Changes in Louisiana Rice Production – Part 2

Aerial application in rice, past and present.

    Last month we discussed several changes in Louisiana rice production over the past 30 years that have led to significant per acre yield increases as well as decreased the environmental footprint of rice production in the state. Improvements discussed include superior inbred and hybrid varieties, Clearfield technology, improvements in ratoon crop production technology, and precision leveling of rice fields. Numerous other technologies have also advanced rice productivity during this time span.

    The advent of GPS and GIS technology has greatly improved rice production in a number of ways. One of the first areas to use GPS technology in rice production was in aerial applications. Thirty years ago aerial applicators were guided across a field by flagmen. These two individuals were positioned on each end of a field with a large brightly colored flag that could be seen by the pilot. The flagmen would hold up their flags to guide the pilot on his spraying swath across the field. They would then walk off a predetermined distance to position themselves to guide the next pass. This was an imperfect system at best. The flagmen used a triangular shaped device called a compass to measure off the specified distance as they walked. This worked fairly well on dry open ground, but it was difficult to be precise if the field layout necessitated flagging in a flooded field or in heavy vegetation. Also, many fields are not true squares or rectangles, and sides may be angular or rounded. This often led to imperfect measurements that resulted in either unsprayed or overlapped areas. Also, the flagmen were often exposed to pesticides used during the spraying operation. The advent of GPS technology quickly eliminated the use of flagmen. Now, the pilot had a light-bank system in front of him that, based on GPS position, indicated exactly where the spray swath should be applied. This allowed for a more precise aerial application with much less human exposure to pesticides.

    Another area where this technology has been important is in improving the precision of rice fertilization. Soil sampling has long been an important tool in determining fertilizer needs. However, advances over the years have made fertilizer application a more precise and environmentally sound endeavor. The typical soil sampling procedure is to take a number of samples in a field and then create a composite sample from these to send to the soils laboratory. The recommended rate of fertilizers is then applied at a uniform rate across the entire field based on the results of this one soil sample. Unfortunately, many fields are nowhere near uniform in their soil fertility levels. This system leads to some areas being under-fertilized and others being over-fertilized. The use of GPS technology has allowed for the development of a system called grid soil sampling, where samples are obtained from pre-determined locations in a field based on a grid. The precise location of any individual sample is known, and the resulting soil tests show varying levels of fertility across the entire field. These soil test results are then loaded into a computer on a variable rate ground rig fertilizer applicator, which is able to apply the precise amount of fertilizer needed in various areas of the field. This allows for increased productivity by making sure that each area of the field has the necessary amount of fertilizer to optimize productivity. It also avoids over fertilization of more highly fertile areas of the field. Furthermore, most modern combines have yield monitors. These devices continually measure the amount of rice being harvested in any particular area of a field. After the field has been harvested, the producer can then look at a yield map that show areas of high, average and low productivity. This, coupled with fertility maps, allows for long-term programs to address specific problem areas in a field and overall improved productivity of that field.

    Other advances from this technology include auto-steer tractors, sprayers, and other field machinery. This technology lets the implement operator remove his or her hands from the steering wheel as the implement moves across a field. The steering is controlled by a system based on GPS technology that precisely controls where the implement is at all times as it moves across a field. This system is beneficial in operations such as drill-seeding. It allows for a more precise spacing of drill rows across a field. Even the best tractor drivers are no match for the precision of auto-steer. Also, the grain drills in use today are much more precise in maintaining a constant flow of seed at a pre-determined seeding rate. The newer drills are much more precise at placing the seed at a constant desired depth of seeding, which can vary based on available soil moisture levels at the time of seeding. All of these improvements have allowed rice producers to lower seeding rates while typically having more consistent and uniform stand establishment. This greatly facilitates timely cultural practices, all in an effort to optimize the yield and quality of the harvested rice crop.

This project was partially supported by USDA National Institute of Food and Agriculture.

Permission granted May 15, 2015 by B. Leonards (LA Farm & Ranch) to republish article on
5/15/2015 10:58:04 PM
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