Show FUNCTIONS OF fertilizers commercial or artificial article Is used to increase fertility above natural capacity by C W assistant Aag latant chemist idaho experiment Wa station tion fertilizers are applied to tho soil eoll for or two general purposes to main tain and to increase fertility chief among those fertilizers that aro are used tor for maintaining the fertil of the land la Is barnyard manure this is its main function and just as long ns as tho that principal constituents of the manure are all derived from the that soil it cannot increase its fertility at best it can only maintain its fertility if however the barnyard manure Is obtained wholly or in part from external sources it may increase ter tilita two such cases are plainly evident por for examples when the barnyard manure le Is purchased from town stables stab lbs as ao it to is often done for truck gardening near cities or when it la Is derived from fertilizing Ing ingredients redl contained in oil cake or other concentrated feeding stuffs consumed by stock wn tho e commercial ur artificial fertilizers which have been employed for a good many years i are used chiefly for increasing tho the fertility of the soil or in other words increasing the t it a productiveness of the soil above its natural capacity although this is their leading function they act as aa restorative agents whenever they axe are applied when barnyard manure la is withheld lit in general the restitution of tho the fertility of the land is accomplished chiefly by the barnyard manure that is returned to tho the soil sell during a given crop rotation and the increase in crops Is produced by commercial or artificial fertilizers |