Campbell Scientific Sentek TriSCAN® Manual v 1.2a - Manual (Page 34)

TriSCAN Manual Version 1.2a
Copyright © 1991 – 2004 Sentek Pty Ltd All rights reserved Page 27
Fertilizer types and application methods
It is essential that notice is taken of the fertilizer application method. The following factors should be taken
into account:
•
The position of the edge of the wetting pattern, where salts will accumulate
•
Points of concentration of fertilizer application, which vary according to application method eg. spot,
within-row, ring or band
•
Mineralization rates of fertilizers eg. animal manures, compost and urea.
Other micro zone selection considerations
There are several other factors when considering micro zone selection that need to be taken into
consideration. These are:
•
On sloping ground in drip irrigated situations, install the access tube below the emitter.
•
Do not install access tube in outside rows. These locations are usually exposed to wind and dust,.
•
Avoid the ‘drip ring’, for example, citrus orchards, where sprinkler irrigation water is channelled by
the canopy to the outside bottom edge of the foliage creating wetter soil conditions at the edge of
the canopy.
•
Avoid wheel tracks (and wheel track rows) as the soil is more compacted in these areas.
•
Inspect the site for any anomalies that could give an unrepresentative picture. These could include
fertilizer spillages, localized salt accumulation or localized drainage non-conformities.
•
If water application is not uniform due to uneven land surface, salts will accumulate in high spots
with little water penetration and leaching.
•
Water accumulating in low-lying areas causes waterlogging and indicat es potential drainage
problems.
•
With furrow irrigated crops, planted on raised beds, water movement is from the furrow into the bed.
Since water moves from the two furrows towards the centre of the bed, any salts present, move with
the water and tend to accumulate in the upper centre of the bed.
•
Salts also accumulate with localized irrigation at the soil surface between emitters, and at the
outside edges of the area wetted by the water applicators. .New plantings can also be affected, if
they take place into these salty areas without prior leaching.
Figure 7: Example of localized salt accumulation in furrow irrigation (after Ayars & Westcott)
Salt accumulation
Salt accumulation