How to Prevent and Treat Nitrogen Nutrient Imbalance in Wheat

Symptoms of nitrogen deficiency in wheat: plants grow slowly, individuals are stunted, tillering is reduced; leaf color fades, old leaves turn yellow, senesce early and wither and drop; stems and leaves often take on a red or purplish-red color; the root system is slender, and total root mass is reduced; young spike differentiation is incomplete, and the spike shape is smaller.

Symptoms of nitrogen excess in wheat: growth is overly vigorous, causing excessive vegetative growth; leaf area increases and leaf color deepens, causing shading and congestion; mechanical tissues are underdeveloped, making plants prone to lodging and susceptible to pests and diseases, with yield reduction especially severe and quality deteriorating.

In sandy soils and soils poor in organic matter, where no basal fertilizer is applied or large amounts of organic fertilizer with a high carbon-to-nitrogen ratio are applied, nitrogen deficiency symptoms are likely to occur. If the previous crop received excessive nitrogen, or if topdressing nitrogen is applied excessively or too late, or if nitrogen fertilizer is applied one-sidedly, nitrogen excess is likely to occur.

The diagnostic indicators for soil available nitrogen (calculated as N) from the tillering stage to the jointing stage are: below 20 mg/kg is deficiency; 20-30 mg/kg is potential deficiency; 30-40 mg/kg is normal; above 40 mg/kg is on the high side or excessive. When the total nitrogen content (N) of the functional leaves at the jointing stage of wheat is below 35 mg/kg (dry weight), it is deficiency; 35-45 mg/kg is normal; above 45 mg/kg is excessive.

The main control measures for nitrogen deficiency in wheat are to build up soil fertility and improve the soil's nitrogen supply capacity; when applying large amounts of organic fertilizer with a high carbon-to-nitrogen ratio such as straw, quick-acting nitrogen fertilizer should be applied together with it; when plowing and preparing the land, a certain amount of quick-acting nitrogen fertilizer should be applied as basal fertilizer; for nitrogen deficiency caused by uneven soil fertility, quick-acting nitrogen fertilizer should be topdressed in a timely manner.

The main control measures for nitrogen excess in wheat are to apply nitrogen fertilizer topdressing at the right time and in the right amount according to the nitrogen requirements of the crop at different growth stages and the nitrogen supply characteristics of the soil, strictly control the amount, and avoid topdressing nitrogen fertilizer too late; under the premise of reasonable crop rotation, determine the appropriate nitrogen application rate based on the rotation system; and rationally apply phosphorus and potassium fertilizers together to maintain the balance of nitrogen, phosphorus, and potassium in the plant.