Cropping and cultivation under warm and moist conditions leads to a
rapid depletion of the organic matter in the soil. In the cropping-areas
of Canterbury the depletion of organic matter is of major importance,
often responsible for the poor establishment of pastures and the low
carrying-capacity of them as well as low yields of crops. Nitrogen is made available in the soil for grass-growth
from at least two important sources : (a) the organic matter-this does
not increase the nitrogen-content of the soil unless it be from leguminous
crops ; and (b) direct from growing legumes. The available nitrogen
encourages vigorous grass-growth, and this when fed off adds to the
organic matter in the soil, and the fertility of the soil is built up.
Calculations of the amount of nitrogen added to the soil by clovers
in pastures have been made, and the amount varies with the clover and
the soil conditions. There is naturally a limit to the improvement
that can be made in the fertility by these means, but on some of the
cropping lands of Canterbury that limit is worth aiming at.
The general benefits of clovers in pastures are well recognized, and
the majority of the mixtures sown contain clovers; but how many
on the cropping lands of Canterbury are satisfied with the amount of
clover that comes from the sowings, particularly in the first few years
in the life of a pasture ?[Show full abstract]
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