226 STATE HORTICULTURAL SOCIETY. 



crop production if it conld be so distributed that it could be used. 

 But we all realize how unequal is the distribution during the growing- 

 season. Ten, twenty or even fifty times as much water falls during^ 

 some months as others. From a report by the Weather bureau we 

 learn of an extreme variation of from one-fourth of an inch in July^ 

 188G, to 272 inches for June, 1894. These excessive rainfalls, of course,, 

 are nearly all wasted, for the water cannot be retained in storage by 

 the soil for future use. In fact, it would be extremely hurtful if it 

 could, for our common farm crops cannot grow if the soil is saturated 

 to anything like its full capacity to hold moisture. Careful experiments 

 having been tried, go to show that growth practically ceases if the 

 moisture exceeds 80 per cent of its normal capacity, 50 io 60 per cent 

 being the most favarable amount for best development. For illustra- 

 tion, our average soils will retain 40 to 60 pounds of water to the 100, 

 Growth, therefore, would best be promoted with a soil moisture of 25 

 to 35 pounds to the 100. But these amounts would be quickly reduced 

 by plantl'growth or by evaporation, one or both, usually both, for it is 

 well-nigh impossible to prevent evaporation from the surface. Its 

 extent maybe greatly modified,' however, by tillage, and almost checked 

 by sufficient mulching. While too much water is detrimental to crops^ 

 too little is equally so. Hence the question of irrigation in what is 

 termed the humid districts presents a two-sided problem : How ta 

 dispose of the excess and how to supply the deficiency. 



To attempt to apply surface irrigation to large areas here, as is 

 done in the West, seems beset with so many ditficulties as to almost 

 preclude hope in that direction. In very rare instances streams could 

 be diverted so as to afford water for irrigating large tracts without ex- 

 pensive reservoirs. In so constructing these reservoirs, we would 

 have to contend with rushing floods that would come, and the bursting 

 influences of heavy frosts. These difficulties may be overcome some 

 day, and probably will. But there is a method of irrigation that is 

 practicable and may be applied to a small or large area, as the means 

 may permit — to a dingle square rod, a single acre, or to many. It is 

 what is termed 



SUB-IRRIGATION. 



It consists of laying drain tiles under the surface, in such a way 

 that when water is applied it will soak into the soil at the most con- 

 venient place for supplying the roots with moisture. It has many 

 points of merit : faj It would not require nearly so much water. 

 One-twentieth of the water needed for surface irrigation would do 

 equally as much good by this method, fbj Hardening and crusting 

 the surface would be avoided, fcj The necessary aeration would not 



