The researchers studied different forms of zinc in rice-growing soils in Assam. They found that water-soluble and exchangeable zinc is important for rice plants, while residual zinc has little impact. Water-soluble zinc has the highest influence on plant zinc concentration and uptake. The study showed that zinc availability to rice plants is influenced by the dynamic equilibrium between water-soluble, organic complex, and amorphous sesquioxide bound zinc fractions in the soil. Overall, water-soluble and exchangeable zinc play a crucial role in the zinc nutrition of lowland rice in acidic soils of Assam.