Report number 4 on the results
of re-vegetation by means of hydromulching at Duck Creek Farm
A northerly facing cut face of an angle exceeding 45 degrees
approximately 90 x 2.5 metres. Due to the northerly aspect and the
steep angle of the
slope the site tends to remain dry even during periods of high
1 June 2006
Evaluation of the site on the 16 October 2006
During the four weeks following the last inspection the site received
frequent and adequate precipitation. Although there had been good
precipitation on the days prior to the inspection most of the upper
section of the bank was found to still be very dry.
On the steepest driest sections of the slope there has been further
massive mechanical failure where whole sections of the upper the bank
have become dislodged. It has become very clear that exceeding the
angle of repose on these sections is responsible for the collapse of
the upper portions of
the bank. This can be clearly seen in the accompanying photographs.
On inspection of the site it was found that good growth has continued
on the lower two thirds to three quarters of the slope. There has been
or no germination of the seed applied, most of which still remains
to the slope in a band along most of the upper slope in the root zone
the vegetation growing above..
The more northwest facing sections of the site have as expected
continued to shown inferior results. A fair amount of germination of
the other seeds applied has occurred in particular flax. In some areas
bent and other grasses with a creeping habit have crept down the slope
from the top.
300 g of Nitrophoska 12% N, 10% P, 10%K, 4.6 % Ca, 1.2 % Mg fertilizer
was distributed over the entire area that was seeded.
The results are satisfactory although not as good as expected. This is
due to a number of factors. Firstly the slope is too steep for the soil
type, which quickly dries out and becomes crumbly. This caused it to
unstable and to collapse before the vegetation could develop a deep
root system to give it some support. The soil type and structure also
moisture from penetrating deep into the soil, causing the slope to dry
rapidly. Even immediately after periods of heavy rain most of the slope
remained fairly dry. The dense band of vegetation that has been
at the base of the bank is acting as an effective filter in preventing
that is becoming dislodged from the bank from washing off of the site
the water coarse below.
The fertility levels should be kept at a level that ensure continued
healthy growth so as to continue the natural heeling process that has
been initiated, stock should be kept off of this area for as long as is
possible to help
continue this process.
Recommendations for future sites
The mechanical failure of the slope that has been encountered, which
contributed to a partial failure of the seeding operation could be
avoided in future
if the slopes can be kept a little more moderate in particular where
soils have a texture and structure, which causes them to crumble when
As most damage occurred on the upper quarter of the slope a further
reduction of the angle of the slope in this area would greatly help
prevent the problem of mechanical failure of the slope. This reduction
in the slope angle would also greatly increase the moisture available
to the seeds both for germination as well as their continued growth, in
addition it reduces competition between the establishing and
established vegetation above. This would go a long
way towards preventing the poor development in these areas as
on this test site.
From the valuable experience gained at this site I recommend that
further work of this nature implement my recommendations above and that
the hydroseeding be carried out shortly before the first rains are
expected in the autumn
to obtain the best results.