Objectives Given that the efficacy of DCD varies in different soils, we studied the precise efficacy of nitrification inhibitor dicyandiamide (DCD) on maize growth, fertilizer nitrogen (N) recovery efficiency, and the N fate in different soil types, to establish a theoretical foundation for the scientific application of DCD in maize N management.

Methods A soil column leaching experiment was carried out using ¹⁵N-labeled urea. The columns were filled with one of the three soil types (red soil, black soil, and fluvo-aquic soil), and DCD was applied at 10% of the urea N application rate or omitted as a control. Water (100 mL) was added to the soil at the 10, 17, 22, 26, 31, 36, and 46 days post-sowing of maize to collect leachate for the measurement of ammonium and nitrate N. After 57 days, the maize plants were harvested to determine their yield and N content in both the aboveground parts and roots. Additionally, the ammonium- and nitrate-N content in the residual soil was measured.

Results Regardless of DCD application, the N leaching patterns in all three soils exhibited similar temporal trends. The majority of ammonium N, nitrate N, and total N leaching occurred during the initial three leaching events, peaking during the first event and then declining rapidly thereafter. Urea N leaching was primarily concentrated in the first leaching event. DCD reduced nitrate leaching by N 0.74 to N 5.76 mg/kg soil across all three soils, with the smallest reduction observed in red soil. While DCD had no significant effect on urea leaching, it increased ammonium leaching in red and fluvo-aquic soils, with the highest increment in fluvo-aquic soil (N 2.99 mg/kg soil). The effectiveness of DCD in reducing N leaching was correlated with the soil’s nitrification capacity, following the order black soil>fluvo-aquic soil>red soil. DCD effectively minimized fertilizer N leaching and enhanced soil N retention in black and fluvo-aquic soils, but had no significant impact on red soil and even increased the fertilizer N leaching rate therein. DCD significantly inhibited gaseous N loss in red and black soils but increased it in fluvo-aquic soil. Across all three soils, DCD improved fertilizer N recovery efficiency for maize, with the greatest improvement observed in black soil. However, DCD only increased maize biomass in fluvo-aquic soil. Compared to fluvo-aquic and red soils, black soil exhibited higher maize fertilizer N recovery efficiency, lower N leaching, and lower gaseous N losses, attributed to its favorable soil conditions for optimal maize growth and minimal fertilizer N loss.

Conclusion The effects of applying DCD on maize growth, N fertilizer use efficiency, and the fate of fertilizer N vary among soil types, primarily due to soil properties. Black soil and fluvo-aquic soil exhibit strong nitrification, so the application of DCD is more effective in reducing the leaching loss rate of fertilizer N and increasing the soil residual rate of fertilizer N, whereas its effectiveness is poorer in red soil. The application of DCD significantly inhibits gaseous N losses in red soil and black soil but increases gaseous N losses in fluvo-aquic soil. This may be attributed to the higher pH of fluvo-aquic soil, where DCD leads to the accumulation of ammonium-N, potentially causing increased ammonia volatilization.