Minimizing Phosphorus Mining through Optimum Phosphorus Fertilization in Maize

Maize, the third most important cereal crop in the world, has recently been introduced in the Ganges-Meghna mega delta coastal ecosystem, but optimum phosphorus (P) fertilizer rates for high yield and to avoid depletion of soil P reserves have not been determined. The objective of the experiment, repeated over three years, was to identify optimum rates of P for maximizing yield and P use efficiency, and for minimizing depletion of P from the soil. In the dry-seasons of 2020, 2021 and 2023, P was broadcast as triple superphosphate at 0, 12, 24, 36, 48, 60, 72, and 84 kg P ha^− 1 to maize (cv. Don-111) on a slightly acid silt loam soil. Maximum grain yield of 11.6, 10.8 and 10.8 t ha^− 1 was found at 72, 36 and 48 kg P ha^− 1 rate in 2020, 2021 and 2023, respectively. Based on the pooled yield, 60 kg P ha^− 1 was the minimum rate required for maximum yield but there was no significant increase in P uptake above 48 kg P ha^− 1. The P partial balance was zero at 45 kg P ha^− 1. At 48 kg P ha^− 1 the partial factor productivity was 201.8 kg grain kg^− 1 added P, agronomic use efficiency was 80.6 kg grain kg^− 1 added P, and recovery efficiency was 0.563 kg P uptake kg^− 1 added P. For sustenance of yield and soil P fertility, 48–60 kg P ha^− 1 was optimal for maize yielding 11–12 t ha^− 1 in the Ganges-Meghna mega delta coastal ecosystem.