- Author: Bruce Linquist
This year we are conducting a study at the Rice Experiment Station to look at lodging differences between M-206 and M-105. There has been anecdotal evidence that M105 is more susceptible to lodging than M-206. We want to quantify this and see if we can manage N to reduce lodging if need be. Anyways, with this experiment, we have both of these varieties side-by-side in experimental plots. We used Cerano as part of the herbicide program. You can clearly see from the picture that M-206 is more susceptible to Cerano bleaching than M-105. Ray talked with Kent McKenzie about this and he also said he had seen similar findings. Anyway, we thought this might be interesting information for you.
- Author: Luis Espino
While checking traps recently, I noticed a lot of activity in the water in several recently flooded fields. A quick glance into the water might make you believe that tadpole shrimp is present in large numbers, or even perhaps that a treatment did not work. Make sure you look closely and don't confuse clam shrimp with small tadpole shrimp.
Clam shrimp
Clam shrimp are small crustaceans that look like a miniature clam; they are about a tenth of an inch and swim in the water slowly. Clam shrimp don't have the "tail" that tadpole shrimp have at the end of their shell. Most freshwater clam shrimp feed on algae and organic detritus. I am not sure what the ones in rice fields feed on, but they do not injure the rice. In the past, I have noticed that these clam shrimp come back after a tadpole shrimp treatment very quickly.
Clam shrimp close up
Large congregation of clam shrimp around decomposing rice roots
Tadpole shrimp are more problematic during seed germination. Once the seedlings have a well anchored root and the spike is green, tadpole shimp are less likely to injure them.
- Author: Bruce Linquist
Following my blog post about a week ago about using urea or aqua-ammonia (aqua), a number of people have been asking to see the data. The study was conducted in 2017 at the Rice Experiment Station. Aqua and liquid urea were applied at three rates (50, 100 and 150 lb N/ac). Both N fertilizers were injected into the soil at 3 to 4 inches depth. Treatments were replicated three times. Across the N treatments, yields were similar between the aqua and liquid urea treatments. Yields were low, but overall state-wide yields in 2017 were low as well. In other studies (data not shown), we used dry urea banded into dry soil before flooding to the same depth as aqua we saw almost identical yields across seven on-farm studies. Based on these data, liquid or dry urea that is injected or buried into a dry soil before flooding, performs the same as aqua.
- Author: Bruce Linquist
This morning I was out with several members of our research team on the northwest side of the valley planting a variety trial. The grower we were working with had just finished planting all of his rice acreage (1200 ac) yesterday (April 30). Pretty amazing how fast the rice is getting in this year. I know the west side is often earlier than the rest of the valley; however, growers around the valley are moving much faster this year. By the end of next week, we will likely have all of our variety trials (we have seven this year) planted. We have accomplished this so early before.
This is a good start to the season! Generally, when we plant early, yields tend to be higher. This is clear from the figure below. This figure shows state-wide yield averages from 1994 to 2019 relative to the date when 50% of the rice acreage had been planted (based on USDA data). One reason for higher yields is that dry springs (which allow for early planting dates), also give growers time to prepare their seedbed exactly how they want to without skipping passes. From the UCCE Rice Yield Contest, we have seen that good and uniform stand establishment is a key for high yields. Realizing, that the yield potential may be higher this year, the N fertilizer requirement may be a bit higher. It will be important to access the crop midseason (around PI) to see if the crop may need more N fertilizer to realize its potential. This can be done with either a Leaf Color Chart or the Green Seeker.
The UCCE Rice Yield Contest (http://rice.ucanr.edu/Rice_Yield_Contest/) will be running again this year and we look forward to your participation and learning more about how to achieve high yields. The 2020 forms will be available soon. You will need to enter the contest by the Annual Rice Field Day in late August.
- Author: Bruce Linquist
I have heard that there may be a shortage of aqua-ammonia (aqua) fertilizer for the start of this year's rice season. This begs the question as to what are the options. In previous studies, we have compared aqua to urea fertilizer. In one study, we compared aqua to liquid urea; and in another study we compared aqua to granular urea. The liquid urea was applied exactly as one would apply aqua (injected 3 to 4 inches below the soil surface). The granular urea was applied to the soil surface, but then lightly incorporated. How much you incorporate depends on the state of the seedbed. If you have a cloddy seedbed, a lot of the urea will fall into the cracks between the clods and relatively little is needed (maybe a light harrow in front of a roller). If you have a fine seedbed it may require a light disking. Importantly (and good news), is that urea dissolves relatively quickly and the flood water also helps move the dissolved urea further down the soil profile (this is not the case with ammonium sulfate). In both studies, we found that urea performed similar to aqua (in terms of yield and N uptake efficiency). However to get these results, you must make sure that the urea is applied to a dry soil before flooding and it be managed so that it gets incorporated below the soil surface before planting (or banded as you do with aqua). I have found that when urea is used, that the crop never seems as uniform as when aqua is used as the main N source; however this has not affected rice yields. It may affect your ability to assess the crop mid-season for an N deficiency.
If you flood the field before applying your nitrogen fertilizer, then have to apply all of your fertilizer N into a flooded rice field. In this case, your N use efficiency will be less and the cost of application will be higher. If you are in this position, apply N in four split applications. Apply 20, 30, 30 and 20% of the N rate at around 2, 4, 6 and 8 weeks after planting, respectively. The first N application should be ammonium sulfate or a starter blend of fertilizer (one that contains N, P and K). We do not recommend urea for the first N application. The other three applications could be urea. Efficiency will be lower in this system, so you may need to increase your overall N rate.