EXPERIMENT STATION BULLETINS. 



157 



Table I. — Showing the distribution of rainfall during the months of April, May, June 



July, and August, 1888 to 1902. 



CROP POSSIBILITIES IN THE RAINFALL OF OUR GROWING SEASON. 



From tables given by Professor King in his Physics of Agriculture and in the 

 Wisconsin Experiment Station literature, Table II is deduced for the purpose of 

 indicating the size of crops possible if our rainfall could be copipletely utilized. 



According to the table the average rainfall for the growing season is completely 

 utilized for crop growing would produce much larger yields than are those now 

 grown on the average farm of Michigan, but it is not utilized completely by our 

 crops because: 



Table II. — Shovnng crop yields possible for different amounts of rainfall completely utilized. 



1. A portion is usually lost by surface drainage. 



2. A portion sinks into the ground beyond the reach of the roots of the crops. 



3. A portion rises again to the surface by capillarity, evaporates, and is carried 

 away by the atmosphere. 



4. The rainfall Is often unevenly distributed. 



If the soil were in proper condition, as. set forth above: 



(a) The losses by surface drainage and by percolation would in many cases be 



entirely prevented, where they are now considerable, while, 



(b) In all cases the losses from all four sources would be materially lessened. 



We have already spoken of the capacity of some soils for capillary water as 

 determined in the laboratory. But these amounts would probably -vary greatly 

 under field conditions. Some data given by Professor King in his Physics of 

 Agriculture indicate that after draining a few days after heavy rains <he first 

 five feet of a sandy loam might contain the equivalent of 10 inches of rainfall, a 

 Clay loam 15 inches and a muck soil probably considerably more than either. 



It hardly needs to be said that not nearly all of this supply is available for 

 crops. At the same time, even in rather sandy soils, intelligent tillage will 

 accomplish some remarkable results with this store of soil moisture. 



