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).

摘要

本研究旨在确定土壤中 NO ₃ -N（硝酸盐 - 氮）的最佳水平。根据随机完整区组设计，在 10 个不同硝酸盐氮含量的位置以尿素 (46% N) 的形式增加施氮量（0、40、80、120、160、200和 240 kg N ha ^-1）在土壤剖面（0-100 厘米）。因此，在 0-20、0-40、0-60、0-80 和 0-100 厘米深度，小麦的最大产品增加量与通过苯酚二磺酸法测定的NO ₃ -N 量之间确定了统计学上显着的关系试验田土壤。考虑到这些关系，Mitscherlich-Bray 方程表示为 [log (Ay) = log A – 0.048 _* b – 0.007 _*x] 对于在灌溉条件下生长在钙质土壤中的面包小麦植物。土壤中NO ₃ -N 的含量以及因此在钙质土壤中施用的氮肥量根据面包小麦最大产量的经济可接受比率而变化。因此，在 0-20 cm 深度测定的 NO ₃ -N值被归类为不足（<20 kg ha ^-1）、充足（20.1 至 34 kg ha ^-1）和过量（>34 kg ha ^-1）。