What question did this study set out to answer?

This study aims to evaluate the effectiveness of ammonium-enriched biochar on nitrogen release and wheat performance in sandy soils.

June 22, 2026Open Access

Chemically Modified Nitrogen-Enriched Eucalyptus Biochar Improves Nitrogen Availability and Wheat Productivity in Low-Fertility Sandy Soil

Key Points

This study aims to evaluate the effectiveness of ammonium-enriched biochar on nitrogen release and wheat performance in sandy soils.
Conducted two pot experiments with different nitrogen and biochar application rates.
Measured spike number, grain dry weight, and nitrogen use efficiency at specific growth stages.
Used pristine and chemically modified biochar treatments for comparison.
At 160 mg N kg-1, spike number, grain dry weight, and nitrogen use efficiency more than doubled with biochar applications.
Chemically modified biochar at 3 g kg-1 significantly increased spike number, grain yield, and nitrogen use efficiency compared to pristine biochar.
Modified biochar improved nitrogen retention and controlled release, enhancing overall wheat productivity.

Abstract

Biochar has strong potential to improve soil nutrient retention and enhance nitrogen (N) use efficiency in cropping systems; however, its role as an engineered slow-release N delivery system remains insufficiently quantified. This study evaluated the effects of ammonium-enriched eucalypt biochar—either pristine (untreated) or chemically modified with HNO 3 and Na 2 CO 3 —on N release, wheat ( Triticum aestivum L. cv. Scepter) performance, and N use efficiency in low-fertility sandy soil. Two pot experiments were conducted. In the first experiment (Exp. 1) (“N rate” experiment), four N application rates (0, 20, 80, and 160 mg N kg -1 soil) were tested at a constant biochar rate. In the second experiment (Exp.2) (“biochar rate” experiment), three application rates (0, 1, and 3 g kg -1 soil) of each biochar type were evaluated at a constant N rate. Plants were harvested at tillering (Zadoks 29) and maturity (Zadoks 92). In Exp. 1 increasing N supply significantly increased spike number, grain dry weight, and nitrogen use efficiency with more than a twofold increase observed across both biochar treatments at 160 mg N kg -1 relative to the 0 N treatment. In Exp. 2, chemically modified N-enriched biochar consistently outperformed pristine biochar at equivalent application rates, significantly doubled spike number, grain yield, and nitrogen use efficiency at 3 g Bc kg -1 . The improved performance of modified biochar is attributed to enhanced nitrogen retention and controlled release, reflecting a shift from physical adsorption to charge-mediated nutrient regulation. Overall, chemically modified ammonium-enriched eucalypt biochar functions as an effective slow-release N fertilizer, reducing nitrogen losses while improving nitrogen use efficiency and wheat productivity in low-fertility sandy soils. Ammonium-enriched eucalypt biochar improved soil N retention and plant N recovery reducing fertilizer requirements suggest more efficient nutrient management and support the sustainable intensification of marginal sandy agroecosystems.

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