Repairing and preventing soil erosion - Soil Essentials: Managing Your Farm's Primary Asset - page 122

A variation of this is the use of graded banks built on a slight slope (say 0.5%)
that will move water safely in the direction of the fall. This water can be run onto a
grassed waterway or constructed head-works to safely take it to a lower level in the
landscape or to collect it in a dam. A further water management tool that has
proved very successful in practice is the keyline farming system as developed by
P. A . Ye o m a n s .
Cropping techniques
A time of high risk of soil erosion is when soil has been conventionally fallowed in
preparation for sowing, which leaves the soil surface bare, loose and broken into
fine particles.
From a soil erosion point of view, the newer planting techniques of minimum
till planting and direct drilling are much preferred options. In these cases, the soil
surface remains intact and often with plant cover right up to the point of sowing
the new crop. This means the opportunity for erosion to occur is almost
negligible.
A modification on these techniques is stubble mulching, where the new crop is
sown directly into the stubble of the preceding crop. Again, this means there is no
time in the cropping phase where the soil is not protected by plant cover.
Another technique used, especially when cropping large areas of sloping
ground, is strip cropping, where contour or graded banks are built at regular
intervals down the slope, and every second bay is cropped with pasture or fallowed
in between the cropped bays. This is especially useful in areas of summer cropping
or when crops are rotated a number of times before a pasture phase (Figure 35 on
p. 115).
Types of crop
Different types of crop vary in their effectiveness in helping to prevent soil erosion.
Pastures, cereal crops, sorghums, millets and brassicas are effective at protecting
soil but other crops such as sunf lower, saff lower and chick-peas are far less
effective due to the distance between plants. The different cultural requirements of
the various crops can also mean that the soil may be unprotected at a time of year
that can be prone to heavy storms or consistent high winds, thus increasing the
risk of an erosion event.
Trees in the landscape
Past practices of extensive land clearing led to extensive soil loss due to erosion,
and these practices are now largely discontinued. Instead, the value of trees, shrubs
and groundcover plants in the landscape has been realised for many reasons,
including their effect in reducing erosion.