Carbon Stock of a Teak Plantation in Rainforest Zone of Nigeria.

Carbon Stock of a Teak Plantation in Rainforest Zone of Nigeria
Joseph S. Ogeh and Solomon O. Lawani
Department of Soil Science and Land management, Faculty of Agriculture, University of Benin,
Benin City, Edo State, Nigeria. E-mail: joseph.ogeh@uniben.edu
Abstract
The field experiment was conducted to estimate the carbon stock in a tropical rainforest teak
plantation. The study covered a 300ha land at Odighi, Edo State, Nigeria located within latitude
06.61467˚N and 06.61842˚N and Longitude 005.77391˚E and 005.76714˚E.
A rigid grid method of soil survey was used for collection of data. Baseline was pre-determined
and traverses were cut at 200m intervals to give a total of 18 traverses. An Omni Star Differential
GPS was used to locate the position of every sampling point and auger points were located at
100m apart along the traverses to produce a total of 131 auger points and samples were collected
at 0 – 15cm for fertility purpose while samples were described at 0-30cm, 30 – 60cm, 60 – 90cm
and 90 – 120 cm respectively. Soil samples were air- dried and passed through a 2mm sieve
before analysis. Total organic carbon (OC) was measured using the Walkley-Black wet oxidation
method. The molybdenum-blue method was used to determine the available P in the soil.
Exchangeable K in the soil was determined by leaching method using ammonium acetate and
potassium chloride. Data were analyzed statistically using Classical descriptors such as mean for
carbon stock and correlation was used to isolate the soil properties under the mapping units and
modal five pedons.
The results showed that the soil carbon stocks were significantly different (p<0.05) across the
five pedons. Of all the soil properties considered, only the Cation Exchange Capacity, Total
Nitrogen, Available Phosphorus, Effective Cation Exchange Capacity and clay content
significantly (p<0.05) affected the carbon stock. The correlation revealed that soil carbon from
all the pedon decreased generally with increasing depth. The highest carbon stock in the soil was
recorded at pedon 5 (46.44tC/ha), followed by pedon 4 (42.44tC/ha), pedon 1 (35.15tC/ha),
pedon 2(28.80tC/ha) and pedon 3(27.86tC/ha) respectively. The result demonstrated that within
the same field, carbon stock may vary among several soil parameters, hence the need to
encourage planting of trees like teak in order to maintain a reliable estimate of carbon stock .
Key words: Carbon stock, teak plantation, rainforest zone, organic carbon, pedon, mapping unit