LETTERS
Correction to a statement in
the paper by Teague and Barnes
(2017) published in the AJRFS
Mick Gammon
Current Address: Port Alfred, South Africa
E-mail Address: [email protected]
Reprinted From: Original e-mail received from Dr Mick Gammon
The Editor: Grassroots,
Having an undying love for the veld and
having devoted much of my life to veld
management research and extension, I
do not want to be branded as someone
whose work has promoted continuous
grazing. Please could you place in the
next edition of Grassroots my correction
to the the following statement in the pa-
per by Teague and Barnes (2017) in the
African Journal of Range and Forage
Science 34: 77 - 86 :
“Most, but not all, grazing studies in the
scientific literature have concluded that
rotational grazing is no better than light
continuous (season-long) grazing (Gam-
mon and Roberts 1978: Gammon 1984
...”
While this has been the conclusion from
some studies, it is not a correct state-
ment of our conclusions. The studies of
patterns of defoliation during continu-
ous and rotational grazing (Gammon
and Roberts 1978) were in three parts:
1. Selectivity of grazing. 2. Severity of
Defoliation. 3. Frequency of Defolia-
tion. In a paddock chosen to offer three
distinctly different veld types, with fur-
ther marked variation between species
within veld types, similar patterns of se-
lection between and within veld types
occurred in the two methods of man-
agement. Truly non-selective grazing
has never been recorded in this highly
heterogeneous veld under any form of
management. By the end of the grow-
ing season the heights of defoliation
were 1 to 3 cm lower under continuous
grazing for most of the major species.
Under continuous grazing frequencies
of defoliation were greater, with 5.7 %
to 11.1 % of the tillers of the most pal-
atable species receiving more than 3
defoliations during the growing season;
none were recorded as receiving more
than 3 defoliations under rotational
grazing. However, under continuous
grazing more than 75% of the tillers of
Grassroots
Vol 18
No 1
each of the major species received less
than 3 defoliations during the growing
season; of these, 21% to 40% were un-
grazed during the growing season.
Considering the indications from rel-
evant clipping trials, it was concluded
that, under continuous grazing by cattle
at moderate stocking rates, slow dete-
rioration of the veld would occur, due to
frequent defoliation of a small propor-
tion of the most palatable species; that,
due to the lenient defoliation of the vast
majority of the sward under continuous
grazing, only moderate increases in
herbage production could be expected
through manipulation of the pattern of
defoliation by other methods of man-
agement.
In interpreting the results of these stud-
ies it should be noted that the form of
rotational grazing applied was a far cry
from the management currently applied
in Holistic Planned Grazing or Adaptive
Multi-paddock Grazing. The treatment
applied was a simulation of Short Dura-
tion Grazing (SDG) with 6 paddocks and
grazing periods ranging from 6 days ini-
tially to 12 days later in the season. The
stocking rate was 10% higher than was
normally recommended for that veld
in good condition. It is interesting to
note that the claims made at that time
for this level of SDG were very similar to
the current claims for far more intensive
management applied under HRM.
The second study referred to in the
above statement (Gammon 1984) did
not in fact involve a comparison with
continuous grazing. Rather, it reported
on comparisons of veld condition on
ranches in Zimbabwe that had applied
intensive SDG with 14 to 42 paddocks
per herd for up to 12 years, with that on
neighbouring ranches applying less in-
tensive management, varying from SDG
with 6 paddocks to rotational resting.
Included in the sample was what was re-
ferred to as the “Advanced Project”, in
March 2018
which adaptive SDG was applied in a 32
- paddock, cartwheel layout on Liebigs
Ranch. Briefly, it was found that the ar-
eas under intensive SDG were not mark-
edly or consistently in better condition
than adjacent less intensively managed
areas.
After discussion of the results, in par-
ticular the case of the Advanced Pro-
ject, and after considering stocking rate
and rainfall effects, the results of experi-
mental comparisons of grazing systems,
factors affecting herbage production
and animal performance, the effects of
numbers of paddocks on grazing varia-
bles, and paddock size and layout, com-
prehensive conclusions were made. The
initial statements of these conclusions
were, “Some form of rotational grazing
and resting of veld is essential if it is to
be maintained in good condition or re-
claimed. SDG, which starts at the point
of prevention of over grazing, is prob-
ably the most effective, practical and
flexible method for most situations.”
References:
•
•
•
Gammon DM. 1984. An appraisal of
short duration grazing as a method
of veld management. Zimbabwe
Agricultural Journal 81: 59 - 64.
Gammon DM, Roberts BR. 1978.
Patterns of defoliation during con-
tinuous and rotational grazing of
the Matopos Sandveld of Rhodesia.
1. Selectivity of grazing. 2. Severity
of defoliation. 3. Frequency of defo-
liation. Rhodesia Journal of Agricul-
tural Research 16: 117 - 164.
Teague R, Barnes M. 2017. Graz-
ing management that regenerates
ecosystem function and grazing-
land livelihoods. African Journal of
Range and Forage Science. 34: 77
- 86.
Kind regards,
Mick Gammon
04