Missouri Rice Tillage Systems Compared

by Bruce Beck
Extension Agronomist/Rice
Poplar Bluff, Missouri

Missouri rice growers produce rice in variations on three basic systems -- conventional tillage, water culture, corrugated tillage and minimum tillage. Following is an outline of those basic systems and some of their modifications, listing pros and cons of each.

CONVENTIONAL TILLAGE.

OPERATIONS:

• Two passes with a disk.
• Land planing (land float).
• Broadcast application of preplant fertilizers.
• Seedbed preparation with a field cultivator followed by a bed conditioner OR one pass with a multipurpose tool such as a "Triple K".
• Planting by grain drill or broadcast seeder.
• Rolling the field with a corrugated roller.
• Laser surveying the field for levees at two-tenths grade.
• Constructing the levees with a levee disk.
• Blading out gaps for the levee gates, placing in constructed gates or plastic sheeting and 2x4's, and butting up with a backhoe.
• Flush irrigating the field when necessary, in order to promote prompt, uniform crop and weed germination and prevent soil crusting.
• One or two herbicide applications with ground rig or airplane.
• Fertilization with 2/3 the total recommended amount of urea (by ground rig or plane) immediately before flooding.
• Flood irrigation.
• Possible field drainage and application of liquid chelated zinc and ammonium sulfate and delayed reflooding -- for control of zinc deficiency, should it occur.
• Flood maintenance at 2 to 4 inches depth for the remainder of the season.
• Possible field drainage (and drying to the point of soil cracking) for control of rice water weevil and/or straighthead disorder, followed by reapplication of urea and reflooding.
• Application of broadleaf herbicide on the levees or the whole field.
• Two mid-season applications of urea by airplane.
• Possible applications of fungicides (twice each for sheath blight and/or blast, should they reach economic treatment thresholds).
• Cease irrigation two weeks after heading, but keep the levee gates closed.
• Open the levee gates two weeks before harvest.
• Harvest the crop by combine.
• If not reflooding to attract ducks during the winter and if rice is not to be planted in the same field the following year, remove the levee gates and pull down the levees with the levee disk.
• Roll the stubble with a toothed roller or disk up the stubble in order to get the straw in good contact with the soil.

• Research and experience are most extensive by far for this system.
• Crop rotation options are open.
• Herbicide options are most numerous.
• Most of the herbicides and fertilizer applications may be made by ground equipment.
• Rice water weevil can be controlled by field drainage if necessary.
• Field size can be relatively larger than for other systems.

• Tillage and planting can be seriously delayed by wet spring weather.
• Levee construction and removal require significant labor and timeliness.
• Levee maintenance and water level maintenance require season-long care.
• Levee weeds demand special attention.
• Crop rotation is imperative for red rice control.
• Sheath blight risk is especially serious.

WATER SEEDING AND CONTINUOUS WATER CULTURE.

OPERATIONS:

• Land plane (land float).
• Broadcast phosphate, potash and zinc (according to soil test recommendation) plus all or most of the urea nitrogen (according to variety).
• Disk the field twice, for seedbed preparation.
• Apply Ordram herbicide (followed immediately by two diskings at cross angles to incorporate it into the soil).
• Roll with a special "groover" which prevent seed drift when the seed is flown on. This operation may not be necessary if a very cloddy surface texture can be obtained dependably by disking.
• Surface apply Bolero herbicide if Ordram is not used.
• Shallow flood the field.
• Pregerminate the seed (24 hours in water followed by 24 to 36 hours drained).
• Seed immediately by plane.
• Drain the field immediately after seeding
• Practice "pinpoint" flooding to maintain continuous soil saturation.
• Apply Londax herbicide for broadleaf and aquatic weed control.
• Flood the field gradually to 2 to 4 inches deep after the rice begins to tiller.
• Apply Furadan granules as soon as an economic rice water weevil threshold is reached.
• Apply copper sulfate for algae control if algae threatens to become a problem.
• Apply urea once or twice at mid-season according to variety and plant area measurements.
• Apply fungicides as necessary for sheath blight and blast control.
• Cease pumping two weeks after heading.
• Drain the field two weeks before harvest.
• Harvest by combine when the grain reaches 22 to 18 percent moisture, taking care not to rut the field.

