Decomposition and Mineralization of Some Organic Residues in Two Contrasting Agro-Ecological Zones
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Date
2017-07
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Publisher
University of Ghana
Abstract
Decomposition and mineralization from plant and animal residues are important
processes that can improve soil fertility and build–up soil organic matter.
Decomposition and mineralization of 5 and 10 t/ha of matured cow dung (CD) in Ada
soil series of the coastal savannah agro-ecological zone, as well as 5 and 10 t/ha of
artisanal empty fruit bunch (EFB-AT) and industrial empty fruit bunch (EFB-IN) in
Kokofu soil series of the semi-deciduous forest agro-ecological zone were studied using
pots. The objective of the study was to assess the decomposition and nutrient release
patterns of manured CD and EFB-AT and EFB-IN in order to give an estimate of the
release patterns and to synchronize the nutrient release to meet the nutrient demands of
crops. The study was conducted between February and June 2017. The dry CD at the
two application rates were used for the study in Ada soil series, classified as Entisols
(USDA classification) by Brammer (1960), which corresponds to Fluvisols under FAO
(1970) classification. Also dry EFBs were used for the Kokofu soil series which are
classified Ultisols USDA (Brammer, 1960). Dry CD was put in nylon litter bags, and
was buried at 8 cm deep in the soil (in the pots) as practised by farmers in the Sege area, where CD is incorporated into the soil on application. Chopped EFBs of 2cm mesh size were put in nylon litter bags, and placed on the surface of soil in the pots as practised by farmers in the Kade area, where EFBs are placed on the soil surface in most oil palm plantations to serve as mulch. The EFB samples were taken from artisanal palm oil producers (EFB-AT) and industrial palm oil producers (EFB-IN). Buried CDs in pots were sampled at 7, 14, 21, 35, 56, 72 and 90 days whiles EFB-AT AND EFB-IN were sampled 7, 14, 21, 35, 56, 72 90,120 and 150 days after being placed on soil surface in pots. Sixty percent (60%) of the initial weight of the CD decomposed within 90 days with no significant difference (t=0.05) in the fractions lost between 5 and 10t/ha by t-
test analysis, based on pair comparison. In the case of EFB-AT, about 20% of the 5
t/ha and 50% of 10 t/ha, of the initial weight had decomposed over the 150 days period.
For EFB-IN about 78% of the 5 t/ha and 75% of the 10t/ha of the initial weight
decomposed over the 150 days period. Comparatively, a t-test analysis, based on pair
comparison, showed a significant difference (t=0.08) between the fractions lost by
EFB-AT and EFB-IN at the two application levels. The estimated half-life (t ½) for
the decomposition of CD were 82 and 99 days for 5 t/ha and 10 t/ha, respectively. For
EFB-AT, the estimated half-life were 112 and 130 days for 5 and 10 t/ha, respectively,
while for EFB/IN half-life was 83 and 87 days for 5 and 10 t/ha, respectively.
Approximately between 10 and 20% of the initial TN content of the CD was released
during the 90 days period with significant difference (t=0.07) in the fractions released
between 5 and 10t/ha of CD. Similarly, approximately 15-20% of the initial TN of the
EFB-AT and between 30 and 38 % of TN in EFB-IN was released during the 150 days
period. Based on pair comparison, the difference in the TN released between EFB-AT
and EFB-IN was significant (t=0.07) even between the two application rates (5
and10t/ha). Between 30-38% of the initial P content of the CDs was released while
about 60% of the EFBs was released with significant difference (t=0.06) in the fractions
released between 5 and 10t/ha, and between EFB-AT and EFB-IN. About 90% of the
initial K content in EFBs was released while about 40-50% of the initial K content of
the CDs was released during the experimental period, with significant difference
(t=0.07) in the fractions of K released between 5 and 10t/ha CD and between EFB-AT
and EFB-IN.
Description
Keywords
Decomposition, Mineralization, Organic residue, Cow dung, Empty fruit bunch