Pressure Regulators | by Jerry Gerdes

Senninger® Pressure Drop

Valley Pressure Regulator

Nelson® Pressure Regulator

Pressure regulators are commonly used in sprinkler package designs. The regulator is installed just upstream of the sprinkler and its function is to maintain a constant water pressure into the sprinkler. The pipeline pressure within a center pivot or linear machine can vary for a number of reasons; friction loss, elevation changes within the field, sprinkler valves turning on and off on a corner span, or an end gun sprinkler turning on and off.

Pressure regulators are recommended for center pivot or linear machines where pressure fluctuations will cause a 10% or greater change in sprinkler flow. Using pressure regulators will maintain a uniform depth of water applied throughout the field. Sprinkler life and performance will also be maximized by selecting a regulator that will operate the sprinkler within its specified pressure range.

Regulators are available in pre-set pressure ratings. The most common ratings are 6, 10, 15, 20, 25, and 30 PSI. Maximum flow capacity for a pressure regulator will range from 15 to 20 GPM, depending on the regulator model. Pressure regulators require a minimum inlet pressure of 5 PSI plus the nominal pressure to produce the correct outlet pressure.

For more information, contact your local Valley Dealer.

Circles for Rice Update - Brazil | by Kelly Downing

Field Day | Alvarez

Center pivot on rice | Alvarez

Field Day | Edwin Neumann, Renan Bueno, Ervin Neumann

Last week, I attended two rice field days hosted by Valmont and our cooperating growers in Brazil. After visiting fields in São Paolo state the previous week, we then went to Rio Grande do Sul state. I traveled with Dr. Jose Parfitt of the Embrapa Temperate Climate Research Center at Pelotas. We spent time at their research plots at Pelotas, Bage, and São Vincente. We also visited the Toniazzo and Alvarez farms near São Borja. Both fields looked great. They are fully headed, within a couple of weeks of harvest.

On Thursday, 20 January, we held a field day at the Alvarez farm. Adalberto Alvarez and his sons, Bernardo and Fernando, welcomed 150 people to view their great-looking rice field, listened to presentations by several professionals and shared a great barbeque lunch. It was a warm, sunny day and most people I saw seemed to enjoy themselves. Bernardo told me that, based on their success this year, they intend to expand the acreage of pivot rice in the future.

After a nice drive across Rio Grande do Sul, we flew back to São Paolo for a field day at Fazenda Agua Grande. Ervin Neumann and his son Edwin welcomed a much smaller, but equally enthusiastic, group of farmers to their rice field. The rice there is also close to harvest. One difference is that, unlike the cooperators in the South, the Neumann field includes two varieties, with the Querencia close to harvest; the Taim will probably take a little longer.

On Sunday, I left the warmth (32 degrees Celsius, 90 degrees Fahrenheit) and returned to the much more comfortable (0 degrees Celsius, 32 degrees Fahrenheit) High Plains of Nebraska. It is always a treat to visit Brazil; the people are beautiful, the scenery is fantastic and the food is always great. However, it was nice to get home, also. I have to admit, I did not notice any problems in Brazil trying to dig our vehicles out of snowdrifts or spinning out on the icy roads!

Rice Status - Brazil | by Kelly Downing

Edwin and Ervin Neumann, Ronney Silva (Valley employee), Renan Bueno (Valley trainee)

Flavio Leandro Medeira | Fazenda Lagoa

Adilson Rodriguez Machado | Fazenda Lagoa Bonita

Sergio Leme | Capuava

This week I was able to return to Brazil to revisit rice fields I first toured in November. This time, I began with the fields in Sao Paulo State: Fazenda Agua Grande, with Ervin Neumann and his son Edwin, Fazenda Lagoa with Field Manager Flavio Leandro Medeira, Capuava Farm with Sergio Leme and Fazenda Lagoa Bonita with manager Adilson Rodriguez Machado.

Most fields were planted in September, and are nearing harvest; the rice at Capuava was planted in late November (I had not seen this field on my last trip), so it is scheduled for harvest in March. This is a location where Mr. Leme is helping CATI conduct some on-farm variety trials, as well as a production area. The rice (all production areas) looks lush and full right now. However, the soil sensor readings were relatively dry, so it will be important for them to keep up irrigation. The other farms are somewhere between two and four weeks from harvest.

As the rice nears harvest, weeds remain a difficult obstacle in most fields. This will require diligence, effective plans and timely applications for future crops. Fazenda Lagoa also suffered through an unusual period of cold weather in mid-December, when the crop was at R4 growth stage, which caused a lot of damage. Fazenda Lagoa Bonita also has significant weed pressure, since they were unable to prevent or control a large infestation of volunteer wheat from the previous crop.

