18 FOR BETTER CROPS IN THE SOUTH 



cent of the nitrogen contained in the feed may be returned to 

 the land in the farm manure. 



In very intensive farming, as in market gardening near large 

 cities, if the land is too valuable to be given up even for a part 

 of a year to the growing of legumes for fertilizing purposes, then 

 it becomes necessary to apply nitrogen; and this is also profit- 

 able, for the products of one acre frequently bring $100 or more 

 for one season. In emergencies, commercial nitrogen, especially 

 cotton-seed meal, may well be used for cotton, because of its 

 high value per acre; but, as a rule, farm manure or legumes as 

 green manures, could be substituted with greater profit in the 

 long run. 



Where it can be obtained, stable manure is usually the most 

 economical and satisfactory form in which to apply nitrogen in 

 market gardening, although cotton seed or cotton-seed meal, 

 dried blood, tankage, sodium nitrate, and ammonia sulphate are 

 also used with profit at times. 



Phosphorus— If the element phosphorus becomes deficient 

 in the soil, the total supply can be increased only by making an 

 actual application of some kind of material containing phos- 

 phorus. ' 



It is well to bear in mind that about three-fourths of the 

 phosphorus required for ordinary grain crops is stored in the 

 seed or grain, while only one-fourth remains in the straw or 

 stalks. Consequently, when corn. or wheat is sold from the farm, 

 three-fourths of the phosphorus required to produce the crop 

 leaves the farm in the grain. 



When the crops are fed to growing animals or milch cows, 

 about one-fourth of the phosphorus contained in the feed is 

 retained in the bones, flesh, and milk, while about three-fourths 

 is returned in the manure. 



The total phosphorus content of the soil on any given farm 

 may be increased by the purchase of stable manure, or by using 

 manure made from purchased feeds, especially from grains or 

 other concentrates, as bran, oil meal, or gluten feed; or we may 

 purchase steamed bone meal from the stockyards companies who 

 buy our cattle, slag phosphate from the steel works— .if the slag 

 contains sufficient phosphorus to make it valuable — or natural 

 rock phosphate direct from the extensive natural phosphate 

 deposits in Tennessee, South Carolina, or Florida, where this 

 mineral is being mined and ground in large amounts. It may 

 be noted that the original stock of phosporus naturally in the 

 soil is powdered rock phosphate. 



Potassium — Potassium, like phosphorus, is a mineral ele- 

 ment contained in the soil, and if the supply in the soil is 

 deficient it can be increased only by a direct application to the 

 Soil of some material. As a matter of fact, aside from peaty 