• Suppresses red rice very effectively after a field has become infested.
• Permits continuous culture of rice year after year, without risk of red rice infestation.
• Eliminates levee construction, maintenance and removal.
• Expedites precision management of water.
• Facilitates a uniform crop emergence and more precise management through the season.
• Simplifies weed control.

• Zero-grade fields cannot be be used dependably to grow rotation crops.
• Precision field grade must be maintained with care.
• Field size must be relatively small in order to pin-point flood and to maintain season-long flood.
• Timeliness and planting is extremely critical.
• Dependent on aerial applications from planting time on.
• Rice water weevil, midge, aquatic weeds, algae and sheath blight are especial risks in this system, with limited control options.
• Seeding rate and pregermination costs are higher.
• Pumping costs are higher.

CORRUGATED TILLAGE.

OPERATIONS:

• Disk the field twice. The second disking must run the direction of irrigation flow and leave the soil surface very rough or cloddy.
• Construct a levee (may be permanent) at the bottom of the field and up each side of the field at least 1/3 the way to the top.
• Place one or more stop-log structures at the bottom of the field for flood depth regulation and for drainage.
• Lay out irrigation pipe across the top of the field. Disposable poly pipe may be preferred.
• Flush irrigate the field.
• Seed dry rice by airplane at normal seeding rate onto a saturated soil surface.
• Apply Prowl (with or without Bolero or Facet) for preemergence control of weeds, after the rice seed has imbibed its moisture.
• Maintain a wet soil surface by flush irrigation, for seedling establishment and weed suppression.
• Control small weeds postemergence with propanil or Arrosolo. May be done with a ground rig.
• Topdress 2/3 the recommended nitrogen (as urea) onto a dry soil at beginning tillering. May be done with a ground rig. Flush irrigate the field immediately to carry it into the soil.
• Flush irrigate as needed until two to four weeks after heading.
• Harvest by combine at 22 to 18 percent grain moisture.

• No internal levees or levee gates to construct, maintain or destroy.
• No loss of field area to levees.
• Convenient to irrigate.
• Uniform stand establishment for easier crop management and better weed control.
• Inexpensive and effective preemergence control of weeds with Prowl.
• Almost no rice water weevil or sheath blight.
• No cold water reduction in rice yield and quality.
• Yields comparable to conventional rice.
• Very easy to harvest.
• Very little grade maintenance.
• No crop rotation restrictions.
• Limited dependence on aerial applications.

• A new system with no research backup.
• Possible or probable risk of blast.
• Possible quality reduction.
• Pump maintenance is absolutely critical.
• Field size is limited.
• Very close attention needed to early weed control.

NO-TILL AND MINIMUM TILLAGE RICE PRODUCTION.

If rice is grown after rice, the levees from the previous crop can be left standing, but nearly always some minor grading or disking will be necessary to remove ruts and potholes.

Just prior to planting, emerged weed are controlled with either Gramoxone Extra or Roundup. The rice can be drill seeded. Water seeding is not recommended because of seed drift problems on a smooth soil surface. Prowl and/or Bolero can be applied for preemergent weed control if the soil can be flushed and kept moist after herbicide application.

Nitrogen fertilization and water management from beginning tillering through harvest will be the same as for the conventional rice culture system.

ADVANTAGES TO MINIMUM TILLAGE SYSTEMS:

• Less planting season labor and rush to prepare the seedbed.
• Reduced overall seedbed preparation because of winter weathering.
• Earlier planting because of no spring tillage.
• Except for planting and preplant weed control, the cultural practices are the same as for conventional tillage.

• Any necessary tillage and leveling needs to be done in the fall.
• Special attention needs to be paid to chemical control of weeds.