I always enjoy driving through Sao Paolo state-the highways generally follow the hilltops (and the hills are large-150 – 200 meters of elevation change), so we get to see the beautiful countryside spread out around us. It is obviously quite a different look from what we see in Nebraska, especially in January. On Sunday I flew to Porto Allegre and we drove to Pelotas. Avoiding large lizards in the road is another thing that is not a problem in Nebraska! This week we will have a field day at the Alavarez Farm in Sao Borja, then back to Sao Paulo state and the Neumann farm for their Field Day, as well as visits to other locations in Rio Grande do Sul.

Sprinkler Models for Center Pivots and Linears | by Jerry Gerdes

There are two types of sprinkler models used for center pivot and linear equipment: fixed spray and rotating spray. Both sprinkler types have a wear plate mounted directly below the nozzle (orifice), which discharges the water and creates a 360°ree; water pattern. Fixed sprays have no moving parts because the wear plate is fixed. A rotating spray wear plate rotates either fast or slow, depending on the sprinkler model.

Water Patterns and Runoff

Rotating sprays produce a large wetted diameter (50' to 70') that creates a low-intensity water pattern; this is a major advantage of rotating sprays. This type of sprinkler works very well on medium to heavy soil types and reduces water runoff. Fixed sprays have a wetted diameter of 15' to 40'. This type of sprinkler works well on light soils where runoff may not be a big issue.

Plate Design

There are a variety of plate designs available to you that can very the droplet size of the water pattern; various designs are available for both rotating and fixed sprinkler types. By selecting a plate that produces smaller water droplets, you can also reduce the water pattern intensity. Smaller water droplets can easily lead to lower application efficiencies from evaporation and wind drift losses. Please note that climate conditions must be considered in the plate selection.

Fixed spray and rotating spray sprinklers are designed to operate at a low pressure in order to minimize energy (pumping) costs. Design operating pressure for fixed sprays is 6 to 30 PSI and pressure for rotating sprays is 10 to 30 PSI.

Circles for Rice Update | by Jake LaRue and Kelly Downing

Currently, the Valley Circles for Rice team is observing fields under center pivots in Brazil, Chile, Zambia, and Australia. Growth stages vary from 1-2 leaf to early tillering.

• 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

Remember: the data from soil moisture sensors is only as good as the installation. Make sure your sensors are properly installed and calibrated, and use the "smell test", i.e. if something smells bad (if the readings seem bad), it probably is. Check conditions around the sensors periodically to make sure that what they report is the real situation in the field.


Have questions?  Please enter them into the Comment box below!

Sprinkler Packages 101 by Jerry Gerdes

I have just completed my first year as a member of the Valley Circles for Rice team, and I have learned much about the process of growing rice. Crop-specific information is very useful when selecting sprinkler package components for a center pivot or linear irrigation (lateral move) machine. The term "sprinkler package" refers to the collection of sprinklers, pressure regulators, drop components, and fittings used to mount the sprinklers to the machine.

The sprinkler package is designed to apply water evenly (ie: uniform depth throughout the field) and efficiently. This is to maximize crop yields, minimize water usage, and operating costs. Sprinkler choices are designed to operate at pressures in a range of 6-30 PSI, depending on the sprinkler model. Products called U-pipes and drop pipes (or drop hose) are used to mount the sprinklers below the span trussing. The combination of low-operating pressure and low-ground clearance maximizes the application efficiency of the irrigation water. This type of sprinkler package was used on all 2010 Valley Circles for Rice fields.

Soil type is an important consideration when selecting a sprinkler model for growing rice. More on this in my next blog entry next month.

Do you have questions on sprinkler packages and how they relate in rice production under center pivots and linears? Leave a comment in the box below or email rice@valmont.com.

Circles for Rice | 2010 Final Yield Report by Jake LaRue

Below you will find the final yield report for the 2010 Circles for Rice growing season in the United States, Ukraine, and Pakistan.

United States

Blodgett, Missouri - 201 bu/ac
Neelyville, Missouri - 186 bu/ac
Scott, Arkansas - 173 bu/ac
Sikeston, Missouri - 160 bu/ac
Crawfordsville, Missouri - 160 bu/ac
Eagle Lake, Texas - 149 bu/ac
Dyersburg, Tennessee - 130 bu/ac

Crimea, Ukraine - 55 bu/ac

Pakistan

AAS 501 (hybrid) - 122.8 bu/ac
HS 777 (hybrid) - 108 bu/ac
Superi (variety) - 81 bu/ac
Shantaj (hybrid) - 79 bu/ac
#385 (variety) - 68.6 bu/ac
Super Guard Basmati (variety) - 62.4 bu/ac

If you have any questions about the yields, or about the Circles for Rice project in general, please send me an email at rice@valmont.com .