How to Adjust Irrigation Strategies Based on Crop Growth Cycles

How to Adjust Irrigation Strategies Based on Crop Growth Cycles

Adjusting irrigation strategies based on crop growth cycles is central to precision agriculture and water-saving irrigation. The core concept is that crop water requirements are not constant, but change dynamically with their growth stages. Successful irrigation management is like "teaching according to age," meeting needs during critical periods and appropriately controlling water during non-critical periods, thereby achieving multiple goals of water conservation, increased yield, improved quality, and disease prevention. Adjustment strategies mainly revolve around three dimensions: "water volume, frequency, and depth."

Phase One: Sowing/Transplanting and Seedling Stage – The key is to "ensure seedling survival and promote root development."

Crop characteristics: After seed germination or seedling transplanting, the root system is shallow and weak, and extremely sensitive to surface soil moisture.

Irrigation strategy: Small amounts, high frequency, and shallow irrigation. Keep the surface soil (usually 5-10 cm) continuously moist, but avoid excessive water that leads to waterlogging, rotting seeds, or excessively low soil temperature. Watering should be "frequent" and "shallow" at this stage to ensure uniform emergence and guide the roots to seek water downwards, promoting deep root development and laying the foundation for drought resistance later.

Phase Two: Vigorous Vegetative Growth Stage – Ensuring "sufficient water and nutrients for healthy growth."

Crop characteristics: This is the stage of rapid stem and leaf growth (such as corn jointing, vegetable rosette stage), and water demand increases sharply, representing the first peak water demand.

Irrigation strategy: Increase water volume and irrigate thoroughly. The irrigation amount should be sufficient to moisten the main root activity layer of the crop (e.g., 20-30 cm for vegetables, 40-50 cm for corn). Ensure sufficient soil moisture to avoid slowed growth and wilting leaves due to water shortage. However, also ensure good drainage to prevent long-term excessive moisture leading to diseases.

Phase Three: Flowering and Pollination Stage – Requiring "careful attention and a smooth transition."

Crop characteristics: This is the most sensitive and "picky" period for water. Water stress (too much or too little) will directly lead to poor pollination, flower and fruit drop, and have a devastating impact on final yield.

Irrigation strategy: Stable water supply, avoiding drastic fluctuations. Soil moisture should be maintained at the upper limit of the suitable range, avoiding drought. However, avoid excessive watering, especially for fruit trees and some vegetables. Overwatering during the flowering period can lower soil temperature and affect pollination. The strategy is to "water frequently with small amounts" or maintain even moisture to create a stable environment for pollination.

Fourth Stage: Fruit Enlargement and Grain Filling Stage – Focusing on "Sufficient Supply, Improved Quality and Increased Yield."

Crop Characteristics: This is the most critical period for yield formation. Crops require a large amount of water and nutrients to fill the fruits or grains, representing the second peak water demand period.

Irrigation Strategy: Provide sufficient and even water supply. Water shortage is absolutely unacceptable at this stage, otherwise it will lead to smaller fruits, underdeveloped grains, and a significant reduction in yield. Ensure the soil remains continuously moist with a stable water supply. For fruit trees and melons, even watering can effectively prevent fruit cracking.

Fifth Stage: Maturity and Harvest Stage – Shifting to "Appropriate Water Control, Improving Quality."

Crop Characteristics: Nutritional growth stops, and fruits or grains tend to mature, beginning to accumulate dry matter and flavor substances.

Irrigation Strategy: Gradually reduce or even stop irrigation. Moderate drought stress is beneficial for the accumulation of sugars, proteins, and other substances, improving fruit sweetness, texture, and color (such as grapes, watermelons, and wheat). It also promotes plant senescence, facilitating mechanical harvesting. However, water control should be gradual, avoiding sudden severe drought.

Practical Points:

Learn to observe the weather, soil, and crops: Combine weather forecasts (whether there will be rain), soil moisture conditions (dryness and depth), and crop leaf status (whether wilting) to make comprehensive judgments and flexibly adjust the above strategies.

Significant differences among different crops: The above are general principles; specific operations need to be combined with the characteristics of specific crops (e.g., rice requires a lot of water throughout its growth cycle, while cotton requires critical water supply during the budding and boll-forming stages).

Tool assistance: Using soil moisture sensors can provide more scientific and intuitive guidance for irrigation decisions at each stage.

In short, the essence of dynamic irrigation strategy is: promoting root growth in the seedling stage, providing sufficient water during the vigorous growth stage, maintaining stability during the flowering stage, providing ample water during the fruit enlargement stage, and controlling water during the maturity stage. By mastering this rhythm, you can grow more and better fruits with less water.