290 PARKS 



the lawn so as to avoid fresh weed seeds, and it should be thoroughly worked 

 into the soil to a depth of 12 inches, at least. This will ensure that the soil 

 is kept open to that depth and will encourage the grass roots to go deeply 

 after food and thus give them a cool, moist foothold in time of drought. 

 An amount of manure up to 80 or 90 cubic yards per acre may be used, 

 part before plowing or spading, and the remainder afterwards. 



Fertilizers. Where the soil contains a satisfactory amount of humus the 

 question of a sufficient amount of nitrogen becomes a minor one. Organic 

 carriers of nitrogen, such as dried blood and tankage and bone meal, are 

 generally superior to mineral carriers such as sulfate of ammonia and 

 nitrate of soda, because their effect is more lasting. Nitrate of soda, how- 

 ever, is the quickest acting nitrogen carrier to use as a top dressing on lawns 

 where the use of well-rotted stable manure is objectionable or impossible. 

 It may be used at the rate of two to three hundred pounds per acre in early 

 spring. When broadcasted upon the soil the rain will carry it down into 

 the soil in solution, and this property makes it preferable to any other 

 mineral salt for this purpose. Since clover is an undesirable plant to have 

 in a lawn area used for sports, it is probable that sulfate of ammonia should 

 be used instead of nitrate of soda as a nitrogen carrier. The residual action 

 of sulfate of ammonia, in the soil, is acid and not alkaline. Therefore, it 

 does not encourage clover and it has been found to discourage many types 

 of weeds. 



Phosphorus is the next most important fertilizer constituent because 

 it is almost always deficient in the soil. Bone meal may be used, and it is 

 often plowed in with a cover crop, at the rate of 600 pounds per acre. Acid 

 phosphate is the best carrier of phosphorus for use in lawn making, and 

 from 800 to 1,000 pounds per acre should be thoroughly incorporated in 

 the top foot or 14 inches of soil. Potash is not generally important in lawn 

 making, especially on clay soils, which are believed to contain a sufficient 

 supply oflpotash ready to be made available by the unlocking action of 

 lime, underdrainage, and humus. 



When it is desired to apply a so-called complete fertilizer, probably 

 the best all-round formula is four per cent of nitrogen, eight to ten per cent 

 of phosphoric acid, and four to six per cent of potash. This would be approx- 

 imately represented by 530 pounds of nitrate of soda, 1,270 pounds of acid 

 phosphate and 200 pounds of muriate of potash, in a ton of the mixture. 

 Land poor or lacking in humus may receive as much as a ton to the acre 

 of this mixture, especially if sandy. Pure chemical or commercial fertilizers 

 should be applied just before the last cultivation of the ground previous to 

 sowing the grass seed, so that they will become thoroughly incorporated in 

 the surface soil. They should not, however, be applied at the same time as 



