Rice seeds were sown in late May and seedlings were transplanted in late Jun of
2009. The total amounts of 250 kg N ha1 as urea, 31.5 kg P ha1 as calcium superphosphate
and 180 kg K ha1 as potassium chloride were applied. The basal fertilizers
were broadcast 3e4 d prior to transplanting at the rates of 30% of total N and all
of P and K. During the growth, 20% of total N was top-dressed at each of earlytillering
(10 days after transplanting), 30% at mid-tillering and 20% at early spike
differentiation, respectively. Field management was done as that locally
recommended.
The soil and rice samples were taken from Nanhu, Tongxiang and Xiaoshan
counties of Zhejiang province, China in order to cover a wide range of soil types,
mainly in terms of pH, organic matter and heavy metal contents. A japonica rice
cultivar Xiushui 63 was used and planted in the 9 paddy fields of each county
(location). At maturity (about 120 d after transplanting), soils at the depth of
0e25 cm and rice plants were randomly sampled for the determination of pH,
organic matter and heavy metal contents