A 30-year study revealed the yield difference obtained by continuous, as opposed to rotational, cropping on manured and unmanured land. Photo / Unsplash / Ash Willson
A 30-year study revealed the yield difference obtained by continuous, as opposed to rotational, cropping on manured and unmanured land. Photo / Unsplash / Ash Willson
We take a lot for granted when it comes to changes in farming.
For a start, we tend to forget that a lot of the processes put in place now never existedin the 1920s.
For instance, cropping was either successful or a dismal failure.
The farmers either got the much-needed rain or they didn’t and there was very little they could do if their soil was lacking in the nutrients needed to grow a good crop.
The results obtained by Messrs. Muller and Hudelson at the Missouri Agricultural Experiment Station from experiments on rotation extending over a period of 30 years are of interest.
The object of the experiments was to discover the difference of yield obtained by continuous, as opposed to rotational, cropping upon manured and unmanured land.
As might be expected, rotation of cropping gave yields superior to those obtained by continuous cropping.
The NZ Herald reported on a crop yield study in 1923. Image / Papers Past
The difference was evident in manured land, but far more marked in that which was unmanured.
It also demonstrated that by lengthening the rotation better results were secured than when a given crop succeeded another of the same kind at a shorter interval.
Thus, with maize, continued cropping gave a yield of 20.9 bushels, 32.6 on a three years’ rotation, 38.5 on four years, 41.5 on six years.
In general, four years’ rotation served to give the maximum yield.
An interesting comparison is made between continuous cropping on manured land and rotational cropping on unmanured land.
With a three years’ rotation continuous cropping on manured land gives better results than rotational cropping on unmanured land, but with a longer rotation, the unmanured land beat the continuously cropped manured land.
Naturally, a combination of rotation cropping and manuring gives the best results.
The addition of manure has also the advantage of maintaining soil fertility better than does rotation without manure.
It was further shown that soil fertility is maintained better when animal manure is used than when chemical fertilisers only are applied.
Two points worth consideration are that a long rotation of four years is better than a shorter one, and that artificial manures, particularly those containing phosphoric acid and potash, should be used with dung.
