Water seeding of rice is becoming rapidly more popular in Missouri and Arkansas. Water seeding has been practiced in the past in Missouri as an emergency measure when wet conditions have prevented conventional seedbed preparation and planting beyond the recommended planting dates. Emergency water seeding has very rarely been successful.
When water seeding is well-planned and practiced as a season-long system, it can produce yeilds comparable to the conventional dryland seeding system. Water seeded culture is especially valuable for the suppression of serious infestations of red rice and/or to permit continuous culture of rice in the same field.
Water seeding, together with season-long flooding, can reduce established red rice emergence by about 50%. The use of preplant incorporated Ordram herbicide can increase red rice suppression to 90%. Reflooding to attract ducks in the winter can further reduce red rice infestations.
In the conventional dryland planting system red rice control depends on the rotation of rice to an alternate crop such as soybeans or grain sorghum and the strategic use of cultivation and grass herbicides that control red rice in the rotation crop.
Following are the recommedations from Missouri and Arkansas on-farm experience and research for successful water seeded culture of rice:
FIELD GRADING.
The first requirement for successful continuous water seeding is zero grade OR a near zero grade field (up to about 0.02 grade -- which allows for some field drainage, permitting a planned crop rotation or planting another crop in the case of rice crop failure). In either system a canal, about 2 feet deep and 2 feet wide, should be dug around the field to facilitate harvest drainage.
Every year, potholes and wheel tracks must be dressed up, since all areas with standing water cause serious problems with crop establishment, and weed and insect control.
PUMP CAPACITY.
Because precise water management is the key to success in water seeded rice, field size must be relatively small and pump capacity adequate to keep the field saturated continuously early in the season and flooded through the remainder of the season.
VARIETY SELECTION.
Know a variety's specific needs well before selecting and planting it. Avoid Millie and Adair if you plan on using molinate (Ordram) herbicide for weed control and red rice suppression. Select a very short season variety if you may have to plant late and if pumping costs are especially high on a given field. Avoid sheath blight and blast susceptible varieties if you have a history of either disease in a field. Plant more than one variety in your operation, to reduce the risk of any single problem and to spread out your harvest period.
SOIL FERTILITY.
Apply phosphate and potash preplant according to soil test. Though phosphate and potash are seldom needed, their occasional deficiency on rice soils can cause serious loss.
Nitrogen may be applied totally preplant incorporated when seeding stiff-strawed varieties -- Lemont, Gulfmont, Lacassine, Bengal, Maybelle, LaGrue, Newbonnet. For other varieties incorporate 2/3 of the total recommended nitrogen preplant, then fly on 30 lbs. actual N at 1/2-inch internode and again in 7 to 10 days. Katy rice is the exception. Incorporate 75 lbs. N preplant followed by 35 lbs. each at 1/2-inch internode and again in 10 to 10 days. Whether all or only two-thirds of the nitrogen had been applied preplant, the plant area measurement board should be used at mid-tillering and at internode elongation to determine whether and how much more nitrogen may need to be applied at midseason.
SEEDBED PREPARATION.
Seedbed preparation includes:
ESTABLISH A SHALLOW FLOOD PROMPTLY.
Prompt flooding of the field suppresses the germination of red rice and other weeds before the rice is planted.
PRE-SOAK THE SEED AS THE FIELD IS BEING FLOODED.
Pre-soak the seed before seeding. Seed should be soaked for 24 hours then drained for 24 to 36 hours before aerial seeding.
INCREASE THE SEEDING RATE.
The seeding rate needs to be increased by 30 percent over conventional drilled dry-seeded rice. The higher seeding rate makes up for poorer germination, reduced tillering and insect injury. Use the RICESEED computer program recommendation, which takes into account soil type, date of seeding and variety.
Do not use giberellic acid (Release) treated seed.
FLY ON THE PRE-SOAKED SEED IMMEDIATELY.
Fly the seed uniformly onto the flooded field. The grooves or cloddy soil surface are necessary to prevent seed from drifting to one side of the field.
DRAIN THE FIELD IMMEDIATELY AFTER SEEDING, THEN PRACTICE "PIN- POINT FLOODING" UNTIL TIME OF TILLERING.
