Ammonia 3 to 4 per cent.
Available Phosphoric Acid 3 to 3 "
Actual Potash 2 to 3 "
Just one-half the guarantee of the high grade mixture A. A ton of this contains:
Pounds.
Nitrogen 57.7 value at 17 $10.10 Available Phosphoric Acid 60 " " 4 2.40 Potash 50 " " 5 2.50 ----- ------ Totals 167.7 $15.00 Add average charge for mixing, etc. 8.00 ------ $23.00
The selling price of this would very likely be not less than $25.
This seems at first sight to be cheaper and more reasonable. But let us see.
In a ton of mixture A he gets 335.4 pounds of plant food for $40, or at an average cost of twelve cents per pound, while in a ton of mixture B he gets 167.7 pounds of plant food for $25, or at an average cost of fifteen cents per pound.
To put it another way, in a ton of the high grade mixture A, he gets 335.4 pounds of plant food for $40. To get the same amount of plant food, 335.4 pounds, in the low grade mixture, B, it will be necessary to buy two tons at a cost of $50.
A low grade fertilizer is always expensive even if the plant food is furnished by high grade materials.
BUY ON THE PLANT FOOD BASIS
The farmer generally buys his fertilizer on the ton basis. A better method is to buy just as the fertilizer manufacturers buy the raw materials they use for mixing, namely, on the basis of actual plant food in the fertilizer. The dealers have what they call the "unit basis," a "unit" meaning one per cent. of a ton or twenty pounds of plant food. A ton of nitrate of soda, for instance, contains 310 pounds or 15 units of nitrogen, which at $3.20 cents per unit would cost $49. Buy your mixture of a reliable firm, find out the actual amounts of the plant foods in the mixture and pay a fair market price for them.
CHAPTER XXIII
COMMERCIAL FERTILIZERS--CONCLUDED
THE HOME MIXING OF FERTILIZERS
When a considerable amount of fertilizer is used a better plan than buying mixed fertilizer is to buy the raw materials and mix them yourself. For example, a farmer is about to plant five acres of cabbages for the market. He finds that a certain successful cabbage grower recommends the use of fifty pounds nitrogen, fifty pounds phosphoric acid and seventy pounds potash per acre. For the five acres this will mean 250 pounds nitrogen, 250 pounds phosphoric acid and 350 pounds potash. To furnish the nitrogen he can buy 1,613 pounds of nitrate of soda or 2,500 pounds dried blood or 1,250 pounds sulphate of ammonia, or a part of each. To furnish the phosphoric acid he can buy 1,786 pounds acid phosphate. Seven hundred pounds of either sulphate or muriate of potash will furnish the potash. These materials can be easily mixed by spreading in alternate layers on a smooth floor and then shovelling over the entire ma.s.s several times. The mixture can be further improved by pa.s.sing it through a sand or coal screen or sieve.
By following this method of buying the raw materials and mixing them on the farm, the farmer can reduce his fertilizer bill by quite a considerable amount and at the same time can obtain just the kinds and proper amounts of plant foods needed by his crops.
KIND AND AMOUNT TO BUY
The farmer should make the best use of farm manures and through tillage to render plant food available for his crops before turning to commercial fertilizer for additional plant food.
If he grows leguminous crops for green manuring, for feeding stock or for cover crops, he can in many cases secure, chiefly through them, sufficient high priced nitrogen for the needs of his crops, and it is necessary only occasionally to purchase moderate amounts of phosphoric acid, potash and lime.
For special farming and special crops it may be necessary to use the commercial fertilizer more freely.
It is impossible to say here just what amounts or what kinds of fertilizer should be purchased, because no two farms are exactly alike as to soil, methods of cropping or methods of tillage.
There are certain factors, however, which will serve as a general guide and which should be considered in determining the kind and amount of fertilizer to buy.
These factors are:
The crop.
The soil.
The system of farming.
THE CROP
Crop roots differ in their powers of feeding, or their powers of securing plant foods. Some roots can use very tough plant foods, while others require it in the most available form. Some roots secure nitrogen from the air. The cowpea roots, for example, can take nitrogen from the air and they can use such tough phosphoric acid and potash that it seldom pays to feed them directly with fertilizers.
A bale per acre crop of cotton requires for the building of roots, stems, leaves, bolls, lint and seed:
103 pounds of Nitrogen.
41 " " Phosphoric Acid.
65 " " Potash.
and yet experiment and experience have proved that the best fertilizer for such a crop contains the following amounts of plant food:
Nitrogen 20 pounds Phosphoric Acid 70 "
Potash 20 "
This means that cotton roots are fairly strong feeders of nitrogen and potash, but are weak on the phosphoric acid side.
The small grains, wheat, oats, barley and rye, can use tough phosphoric acid and potash, but are weak on nitrogen, and as they make the greater part of their growth in the cool spring before nitrification is rapid, they are benefitted by the application of nitrogen, particularly in the form of nitrate, which is quickly available.
Clover, peas, beans, etc., have the power of drawing nitrogen from the air, but draw from the soil lime, phosphoric acid and potash. Hence the phosphates, potash manures and lime are desirable for these crops.
Root and tuber crops are unable to use the insoluble mineral elements in the soil, hence they require application of all the important plant foods in readily available form. Nitrogen is especially beneficial to beets. Turnips are benefitted by liberal applications of soluble phosphoric acid. White and sweet potatoes require an abundance of potash.
If we are growing tender, succulent market garden crops, we need nitrogenous manures, which increase the growth of stem and foliage.
Fruit trees are slow growing plants and do not need quick acting fertilizers.
The small fruits, being more rapid in growth, require more of the soluble materials.
A dark, healthy green foliage indicates a good supply of nitrogen, while a pale yellowish green may indicate a need of nitrogen.
A well developed head of grain, seed pod or fruit indicates liberal supplies of phosphoric acid and potash.
THE SOIL
Soils that are poor in humus are generally in need of nitrogen.
Heavy soils are generally supplied with potash but lack phosphoric acid.
Sandy soils are apt to be poor in potash and nitrogen.