Zeolite increases paddy soil potassium fixation, partial factor productivity, and potassium balance under alternate wetting and drying irrigation

Alternate wetting and drying irrigation (AWD) affects soil and plant K availability in the paddy field. However, it is unclear how zeolite amendment alters soil K fixation, K utilization, and K balance in the paddy rice systems under AWD compared with continuous flooding irrigation (CF). A two-year lysimeter experiment with a split-plot design was used to evaluate the effect of irrigation regime and fertilization management in paddy fields in Donggang, northern coastal China in 2018 and 2019. The field experiment included two irrigation regimes (CF and AWD) as the main plots, and three zeolite/K managements (Z0K0, no added zeolite or K; Z5K30, 5 t ha–1 zeolite and 30 kg ha–1 K; Z0K60, no added zeolite and 60 kg ha–1 K) as the subplots. The results showed that zeolite mitigated the reductions in grain yield and aboveground biomass caused by water stress in AWD. Zeolite addition also caused soil K fixation under AWD, which reduced K leaching losses and avoided excessive K absorption by rice plants, thus contributing to sustainable rice production by preventing soil K depletion. The Z5K30 treatment had lower total K leaching losses and higher K partial factor productivity (the ability of rice to use K to produce yield) than the commonly used practice (Z0K60). Compared with Z0K60 under CF, the Z5K30 treatment under AWD produced higher grain yield, economic benefit, water use efficiency, and total K balance. Therefore, appropriate zeolite and K amendments could be economically and environmentally feasible for rice production under AWD conditions.