62 



FORESTRY AND IRRIGATION 



February 



duty of water in agriculture is not 

 at present possible on account of lack 

 of a sufficient body of well established 

 facts ; and this is especially true of that 

 phase of the problem relating to the 

 influence of tree planting upon the 

 duty of water. The body of accu- 

 rately determined facts regarding the 

 influence of wind-breaks of any type 

 upon the wind movement close to the 

 surface, and especially upon the rate 

 of evaporation from foliage, soil, and 

 water surfaces, is extremely small, 

 and yet such knowledge is necessary 

 to a proper treatment of the subject. 

 Some general facts and tendencies 

 have been ascertained which are help- 

 ful for a preliminary consideration of 

 this subject. 



INFLUENCE OF WIND-BREAKS UPON 

 VEGETATION. 



There is no doubt but that under 

 certain critical conditions wind-breaks 

 do exert a very measurable influence 

 upon vegetation. In the spring of 

 1894 (Bulletin 42, Wis. Agri. Exp. 

 Stations) during May and June, an 

 opportunity was afforded to make a 

 somewhat critical study of this sub- 

 ject under field conditions. There 

 is in Wisconsin an area of some 

 ten thousand square miles of light 

 sandy soil or sandy loam, and upon 

 the lighter and more sandy portions 

 of these soils crops are occasionally 

 very seriously damaged by the drying 

 effect of the wind ; and the fertility 

 of the soil is much reduced by the 

 drifting which occurs at such times. 

 At the time in question, there had been 

 a heavy fall of rain on the 5th and 

 6th of May, but on the /th it was clear 

 and cold with a strong wind blowing 

 from the northwest. During this and 

 the following days, notwithstanding 

 the rain, the soils on many fields about 

 Plainfield and Almond, Wis., had been 

 badly drifted. On the morning of the 

 8th the drifting had gone so far, on 

 many fields, that at both places, the 

 loose sand with which oats had been 

 o >\vred, whether with seeder or with 

 drill, had been driven from the fields 

 to such an extent as to leave the ker- 



nels entirely exposed and the plants 

 lying flat upon the ground hanging 

 by the roots and whipping in the wind. 

 On the fields where the whipping had 

 not been so severe and where oats 

 stood 3 inches high, the oats had been 

 cured like hay close to the ground, 

 and even the leaves of dock sorrel 

 were blackened and so dry as to crum- 

 ble in the hand. Very many of the 

 blades of oats, through wilting, had 

 broken over close to the ground, pre- 

 senting an appearance which suggest- 

 ed to the farmers that they had been 

 cut by the sand. It was at once evi- 

 dent, to the most casual observer of 

 the fields at this time, that wherever 

 a field lay to the leeward of any sort 

 of shelter the destructive effects of the 

 wind were either not apparent or else 

 they had not been nearly so severe. 



About three weeks after the first 

 serious injuries had occurred a care- 

 ful study was made of many fields and 

 the results are recorded in detail in 

 the bulletin to which reference has 

 been made. Some of the observations 

 made at this time are cited here in il- 

 lustration of the decisive evidence re- 

 garding the influence of wind-breaks 

 upon vegetation. A north and south 

 road 2 rods wide fenced with wire, 

 along which are scattering trees 10 to 

 1 8 feet high, together with a scanty 

 growth of hazel, had a field of oats 

 lying to the east which was greatly 

 damaged ; but a strip 2 rods wide, next 

 to the road, appeared wholly unin- 

 jured. A field of oats lying to the 

 east of a field of timothy, in which 

 there was a strong growth of dock 

 sorrel, had a strip of oats 200 feet wide 

 next to the grass where the stand was 

 good, while on the eastern half, 30 

 rods wide, the plants were entirely de- 

 stroyed. Another oat field having 

 grass on the north and west sides, and 

 bordered by a rail fence, showed a 

 strip of uninjured grain 100 feet wide 

 next to the two fences and fully 200 

 feet wide in the northwest corner of 

 the field in the lee of the two fences. 

 In another oat field fully five-eights of 

 it had been so thoroughly destroyed 

 bv the wind that it was harrowed and 



