198 STATE HORTICULTURAL SOCIETY. 



after tlie leaf starts we lessen the growth, and if we do it at this time of 

 year, as our friend suggests, they will bleed to death. 



Mr. Greening: If the conditions are such, and the trees are very large, 

 I do not recommend June pruning. If there are many small limbs to be 

 pruned, I would recommend early spring trimming. 



IRRIGATION AT MICHIGAN AGRICULTURAL COLLEGE. 



BY PROF. L. R. TAFT. 



I had hoped that, owing to the severe drouth of the past two seasons, 

 the subject of irrigation would prove of general interest, but I infer from 

 the remarks of Dr. Thomas, yesterday, that Lenawee has been in fact, if 

 not in name, a wet county, and possibly, to the people of Lenawee, irriga- 

 tion may seem out of the question; but I trust that to others it may be of 

 interest to know how we, in Lansing, manage to get drinks — for our 

 plants. 



In the way of irrigation, it may be well to say that you will find, if you 

 go among the people of the west, through the Great American Desert — 

 so-called in the past — that they will say, "They are oh! so sorry for those 

 poor folk at the east, who have to depend on the Lord for their water; 

 that they have to take it when it comes — no water at all at one time, and 

 too much at others — whereas we, here, have a supply on the mountains 

 that we can bring down at any time and in any quantity;" and thus they 

 feel that they are far ahead of us — at least they say so. 



There is one side of the question, however, that perhaps accounts in 

 part for the success they have obtained in raising the various crops for 

 which they use water. We all know that the water is taken up by the 

 plants from the soil, and, after the plant food has been taken out and used 

 in the upbuilding of the plant structure, it is for the most part given off 

 by the leaves. You can very well see that, if everything else is equal 

 (supposing, of course, that the water is in the soil), if we have a dry 

 season more water will be given off than in a wet season, and naturally 

 more plant food will be brought into the plants, and we can expect a 

 better growth. Also, in a sunny season, there will be more sunshine, and 

 provided the plant food and water are supplied to the soil (artificially, per- 

 haps), there will be a chance for a greater growth than had they relied 

 on the water coming from the clouds, even in a wet season. 



Most people would be surprised if they should accurately measure the 

 amount of water given off by crops. It has been done with a great 

 variety of crops, and, for the more common crops that we grow, the esti- 

 mate is that during the growing season from 200 to 300 times the actual 

 weight of the dry matter in the plants is given off from the leaves in the 

 form of water. 



Another way of putting it is that during the growing season they will 

 give off from twentv-five times to thirty-five times their whole weight. 

 Thus acorn crop of fifteen tons will give off 450 tons of water in the grow- 

 ing season, and here we shall hove 4,000 barrels of water given off from a 



