426 



THE IRRIGATION AGE. 



In considering the soil, we first made a study of its 

 general composition, such as clay, gravel, free soils, pumice 

 or volcanic ash. This included a close study of the sub- 

 soil as well as the top soil, as often the sub-soil is more 

 important than the top soil. Mechanical conditions were 

 investigated and the question as to whether the soils are 

 full of humus or deficient. After the water was applied 

 we have studied the soil carefully as to its tendency to 

 puddle or pack or its characteristic of cracking as it dries. 



\Ye have taken into consideration the relation of culti- 

 vation to irrigation and have compared tilled soils with 

 those that are both tilled and irrigated. The temperature 

 of the soil, including the sub-soil before and after irrigat- 

 ing, has been investigated, and the rapidity with which 

 water travels through the furrow and percolates through 

 the soil. 



As concerns the fruit, we have noted whether there 

 are any changes in color. Is the size influenced? What 

 are the percentage of large, medium and small apples se- 

 cured from different amounts of water? The firmness, 

 shipping and keeping quality, total yields, the form of the 

 fruit, its time of maturity and a chemical study have all 

 been made. 



We have already studied carefully the chemical com- 

 positions of the apple as influenced by irrigation over a 



we found it possible to complete certain lines that we 

 have begun on. We are continuing this work from year 

 to year and hope the future will give us more information 

 relating to the true duty of water in fruit production. 



It must, of course, be understood that from the start 

 that irrigation of an orchard means that such individual 

 grower must .;tudy his problem carefully himself, and 

 while he will be able to get a good deal of information, 

 from the experience of others, he will have to work out 

 the special application under his own peculiar conditions. 

 The age of his trees, variety, type of his soil, the average 

 climatic conditions, will all influence his problem. If, 

 however, we can get the grower interested in studying 

 his problem carefully and realizing the importance of such 

 a study, we have won a great victory, especially if we can 

 teach him that he should work on the basis of how little 

 water is necessary rather than how much, and that irriga- 

 tion cannot successfully be made to take the place of 

 tillage. The irrigator must be led to learn that he is cer- 

 tainly his brother's keeper. If his neighbor suffers because 

 of his unwist irrigation, sooner or later he will suffer 

 himself. 



In our work we have found that irrigation aided in 

 giving us a larger percentage of fruit that came up to good 

 packing size. This meant that there was a smaller per- 



Orchard Irrigation Experiment at the Oregon Agricultural College. 



period of two seasons. This needs to be carried over a 

 series of years in order to give conclusive results which 

 can be published. We have studied the tree itself, con- 

 cerning bud and wood growth, the effect on wood growth 

 and the effect on the tree in a general way; the relation of 

 irrigation to the terminal buds according to their size. 

 Are they large or small, firm or soft? Is the percentage 

 of fruit buds increased by irrigation? What is the average 

 growth and length and diameter of the annual growth? 

 At what date does the wood ripen? Is it affected by frosts 

 or winter injury? Is the foliage vigorous? How is its 

 color influenced? At what time does it color in the fall? 

 What is the date of the droppings of the foliage? 



We studied the tissue and cell structures of the fruit, 

 leaf and wood. We must, of course, take into considera- 

 tion the age and vigor of the trees and the way they have 

 been cultivated and pruned. 



The division of horticulture of the college has issued 

 Bulletin 113 on "Orchard Irrigation Studies in the Rogue 

 River Valley." Unfortunately we do not have enough of 

 these bulletins so that we can send them broadcast for 

 general distribution. The bulletin is to be published, how- 

 ever, by some of the leading horticultural magazines and 

 those interested will undoubtedly have an opportunity to 

 secure an issue which contains the bulletin. 



In a period of five years we have not found it possible 

 to carry on all these lines of investigation, neither have 



centage of culls on the irrigated than on the non-irrigated 

 soils. We were able, also, to reduce the percentage of 

 windfalls. The saving at times amounted to as high as 15 

 per cent of the crop. 



When the fruit trees ar: heavily loaded in the fall 

 the strain on the tree is, of course, very heavy. If the 

 tree does not receive the amount of moisture necessary 

 to mature the crop, it immediately begins to shed its fruit 

 heavily, and this loss at times becomes extremely great, 

 the fruit beginning to drop a few weeks before picking 

 time and continuing up to harvesting. 



In one experiment which we conducted on a dark 

 alluvial loam with Yellow Newtown trees 19 years of age, 

 the first plot was given 600 gallons of water to each tree, 

 in two applications, about the middle of July and the 

 middle of August; the second plot 1,500 gallons to the 

 tree the last of July and the latter part of August. The 

 difference in favor of the greater irrigation was 5 per 

 cent less culls and 15 per cent less windfalls. Had the 

 owner been willing to have had an additional irrigation 

 given in September we could have reduced quite ma- 

 terially the percentage of windfalls but the trees were so 

 heavily loaded with fruit that we feared that with irri- 

 gating we would knock off many of the apples. 



We have noted that the shape of the fruit can be 

 materially changed by irrigation. The additional mois- 

 ture gained has a tendency to cause ths fruit to be more 



