Greenhouse Vegetable Fertilization Methods for Increasing Yield and Precautions

Greenhouse vegetables are a high-input, high-output mode of production in a specific environment. Different fertilization methods not only affect fertilizer use efficiency, but also affect the economic benefits of production. So how should greenhouse vegetables be fertilized to increase yield? What issues need attention during the fertilization process? Below, we introduce the precautions for greenhouse vegetable fertilization.

Common misunderstandings in current greenhouse vegetable fertilizer application

1. Drying organic fertilizer in the sun

Human manure and chicken manure have become the main base fertilizers for greenhouse vegetable production, but for convenience of application, vegetable growers often spread human manure and chicken manure in the field to dry and lose water. This practice causes fly maggots to breed and nitrogen to volatilize, losing the nitrogen nutrients of the fertilizer.

2. Applying calcium magnesium phosphate as a base fertilizer on alkaline soil

Calcium magnesium phosphate is a weakly acidic fertilizer, insoluble in water, and only under weakly acidic conditions can it gradually transform into water-soluble phosphate for absorption by crop roots. When applied on alkaline soil, it cannot meet the urgent need of crop seedlings for phosphorus, causing physiological phosphorus deficiency.

3. Broadcasting superphosphate on the soil surface as a topdressing

Phosphorus has low mobility in soil, with a movement range of 1 to 3 cm. Therefore, surface application makes it difficult to reach the crop rhizosphere, and thus it cannot supplement phosphorus in the crop.

4. Watering immediately after broadcasting urea.

Urea is an amide nitrogen fertilizer, easily soluble in water. After being applied to soil, it must decompose before it can transform into ammonium bicarbonate and be absorbed and used by crops. Watering immediately after surface application easily causes urea to be lost with water, reducing fertilizer efficiency.

5. Broadcasting ammonium bicarbonate along with water

This method often results in more fertilizer at the water inlet, uneven crop growth, and difficulty in management. In the afternoon, as the greenhouse temperature rises, ammonia gas escapes from the soil, scorching the lower leaves of the crops and causing fertilizer damage.

How should greenhouse vegetables be fertilized to increase yield?

1. Apply chemical fertilizers in appropriate amounts

Because greenhouse vegetables have protective facilities, the soil cannot be fully leached by rainwater, and fertilizers are not easily leached away. Therefore, excessive application of chemical fertilizers easily causes salts to accumulate in the surface soil, which at best affects vegetable growth and at worst leads to soil salinization. Therefore, before fertilization, soil nutrient diagnosis must be carried out, and a reasonable formula fertilization plan must be formulated to prevent blind excessive application of quick-acting fertilizers.

2. Pay attention to increasing potassium fertilizer:

Applying potassium fertilizer to melons and solanaceous vegetables has a clear yield-increasing effect. This is because continuous excessive application of nitrogen and phosphorus chemical fertilizers to greenhouse vegetables year after year causes the soil's potassium supply capacity to weaken as planting years increase and vegetable yields rise. According to experiments, for greenhouse cucumbers, supplementing 7.5 kg of potassium oxide per mu showed thick stems, fresh green and thick leaves, and straight fruits; for winter Chinese cabbage, yield and quality were significantly improved. It should be noted that when choosing potassium fertilizer varieties, it is best not to use potassium chloride, so as to avoid soil salinization.

3. Topdressing should be applied in small amounts many times:

Vegetables require relatively large amounts of fertilizer. In addition to applying sufficient base fertilizer, topdressing is also needed. When topdressing, apply small amounts many times. This can first prevent nutrient loss, and second fully exert fertilizer efficiency and improve fertilizer use efficiency.

4. Supplement micronutrients according to what is deficient:

Although vegetables require only small amounts of trace elements, micronutrient fertilizers are indispensable nutrients involved in the physiological functions of vegetables. If trace elements in the soil are insufficient, vegetables will show different deficiency symptoms, yield will decrease, and quality will decline. If trace element content in the soil is too high, it will also cause vegetable toxicity, likewise reducing yield and lowering quality. Therefore, supplementary application of micronutrient fertilizers must be based on soil test results and vegetable deficiency symptoms, and must follow the principle of supplementing whatever is deficient.

5. Root-outside topdressing must be accurate:

Foliar spraying is simple, saves labor and time, can avoid increased vegetable disease incidence caused by excessive watering leading to high soil moisture, and can also quickly supplement nutrients. However, the application concentration must be controlled, otherwise fertilizer damage is likely to occur and “burn” the leaves. General foliar spray concentrations are: urea 1%, potassium dihydrogen phosphate 0.2~0.5%, diammonium phosphate 1%, zinc sulfate 0.1~0.2%, manganese sulfate 0.1~0.2%, borax 0.1~0.2%, ammonium molybdate 0.05~0.1%, copper sulfate 0.02~0.2%, ferrous sulfate 0.2~1%.

Precautions for greenhouse vegetable fertilization

1. Inorganic and organic fertilizers are unbalanced.

The amount of organic fertilizer applied is relatively low. Some vegetable growers only apply a small amount of organic fertilizer to vegetable fields near the village or convenient for transportation, and do not apply it to distant fields. This is not conducive to building high-yield vegetable fields, nor to producing high-quality greenhouse vegetable products and sustainable development. Therefore, organic fertilizer application should be increased. Organic fertilizer not only has comprehensive nutrient content and can provide the macroelements and medium and trace elements needed for vegetable growth and development, but can also improve soil physical and chemical properties, improve soil water, fertilizer, air, and heat conditions, enhance fertilizer and water retention capacity, and promote normal vegetative growth of vegetables.

2. The application of medium and trace elements has not received enough attention.

Medium and trace element fertilizers are indispensable for greenhouse vegetable growth. Vegetables are especially sensitive to trace elements; too much is harmful. However, relying only on organic fertilizer supplementation will cause medium and trace elements in the soil to show a decreasing trend as greenhouse age increases, easily inducing various diseases, such as celery stem splitting and tomato blossom-end rot.