Similarity Of Requirements

Categories: MIXTURES FOR CROPS

Many of our staple crops are very similar

in their fertilizer requirements, and this simplifies fertilization.

Setting aside the impression gained from the dissimilarity in the

so-called corn, potato, wheat, and grass fertilizers on the market, the

farmer knows that the soil which is in a good state of fertility is

best for any of them, and if the soil is hard-run, it should have its

plant-food supply supplemented. The hard-run soil usually is lacking in

available supplies of all three plant-food constituents. If a

fertilizer containing 3 per cent of nitrogen, 10 per cent of phosphoric

acid, and 6 per cent of potash serves the wheat well, it will serve the

timothy that starts in the wheat. Likewise it will serve the corn,

although a heavier application will be needed because corn is a heavy

feeder. Experience has taught that it will serve the potato similarly,

and that the potato will repay the cost of free use of fertilizer. If

the soil is sandy and deficient in potash, the percentage of phosphoric

acid may be cut to 8, and the percentage of potash raised to 10, and

all these crops will profit thereby. If the nitrogen content in the

soil is high, none of these crops may need nitrogen in the fertilizer.

This is a general principle, and safe for guidance, though the best

profit will demand some modification that readily occurs to the farmer

as he studies his crops and their rotation. To illustrate: The corn is

given the clover sod or the manure partly because it requires more

plant-food than the wheat. It gets the best of the nitrogen, and may

need only a rock-and-potash fertilizer, while the wheat that follows

may need some available nitrogen to force growth in the fall. There is

no fixed formula for any field or crop, and the point to be made here

only is that the requirements of many standard crops do not have the

dissimilarity usually supposed, except in respect to quantity. A marked

exception is found in the oat crop, which does not bear the application

of much nitrogen, and often fares well on the remains of the manure

that fed the corn, if some phosphoric acid is added.