Wet preparation is the most common way of preparing lowland fields. In this method, the soil is tilled in a saturated or flooded condition.
It helps improve weed control and facilitates incorporation of nutrients in the soil. With its nature, wet preparation has a high water requirement.
The following are the steps and processes involved in wet preparation:
Bunds or dikes enable the field to hold water. This is important especially in areas where water supply is not reliable.
For rat control, construct 30 cm x 30 cm bunds.
Irrigate the field with 2−3 cm of water for about 3−7 days or until it is soft enough and suitable for an equipment to be used.
Primary tillage is normally undertaken when the soil is wet enough to allow the field to be plowed and strong enough to give reasonable levels of traction. This can be immediately after harvest or at the beginning of the next season, depending on soil moisture and water availability.
Power: 4-wheel tractor / 2-wheel tractor / animal power
Attachments: moldboard plow / disc plow / rotavator
Make the first pass along the edges of the field in a clockwise pattern. For the second pass, move counterclockwise and finish at the center.
Read: What are the different plowing patterns? (Training resource)
The soil should be plowed to attain a reasonable depth (10−20 cm of cultivated soil) with varying clod sizes, and to kill weeds by burying or exposing the roots.
Depending on the, another tillage operation can be done using primary tillage implements. Additional primary tillage operations are generally done with disc plow or rotavator.
What is rotary tilling?
Primary tillage may also be done through rotary tilling. A power tiller or tractor-mounted rotary tiller is used in this operation.
Tiller blades or knives completely cut and mix the soil. They also break up and shred plant stubble or weeds, speeding up the decay of plant materials.
Rotary tilling can be done during primary and/or secondary tillage of soil.
Keep the field submerged for 10−14 days after plowing to soften clods and to decompose organic materials.
Depending on climate and soil type, this should be done 10−14 days after primary workings.
Implements: Power tiller, Hydrotiller, Rotovator
Puddling works the soil into a muddy or watertight paste. This minimizes water loss and increases nutrient retention and availability.
Implements: Power tiller with attached comb-tooth harrow, Rotovator
Harrowing breaks up the soil clods and incorporates weeds, straw, and stubble into the mud. This hastens their decomposition.
Pass the harrow crosswise to break the soil clods. The second pass should be done lengthwise.
If the field is flooded, reduce the depth of the water to locate uneven and high surfaces of the soil before harrowing.
The third and final harrowing aim to do initial land leveling and final incorporation of crop residues, and provide proper soil tilth for crop growth.
If using a small tractor or a draft animal, do the final harrowing with a plank leveler; if using a large tractor, use the rotavator and leveler, 2 days before planting.
Leveling should be done two (2) days before planting.
Implements: Power tiller with attached wooden plank, Rotovator wide puddler with attached laser leveler
Use a wooden plank when leveling with a draft animal or small tractor. This requires total water coverage of the field for 12 days.When using a two-wheel tractor, 7−8 days of water coverage is required per hectare of land.
A leveled and smooth soil surface provides for uniform germination and growth of the crops. A well-leveled field improves water coverage and is also proven to increase crop yield and quality.
Read: Guide to laser leveling
You can also combine wet and dry tillage methods
A well-prepared rice field has the following characteristics: