244 MISSOURI AGRICULTURAL REPORT. 



that during- 64 summer days in a fallow field there was an average daily 

 evaporation of .67 pounds of water per square foot of surface. Should 

 evaporation continue at this rate during the whole growing season of 

 the corn crop, allowing 130 days as the length of this period, the total loss 

 would be equivalent to 16.8 inches of rainfall. Adding this to the amount 

 that must pass through the corn plant we have a total of 27.4 inches that 

 must be supplied during the growing season to produce 50 to 60 bushels 

 of corn per acre. To meet this enormous demand we have the water that 

 has accumulated in the soil during the winter and the regular rainfall of 

 the season. If the soil were completely saturated, the first five feet would 

 contain about 20 inches of water. Not over half of this can be withdrawn 

 by the plants. This leaves 17.4 inches that must be supplied by the sum- 

 mer rains. It is rare that the rainfall in our corn producing states during 

 the months of May, June, July and August, is equivalent to this amount. 

 We must therefore do everything possible to increase the storage capacity 

 of the soil and to prevent loss by evaporation. Both can be accomplished 

 to a certain extent by tillage. Deep fall plowing makes the soil porous 

 thus allowing the water of the fall and winter rains to percolate down into 

 the soil instead of running away into the streams and rivers, as much as 

 it would otherwise do. The efficiency of a dust mulch in preventing evap- 

 oration is so well known that it need not be discussed here further than to 

 sav that the enormous loss above referred to can be reduced as much as 

 25 per cent, to 50 per cent, by surface tillage after each summer rain. 

 There is room for the inventive genius of some American to give us an 

 implement that will do this work quickly and cheaply. 



IMPROVEMENT BY UNDERDRAINAGE. 



I believe there is room for some very careful experiments along the 

 line of underdrainage for the express purpose of removing air from the 

 soil rapidly during heavy rains. Water enters soil by passing into the 

 spaces between the soil particles. But these spaces are already occupied 

 by air and this air must escape before the water can enter. Often rain 

 falls so fast that the soil is covered with a sheet of water. The air must 

 escape through this water and the process is a slow one. Meantime much 

 of the water that is falling flows away into surface drainage ditches and 

 streams. If underground outlets for the air could be provided it would 

 pass out this way rapidly and the water would as rapidly follow it into the 

 soil. In this way much water now annually lost by drainage would be 

 utilized in the production of crops. Underdrainage and its value to 

 lands injured by standing water is so well understood that it needs no dis- 

 cussion here. 



