- Weed control is a challenge and becomes a big problem if the weeds are not controlled when they are small. Grasses in particular seem to be a problem and, in some cases, are taller than the rice.
- A plan and knowing available herbicide options when you start a rice crop is critical for pre-emergence and post-emergence treatment.
- Please follow the herbicide label. If the herbicide is not labeled for rice use, DO NOT use it.
- Irrigation management requires an understanding of the rice root zone from week to week. When talking "field capacity," we mean that when the soil is completely saturated and a rain event occurs, the rain would either run off the field or leach quickly through the root zone. Due to this, in general, you should refill the root zone of the crop to within 15% or so of field capacity to allow room for a rain event.
- An example - rice at early tillering:
- Root zone -- 7.5 to 10 cm
- Soil -- silt loam
- Allow 30% depletion at this stage -- up to 60 mm
- Crop water use
- Confirm the evapotranspiration (ET) -- let's assume it is 7 mm/day
- Assume rice at this stage has a crop coefficient of .35 mm
- Daily use would be about ET x crop coefficient (7 x .35 = 2.45 mm)
- Center pivot can apply 9.5 mm/day
- Probably need to be applying about 6 to 7 mm every other day
- If you have soils that tend to crack, start irrigation during the tillering stage when cracks are 2 to 3 mm wide
- Both light, frequent applications and heavy applications can be a problem. Watch your wheel tracks and watch for runoff
- Check the crop root zone and confirm that you are refilling the profile without runoff or irrigation moving out of the root zone
Have questions? Please enter them into the Comment box below!
It is with our great pleasure to announce that Kelly Downing, a member of the Valley Rice Team, has become a Certified Crop Advisor, as determined by the American Society of Agronomy.
This morning, one of the very first things I did was check the Delta Farm Press website for any new articles on rice that I could share with you all. What I found was this article, and I was quite moved by it. This article is about a passionate group of rice growers in the United States Delta region who have recently toured rice fields that are far from perfect. The members of the group talked amongst themselves and with other rice producers about each one can do to help make their rice growing situations better, in terms of management, technology, weeds, and other factors. Other conversations stemmed around rice growers who have already started to overcome and solve issues on their fields.
Hello, everyone! Valmont Irrigation attended the 2010 Farm Progress Show this week in Boone, Iowa, USA. Both Jake and I helped staff the booth, and we talked about Circles for Rice whenever we had the chance! 
I am back in the U.S. after traveling for two weeks in France and Spain. I visited farmers, customers, and Valley Dealers.
Last week, I visited the rice fields down South. Some observations have been made:
An observation we have seen in very lightly textured soils under a center pivot is new emerging leaves appear yellow (photo on right). Tissue and soil samples were collected in both areas of healthy plants and areas of yellowing plants; these were then taken and examined by specialists at the University of Missouri Delta Research Center, where a conclusion was made that the yellowing was caused by a fertility issue. The analysis was run by the Delta Center Soils Lab, and, while there were no specific recommendations for center pivot irrigated rice, it appeared that sulfur may be the culprit. Ammonium sulfate was applied and watered in the field on July 3, 2010. We will follow up with the issue this week.
Irrigation management is a continuously critical factor, and we recommend applying more water as the rice crop matures (per our observations on the loamy sand to clay loam soils); HOWEVER, we do not want the water moving from where it is applied (ie: runoff - photo on the right). Some fields can take up to .75", while other fields are limited to only .5". We must also be careful to cover the field and return to the driest areas in a timely fashion. Remember that the rice root system is much shallower than corn, cotton, and soybeans, which means that there is a small volume of soil to manage.
We also need to keep an eye on the pressure at the pivot point (photo at left). As pumping levels change, we have observed a reduction in the pivot pressure; if the pivot pressure is below the sprinkler chart (design pressure), the depth of water applied is reduced. This reduction can lead to the situation as shown in the picture below where, due to reduced pressure, the correct overlap is not maintained and streaking has developed in the field. The darker areas are rice plants exhibiting signs of moisture stress, while the lighter areas are plants that have adequate moisture.
We have started to collect infrared images to help identify issues in the fields, which we then compare with adjacent flood fields (photo at right). Please note the half-circle center pivot and the flood field in the lower right-hand corner. We like to see uniform color across the field.
Online newspaper The Fence Post recently posted an article about the history of the center pivot. The article illustrates the life of inventor Frank Zybach, the inventor of the first center pivot mechanized irrigation machine.
The rice under the center pivots continues to develop well. Currently, the growth stages range from 2 leaf to 5 leaf (first tiller). Most fields have received nitrogen, either dry Urea or 28% liquid. Most growers are using the center pivots to apply the 28% liquid nitrogen; in most cases, the application includes sulfur.
