What are the three key principles for greenhouse tomato cultivation?

Introduction Since the 1990s, with the adjustment of agricultural planting structures, the area of protected agriculture represented by protected vegetable cultivation has continued to expand. The position and role of protected vegetables in China's agricultural and rural economic development have become increasingly prominent. Among them, greenhouse tomatoes are widely welcomed by the market and their prices are stable, playing an important role in increasing farmers' income. At present, greenhouse tomato cultivation mostly adopts a two-crop-per-year model, divided into the autumn-winter crop and the winter-spring crop. Due to climatic differences, the growth patterns, nutrient demand patterns and field management of the two tomato crops differ. How should winter-spring greenhouse tomatoes be cultivated scientifically? Experts suggest that farmers should strengthen soil, fertilizer and water management, and follow the "three key principles" of soil, fertilizer and water.

????Follow the "soil principle"

Strengthening soil management is the foundation of scientific balanced fertilization and water management. Farmers can follow two major principles in soil management.

First, reasonably supplement organic fertilizer to maintain soil health. Because the interval between crop changes in the winter-spring crop is short, soil management measures such as fallowing and solarization cannot be carried out. Generally, after the previous crop is cleared, fertilization, plowing, ridging, laying drip irrigation pipes and transplanting should be carried out as soon as possible. Before plowing, reasonably supplementing high-quality organic fertilizer has an obvious effect on building soil fertility. Generally, apply 300-500 kg/mu of high-quality bio-organic fertilizer and 100-300 kg/mu of soybean meal.

Second, adopt ridging cultivation, which facilitates aeration and water permeability and cultivates strong roots. Rotary tillage should mix the organic fertilizer evenly with the soil, and the rotary tillage depth should preferably be 20 cm. After rotary tillage, form ridges with a ridge width of 60 cm and a height of 20 cm, with 80 cm between two ridges. Adopt the cultivation pattern of two rows per ridge on the ridge, with 2 drip irrigation pipes laid on each ridge.

????Follow the "water principle"

After tomato planting, plastic film can be applied, and drip irrigation should be used to water 30 cubic m/mu. After 5-7 days, water a second time for seedling recovery, with a watering amount of 20-25 cubic m/mu. Before tomato topping (seedling stage and flowering and fruit-setting stage), drip irrigate once every 7-10 days, with 20 cubic m/mu each time. A tensiometer can be installed at a soil depth of 20 cm directly below the dripper to indicate soil moisture content. When the tensiometer reading is -25 kPa, drip irrigation can begin, with 15-20 cubic m/mu each time. After tomato topping, as the temperature rises, tomato water consumption increases, and the irrigation interval should be reduced to 5-7 days, with 20-25 cubic m/mu each time. The irrigation interval can also be determined by tensiometer readings.

The drip fertigation schedule should be adjusted promptly. During consecutive cloudy days, evaporation decreases, so irrigation should be appropriately postponed or advanced, and the irrigation amount should be reduced at the same time. When there are conditions of high temperature, low humidity and high evaporation, the irrigation amount should be increased and irrigation should be advanced, increasing the irrigation frequency or irrigation quota.

Follow the "fertilizer principle"

Greenhouse tomatoes grow quickly, bear many fruits and like fertilizer, but their root systems have weak fertilizer tolerance and have relatively strict requirements for soil nutrient conditions. According to measurements, for every 1000 kg of tomatoes produced, 3.2 kg of nitrogen (N), 0.9 kg of phosphorus (P2O5) and 5.4 kg of potassium (K2O) need to be absorbed from the soil, with a ratio of 1:0.3:1.7. Tomatoes need the most potassium throughout the entire growth period, followed by nitrogen, and then phosphorus. In addition, tomatoes have a relatively high demand for calcium, comparable to nitrogen.

Before rotary tillage for tomatoes, apply 100 kg/mu of superphosphate to supplement calcium nutrition and meet the crop's demand for phosphorus. After planting, a small amount of rooting-type amino acid and humic acid water-soluble fertilizer can be applied through drip irrigation, but filtration must be done well to prevent clogging of the drip holes. Start fertilizing from the 4th drip irrigation watering, and fertilize 4-5 times before tomato topping. The recommended formula is 20-5-20, with an application rate of 13.3 kg/mu. After tomato topping, apply a high-potassium formula (12-5-35) water-soluble fertilizer, with an application rate of 10 kg/mu each time, for 5-6 applications.

In the middle and late stages of tomato growth, foliar spraying can be used to supplement some medium and trace elements. Tomatoes need a lot of calcium, and calcium deficiency can easily lead to blossom-end rot and fruit cracking, affecting yield. Foliar spraying of a 0.3%-0.5% calcium nitrate aqueous solution or an 800-1000 times sugar alcohol calcium aqueous solution can be adopted to supplement calcium while also supplementing trace elements such as boron and zinc, which is beneficial for fruit expansion and increasing yield.

Precautions

Farmers should pay attention to six aspects when carrying out soil, fertilizer and water management for winter-spring greenhouse tomatoes.

First, farmers with drip irrigation facilities should use ridge cultivation as much as possible, which can increase soil temperature, allow aeration and water permeability, and benefit tomato root growth, achieving the goal of strong roots and vigorous seedlings.

Second, apply organic fertilizers with a relatively high carbon-to-nitrogen ratio as much as possible, reduce the application of pure chicken manure, pig manure and other livestock and poultry manure, and increase the input of microbial fertilizers.

Third, fertilization should be done in small amounts and multiple times, with one watering and one fertilization. Do not irrigate with plain water during the fruit-setting period. For fertilizer application, grasp the principle of phosphorus in the early stage (root growth), nitrogen in the middle stage (plant growth) and potassium in the late stage (fruit growth).

Fourth, irrigation should as much as possible not leach beyond the root growth range of 30 cm. Check by digging out roots to see whether irrigation requirements are met. The irrigation amount is generally around 20 cubic m/mu.

Fifth, follow the principle of synchronizing water and fertilizer (integrated water and fertilizer management), apply water-soluble fertilizers of good quality, and perform filtration well during irrigation to prevent drip hole clogging from affecting the use of irrigation equipment.

Sixth, during irrigation, grasp the principle of watering first - then fertilizing - then watering again, which helps the applied fertilizer fully move to the tomato root zone. At the same time, prevent salt accumulation in the drip irrigation pipes from causing dripper clogging.