EFFECT OF POLYPHOSPHATE NPK FERTILIZER ON RICE YIELD IN ACID SULFATE SOIL IN TAY NINH PROVINCE

Abstract

In acid sulfate soil, applied phosphorus (P) is often rapidly fixed due to reactions with Al³⁺ and Fe³⁺ ions, reducing its availability to plants. Selecting an appropriate fertilizer is therefore essential to improving rice yield on this soils This study aimed to evaluate the effectiveness of polyphosphate NPK fertilizer on rice growth, yield and soil P fractions on acid sulfate soil. The field experiment was conducted during the Winter- Spring 2023 - 2024 in Tay Ninh province using a randomized complete block design with six treatments and three replications: (1) NPK 16-16-8 + TE with polyphosphate technology (SPM6), (2) NPK 16-16-8 + TE using steam granulation technology (SPM7), (3) NPK 16-16-8 + 13S using steam granulation technology (SPM8), (4) conventional NPK, (5) no NPK application and (6) no P application. The results showed that the highest rice yield was observed in the SPM6 treatment, which was significantly higher than those of SPM8, conventional NPK, no NPK and P applications. SPM6 also recorded the highest agronomic P-use efficiency. However, Al- and Fe-bound P fraction was no statistically different among treatments.