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Maintaining Fertility

Categories: MIXTURES FOR CROPS

A heavy clover sod gives assurance that a good

crop of corn or potatoes can be grown. If the amount of plant-food in

the sod is not excessive, a heavy crop of wheat can be produced. The

condition of the soil favors many crops. The clover has placed it upon

a productive basis for the time being.



The object that should be kept in view, when a scheme of soil

fertilization is worked out, is the maintenance of
such a state of

fertility that the land can be depended upon for whatever crop comes

round in the rotation. When a 3-10-6 fertilizer, or a 3-8-10

fertilizer, is used, the effect upon a thin soil is to restore it

temporarily to this good-cropping power, the size of the application

varying with the crop. A richer soil may want the phosphoric acid and

potash without the nitrogen. A manured soil may need only the

phosphoric acid. The purpose of the fertilizer in any case is

maintenance or increase of fertility, and when this object has been

secured, the crop may be whatever the rotation calls for. It is this

rational scheme that gives success to the Pennsylvania station's

methods on some of its test plats. A given amount of plant-food is put

upon the land, which is under a four-years' rotation. One half of it is

applied every second year. The corn gets one half because it can use it

to advantage. The oat crop that follows finds enough fertility because

the soil is good. Next in the rotation is the wheat, and the wheat and

timothy and clover plants can use fertilizer with profit. There is no

change in its character because it is the soil that is getting the

assistance, and not primarily just one crop in a rotation. The land in

this experiment that is well fertilized is more productive than it was

thirty years ago, although no manure has been applied, and it is the

general productive condition that assures good yields, and not chiefly

any one application of fertilizer.



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