HORTICULTURE 41 



the features of intensive horticulture is to give the trees or plants 

 good care at the start and then to keep it up continuously. (Y. B. 

 1904.) 



Agricultural Soils Have Two Forms of Plant Food. (a) In 

 new fruit-growing districts, where the land has not yet been cropped 

 extensively, the soil is usually rich in plant food that is readily avail- 

 able for use. This is the soluble form. (6) Soils contain in addition 

 plant food in forms not readily available to the roots of crops. Many 

 soils consist almost wholly of this unavailable plant food. This is 

 especially true of those that have been improperly farmed for long 

 periods. This is the insoluble form of plant food. 



Each year a portion of the insoluble plant food in the soil is ren- 

 dered soluble, or at least is got into such condition that the roots of 

 plants can use it. Where this process fails to supply an amount suffi- 

 cient to produce a crop, and where there is no reserve of soluble food 

 left from previous years upon which the plant may draw, this lack 

 may be supplied by the addition of suitable fertilizers, either animal, 

 vegetable, or mineral. In sections of this country longest cultivated 

 lands of this character abound, and consequently the application of 

 fertilizers is a necessary if a full crop is to be grown. 



There are new soils already so rich in plant food that nothing is 

 gained by manuring them. In fact, fruit trees on such soils are often 

 injured by the use of too much fertilizer, which causes growth to con- 

 tinue until late in autumn. But such cases are comparatively rare. 

 Practically all of our fruit lands, particularly those in the older fruit- 

 growing sections, are greatly improved by the judicious application 

 of manures. (U. S. E. S. B. 178.) 



Red Soils Oxidize Organic Matter Readily. While red soils are 

 known to be good fruit soils, it should be remembered that they oxi- 

 dize or burn out their supply of humus or organic matter very rap- 

 idly. Because this organic matter is exposed to the air, just as it is in 

 the sandy soil, and is therefore quickly oxidized, therefore manure 

 applied to a red soil or a sandy soil will show greater results in the 

 first year or two than on a tight, close clay, but the benefits will not 

 be nearly so lasting. The same is true of a crop of green manure. 

 Such types of soils as these therefore become deficient in humus 

 much quicker than what we commonly term slower and tighter 

 clay lands. 



It is, furthermore, true in the case of the red soils that in the 

 change from a moist to a dry condition of the soil there are im- 

 portant chemical changes in the iron itself which greatly facilitate 

 the burning out of the organic matter. This is due to the fact that 

 the red oxide of iron in contact with organic matter and in the pres- 

 ence of moisture is reduced to a sub-oxide, giving off by this process a 

 portion of its oxygen to burn the organic matter present in the soil. 

 In the drying of the soil, the sub-oxide of iron is quickly raised to 

 the higher form of the red oxide, ready to give up again in the pres- 

 ence of moisture its oxygen to burn out the vegetable matter. This 

 process of oxidizing organic matter continues as the land alternates 

 between wet and dry conditions. It is of the utmost importance, 



