What should be noted when applying base fertilizer to greenhouse vegetables?

Greenhouse vegetables have a high multiple cropping index, high yields, and large fertilizer requirements, while base fertilizer has a great impact on vegetable yield, quality, and soil properties. It is the most basic step in fertilization and is crucial to the growth and development of vegetable crops. Therefore, base fertilizer must be applied rationally, and the following issues should be noted when applying base fertilizer:

I. Determine the fertilization amount according to the target yield of the vegetables

To determine the amount of base fertilizer applied in a greenhouse, factors such as the level of soil fertility and the size of the vegetables' fertilizer requirement must be considered. Generally, 30% of the total nitrogen fertilizer, 80% of the phosphate fertilizer, and 50% of the potassium fertilizer are used as base fertilizer, while biological fertilizer and micro-fertilizer should all be applied as base fertilizer at one time as much as possible. For example, the yield of autumn tomatoes is generally about 8000-9000 kg. Within this yield range, every 1000 kg of tomatoes produced requires the uptake of 4.4 kg of nitrogen, 1.1 kg of phosphorus pentoxide, and 4.8 kg of potassium oxide, with a nitrogen, phosphorus, and potassium ratio of 1:0.25:1.1, and also requires more calcium, boron, etc. Among these, high-phosphorus fertilizer should be selected for base fertilizer, and low-phosphorus fertilizer should be selected for topdressing. The base fertilizer amount should preferably be 40-50 kg, with an approximate nitrogen, phosphorus, and potassium ratio of 1:1:0.75; the topdressing amount should be 75-85 kg, with a nitrogen, phosphorus, and potassium ratio of 1:0.2:0.85.

II. Ensure sufficient organic fertilizer amount

Organic fertilizer (including farmyard manure, barnyard manure, and cake fertilizer) is most suitable for application as base fertilizer. For older greenhouses with relatively high soil fertility, more biological organic fertilizer should be applied as base fertilizer. To keep the soil fertility and organic matter in the greenhouse from decreasing or slightly increasing, organic fertilizer must be supplemented into the greenhouse soil. According to the calculation based on the change pattern of soil organic matter in greenhouses and the principle that yield is highest when the ratio of organic nitrogen to inorganic nitrogen is 1:0.4-1, to maintain soil organic matter in the greenhouse above 2% and ensure relatively high yields, no less than 2000 kg/mu of organic fertilizer with an organic matter content of 30% should be applied each year.

III. Determine the base fertilizer application method according to weather and growth characteristics

When applying base fertilizer, large-volume coarse organic fertilizers such as decomposed soil manure and dung should be the main component, with an application rate of 6-8 cubic meters per mu, to increase soil organic matter and carbon substances, while also combining a small amount of high-quality biological organic fertilizer (generally 100-150 kg) and slow-release potassium sulfate compound fertilizer 75-100 kg. Controlled-release fertilizer should be used to regulate the release rate of nitrogen fertilizer in the base fertilizer, avoid excessive growth under high temperatures, and prevent root diseases. After fruit setting, full-element fertilizer containing nitrogen, phosphorus, and potassium should be applied in split applications with irrigation water.

Li Chunzhen, Gucheng County Agriculture Bureau