Determination of the Nitrate Sufficiency Limit Value for Nitrogenous Fertilization Use in Wheat Grown on a Calcareous Soils Through Application of Mitscherlich-Bray Equation

ABSTRACT

This study was carried out to determine the optimum levels of NO₃-N (nitrate – nitrogen) in soils. According to the randomized complete block design, increased N applications (0, 40, 80, 120, 160, 200 and 240 kg N ha⁻¹) were applied as urea (46% N) in 10 locations with different amounts of nitrate-nitrogen in the soil profile (0–100 cm). As a result, statistically significant relationships were determined between the maximum product increase in wheat and NO₃-N amount determined by the phenoldisulfonic acid method at 0–20, 0–40, 0–60, 0–80 and 0–100 cm depths of the trial field soils. Considering these relationships, Mitscherlich–Bray equation was expressed as [log (A-y) = log A – 0.048_*b – 0.007_*x] for the bread wheat plants grown in the calcareous soils under irrigated conditions. The levels of NO₃-N in the soil and consequently the amount of nitrogen fertilizer to be applied in calcareous soils varies according to the economically acceptable rate of maximum yield of bread wheat. Hence, the values of NO₃-N determined at 0–20 cm depth was categorized as insufficient (<20 kg ha⁻¹), sufficient (20.1 to 34 kg ha⁻¹) and excessive (>34 kg ha⁻¹).

KEYWORDS:

• Wheat
• phenoldisulfonic acid method
• calibration
• nitrate-nitrogen sufficiency values

Acknowledgments

This study was supported by TUBITAK (The Scientific and Technical Research Council of Turkey), Project No. 217O180.

Notes

1 It is assumed that in 0–20 cm depth there is 2500 ton of soil ha⁻¹.

Additional information

Funding

This work was supported by the TÜBİTAK (The Scientific and Technical Research Council of Turkey), Project No. 217O180.