t902. 



FORESTRY AND IRRIGATION. 



199 



others. One-half of each subplat was 

 irrigated, some of these once a week 

 and some once in two weeks. A labo- 

 ratory was fitted up in the pump-liouse 

 in which soil samples were analyzed for 

 their water content and their soluble 

 nitrates. Two men were kept busy 

 during the season taking soil cores ( in 

 foot lengths, to a depth of four feet, by 

 driving down a brass tube and pulling 

 it up with the soil inside) and conduct- 

 ing the analyses. These soil samples 

 were taken in certain rows and furrows 

 just before each irrigation and at inter- 

 vals after irrigation and the movements 

 of water and nitrates closely followed. 

 Many hundreds of soil samples were 

 thus anah'zed during the summer. 



I am not in possession of the results 

 of these experiments in detail, and if I 

 were I could not use them in this con- 

 nection, as the government reserves the 

 right of first publication of its findings. 

 I may, however, state some well-known 

 facts concerning the irrigation of sandy 

 lands. In the case of such porous soil 

 and open subsoil (pure sand) as we 

 have to deal with, water passes down 

 rapidly, and if too large an amount is 

 applied there is more or less leaching 



of thenitrates(plant 



foods) from the soil 

 into the soil water 

 below and carried 

 through springs into 

 the rivers, where 

 they are mostly 

 taken up by water 

 weeds, or liberated 

 b)^ denitrifying or- 

 ganisms in the water 

 and the nitrogen re- 

 turned to the air. 



Well water, espe- 

 cially in such soils, 

 is therefore very 

 much richer in ni- 

 trates than river 

 water, and therefore 

 much better suited 

 to maintaining fer- 

 tility in the soil, as 

 a part of the nitrates 

 which have been 

 leached out of the 

 soil may be pumped 

 up and returned to 



it in a form all read\- for plants to use. 

 We got better results from our garden 

 irrigation with well water than from our 

 field irrigation with river water, due 

 partly, no doubt, to leaching in the 

 field by applying too large quantities of 

 water, and partly to the difference in 

 nitrate content of river and well water. 

 Where conditions are favorable, there- 

 fore, the well and windmill or other suit- 

 able power cannot be outdone for small 

 areas, and I am not sure that manj' wells 

 and small systems of irrigation may not 

 be preferable to one large plant using 

 river water on a large area. 



In case an engine or horse-power is 

 used to pump from a well, hose may be 

 attached directly to the pump and the 

 water allowed to run into furrows; but 

 with a windmill a pond is necessar}^ to 

 accumulate water enough to pay to 

 attend to running it. Wind is too un- 

 steady a power to allow it to pump 

 directly into furrows, as it would re- 

 quire constant attention to secure an 

 equal and economic distribution of 

 water. 



The muck soil of swamps and marshes 

 which fringe many of our rivers is made 

 up largeh' of decomposed water weeds 



THIS CUT SHOWS WATER RUNNING IN THE FURROWS, WITH THE 

 SLUICE HOSE IN THE FOREGROUND. 



