This year we tested no-till (NT) drill-seeded planting of rice. This was our second year of these trials. No-till drill seeded planting offers some real opportunities to conserve water, plant early, save on tillage costs, and change the irrigation system which will shift weed species from a continuously flooded system (the system will be grass dominant).

This study was conducted at the Rice Experiment Station looking at N management, pests, diseases and weeds. We tested NT drill seeding into three different seedbeds and compared this to a conventional water-seeded system. The treatments of our study were:

1. Fallow stale-seedbed (FSS): field was fallowed in 2023. It was disked and leveled during the summer of 2023 and not flooded during the winter. No tillage was done in 2024 before drilling the rice in early spring.

2. No-till. We had two strict NT treatments. Rice was grown in 2023. After harvesting with care not to rut the field, the straw in the field was subjected to one of two treatments:

a.Chopped (NT-Chop)

b.Half removed to simulate baling (NT-Remove)

3. Water-seeded. Rice was grown in 2023. Straw was chopped and disked, and the field flooded during the winter to promote straw decomposition.

For the FSS and NT treatments, we planted May 1 using a NT drill seeder, flushed once after planting and then applied a permanent flood on May 30. Just before the permanent flood, we applied N fertilizer (urea) and herbicides (Pendimethalin, Super Wham and Loyant). On July 11 we applied Clincher. The water-seeded treatment was seeded on May 27 and managed conventionally. We harvested the FSS and NT plots on September 17 and the water-seeded plots on October 14.

The water-seeded treatment had the highest yield at 93 cwt/ac; this was followed by 84 cwt/ac in the FSS, 76 cwt/ac in the NT-Chop, and 74 cwt/ac in the NT-Remove. All of these treatments achieved maximum yields at N rate between 175 and 200 lb N/ac. These results are promising, but a bit different from last year. In 2023, we saw a yield reduction in the NT treatments, but the FSS and water-seeded yields were the same.

This year, several farmers tested these practices on their farms. While we do not have an exact comparison of yields at this time, the early indication is that the NT and FSS fields performed similar to water-seeded fields.

There are several reasons for using no-till practices. These include being able to plant earlier, saving water, using different herbicide formulations, and reducing tillage and herbicide costs. We were able to plant early; in fact, the FSS and NT treatments were the first planted fields at the Rice Experiment Station this year. Regarding water savings, the NT and FSS treatments saved about 6 inches of water. This water savings came in the first month after planting where we only flushed the field once (right after drill-seeding) and then let it dry up until permanent flood about four weeks later. These practices allow for the use of soil water as well as reduce evaporation. In water-seeded systems, a major pathway of water loss in the first month is evaporation.

Arthropods and Diseases

Arthropods were not an issue in any of the basins where we conducted the study. Tadpole shrimp or rice seed midge would not be expected to be a problem in the FSS or NT systems, but they can be a problem in the water-seeded system. In fact, in our study, we used the insecticide lambda cyhalothrin in the water-seeded treatments but not in the FSS or NT treatments. This is a savings that can be realized in drill-seeded systems.

The only disease that occurred in the study area was stem rot. Stem rot severity was 20% lower in the FSS and water-seeded treatments than in the NT treatments. While the effect of the fungicide azoxystrobin on stem rot severity was not significant, its use reduced the severity of the disease 30% in the FSS and water-seeded treatments. Interestingly, we noticed that the timing of heading was not similar in all treatments. The NT treatments headed earlier than the FSS treatment. The fungicide application to all the drill-seeded treatments was made on the same date; at this time, the FSS treatment was at the very early heading stage while the NT treatments were past 50% heading. This may be the reason why we did not see an effect of the fungicide on the NT treatments. The differences in heading time may be due to differences in N availability between treatments.

Weeds

Weed management in this system is similar to managing weeds in a drill-seeded system. The main differences are:

•Necessary to manage winter weeds prior to planting (registered herbicides are glufosinate, glyphosate, saflufenacil (Sharpen), and 2,4-D). Always make sure to check the specific product label for use restrictions and registration.

oNOTE: oxyfluorfen is not an option due to plant-back restrictions (minimum of 10-month plant back period for rice).

•Effects of straw on weed emergence in the Chopped treatment (NT-Chop) (reduced weed emergence compared to the straw removed treatment)

•If repeatedly using No-till year after year, then perennial weeds are more likely to establish. Some we have noted initially include ricefield bulrush (roughseed) and tulles (cattails). 

This system is dominated by grasses, similar to our other drill-seeded systems. The main species we saw in 2024 were sprangletop and the watergrasses (specifically barnyardgrass). One of the predicted positives of the fallow treatment (FSS) is a reduction in watergrass emergence, however we do not have conclusive data on this currently.

There are no current recommendations for specific herbicide programs for these systems, but we will be doing a study next summer which will hopefully provide some specific combinations and sequences. Due to the inability to use granular formulations in this system, pendimethalin was applied upfront as a pre-emergent (please check the label for specific use instructions), followed by a foliar tank mix applied pre-flood (SuperWham and Loyant). We also followed up with a cleanup spray at tillering (Clincher).

The other option for a pre-emergent is Abolish (thiobencarb). For foliar tank mixes, there are many options for grass and sedge control, but keep in mind that sprangletop control is necessary, and the only two foliar options are: Clincher (cyhalofop) and Loyant (florpyrauxifen-benzyl). All programs should include one or both of these options, and rotation of chemicals (within and between seasons) is necessary to prevent the selection for herbicide resistance.