Key Technical Points for Dragon Fruit Irrigation and Drainage (Part 2)
(2) Irrigation methods and irrigation amount ① Flood irrigation In areas with abundant water sources and flat terrain, whole-orchard irrigation is often practiced. However, this method causes certain damage to soil structure, is labor-intensive and time-consuming, and is uneconomical, so it is now gradually being used less. ② Furrow irrigation Build a tree basin around each plant, or make long furrows along the tree rows, and lead water into the tree basins or furrows during irrigation....
(2) Irrigation methods and irrigation amount
① Flood irrigation In areas with abundant water sources and flat terrain, whole-orchard irrigation is often practiced. However, this method causes certain damage to soil structure, is labor-intensive and time-consuming, and is uneconomical, so it is now gradually being used less.
② Furrow irrigation Build a tree basin around each plant, or make long furrows along the tree rows, and lead water into the tree basins or furrows during irrigation. This method saves water and is easy to manage, so it is widely used. However, it likewise damages the soil structure of the tree furrows, causing the death of absorbing roots.
③ Hole irrigation When water sources are scarce, dig 8-12 holes about 30 cm in diameter outside the outer edge of the tree canopy drip line, with a depth that does not damage the roots, pour water into the holes, and fill them level after the water seeps in.
④ Furrow irrigation between rows Dig irrigation furrows at regular intervals between 2 rows of trees, with a furrow depth of 20-30 cm and a width of about 50 cm. Generally, 2 furrows are dug per row; for dwarfed and densely planted orchards, 1 furrow may also be used. Lead water into the furrows so that it gradually seeps into the soil. This method both saves water and causes less damage to soil structure, and should be promoted.
⑤ Drip irrigation Drip irrigation is an advanced mechanized and automated irrigation technique developed in recent years. It is a method of irrigation in which water droplets or a fine stream of water are slowly applied to the plant root zone. It is now gradually being adopted in production. Drip irrigation has many advantages: for example, it moistens only the soil layer near the crop roots and the surface soil, greatly reducing water evaporation; this system can be fully automated, reducing labor to a minimum; moreover, it can regularly supply water to the root-zone soil, evenly maintaining soil moisture so that it is neither overly wet nor overly dry, while also keeping the root-zone soil well aerated. If drip irrigation is combined with fertilization, it can continuously supply nutrients to the root system, which is most beneficial to the growth and development of fruit trees, achieving two benefits at once. According to foreign reports, drip irrigation can increase fruit tree yields by 20%-50%. However, a drip irrigation system requires more piping materials and a relatively large investment, and needs a water tower with a certain pressure and a filtration system, as well as main pipelines and branch pipelines leading water into the orchard, and capillary tubes and emitters surrounding the trees. In addition, the pipelines and emitters are easily clogged, strictly requiring good filtration equipment.
Regardless of which irrigation method is used, the amount of water applied at one time must not be too large or too small; it is suitable to moisten thoroughly the soil layer where the main root system is distributed. Specifically determining the irrigation amount also requires considering soil quality, the growth and development stage of the fruit trees, fertilization conditions, and meteorological conditions. For theoretical calculation of irrigation amount, determining it by soil moisture is the most commonly used. It is generally believed that the minimum irrigation amount is when soil moisture is 60% of the soil's maximum water-holding capacity, while the ideal amount is 80% of the maximum water-holding capacity. In addition, based on the long-term accumulated experience of fruit growers and technicians, when irrigating, what they consider as having irrigated thoroughly is in fact the most suitable irrigation amount.
2. Drainage
The roots of dragon fruit are most afraid of oxygen deficiency and are intolerant of water accumulation. When there is too much soil moisture, aeration performance weakens, which hinders root respiration; in severe cases, it can suffocate the active parts to death, causing fruit drop, reducing fruit flavor, and even causing plant death. Therefore, in addition to doing a good job of water conservation and timely irrigation, drainage work such as flood control and waterlogging prevention should also be done well, with drainage ditches and flood discharge channels built, and preparations for flood control and drainage made during the rainy season. The number and size of drainage ditches in the orchard should be determined according to the local rainfall, the strength of the soil's water-holding capacity, and the level of the groundwater table. Under normal circumstances, the drainage ditches in a dragon fruit orchard are about 1 m deep.