352 MISCELLANEOUS FARM SUBJECTS 



have to decide whether these can most profitably go back into for- 

 ests, or, if taken up for agricultural holdings, what crops and what 

 methods of cultivation can be adapted to them? Some of these 

 lands it is known are strong agricultural soils, while others are 

 known to offer such difficulties to the production of economic crops 

 as to make the problem of their adaptation extremely difficult. 

 (Bu. of Soils B. 55; Y. B. 1906; Univ. 111. B. 124; Y. B. 1909.) 



RELATION OF THE SOIL TO PLANT NUITRITION. 



The old idea of soil fertility was that plants could not avail 

 themselves of the potash or phosphoric acid until the rock particles, 

 the minerals, were decomposed and their constituents made avail- 

 able to the plants. It is, however, merely a question of the solu- 

 bility of the mineral particles themselves. One can take the min- 

 erals obtained from the soil, or minerals from museum collections, 

 and by grinding them up and adding water and a little nitrate 

 can get a soil solution which is comparable with the soil solutions 

 of our fields, and can grow as good plants in the extract from the 

 cabinet specimens so prepared as in the extract of the soils itself. 

 The plants can avail themselves of the potash, phosphoric acid, and 

 lime which are dissolved directly from these mineral particles. Not 

 only so, but if we take these minerals and wash them by repeated 

 teachings, we will continuously get quantities of potash, phos- 

 phoric acid, and lime dissolved in the water. After leaching re- 

 peatedly and frequently during the day, if we leave the particles 

 in contact with a fresh portion of water overnight, in the morning 

 the concentration of the solution will be about the same as it was 

 the morning before, so immediate and rapid is the recovery and so 

 adequate and ready is the supply of these mineral nutrients. 



We have in our soil moisture a solution which carries suffici- 

 ent mineral nutrients for the support of the plants. It is capable 

 of maintaining its concentration by re-solution from the minerals 

 to supply any portion of these plant food constituents that may be 

 withdrawn. Under ordinary conditions of drainage and of rain- 

 fall the concentration can not get too large, nor can it for any con- 

 siderable period get too small for the need of plants. In other 

 words, we have in the soil a most efficient system for supplying 

 the nutrient food for plants. 



This, therefore, is the nature of the soil and of the soil mois- 

 ture. It is a great nutrient medium for the support of plants, spread 

 out over the surface of the earth, and as all soils, with but possibly 

 few and unimportant exceptions, are made up of a great number 

 of minerals, it follows that the concentration and the composition 

 of the soil moisture in our different types of soil varies but little. 

 One might expect to find that in such extreme cases as the heavy 

 clay soils of the limestone Valley of Virginia, the black prairie 

 soil of Texas, or the Norfolk sand of the Coastal Plains there would 

 be marked differences in the composition of the soil moisture, but 

 investigations show that the moisture has about the same composi- 

 tion in each of these widely different types of soils, or at least 



