On-farm performance of selected improved forage varieties under smallholder farming conditions in the Southern Highlands of Tanzania
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Date
2024
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Publisher
Sokoine University of Agriculture
Abstract
Scarcity of high-quality forages especial in dry season, hinders the
development of the dairy industry in Tanzania. Adopting improved forage
varieties is viewed as a breakthrough for smallholders in dairy-producing
areas such as the Southern Highlands of Tanzania. The study was
conducted to assess selected soil properties of pasture plots, and the
performance of improved forage varieties in smallholder farming settings
in Southern Highlands of Tanzania. The Highlands are located between
6° and 12° S latitudes and longitude 29° to 38°E, receive 823-2850 mm
of rainfall annually from November to April, and have a mean annual
temperature of 13°C-19°C. Two wards per district: Igowole and Mtwango
(Mufindi), Ikuna and Kichiwa (Njombe) and Kiwira and Lufingo (Rungwe)
were selected for the study. From 101 randomly interviewed
respondents, 38 households with >0.1 acres pasture plots were
purposively picked for soil performance study, meanwhile 30 among 38
households, with set of Brachiaria hybrid cvs. Cayman and Cobra and P.
purpureum cvs. ILRI 16835 and Ouma, were purposively picked for
forage performance study. Soil auger was used to draw soil samples at
0-20 cm and 21-50 cm depths. Composite soil samples per depths per
plot were sent to Lab, air-dried for a week and sieved to pass through 2
mm sieve. In Lab soil sample were analysed for, Texture by hydrometer
method, soil pH by pH meter in 1:2.5 soil-water suspension and 1N KCl,
Total Nitrogen (TN) by Kjeldahl method, Available P by Bray method
since the soil was acidic, Exchangeable Calcium [Ca2+] and Magnesium
[Mg+] by atomic absorption spectrophotometer and Exchangeable
Sodium [Na+] and Potassium [K+] by flame photometer. Prior evaluation
of forage performance, swards of Brachiaria hybrid and P. purpureum
cultivars were standardised at 5 cm and 7 cm stubble cut, respectively.
Data for forage growth, biomass yield and nutritional values, were
collected from 4 m2 sampling unit per cultivar per plot, at the end of each
of the two phases of 6-weeks. Six plants were randomly selected in each
sampling unit and a tape measure was used to measure the height from
ground level to plant tip (inflorescence excluded), length and width of the
constantly third-from-top leaf were measured. Live and sprouting tillers
from each plant's shoot were counted for tiller numbers. Sampling unit harvest used to estimate biomass yield per-hectare. 300 g fresh forage
sample from each plot was weighed, air-dried at 65 oC for 48 hours and
ground to pass a 1 mm sieve. Association of Official Analytical Chemists
standard procedures were used to analyse oven-dry matter (DM) (ID
930.15), Ash (ID 942.05), Crude protein (CP) by Kjeldahl method (ID
954.01), neutral detergent fiber (NDF) and acid detergent fiber (ADF)
were analysed using Van Soest procedures. Soil pH, TN, available P-,
exchangeable cations (K+, Ca2+, Mg+ and Na+), and particle sizes (clay,
silt, and sand) were analysed using ANOVA type III mixed effect model:
Y = Soil depth (Fixed) + District (Fixed) + Soil depth*District (Fixed) +
Ward (Random) + Residual error. Tukey's method compared mean soil
parameters across soil depths and districts and P<0.05 was deemed
significant. Kruskal-Wallis H test was used to analyse and compare
median plant height, leaf length and width, tiller numbers, and forage
biomass yield. DM, Ash, CP, NDF and ADF were analysed using an
ANOVA mixed effect model: Y = Cultivar (Fixed) + Growth phase
(Random) + Ward (Random) + Residual error. Tukey's method was used
to compare cultivars' mean nutritional characteristics at p 0.05. Selected
soil properties varied significantly (p<0.05) by depth and district. All
districts had acidic soil pH (<5.5) in two soil depths except Rungwe,
which was medium. TN was generally medium (0.2-0.3%) in all districts.
Available P was medium in Mufindi (8.7 mg/kg), but was low in Njombe
(2.9 mg/kg), and Rungwe (0.03 mg/kg). Exchangeable K + was in
borderline (0.2 Cmol+/kg) between medium and low values in Mufindi
and Njombe, but medium in Rungwe (0.6 Cmol+/kg). Plant height, leaf
length and number of tillers among cultivars varied significantly (p<0.05).
Cayman (28.8 cm) and Cobra (26.6 cm) had shorter plant height than
ILRI 16835 (50.7 cm) and Ouma (56.4 cm). Cobra and Cayman (21 cm
both) had shorter leaf length than ILRI 16835 (46.7 cm) and Ouma (47.6
cm). Cayman (64) and Cobra (67) had the highest numbers of tiller than
ILRI 16835 (22) and Ouma (21). Cayman had the widest leaf width (2.1
cm) while Ouma had the lowest (1.7 cm). Above-ground forage biomass
DM and ash contents were not statistically different (p>0.05) among
cultivars. NDF and ADF varied between cultivars (p<0.05). Cayman had
the lowest NDF and ADF values (539 g kg-1 DM) and (256 g kg-1 DM) compared to other cultivars (545-571 g kg -1 DM), and (264-292 g kg-1
DM) respectively. Crude Protein values did not vary statistically (p>0.05).
Study concluded that, soil conditions were not sufficient to support
production of improved forage varieties despite fertilizer uses. CP values
was similar across cultivars and Cayman was the best cultivar in the
southern highlands for its lower NDF. Evaluated cultivars alone cannot
meet lactating cows’ nutritional needs, so they must be supplemented.
Description
Dissertation
Keywords
Smallholder dairy farmers, Dairy cattle nutrition, Pasture plots, Soil fertility, Improved forage varieties, Forage biomass yield, Forage nutrition value.