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Durability Of Manure

Categories: CROP-ROTATIONS

Tests of the durability of manure in the soil

involve some uncertain factors, but we are interested only in the

effects of applications. These effects may continue for a long term of

years, and an example will illustrate. Land may be too infertile to

make a good clover sod. If a good dressing of manure be given half the

land, affording proper conditions for making a sod, the result will be

a heavy growth of clover, whi
e the seeding on the unmanured half will

be nearly a failure. If no manure or fertilizer be used in the

crop-rotation, the probability is the manured portion of the field will

again make a fairly good sod. How much this success may be due to the

remains of the manure, and how much is attributable to the effect of

the clover and to better bacterial life introduced and favored by the

manure, no one knows. Probably the greater part of the benefit comes

only indirectly from the manure applied three or four years previously.

Half of the field may thus be lifted out of a helpless state and remain

out of it for a long term of years, while the other half grows only

poorer. A probable illustration of this lasting indirect effect may be

seen in one of the plats in the soil fertility experiments on the

Pennsylvania experiment station farm.



Experiments at the Rothamstead station, England, show some lasting

results from applications of manure. Director Hall cites the case of

one plat of grass land which was highly manured each year from 1856 to

1863, and has since been left unmanured. In 1864 this plat gave double

the yield of an adjoining plat which had been left unmanured during the

eight years. In 1865 the plat, last manured in 1863, gave over double

the yield of the unmanured. In the following ten years its yield was a

half more than that of the unmanured. In the next ten years the yield

was a quarter more. In the next ten years it fell to 6 per cent more

than the plat that had received no manure in the beginning of the

experiment. In the following ten years it rose to 15 per cent. Here is

a lasting effect of manure for over forty years where grass was grown

continuously.



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