Show Conservation Notes b by V. 11 Earl Rhine hart 1 To show the need for application application application tion of conservation practices in other fields Armco's Highway Magazine for February February ar ary carried quite an interesting article more less related to conI conservation conservation con con- entitled Grass Protects Protects Protects Pro Pro- I Airport Surfaces It was brought out that paved paved paved ed runways t a x i w a ay y s sand and aprons of commercial and other airports seldom constitute more than 12 to 16 per cent of the airfields airfield's surface thus some 85 per cent of the area of man many fields and the entire surface of others used primarily for private flying have ha other than hard sur sur- faces Such surfaces are economically economically econom econom- provided in most cases by sod or other types of vegetative vegetative vegetative tive cover There here are innumerable grasses and other types of vegetation ves useful in stabilizing the surface of the soil soU to prevent dust mud drifting sand and erosion It was emphasized that topsoil and natural ground cover should be conserved wherever where possible during construction of an nn air air- port However where it is necessary necessary essar essary to stockpile or borrow topsoil it sometimes is more economical ec- ec economical economical ec ec- to build up a sufficiently sufficient sufficient- I ly good soil from the subsoil buse by b byuse byuse use of fertilizers Also an Important note Is the drainage of the tho area on which grass is to be grown A Awell Awell well drained soil Boll encourages the growth of healthy health re drought vegetative cover A well developed sod will absorb a relatively relatively rel rel- ely high per cent of ot surface water and still retain a wear re surface Experiments have shown with the rain making machine that thata a good grass cover er absorbs ten times as much water as a thin sod Thus surface runoff factors for design of drainage systems are aro considerably affected by the typo and del density of cover that can be established on an airport soon after acter construction construction is completed com com- It further states that it lt should be emphasized that rapid runoff with consequent erosion and gul gul- lying is not confined to regions of relatively higher rainfall Flash storms in arid and semIarId semiarid semiarid semi- semi arid regions may cause serious washing in a relatively short time and md small gullies in fresh fills rills may develop rapidly Into deep channels Paved gutters and waterways are necessary on some slopes ad- ad to airfields but as been found to be a more economical ec- ec ec economical expedient under most conditions |