Irrigation and drainage techniques on orange trees

Orange trees need even moisture but are afraid of waterlogged roots. Instructions for watering according to the stages of bud blossoming, flowering, fruit growing, pre-harvest and drainage design to reduce fruit cracking, root rot, and yellow leaves in orange orchards.

Summary: With oranges, lack of water causes flowers and young fruits to drop; Excess water causes root rot, yellow leaves and cracked fruit. Therefore, irrigation and drainage must go together. The orchard has a good irrigation system but poor drainage ditches still fail during the rainy season. This article provides instructions on water management according to growth stage and how to test soil to decide on irrigation.

Applies to: Saffron oranges, V2 oranges, diamond oranges, Cao Phong oranges and commercial orange orchards in the Northern, Central, and Mekong Delta mountainous areas.
Duration: Year-round management, focusing on dry season and heavy rains.
Difficulty level: Basic. It's important to keep it evenly moist, avoiding dry-wet shock.
Estimated additional costs: 5-30 million VND per hectare depending on investment in drip irrigation, root canals and drainage ditches.

Characteristics of orange roots

Orange roots are concentrated in the topsoil, where there is a lot of oxygen and organic matter. Roots need moisture but cannot stand being submerged for long:

Prolonged dry soil causes flowers and young fruits to fall.
Sudden watering after a drought can easily cause fruit cracking.
Soggy soil causes roots to lack oxygen, increasing root rot caused by soil fungi.
Prolonged humidity in the orchard also makes ulcers, scars, and anthracnose worse.

The principle is to keep the soil evenly moist, not letting it get too dry or too wet.

Check soil moisture

Do not water only on a fixed schedule. How to quickly check:

Dig 20-30 centimeters deep at the edge of the canopy.
Hold the soil in your hands.
Soil that is lightly compacted and does not leak water is moderately moist.
Loose, crumbly soil means it lacks moisture.
Soil that is sticky, oozing, or smells sour is too moist.

orchards with sandy soil need watering less but more often. Clay orchards need to be watered more sparingly and pay attention to drainage.

Irrigation in stages

After harvest

Irrigation if the soil is dry.
Combine organic fertilizer and recovery fertilizer when the soil is moist enough.
Do not let the tree dry out for a long time after the fruit-bearing season.

Prosperity and flowering

Keep moist evenly for healthy hair.
Avoid water shock before flowering.
When the flowers are blooming, do not spray heavily on the canopy.
If it's dry at the flowering stage, water lightly around the root area.

Fruit setting and fruit cultivation

This is the stage that needs the most stable water.
Do not let it dry and then water all the time.
Clean organic root cabinet to retain moisture.
Monitor young fruit after heat waves.

Before harvest

Keep moderately moist, don't water too hard.
7-10 days before cutting the fruit, reduce watering if the soil is still moist enough.
Avoid watering after a dry period because the fruit can easily crack.

Irrigation method

Drip irrigation

Save water.
Keep the root area evenly moist.
Can combine fertilization with water if the system meets standards.
Need to filter the water and check the drip tip.

Watering the roots

Suitable for business orchards.
Water distribution is wider than dripping.
You should avoid spraying directly on the trunk and root collar for too long.

Manual watering

Easy to use in small orchards.
Need to measure time/flow to avoid excess or insufficient plants.
Equally laborious and difficult.

Do not encourage sprinkler irrigation in orchards with leaf or fruit diseases.

Drainage of water in the rainy season

Orange orchards need drainage before heavy rain:

The main ditch must exit into the orchard.
Auxiliary ditches between rows are not blocked.
The lowlands need to be upgraded.
Do not leave water standing around the base for more than 24 hours.
After heavy rain, check for water stagnation and drain immediately.

If the orchard's leaves turn yellow after a lot of rain, check the roots before fertilizing. Waterlogged roots cannot absorb fertilizer.

Limit fruit cracking

Fruit cracking is often related to uneven juice:

The tree dries out for a long time and then gets heavy rain or strong watering.
The fruit shell cannot keep up with the rate of increase in water inside.
Calcium/boron deficiency makes fruit skin weaker.

Room by:

Keep evenly moist during the fruit growing stage.
Dry season storage.
Do not irrigate after a drought.
Provide balanced nutrition, pay attention to calcium and boron when lacking.

Common mistakes

Only invest in irrigation, skip drainage: in the rainy season, the roots still rot.

Irrigation on a fixed day: does not include rain, soil, or tree age.

Irrigation sprayed on canopy when flowers/fruits are young: increases flower drop, leaf disease and fruit disease.

Let it dry and then water a lot: it can easily crack and cause root shock.

Fertilizing when the soil is too dry or too wet: low efficiency, easy to damage roots.

Monitor and record

[ ] Watering date, water quantity or watering hours.
[ ] Soil moisture before irrigation.
[ ] Intermittent rainfall.
[ ] Water stagnation after rain.
[ ] Rate of flower and young fruit loss.
[ ] Rate of fruit cracking near harvest.

After a year, water data will indicate which batches dry quickly and which batches are waterlogged, thereby adjusting the system more effectively.