WRC ESS Impact of climate variability on restoration and crop production in Stulwane, Bergville

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Impact of climate variability (heatwaves, rainfall variability) on
restoration and crop production in Stulwane, Bergville March 2023
The Institute of Natural Resources (INR) is undertaking some restoration demonstration activities at
Stulwane, in partnership with Mahlathini Development Foundation. Stulwane is located in the
Northern Drakensberg, about 20 km from the town of Winterton. Mahlathini has ongoing projects in
the area and has been working with a group of youth that were initially appointed as Ecochamps
through the Amanzi Ethu Nobontuprogramme.With technical guidance from the INR team, and
under the oversight of Mahlathini field staff, this group of youth have been busy with marking
contours, using a simple A-frame tool and constructing brushpacks from wattle that they have been
clearing in the vicinity of the gulley that they are stabilizing. They have been monitoring sediment
capture and revegetating the areas where the sediment is providing a good growing environment for
grass seed.
With the majority of the brushpacks in place, the decision was taken to use this site for collecting
information about how the interventions potentially reduce run-off and increase infiltration.
Sylvester Selala, who has installed run-off plans in conservation agriculture experiments for
Mahlathini, spent time with the youth group, explaining the
choice of positions for the run-off plots and developing a
monitoring process for measuring both rainfall and run-off. Two
of the young women that are part of the group have been
appointed by INR to record both rainfall and run-off figures after
any rainfall event. These are then sent through to INR for
analysis.
So far, the process has been interesting, but not without its
challenges. Intense storms accompanied by high winds and
heavy rainfall have disturbed some of the buckets, calling for
innovative solutions to keep the buckets in position.
Figure 1: Run-off plots have been installed at different positions within the
gulley that is being restored through the demonstration funded through the
WWF-PepsiCo upper uThukela Partnership.
The challenge with run-off plots is finding a way of placing them that provides an indication of run-
off within the broader landscape and
how the interventions are reducing the
run-off. Sylvester came up with the idea
of constructing ‘mini brushpacks’ within
one of the run-off plots to be able to
represent the broader landscape, as
shown in Figure 2.
Figure 2: Mini brushpacks constructed in one run-
off plot to allow for a comparison with the
adjacent plot.
Exploring the benefits of conservation agriculture with farmers
Besides their involvement with the restoration activities at Stulwane, Mahlathini is also supporting
farmer experimentation that is exploring conservation agriculture (CA). Rainfall during the 2022/23
season has shown a trend of late onset, with low monthly averages for October and November and
substantial rainfall in December. This is similar to the trends for the last three years. What is
different, is that rainfall for January was extremely low this season, providing a marked mid-season
drought effect. In addition, a heatwave was experienced.
The SAWS definition of a heat waveisthree consecutive days of max temperature at least 5C
warmer than the mean max of hottest month.The number of heatwaves are increasing over time as
shown in the graphbelow.
Figure 3: Annual heatwaves as recorded at the Mikes Pass weather stations 1948-2023.
The average temperatures of these heatwaves are normalising and increasing over time
Figure 4: Normalised average temperature of heatwaves at the mike’s Pass meteorological stations 1948-2023
In January 2023, we experienced aheat wave, one day below the threshold, followed by a four-day
heat wave. The max temperature during the Jan 2023 heat wave at Mike's Pass did not exceed 30C.
By late January, in Bergville, the majority of participants’ maize were showing signs of drought
stress. A few of the lead farmers, such as Phumelele Hlongwane, in Ezibomvini, however, were
spared and their crops remained vibrant. The two photographs below were both taken on the 24
January 2023. The homesteads of Cabangani Hlongwane and Phumelele Hlongwane are right next to
each other and their fields are separated by no more than 50m.
Both these farmers have been practicing CA since2014, however the sites have quite different soil
characteristics(some innate and some due to farmer’s management strategies), which is likely to be
responsible for the difference in the performance of the crops.
Phumelele’sfields have higher clay percentage (43% versus 27% for Cabanagani), N% (0.19 versus
0.15), organic carbon (2% versus 1.6%) and pH (5.1 versus 4.9). This set of photographs
demonstrates that CA improves the capacity of cropsto perform well even under circumstances of
mid-season dry spells, which are likely to become more common as we experience the impacts of
climate change, but only if all three principles of minimum tillage, increased soil cover and crop
diversification are diligently followed.
Figure 5: Maize showing heat stress in Cabangani Hlongwane’s CA plot (above) and Maize and cover crops looking vibrant
with good canopy cover in Phumelele Hlongwane’s field (below). Note: The pictures were taken on the same day and fields
are in very close proximity.
Besides measuring the impact of CA on yield and soil characteristics, Mahlathini has also been
exploring the impact of tillage practice on run-off. Participant farmers have been provided with
monitoring sheets to record rainfall events and run-off for their CA trials and their control plots.
Control plots were either ploughed and planted to mono-cropped maize or were a CA mono-
cropped maize plot. The CA trial plots were averaged for a maize and bean intercropped plot and a
maize only plot within the trial plot layout. Averages have been calculated for monthly rainfall and
runoff for each area as recorded by the participant farmers. The table below indicates the records
for the 7 Bergville participants, two of whomare from Stulwane.The difference in runoff between
the control and CA plots was not statistically significant.
Table 1: Summary of rainfall and runoff measurements for 7 participants in Bergville (October 2022-January 2023)
Village
Farmer
Rainfall
(mm)
Runoff Control
(litres)
Runoff CA trial
(litres)
Eqeleni
Sthabiso Manyathi
244,3
26,7
28,5
ThulisileZikode
474,0
15,3
19,0
Ezibomvini
Phumelele Hlongwane
392,5
24,7
23,6
Stulwane
Nelisiwe Msele
552,2
33,7
28,3
Nothile Zondi
458,9
63,6
74,8
Vimbukhalo
Sibongile Mpulo
387,0
13,1
13,1
Zweni Ndaba
418,5
14,1
21,8
418,2
27,3
29,9
0,21
Percentage rainfall conversion
7%
7%
The small tablebelow compares the annual runoff results for the last 4 years(2019-2023).
% Rainfall conversion to runoff (N=6-8)
Runoff CA trial plot (L)
Runoff control plot (L)
2019/2020
4%
7%
2020/2021
6%
11%
2021/2022
5%
7%
2022/2023
7%
7%
Average
5,5%
8%
For the last two years of exceptionally high rainfall, runoff between the CA trial and the conventional
control plots has been similar, unlike the previous years where there is markedly less runoff in the
CA trial plots. In addition, runoff from the trial plots are consistently free of sediment, which is not
the case with the conventionally tilled plots.
This indicates the positive effects of implementation of Conservation Agriculture on reduced runoff,
reduced sedimentation and increased infiltration, but also indicates the limits of this intervention
with really high levels of rainfall that lead to saturation of soil.