Elements of farm practice, prepared Elements of farm practice, prepared especially for teaching elementary agriculture; elementsoffarmpr01wils Year: 1915 16 ELEMENTS OF FARM PR ACT WE 2. How many pounds of corn are produced on an acre yielding 40 (A bu. of shelled corn weighs 56 lbs.) 3. How many pounds of potatoes are produced on an acre yield- ing 150 (A bu. of potatoes weighs 60 lbs.) AVAILABLE PLANT FOOD Amount of Plant Food.—Most soils contain enough plant food to grow crops for many years, several hundred perhaps, but this plant food is not present in the soil in a soluble f
Elements of farm practice, prepared Elements of farm practice, prepared especially for teaching elementary agriculture; elementsoffarmpr01wils Year: 1915 16 ELEMENTS OF FARM PR ACT WE 2. How many pounds of corn are produced on an acre yielding 40 (A bu. of shelled corn weighs 56 lbs.) 3. How many pounds of potatoes are produced on an acre yield- ing 150 (A bu. of potatoes weighs 60 lbs.) AVAILABLE PLANT FOOD Amount of Plant Food.—Most soils contain enough plant food to grow crops for many years, several hundred perhaps, but this plant food is not present in the soil in a soluble form and it is well it is not. If it were soluble it would be dissolved by the water during a heavy rain, and as the water flowed off over the fields and into the river it would carry with it the plant food, thus leaving the soil unproductive. This may be better understood if one takes two glasses of water, puts a spoonful of sand into one and a spoonful of sugar into the other, and stirs. Then carefully pour the water out of both glasses. The sugar being soluble has been dissolved and will pass out Figure 5.—(1) A piece of sod showing the grass roots. (2) A lump of earth taken from a field that has grown corn continuously for fourteen years and which is badly depleted of vegetable matter.
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