Effect of Biochar on Phosphorus Availability and Fixation in Some Rubber Growing Soils of Sri Lanka
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Date
2013
Journal Title
Journal ISSN
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
In most rubber growing soils in Sri Lanka, Phosphorus (P) availability is very low and added P
fertilizer becomes unavailable to the rubber plant due to strong fixation into Fe and Al oxide
minerals prevalent in these soils (Dissanayake et al., 1994).
Biochar (BC) may significantly improve soil fertility in acid and highly weathered soils
(Lehmann and Rondon, 2006). With respect to soil chemical fertility, Dharmakeerthi et al.
(2012) observed a significantly high P uptake in some BC amended rubber growing soils. BC
have high P concentration than in other organic materials (Brown 2009). However, no
experiment has been so conducted so far on dynamics of soil P (availability and fixation) in BC
amended rubber soils, both in Sri Lanka and other rubber growing countries.
Therefore, objectives of the present study were: (i) to study the changes in P availability with
time in three contrasting soil types in rubber growing areas when they were amended with
rubber wood biochar (RWBC), and (b) to determine the effect of RWBC on P fixation in those
soils.
Methodology
Two factorial experiments with two factors; three soil types and three BC rates were conducted
under laboratory conditions at Rubber Research Institute of Sri Lanka. . Biochar was produced
from rubber wood (RW) at 350°C and added in to the three soils: Reddish Brown Latasolic soil
from Parambe (PR), Reddish Brown Earth soil from Thanamalwila (TW), and Red Yellow
Podsolic soil from Payagala (PY). Three BC rates were 0, 2 and 5% (w/w) from RW BC. Soils
and BC samples were characterized for some important chemical properties using standard
methods.
In the first experiment each soil type was amended with the 3 BC rates and incubated in four
replicates at 80% of water holding capacity (WHC), for 4 weeks. Available P contents were
measured at 0, 1, and 4 weeks after incubation. In the second experiment, P fixation capacity of
the three soils amended with three different BC rates was assessed, in triplicate, using the Portch
and Hunter (1998) method with slight modifications. Five ml solution containing 0, 20, 40, 60
and 80 ppm of P were added to BC amended and unamended soils after air-drying of 3-5 days.
Available P from these two experiments were extracted according to the Bray II (Bray and
Kurtz, 1945) method and determined by using a SKALAR San++auto analyzer. Data were
analyzed using PROC GLM program of the SAS software package
Description
Keywords
Agriculture, Export Agriculture, Crop Production, Rubber Production, Rubber Technology, Soil Science