Effects of fertilizer application and season on the yield and quality of natural pasture at Magadu Dairy Farm, Sokoine University of Agriculture
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Date
2025
Authors
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Journal ISSN
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Publisher
Rangeland Society of Tanzania (RST)
Abstract
More than 90% of Tanzania national ruminant livestock herd
thrive on natural pastures. Improvement of natural forage
productivity as well as its quality, would have a significant impact
on the production of this national ruminant livestock herd.
Fertilizer application as a management tool to improve tropical
natural pastures has rarely been reported. A study was therefore
conducted to test fertilizer as a management tool to improve
natural pastures on an existing one hectare of mixed natural
pastures, mainly of natural grasses at Magadu Dairy Farm of
Sokoine University of Agriculture. The main aim of this study was
to find out if fertilizer application can be to improve the yield and
quality of the natural pastures. The one-hectare plot was divided
into two sub- plots. The first sub-plot was used in the short rains,
while the second sub-plot was used in the long rains as the study
area falls under bimodal rainfall regime. The pasture in each sub-
plot was mowed down at the beginning of each rain season and
thereafter the sub-plot was again divided into two equal sub-sub-
plots. One sub-sub-plot was applied with a mixture of nitrogenous
(174 kg N/ha) and phosphorus (92 kg P/ha) fertilizers at once and
the second was a control. Pastures at both rainfall regimes were
harvested at 50 % flowering and thus, pasture regrowth was
harvested at 90 days old in the short rains those in the short rains
was harvested at 65 days old. Dry mater yield estimation was
conducted by throwing a quadrat of 0.25 m 2 randomly ten times at
an equal distance along the two diagonals of each sub-sub plot. Pasture samples were collected and sent to the laboratory for
oven drying, chemical composition analysis and determination of
in vitro dry matter and organic matter digestibility (IVDMD and
IVOMD). Fertilizers application increased significantly (P≤ 0.01)
the natural pastures dry matter yield. regardless of the rain
seasons. Fertilizers improved crude protein of natural pastures
significantly (P≤0.001). Short rain season natural pastures had
significantly (P≤ 0.001) higher NDF contents than those of long
rain season regardless of fertilizer application. The energy
contents ME (MJ/kg DM) for both fertilized and unfertilized long
rain forages were significantly (P≤ 0.001) higher than all
pastures of the short rain. Long rain fertilized pastures had
significantly (P≤ 0.001) higher IVOMD than unfertilized forages
of the same season. In the short rain fertilized forages had
significantly (P≤ 0.001) higher IVOMD than unfertilized pasture.
The long rain fertilized forages had significantly (P≤ 0.001)
higher IVOMD than all other pastures. From this study it can be
concluded that fertilizer application significantly improves both
the quantity and quality of natural pastures and that fertilizers
can be applied at any season as long as there is sufficient soil
moisture. However, harvesting at 50% flowering compromised
forage quality in short rains due to extended period to flowering
stage of growth as compared to long rains.
Description
Healthy Rangelands for Sustainable Economic Development PP. 69-80
Keywords
Short rain season, Long rain season, Fertilized pasture, Unfertilized pasture, Forage production, Energy content