African
Journals Online
UNISWA Research
Journal of Agriculture, Science and Technology
VOLUME 3 No. 1 July
1999
Spatial Analysis of Soil Erosion in
Swaziland
Absalom M. Manyatsi
ABSTRACT
In this paper a spatial analysis was undertaken to
identify the impact of the factors controlling soil
erosion: land management systems, stocking pressure, soil
erodibility, average slope of the land, and mean annual
rainfall. A binary classification was applied to a broad
land cover classes map produced from image classification
to separate the land cover classes into “eroded
lands” and “non-eroded lands” in the
country. The relationships between the proportions of
land eroded in each dip-tank area and the five factors
controlling erosion were investigated. A case study site
was selected to determine the distribution of soil
erosion in relation to proximity to dip-tanks, watering
points, and homesteads.
Flood Peak Estimation Using
Rainfall Run off Models
Jonathan I. Matondo
ABSTRACT
The design of hydraulic structures such as road
culverts, road bridges and dam spillways requires the
determination of the design food peak. Two approaches are
available in the determination of the design flood peak
and these are: flood frequency analysis and rainfall
runoff models. Flood frequency analysis requires a
selection of an appropriate probability distribution
function and the availability of a long record of
instantaneous flows and therefore, is not appropriate for
the estimation of a design flood peak for catchments with
no flow measurements. Rainfall runoff models on the other
hand do not require the availability of stream flow data
for the estimation of the design flood magnitude. They
only require rainfall data and the physical
characteristics of the catchment as input variables. Five
rainfall runoff models (rational formula, synthetic unit
hydrograph, TRRL East African Model, HEC-1 Model and
MULTSED Model) have been used for the estimation of the
50 year design flood peak for the Sinza river in
Tanzania. Simulated design flood peak values (50-yr
flood) range from 37.6 to 44.34 m/s and have a standard
deviation of 2.4m/s and therefore, are regarded as
satisfactory.
A simple Micro-relief Meter for
Estimating Surface Roughness and Rilled Layer Porosity
E.J. Mwendera and J. Feyen
ABSTRACT
A simple micro-relief meter which can be operated by
one person and be used both in the field and the
laboratory was designed and used to measure the surface
micro-relief of ploughed (P), ploughed and then harrowed
(PH), and ploughed, harrowed and then rolled (PHR) soils.
The measurements were used to estimate the plough layer
porosity of the tilled soils. The estimated values of
tilled layer porosity (P) were compared with those
determined in a laboratory from 100 cubic cm core samples
and from water retention curves (WRC) of the soils. The
results showed that both WRC and core methods gave
significantly lower values of P for the ploughed soil,
which the WRC method consistently gave lower values of P
for all the tilled soils. The results indicated that such
a meter can be used to characterize surface roughness of
tilled soils and that the micro-relief measurement method
can give reasonable estimates of the porosity of freshly
tilled soils with rough structures dominated by large
clods and often loose soil material.
Farmers' Knowledge and Cultivation
of Bambara Groundnut [Vigna subtarranea(L) Verdc.] in
Swaziland
1A. Sesay, I.S. Kunene and D.M. Earnshaw
ABSTRACT
A country-wide farmers' survey was carried out in 1998
among 124 subsistence farmers in the 18 Rural Development
Areas (RDAs) in Swaziland. The objective of the survey
was to provide baseline information on the cultivation of
bambara groundnut, (jugo beans), (Vigna subterranean) by
subsistence farmers, as part of the first phase of
proposed multi-disciplinary research programme on the
crop at the University of Swaziland. The results
highlight the importance of bambara groundnut in
Swaziland and the knowledge of the crop that exists among
subsistence farmers. The crop has survived generations of
cultivation as a subsistence crop and has remained a
popular and important food and cash crop throughout the
country. Eighty-nine percent of the farmers interviewed
were either growing the crop in the 1997/98 cropping
season or had done so in the past. Bambara groundnut is
grown mainly by women, and mainly in the Manzini and
Lubombo regions, and in the Middleveld and Lowveld
agro-ecological zones. Nevertheless, the crop has
received little scientific attention in Swaziland.
Traditional beliefs are still deeply rooted in the rural
agricultural communities and impact on the cultivation of
bambara groundnut. Farm yields are low, and over the
years, there has been a decline in the area under bambara
groundnut. However, 98% of all farmers interviewed would
like to see the crop developed and its production
increased. This would contribute to crop diversification,
farm income and food security in Swaziland.
