Rice Irrigation Options

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.

Irrigation management and scheduling is similar to how one would manage center pivots or linears on other cereal or row crops.  

Valley Irrigation offers a number of solutions to maximize the rice production area in any field, such as towable pivots, corner arms and linears.

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.

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.

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.

We do not recommend growing rice under center pivots in consecutive seasons, due to Blast spore buildup in the soil. With resistant varieties and careful management, it is possible. Some yield reduction should be expected.

We expect yields under center pivots to be 90%-110% of those with flood irrigation. Profits should be higher, even if yield is slightly lower.

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.

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.

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.

Our cooperators report using very similar herbicide programs with center pivot rice, but application timeliness is critical, since growing conditions for all plants (including weeds) are nearly perfect.