Materials and Methods Tjoa
71 Table 1. Soil chemistry of ultramafic soils from Sorowako, Indonesia.
Parameters Topsoil
Overburden Laterite 0-15 cm
Limonitic Saprolitic
pH
1
5.75 6.52
7.01 P total
2
237.00 110.00
83.10 P extractable
3
3.87 0.23
0.32 K total
2
5164 4018
4138 K exch.
4
0.03 0.01
0.02 CEC
4
42.50 35.10
19.90 Mg exch.
4
0.52 0.61
4.64 Ca exch.
4
0.81 0.24
0.45 Mg:Ca
0.64 2.54
10.31 Ni total
2
7051 7884
10524 Ni extractable
3
7.54 20.70
30.20 Fe total
2
131668 436372
240068 Co total
2
57 294
536 Mn total
2
1076 3053
4926 Al total
2
154849 73984
35029 Cr total
2
17216 11263
8595 Notes: 1 pH in H
2
O extract 2 hot HNO
3
-HCl soil digestion elemental concentrations in gg d.w.
3 Bray-1 extractant P in gg dry weight soil. 4 Extracted with 1M ammonium acetate at
pH 7, concentrations in meq100g dry weight soil. Values are average of two samples, analysed with ICP-OES
E.sonchifolia is abundant available at the Sorowako ultramafic site, in the
field it accumulates 190-280 mg kg
-1
of Ni. This experiment used seeds that reproduced from collated seeds of Sorowako Ni mining area. Dry weight
and metal and non-metal concentrations of shoots are presented in Table 2. Shoot production was higher when E. sonchifolia grown in topsoil and
limonitic overburden compared to saprolitic. This strong growth inhibition on saprolitic overburden was accompanied with symptoms of toxicity as
necrosis. Ultramafic is well known to have low nutrients but high in heavy metals, and for nutrients which are strongly fixed to the soil matrix like P,
K and NH
4
, diffusion is the main pathway for transport to the root surface [9]. As consequence of this short distance transport, spatial availability is a
crucial aspect for delivery of these nutrients to the roots. Spatial availability is affected by root growth, and it is strong related to soil texture.
Table 2. Shoot biomass and shoot concentrations of Ni, Fe, Cr, Zn, K and Mg of E.sonchifolia
Soil Shoot
Shoot Concentration D.M.
Ni Fe
Cr Zn
K Mg
g mg kg
-1
g kg
-1
T 1.0±0.05b
14.7±1.1c 406.8±157.4b 9.3±2.0b 28.8±0.3b 41.6±0.5a 5.7±0.5b
T1 3.6±0.28a
12.5.±2.8c 40.0±8.3c
3.6±0.2b 32.2±3.2b 46.9±3.0a 3.1±3.0b
72
Soil Shoot
Shoot Concentration D.M.
Ni Fe
Cr Zn
K Mg
g mg kg
-1
g kg
-1
M 0.8±0.04b
29.7±0.8c 215.0±122.8c 10.5±0.9b 43.5±2.3a 42.9±1.6a 5.4±1.6b
M1 3.4±0.06a
30.7±5.2c 134.0±96.8c 5.8±1.5b 39.2±2.0a 44.6±1.0a 3.9±1.0b
Y 0.4±0.04d 210.7±10.1b 633.5±34.2a
28.3±2.7a 26.2±1.4c 44.0±0.7a 13.6±0.7a Y1
0.7±0.12bc 254.7±51.5a 130.2±49.1c 34.0±10.9a 29.8±4.9b 45.2±0.8a 15.3±6.9a Notes: T, M, Y is standing for topsoil, Limonitic laterite, Saprolitic laterite but untreated while T1,
M1, Y1 was treated with chicken manure
Chicken manure application increased significantly shoots productions in all soils T1, M1 Y1, but less pronounced in saprolitic laterite Y.
Ultramafic is a poor soil and amendment of organic matter may play positive role. Addition of organic matters to soil may reduce potential risk
of heavy metals in the environment, by reducing its mobility and availability. This reduction may be influenced by several factors, among them: nature
itself and degradability of organic matter, salts contents, effect of soil pH, by the redox potential and by the type of soil [10]. The critical factor to
conduct phytomining is to reduce the moving of the “crusty” silty with high Fe properties of limonitic and saprolitic laterite during frequent heavy rains,
eliminating the burying of the germinated seedlings and the splashing of silt up on to the surface of the leaves which has proven to severely stress the
young plants and reduce plant establishment. The highest uptake of Ni and Cr were found for saprolitic followed by limonitic and topsoils. This is in
accordance the soils properties while saprolitic has the highest Ni plant availability concentration. The uptake of Fe was strongly influenced by the
organic matter amendments. Chicken manure application significantly suppressed the Fe shoot uptake. Organic matter may interfere with the
formation of stable metal precipitation, on other hand may enhance adsorption on mixed assemblages of fulvic acid and Fe oxide [11]. Differed
from Fe, Zn was not influenced by application of organic matter, and was higher in shoot Table 2 of limonitic soil. Concentration K in shoot was
very similar for all soils and treatments. The saprolitic laterite has highest Mg:Ca concentration ratio Table 1, and led to higher uptake of Mg Table
2. Soil developed on ultramafic bedrocks share chemical peculiarities including high content of specific metals, a high of Mg:Ca concentration
ratio and low concentration of macronutrients [12, 13].