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Phosphorus (P) is a macronutrient for the growth of crops besides nitrogen and potassium. Recently, P has been identified as an unrenewable resource due to the prediction that natural phosphate rock resources are nearing depletion (Cooper et al. 2011, Cordell andWhite 2015). In soils, the pool of P available for crop utilisation is often limited because many P forms are insoluble compounds and they are adsorbed onto clay minerals (Weil and Brady 2017). To improve P nutrition, farmers apply P fertiliser to overcome this production constraint.In some circumstances, farmers have applied more P fertiliser than the amount of P removed with the harvest, which has caused soil P accumulation and potential eutrophication (Wang et al. 2013). Farmers in the Vietnamese Mekong Delta (VMD) region have increased production intensity from single rice crops to double and triple rice crops per year. Most farmers have maintained the P fertiliser dose higher than the recommended rate of 26.2 kg P/ha for each crop needed for a double and triple rice cropping system (Long et al. 2016). According to Long et al. ( 2016), 87% of farmers applied more than 26.2 kg P/ha, and 60% used more 39.2 kg P/ha for one cropping season in triple rice cultivation in the VMD region. Besides, Rakotoson et al. (2022) reported that the P fertiliser rate applied to paddy rice ranged from 17.0 to 25.0 kg P/ha in several countries in Southeast Asia such as Philippines, Indonesia, Cambodia, and Vietnam.