The changes of extractable Fe with treatment were at best
erratic. In this study, no particular trend was observed. This
means that we are not sure whether applying any of the
amendments under investigation would be able to alleviate
Fe toxicity for rice cultivation. Extractable iron in the acid
sulphate soil under study for both cycles 1 (Table VI) and 2
(Table VII) was lower than the critical concentration for the
growth of rice. According to Dobermann and Fairhurst
(2000), Fe toxic level for crop production is 300 mg kg−1.
The lower‐than‐expected Fe content in the soil is probably
the reason why solution pH did not rise significantly when