Why does an increase in pH value affect the absorption of nitrate nitrogen?

Why does an increase in pH value affect the absorption of nitrate nitrogen?

Increased pH value affects nitrate nitrogen absorption: (1) Hydroxide (OH⁻) and nitrate nitrogen (NO₃⁻) compete in the soil, making nitrate nitrogen absorption difficult in alkaline soils. (2) When nitrate nitrogen (NO₃⁻) is assimilated in plants, the intracellular pH value increases (alkalinity increases). In order to maintain the acid-base balance in the plant, it needs to be neutralized by organic acids formed in the cells. Excessive hydroxide (OH⁻) will affect the formation of organic acids in the cells, further affecting the absorption of nitrate nitrogen.