Heterosis in Swazi-bred Maize
Hybrids: The 1993 and 1994 Test Hybrids
Roger C. Kuhn
ABSTRACT
Maize is the staple food crop of Swaziland and most
farmers use hybrid cultivars. A small scale maize
breeding project was started in 1986 to develop local
cultivars. Inbred lines have been developed, mostly from
local and international maize and what improvement center
(CIMMYT) open pollinated cultivars. Single cross test
hybrids made in 1993 among these inbred lines (mostly S
and S lines) were yield tested in two replications with
parental and commercial checks in the 1993/94 and 1994/95
trial also included single cross test hybrids made in
1994. Trial mean grain yield was 5.5 Mg/ha in 1993/94 and
4.8 Mg/ha in 1994/95. The top yielder was a test hybrid
in both growing seasons, TH9308 in 1993/94 and TH9401 in
1994/95. TH9308 was the second highest yielder in 1994;
and one other test hybrid, TH9308 and TH9401 both
resulted from CIMMYT X Local single crosses. Thus, this
breeding project has identified high yielding locally
developed hybrids that appear to be stable for Luyento.
However, if Swaziland was sustained development of local
cultivars it will need to start a full scale national
maize breeding program.
Popping Quality and Acceptability
of Sorghum Pops in Selected Sorghum (Sorghum
bicolor (L) Moench) Genotypes
B. Tiisekwa, P.P. Magagula and M.S. Mkhabela
ABSTRACT
Forty sorghum genotypes comprising five local and 35
introductions were evaluated for physical, popping
qualities and grain yield. Twenty five of the forty
genotypes were further characterized for sensory and
acceptability qualities. The study revealed genotypic
differences in grain yield, grain physical
characteristics and popping qualities. Grain yield ranged
from 751 to 2861 kg ha-1, with only 10 percent of the
genotypes had grain yield of more than 2000 kg ha-1.
Popping yield ranged from 61 to 95 percent and 25 percent
of the genotypes yielding above 90 percent. More than 50
percent of the genotypes had popped volume of 12 to 14.3
mililitres (ml). Sorghum pops prepared from the genotype
80c 2241, MR114-90M11 and SDSH 49 were the most preferred
for color, while TX2767 was most preferred for both
texture and taste. These genotypes were accepted with a
high hedonic rating of between like very much to like
extremely. These genotypes were among the top eight in
popping yield rating. The most liked sorghum pops were
those that were prepared from the white colored sorghum
genotypes, while the red and particularly the brown
colored ones were least liked for both color and taste.
Generally the sorghum introductions were superior in
popping and acceptability qualities than the local
cultivars. Based on these results it is recommended that
farmers should be encouraged to grow the top ranking
genotypes for preparation of their traditional foods as
well as for popping purposes.
Response of Cowpea (Vigna
unguiculata (L) Walp) to Nitrogen Fertilizers and
Leaf Plucking Frequencies
M.S. Dlamini and O.T. Edje
ABSTRACT
Cowpea (Vigna unguiculata) seeds and leaves are
an important item in the diet of most farmers in the
tropics. The tender and succulent leaves are generally
plucked and used as green vegetables until about
flowering, when leaf plucking stops. Defoliation may
adversely affect seed yield due to reduction in
photosynthetic area. One possible means of reducing the
adverse effects of defoliation on seed yield is, to apply
additional nitrogen fertilizer to stimulate vegetable
growth, hence this experiment. The effects of three
nitrogen levels (0,50 and 100 kg/ha) and four leaf
plucking treatments (no plucking, plucking once a week,
once in two weeks and once in three weeks) on leaf and
seed yield of cowpeas were investigated at the University
of Swaziland, Faculty of Agriculture, Luyengo during the
1997/98 growing season. The design of the trial was
randomized complete block with twelve treatment
combinations and each was replicated three times. Data
collected included canopy height and width, area of
plucked leaves, fresh and dry weight of plucked leaves,
100-seed mass, seed yield and monetary value of seeds and
leaves. Data showed that additional nitrogen increased
seed yield significantly (P<0.01). Plucking cowpea
leaves weekly had more adverse effect on seed yield than
the other leaf plucking treatments. Leaf area and
100-seed weight were the yield components mostly affected
by leaf plucking. Although leaf plucking caused reduction
in seed yield, the combined monetary value of seeds and
plucked fresh leaves was generally higher than those from
unplucked plants. The implications of these findings for
farmers who utilize both leaves and seeds for relish are
discussed.
