Frequently Asked Questions
For more than 20 years, several growers across the world have tried producing rice under center pivots and linears. However, the net return from the field did not meet expectations. Valley Irrigation conducted extensive research to identify and develop production guidelines to help farmers meet their economic expectations and provide a secure, efficient, and cost-saving option for growing rice under mechanized irrigation.
About the Project
What is Valley Irrigation doing to support rice under mechanized irrigation?
In 2008, a team of dedicated personnel was created. This team conducted research, multiple worldwide trials and field-scale studies; provided technical information to growers; and developed educational and marketing materials, such as the Valley Irrigation Rice Production Guide.
Mechanized Irrigation and Management
What is a center pivot?
A center pivot is a precision, mechanized irrigation machine that irrigates a field in a circle. The spans of a center pivot revolve around a central pivot point. Valmont Industries manufactured the industry's first center pivot mechanized irrigation machine in 1954. Use of a center pivot can result in a reduction in operating costs, a quick return on your initial investment, and the conservation of resources.
What is a linear machine?
A linear machine is similar to a center pivot, except that it moves up and down a field.; it is perfect for a square or rectangular field. Linears can achieve up to 98 percent field coverage and use water from either a canal/ditch or pipeline. A linear does not revolve around a central pivot point, rather its spans are attached to a moving cart.
How much water will be required for a center pivot to supply the necessary amount of water for rice production?
In the Valley rice fields, we have consistently achieved a water savings of 50 percent or more over traditional flood irrigation. The actual water required is dependent upon the climatic conditions and soils of your field.
I am not familiar with irrigation management and scheduling for pivots, I am only familiar with flooding. How will I manage and schedule irrigation?
Irrigation management and scheduling is very similar to how one would manage center pivots or linears on other cereal or row crops. Valley Irrigation, in conjunction with universities and research groups, has been using several methods to develop guidelines. Methods include manual soil probe, soil moisture sensors, and computer models.
What do I do about corners and other areas of the field I cannot irrigate with a center pivot?
Valley Irrigation offers a number of solutions to maximize the rice production area in any field, such as towable pivots, corner arms, and linears.
If it is typical to make more rotations to irrigate rice, are there more maintenance requirements?
As with any piece of farm equipment, maintenance is required. Center pivots and linears are designed to be economically operated for 20,000 hours or more. Most maintenance is based on monthly or annual time rather than operating hours.
How late into the season does rice need to be irrigated with center pivots?
This is an area requiring more study. You will probably apply water through the pivot or linear later in the season than you would for flooded fields, but that is because it can take two to three weeks to drain a flooded rice field. Even with these additional applications of water, you can still realize a 50 percent water savings over what is pumped into a flooded field. The findings from our 2009 trials indicate that you need to take the crop growth stage and soil type into consideration when determining when to stop applying water.
Rice Varieties and Hybrids Will I be able to grow rice varieties I am familiar with under center pivots and linears?
You can, but you may want to consider other options, as well. The varieties you use under flood irrigation can be used under center pivots, but some will adapt to the different growing environment better than others, presenting you with the potential for higher economic returns. There are some specific seed characteristics we look for when choosing what to grow under mechanized irrigation, among those are vigorous tillering and blast resistance. Can I grow rice two years in a row?
You can grow rice after rice, however, crop rotation is advised, just as it is with every other crop. Every monoculture system (rice after rice, soybeans after soybeans) imposes several factors that will limit higher yields. In the case of rice, noticeable reductions in yields are observed after the third year of growing rice after rice. Will I be able to produce the same yields and profits if I grow rice under center pivots?
With today's advancements in crop technology, there is no reason to assume you cannot produce the same rice yields under center pivots and linears as you can with flood irrigation. However, it is not unreasonable to experience a slight drop in yields the first year or two when using mechanized irrigation. This is mainly due to your need to adjust to a new growing system. Despite the drop in yields, you can still find yourself more profitable than with flood irrigation due to the overall lower production costs.
Pests and Diseases Will I have more or fewer problems with red rice if I produce rice under mechanized irrigation?
After two or three years of growing rice under center pivots or linears, as well as using a crop rotation scheme and no-tillage system, you are likely to observe reductions in your previously infested rice fields. What are the major pest and disease concerns when producing rice under center pivots and linears?
The pests commonly experienced with flooded rice may also be an issue in mechanized irrigated fields. In our experience in Brazil, USA, and Pakistan, no pest differences have been seen between flood and pivot-irrigated rice. There are some diseases, however, that will require attention, such as rice blast, brown spot, and sheaf blight. Typically, there is a higher potential for blast to develop in a rice field under mechanized irrigation and less potential for sheaf blight. In field experience, the brown spot has been about the same. Choosing the right seed with resistance, as well as being prepared to apply a preventative fungicide application at the appropriate time will greatly assist in disease management. Do light, more frequent applications of water promote more disease?
The goal of the Valley Irrigation rice program is to try to ensure the crop canopy has a chance to dry out between applications, including the soil surface. The micro climate in the rice may actually be less humid using mechanized irrigation than in a flooded field. I flood my field primarily for weed control. Won't I have a bigger issue with weed control if I grow my rice under a center pivot or linear machine?
Flood irrigation is all about controlling many weed species. However, there are some weeds that thrive under a flooded environment, such as red rice. Under mechanized irrigation, more weed species may be observed due to the absence of standing water, but the severity of infestation can be reduced by good management and, in most cases, the management is very similar to what is done under flood irrigation.