Thesis (M.Sc.(Agronomy)) --University of Limpopo, 2015 / The changes in climate, especially poor rainfall patterns and distributions are key
issues posing major agricultural challenges for food security and threaten the rural
livelihoods of many communities in the Limpopo Province. Rainfall (P) is low and
limited. These limited P is mostly lost through runoff and evaporation, which result in
low soil moisture availability and possible crop failure. Therefore, techniques that
reduce these water losses are important for improving dryland crop production and
rainwater productivity (RWP). The objectives of this study were to determine the
potential and effectiveness of rainwater harvesting and conservation techniques
(RWH&CT’s) to conserve and improve plant available water (PAW) for dryland maize
production and also determine the efficiency of the RWH&CT’s to improve dryland
maize yield and RWP compared to conventional tillage (CON). The study was
conducted over a period of two growing seasons (2008/09; 2009/10) using maize as
indicator crop at the Towoomba Research Station of the Limpopo Department of
Agriculture in the Limpopo Province of South Africa, on an Arcadia ecotope. The
experiment was laid out in a randomized complete block design, with four
replications and five treatments. The five treatments used in the study were;
conventional tillage (CON), No-till (NT), In-field rainwater harvesting (IRWH),
Mechanized basins (MB) and Daling plough (DAL). The IRWH and DL were
classified as rainwater harvesting techniques (RWHT’s), whilst MB and NT were
classified as water conservation techniques. Two access tubes were installed at
each treatment to measure the soil water content (SWC) at four different soil depths
of 150, 450, 750 and 1050 mm using the neutron water meter. The data collected
included climatic data, soil and plant parameters. The data were subjected to
analysis of variance through NCSS 2000 Statistical System for Windows and
GENSTAT 14th edition. Mean separation tests were computed using Fisher's
protected least significant difference test. The SWC of IRWH, DAL and MB were
about 510 and 490 mm higher compared to CON and NT treatment during the
2008/09 and 2009/10 seasons, respectively. The PAWT of the IRWH, MB and DAL
was significantly different from the CON treatment during the 2008/09 season. For
both seasons the biomass yield of the IRWH treatment was significantly different
from the NT treatment, producing 23 and 50% more biomass in the 2008/09 and
2009/10 growing seasons, respectively. The grain yield under IRWH was significantly
different from the NT treatment during both 2008/09 and 2009/10 seasons. The
highest maize grain yield of IRWH was achieved during the 2009/10 season with
56% higher grain yield than the NT treatment. RWP from various RWHT’s were
significantly different from the NT treatment. These results indicate that IRWH and
DAL were 12 and 2% more effective in converting rainwater into harvestable grain
yield than the CON treatment. R2 values of 68.6 and 78.4% for SWC and
transpiration (Ev) were obtained when correlated with maize grain yield respectively.
This indicates the importance of moisture conservation for improved dryland maize
production under low P areas. Therefore, the use of appropriate RWHT’s by smallscale
farmers maybe crucial to improve dryland maize production. IRWH
outperformed all other treatments in terms of the soil parameters and plant
parameter measured during the period of this study. Therefore, these results suggest
IRWH has potential of sustaining maize yields under low rainfall conditions.
Key words: Rainwater harvesting, conservation techniques, ecotope, rainwater
productivity, maize yield, precipitation use efficiency.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ul/oai:ulspace.ul.ac.za:10386/1407 |
| Date | 31 March 2015 |
| Creators | Ngwepe, Mantlo Richard |
| Contributors | Botha, J. J., Mariga, I. K. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | xiv, 79 leaves |
| Relation |
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