Studies with Water Absorbing
Polymers: II Nitrogen Retention Capacity and
Effects on Phaseolus Bean Development, Growth and Yield
O.T. Edje and J.M. Hlatshwayo
ABSTRACT
Agrogel is a water absorbing polymer that swells and
forms gelatinous mass with water. The mass can retain
water and nutrients and release it slowly over time.
These characteristics have stimulated interest in their
use, especially for greenhouse crop production, where
watering is frequent resulting in leaching of soil
nutrients. The experiment reported below was designed to
investigate the effects of polymer on nitrogen retention
and on yield of Phaseolus beans. The greenhouse
experiment consisted of two polymer levels (no polymer
and 1.5g polymer per kg of sand), two nitrogen sources
(urea and limestone ammonium nitrate) and three levels of
each {0. 30 and 60 kg/ha N}. The medium was river sand
and bean seeds were sown in pots. Results showed that
treatments with polymer retained 33.3% significantly
[P<0.01] more nitrogen compared to the control and
nitrogen retention in urea form was 10% higher compared
to that from limestone ammonium nitrate. The highest seed
yield, of 1862 kg/ha, was obtained with the treatment
combination containing polymer with 30kg ha N from the
urea source.
Effects of Plant Population and
Tiller Number on the Growth and Yield of Pearl
Millet (Pennisetum typhoides (Burm). Stapf and Hubb)
S.K. Karikari and S. Ngwako
ABSTRACT
A study was undertaken at the Botswana College of
Agriculture to evaluate the effect of plant population
and tiller number on the growth and yield of millet (Pennisetum
typoides), variety Serere 6A. The plant populations
were 166,000 250,000 and 500,000 plants/ha and tiller
numbers of one, three and five were maintained and
compared to a control where tiller production was not
regulated. Grain yield was significantly (p<0.05)
reduced at low and increased at high population
densities. Dry matter was however, higher at low than
high densities due to more tiller production at low
densities. Maintaining three tillers per stand increased
grain yield by 40% but maintaining five tillers or
reducing tillers to one did not increase yield
significantly and was similar to control in which tiller
number were not regulated.
The grain yield advantage of maintaining a few tillers
is due to the fact that not all tillers produced heads
and those that did not produce heads were parasitic on
the main shoot for resources. Interplant competition
possibly for nutrients as too many heads were formed was
detrimental to grain yield. This experiment indicates
that farmers growing millet in Botswana and areas with
similar climate could increase yields by planting at
higher populations and regulating tiller production.
Effect of early and Late Feed
Restriction on Compensantory Ability of Broilers
Andrews C.L. Safalaoh
ABSTRACT
An experiment was conducted to determine the effect of
early versus late feed restriction on growth
characteristics of broilers. Treatments used were full
feed control and 55% quantitative feed restriction which
was initiated between 7 and 21 days and between 21 and 35
days. The quantitative feed restriction was based on the
previous 24 hour voluntary feed intake values of
full-feed control birds.
Complete compensatory growth was not accomplished by
the feed restricted birds relative to the full feed
controls at day 49. Full-feed control birds had
significantly (P<0.5) higher body weights (2469 g)
than early (2342g) and late (2262g) restricted birds.
Body weights of restricted birds were not significantly
different. Although attainment of growth compensation was
not achieved in previously restricted birds, accelerated
growth was observed immediately following
re-alimentation. The accelerated growth was accompanied
significantly (P<0.5) higher feed intakes and superior
feed efficiency relative to control birds during the
refeeding period. Although feed restriction significantly
(P<.01) improved overall feed conversion (g, feed: g,
body weight gain) of early (1.86) and late (1.80)
restricted birds, these benefits were not reflected in
final body weights.
Both early and late feed restriction regimes resulted
in significantly (P<.05) lower abdominal fat pads
compared to control birds. This study shows that 14 day
long feed restriction periods imposed during early and
late broiler growth are too severe for birds to exhibit
full compensatory growth during refeeding periods. Milder
feed restriction and shorter feed restriction periods may
be necessary to achieve full growth compensation.
An evaluation of the Methylene
Blue Reduction Method Used for Raw Milk Quality
Control in Swaziland
Dlamini A.M.
ABSTRACT
The accuracy of the methylene blue reduction test to
grade the bacteriological quality of raw milk in
Swaziland was evaluated. Milk samples 9130) taken from
raw milk received at Swaziland Dairy Board processing
plant were analyzed for dye reduction and plate counts.