Drain the field immediately after seeding in order to allow the seed to "peg". Then practice "pin-point" flooding up to time of tillering in order to keep the soil saturated (muddy) at all times. It is absolutely essential that the soil be kept saturated or flooded throughout the season. The soil must never be allowed to crack.
Avoid deep flooding before tillering. Deep flooding early in the life of the rice crop retards rice growth and tillering.
SCOUT FOR MIDGE INJURY IMMEDIATELY FOLLOWING SEEDING.
Midge larvae may eat the embryo and shoot before the seedlings can emerge and become established. This is more likely if seeding has been delayed after the field was first flooded and if the weather is warm. There is no recommended control of midge infestations, but prompt discovery of a problem may permit reseeding or more careful management for a reduced rice stand.
DETERMINE THE EXACT DATE OF EMERGENCE.
Check the field for emergence for an accurate DD50 Rice Growth Prediction Report. The exact emergence date is when there is an average of 10 shoots, 3/4-inch tall, per square foot across the field. Note that in water seeded rice the coleoptile (shoot) rather than the coleorhiza (seedling root) emerges first.
WEED CONTROL.
Always use a preplant herbicide. Select Ordram if red rice and barnyardgrass are the major concerns. Select Bolero for control of anticipated infestations of aquatic weeds (dayflower, eclipta and false pimpernel), barnyardgrass, crabgrass, fall panicum and the sprangletops.
Ordram 8E should be applied at the rate of 4 pints per acre and incorporated immediately. Beware, if Ordram is to be used for weed control, do not plant Millie or Adair varieties, since they are very susceptible to injury from Ordram.
Bolero should be surface-applied at the rate of 4 pints per acre.
The field must immediately be flooded then kept either saturated or flooded continuously after the Ordram or Bolero has been applied.
Aquatic weeds are likely to be a problem in water seeded rice. Aquatic weeds are more likely to be a problem when there is a delay in seeding after seedbed preparation and after the field has been flooded. When the field has a history of aquatic weeds, Bolero should be surface-applied before flooding prior to seeding. After aquatics have emerged, but are no larger than two leaves for economical and effective control Londax will control ducksalad, eclipta, ammania, gooseweed, false pimpernel, water hyssop and flatsedge.
Algae can be a problem in water seeded rice, especially when the rice grows slowly (often due to flooding the field too deep) and when the water is warm. Apply a labelled copper sulfate material promptly when algae shows up.
SCOUT FOR RICE WATER WEEVIL.
Rice water weevil is a serious threat to water seeded rice. Scout early and regularly for rice water weevil damage and apply Furadan 3G promptly when the treatment threshold is reached.
INCREASE FLOOD DEPTH AFTER TILLERING.
Gradually increase flood depth after the rice begins to tiller, to 2 to 4 inches at midseason.
USE THE PLANT AREA BOARD.
Use the plant area measurement board at mid-tillering and again at beginning of internode elongation, to determine whether more nitrogen needs to be applied at mid-season. Nitrogen rate strongly influences disease susceptibility, maturation and standability of the rice.
SCOUT FOR DISEASES AT MID-SEASON.
Begin scouting for sheath blight and blast just prior to mid-season (internode elongation). Reduce midseason nitrogen if either disease is threatening and apply the appropriate fungicide for either disease at the proper time after treatment threshold is reached.
DRAIN EARLY BEFORE HARVEST.
Except on sandy soils that lose water rapidly, you can cease pumping water two weeks after heading. Then pull the levee gates and drain the field two weeks before harvest -- using the DD50 prediction.
HARVEST PROMPTLY BUT WITH CARE.
Harvest the rice when grain moisture is between 22 and 18 percent. Thresh with care, adjusting cylinder clearance and speed in order to maximize milling quality and yield. Avoid rutting the field.
ROLL THE STUBBLE SOON AFTER HARVEST.
Roll the stubble as soon after harvest as feasible. This promotes stubble decomposition and germination of volunteer rice and red rice seeds.
REFLOOD THE FIELD FOR THE WINTER.
Plugging the field drain and allowing rainfall to reflood the field invites ducks. Ducks greatly reduce volunteer and red rice seed in the soil.