320 Missouri Agricultural Report. 



Field treatment of the corn crop has to do with the feeding of 

 the plant, inasmuch as the whole process up to the time of the ma- 

 turing of the crop is simply a series of operations which enable 

 the latent force that lies within the seed grain to undergo its devel- 

 opment in extracting from the soil and the air the necessary plant 

 foods at its command. 



Two things are necessary to enable the plant to perform its 

 function of development, viz., that the mineral plant foods be present 

 in the soil, and that the soil also contain enough humus or decom- 

 posed organic matter to absorb enough moisture to hold the plant 

 food in soluble form to be taken up by the fine rootlets of the plant. 

 Also a soil devoid of humus would contain little, if any, nitrogen. 



The field treatment of the crop must then necessarily include 

 the having present in the soil of the three exhaustible plant foods 

 marked in the commercial fertilizer catalogs : "nitrogen," "phos- 

 phoric acid," "potash" and the necessary amount of water to hold 

 them in solution. ; 



How is this to be accomplished? A virgin soil usually contains 

 the plant foods and the humus. In continuous cropping they must 

 be retained or replenished. Returning the farm manures to the 

 fields retains them largely, and keeps up the supply of humus very 

 well. 



Applications of commercial fertilizer replace in the soil the 

 plant foods without any appreciable amount of humus, and in case 

 humus is badly deficient, the conditions of moisture are so uneven 

 as to make the results far short of what could be secured under ideal 

 conditions of the soil. 



A double purpose is served in plowing under of a leguminous 

 crop, thus securing much humus, and, with the same, capturing 

 large quantities of free nitrogen from the air, which is thus incor- 

 porated into the soil as available plant food. 



The moisture problem is, within itself, a very great one. Sel- 

 dom do we find a field where the soil is continuously too dry. At 

 times the amount of moisture present is far in excess of that re- 

 quired, and this fact makes its absence severely felt when such a 

 climax ensues. 



On slightly rolling land, with a pervious subsoil, the proper 

 moisture conditions are readily secured. On flat land, with per- 

 vious subsoil, tile drainage takes care of the surplus water. On 

 flat land, with an impervious subsoil, tile drainage is a failure, and 

 we resort to surface grading of the land by back furrowing the 

 field some three or four years into loaves or elevations, some eighty 



