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8 A Multi-disciplinary Challenge for Phytoremediation of Metal-Polluted.. . 149

Fig. 8.4 Aspect of pyrite (a) and crop species (b, c, d) after 60 days of cultivation in rhizoboxes
under various treatments. U: uncontaminated reference silty-loam soil; P+15: pyrite cinders
capped with 15 cm of unpolluted soil; P+7: pyrite cinders capped with 7 cm of unpolluted soil;
P: pyrite cinders

initially. In this way, in the sowing bed (top 0.15-m layer) pollution was roughly
halved by ploughing and, despite some upward cinder movement, ripping led to
lower contamination than ploughing (total and DTPA-extractable: ~ 30 %)
(Table 8.1).
Given the low fertility of pyrite (Marchiol et al. 2007, personal comunication in
2005), before sowing 100 kg ha 1 of each N, P 2 O 5 and K 2 O as chemical fertilisers
were incorporated into the soil by harrowing. Four crop species, i.e., sunflower,
Italian ryegrass (Lolium multiflorum Lam.), alfalfa and fodder radish (Vamerali
et al. 2011b), and four woody species, i.e., white poplar (Populus alba L.), black
poplar (P. nigra L.), European aspen (P. tremula L.) and white willow (Salix alba
L.) (Vamerali et al. 2009), were grown under the two soil tillages and compared
with the ploughed uncontaminated soil reference of the experimental farm of the
0

University at Legnaro (45 21 N, 11 58 E, 12 m a.s.l.). Sowing of crops and
0

transplanting of 2-year-old bare rooted cuttings of woody species took place in
May, and shoot (biomass) and root investigations (RLD, volumetric root length
density, by auger sampling) at the end of July and in mid-September, in both groups
of species respectively.
Pyrite waste was an inhospitable substrate for all plants, as also reported by
Fellet et al. (2007) and Marchiol et al. (2007), at the same site for other species. The
anomalous physical properties (high bulk density and low water infiltration),
together with high Fe and S, and multiple contamination of pyrite, greatly limited
plant growth, almost regardless of tillage system. Only fodder radish profited by the
lower contamination of ripping (Fig. 8.5). Improvements in the habitat should
involve soil drainage and adequate irrigation, as we accomplished by digging
shallow drains and setting up a low-intensity sprinkling system in summer.
The lower contamination due to ripping seemed to be less favourable for metal
concentration in plants but more useful for growth, especially in fodder radish.