical changes 

 which vegetable mattex*, such as gi-een manure and farmyard manure 

 undergo in the ground, gi-eatly increases the decomposition of soil parti- 

 cles, and the mineral and animal additions in like manner act in the same 

 way to the common end. And last, but not least, the world of animal life 

 —insects, worms, and bacteria, all play their part well in improving the 

 soil by contributing their life and energy to the changing of mineral and 

 vegetable matter into plant food, and, in addition, gathering niti-ogen in 

 some unexplained way from the air that becomes plant food. 



The thoughtful orchardist adapts his work to these forces and gets 

 the largest results from these sources. In this connection it should be 

 remembered that the more favorable conditions for one force to operate, 

 with good results, may mean and often does mean less favorable circum- 