Samples were highest in Psychotrophic counts (10 cfu/ml)
and lowest in thermoduric counts (10 cfu/ml). Regression
relationship between log plate counts and dye reduction
times were poor. The regression relationship between
these two tests was not consistent to support continual
use of the methylene blue test as an estimate of
bacterial counts. Correlation coefficient values were
also low (r=0.44 to 0.69). Standard errors of estimates
were very high (0.40 to 1.91). This supported the
conclusion that the methylene blue test did not
accurately estimate the bacterial load of the raw milk in
Swaziland.
A Comparison of the Growth and
Milk Conversion Rates of Lambs and Goat Kids in
Malawi
J.W. Banda
ABSTRACT
Growth rate of local (LL), Dorper (DD) and crossbred
(DL) lambs and of local (LL) Boer (BB) and crossbread
(BL) goat kids were studies over two seasons of
kidding/lambing until 24 weeks of age. The kids
and lambs suckled their dams indoors for one month.
Thereafter, both the dams and the young grazed natural
pastures, but were also provided with a concentrate. The
mean birth weight, weaning weight at 17 weeks of age and
preweaning daily liveweight gains for lambs were 3.19
plus/minus 0.05 kg, 18.5 kg, 18.5 plus/minus 0.32 kg and
128.9 plus/minus 2.5 g. Postweaning weights and weight
gains were 24.5 plus/minu 0.38 kg and 80.9 plus/minus 4.5
g, respectively. Season of lambing and genotype exerted
significant influences on all traits. The mean birth
weight weaning weight at 17 weeks of age and preweaning
daily live weight gains for goat kids were 2.77
plus/minus 0.08 kg, 13.0 plus/minus 0.41 kg and 87.0
plus/minus 3.5g. Postweaning weights and weight gains
were 20.0 plus/minus 0.57 kg and 55.1 plus/minus 3.8g,
respectively. Season of kidding had a significant effect
on all the traits, but genotype affected only kid birth
weight. Milk conversion was 0.084 kg/kg milk (P<0.001)
for lambs and 0.064 kg/kg milk (P<0.001) for kids.
Generally, the performance lambs was significantly to
(P<0.001) higher at all growth stages than that of
kids. Although the recommendation for meat production
favors lambs due to faster growth, it is important that
this recommendation be based on biological efficiencies
which should include the dam weights, milk production,
mortality and reproductive performance of both species.
Lactation Pattern and Milk
Composition of Sheep and Goats in Malawi
J.W. Banda
ABSTRACT
The pattern of lactation and the composition of milk
of local goats (LL) Boer goats (BB) and their crossbreds
(BL) and of local sheep (LL), Dorper sheep (DD) and their
crossbreds (DL) were studied over two seasons of
kidding/lambing for the first 12 weeks of lactation.
Stage of lactation significantly (P<0.01) affected the
pattern of lactation. The milk yields of goats increased
from 1021 plus/minus 35 to a maximum of 1123 plus/minus
35g at Two weeks and decreased thereafter to 795
plus/minus 35 at the end of the measurement period at 12
weeks (P<0.001). The daily yields of sheep, on the
other hand, decreased from 819 plus/minus 20 g at the
beginning of the lactation to 559 plus/minus 20 g at the
end. The differences between the species and at all
stages of lactation were highly significant (P<0.001).
The overal mean levels of total solids, fat,
solids-non-fat (SNF), ash, protein, lactose and energy
for goats were 17.4%, 6.8%, 10.6%, 0.88%, 4.5%, 4.7% and
4.44 MJ/kg, respectively. The respective values for sheep
were 18.3%, 6.0%, 12.3%, 0.94%, 5.2%, 4.9% and 4.39
MJ/kg. There were significant species differences
(P<0.001) in all the variables except energy content.
It is concluded that goats may be the more suitable
species to be used for milk production due to their
better lactational performance.
Evaluation of the Artificial
Insemination Programme for Small Scale Dairy Farms
in Malawi
Chagunda, M.G., C.B.A. Wollny, E. Bruns and L.A.
Kamwanja
ABSTRACT
A study was conducted to examine the current status of
the artificial insemination (A1) program in Malawi. Data
available from the Blantyre milk-shed area showed that
the Government controlled artificial insemination program
applies a breed substitution strategy resulting in an
increase of high grade Holstein-Friesian x Malawi Zebu
crosses (>7/8 Friesian) from n=388 in 1985 to n=1228
in 1994. The semen is locally produced at the national A1
centre. Data for the estimation of breeding values of
sires is not available. Pedigree breeding or rotational
crossbreeding is not conducted. The annual number of
inseminations per A1 technician was very low (average 1
45 p.a.) suggesting low efficiency of the program.
