22 N. H. EXPERIMENT STATION [Bulletin 319 



the survey of this county will be completed early in 1940. 



The survey of Strafford county was continued during 1939 with 

 the cooperation of the Soil Conservation service in addition to that 

 of the Division of Soil Survey. The mapping in Strafford county in- 

 cludes an estimate of erosion control and an analysis of land cover 

 in addition to soil types and slope classes. The extra detail has ne- 

 cessitated plane-tabling the open land and has involved much addi- 

 tional time over that recjuired for a survey such as the one in Hills- 

 borough county. The Strafford survey will probably be finished 

 about August 1. 1940. (Pumell Fund) 



The Determination of Run-Off and Erosion from New Hampshire 

 Uplemd Soils 



In cooperation with Soil Conservation service a detailed map was 

 made of a three-mile section of the Merrimack river below Nashua 

 from which it was possible to evaluate the benefits of different spe- 

 cies of riverbank vegetation and to measure the amount and kind 

 of stream bank cutting there. It was found that stream bank cut- 

 ting contributed practically all the sand which washed t)n valuable 

 farm land during floods. With a view to control stream bank ero- 

 sion, studies were conducted in the greenhouse on the rooting of 

 cuttings from several species of plants found on river banks. Chem- 

 icals which induce rooting were tried on these cuttings. Willows 

 pnd spirea species were found to l)e most promising for stabilization 

 of river banks. The chemicals aided rooting in some instances but 

 did not influence the subsequent rate of growth of the rooted cutting. 



Four banks on the Merrimack river \\ ere selected in June. 1938. 

 for a study of the rate at which the unprotected sand was washed 

 away by the river. Cross sections of these banks were ol)tained at 

 that time. A year later, a second survey of the same banks was 

 made and the amount which had washed away during the year was 

 calculated. The banks which were on the outside of the bends and 

 subject to direct and constant action of the water exhibited the most 

 cutting. 



The river bank project was discontinued in July. 19.39. and atten- 

 tion directed to the losses occasioned by erosion on upland potato 

 farms. 



During the summer an exploratory survey of the state has been 

 made. The soil tyi^es upon which potatoes are grown, and the 

 amount of erosion that has occurred on these soils have been record- 

 ed. Most of the potatoes are grown upon the heavier soils. The 

 rolling upland soils upon which potatoes are grown are jiredominant- 

 ly loams and silt loams and have a hardpan at about 20 inches. This 

 hardjian insures an adefjuate water supjily for crop growth In- pre- 

 venting rapid gravitational flow of water, and this very characteris- 

 tic also contributes to sheet erosi(»n. Paxton loam is tho ty])ical up- 

 land potato soil in southeastern New Hampshire, and studies will be 

 confined to this soil. 



A field has been selected at Northwood Ridge for the establish- 

 ment of run-off plots to ascertain the time of year erosion takes 

 place and the conditions which cause it. One plot is entirely grass. 