Logistics were the most significant constraint.
Information from the study suggest that the artificial
insemination program for the small scale farmers in
Malawi requires a thorough revision. An inventory of the
Malawian diary cattle population and its genetic
composition are recommended to provide basic information
for the development of an appropriate breeding program. A
cost effective recording scheme is needed to provide
meaningful data on the biological and economic efficiency
of dairy cattle production in the small scale sector in
Malawi.
Evaluation of the Performance of
the Malawian Local Pig:1 Reproduction
J.P. Mapemba, R.K.D. Phoya and C.B.A. Wollny
ABSTRACT
10 sows and two boars bought from smallholder farmers
in Salima, Ntcheu and Dedza districts of Malawi were used
as a foundation breeding stock on station. 129 piglets
were farrowed over two mating periods. Litter sizes at
birth were 7.3 plus/minus 2.5 and 9.2 plus/minus 4.2
respectively. Litter size at weaning for the two mating
periods was similar and averaged 6.3 plus/minus 1.9.
Piglet mortality in the first mating period and second
mating period were 13.8% and 32.4% respectively. An
antagonistic relationship between litter size at birth
and survival rate could be assumed. Causes of piglet
mortality were stillbirths, crushing due to sow behavior,
starvation and weakness. Stillbirths accounted for 3.5%
and 25.5% in the first mating period and second mating
period respectively. Insufficient nutrition was
considered as an immediate factor contributing to large
number of stillbirths in the second mating period.
Reproductive performance of the pigs in this study
compare favorably with most of the African breeds. High
coefficients of variation of litter size at birth and
weaning indicate high pheno-typic variability.
Evaluation of the Performance of
the Malawian Local Pig: 2. Pre-weaning and
Post-weaning Growth
J.P. Mapemba, C.B.A. Wollny and R.K.D. Phoya
ABSTRACT
About 130 (129) piglets of the Malawian local type
were used to study the pre-weaning growth traits, birth
weight, weaning weight and pre-weaaning average daily
gain. Birth weight, weaning weight and pre-weaning
average daily gain averaged 1.0 kg plus/minus 0.3,5.5 kg
plus/minus 1.1 and 125 g/day plus/minus 35.0
respectively. After weaning, 36 weaners were fattened to
45 kg of liveweight. Postweaning daily gain, daily feed
intake, geed: gain ratio and age at 45 kg of liveweight
averaged 232 g/day plus/minus 44.5, 1.3 kg plus/minus
0.2, 5.9 kg/kg plus/minus 2.1 and 209 days plus/minus
23.4 respectively. The growth performance of the pigs in
this study are within the range of local pig populations
in Africa. A remarkable phenotypic variation of growth
parameters was observed. It is concluded, that the
performance could be improved through feeding and
management in the short term and through genetic
selection within the population in the long-term. The
local pig in Malawi should be kept as genetic resource.
Carcass Characteristics of Boer x
Malawi Crossbred Goats at Different Slaughter
Weights
E. Otsogile, R.K.D. Phoya, M.W. Mfitilodze, and
J.W. Banda
ABSTRACT
The developmental patterns of carcass traits were
studied in _ and 3/4 Boer x Malawi crossbred goats
slaughtered at 30, 35 and 40 kg live weights. Empty body,
hot and cold carclass weights, and head proportions
differed among the three slaughter groups. There were no
significant differences in carcass and total internal fat
proportions among slaughter groups or between genotypes.
Leg length and circumference were different among all
groups, being higher (P<0.05) in goats slaughtered at
heavier weights. However, lean to bone, lean+fat to bone
ratios were higher (P<0.05) in goats slaughtered at 40
and 35 kg than 30 kg. Dressing out percentage increased
significantly from 47.77% in the 30 kg to 52.88% in the
40 kg group. The total weight of edible and seleable
components (portions) also differed among the groups.
There were no significan t differences in skin, feet,
edible, and seable proportions, and rib eye muscle among
slaughter groups. There were also no differences in
carcass characteristics between the two genotypes. It is
concluded that it is possible to raise Boer x Malawi
crossbred goats to higher slaughter weights to realise
heavier carcasses with higher meat yields, which can
contribute to increased animal protein availability and
income per animal.
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