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Title: Center Pivot Irrigated Rice- Nitrogen Management and Disease Control

item STEVENS, GENE - University Of Missouri
item Vories, Earl
item HEISER, JAMES - University Of Missouri
item RHINE, MATTHEW - University Of Missouri
item WRATHER, ALLEN - University Of Missouri
item LARUE, JACOB - Valmont Industries, Inc

Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2009
Publication Date: 12/1/2010
Citation: Stevens, G., Vories, E.D., Heiser, J., Rhine, M.D., Wrather, A., Larue, J. 2010. Center Pivot Irrigated Rice- Nitrogen Management and Disease Control. Rice Technical Working Group Meeting Proceedings. CD-ROM.

Interpretive Summary:

Technical Abstract: Rice fields are normally flood irrigated but center pivots may be used to expand rice production to fields with soils that cannot be flooded. Nitrogen and disease management programs for center pivot rice are being tested at the University of Missouri- Delta Center in Portageville. Blast disease in sprinkler irrigated rice tends to increase because of the wetness of the foliage after watering. In the 1980s, several researchers studied pivot irrigated rice but stopped developing the technology because of low yields resulting from blast. At that time effective fungicides and blast resistant rice cultivars were not available. In experiments at Portageville in 2008, blast disease was not found. However, in 2009, center pivot plots were decimated by blast in non-resistant cultivars such as ‘Wells’ and ‘Francis’ with no fungicides. In plots planted with the blast-resistant cultivar ‘Templeton’ or a resistant hybrid, rice yield ranged from 7560 to over 1048 kg ha-1. Yields were highest in blast susceptible varieties when fungicides were applied by chemigation using an injection pump at early boot stage to deliver fungicide in irrigation water through the pivot. The research project was begun in 2008 using a 7.3-ha center pivot donated by Valley Irrigation. The first challenge of the test was weed control, in particular palmer amaranth. Clearfield technology using imazethapyr and imazamox herbicides did not provide satisfactory broadleaf control because of Acetolactase Synthase (ALS) resistance in the pigweeds. Fortunately, alternative programs were developed using clomazone, propanil, quinclorac, halosulfuron, acrifluorfen, and bentazon. In 2009, our main program was clomazone pre-emergence followed by applications of propanil and quinclorac when the pigweeds were in the 2 to 4 leaf stage. The spray timing was very critical for weed control. The main focus of the project is evaluating nitrogen fertilizer programs using dry urea and weekly fertigation applications with 32% UAN through the center pivot. Splitting N with fertigations produced more uniform plant height and green color rice across the field than a 2-way split with urea alone. In 2009, the highest yielding nitrogen fertility program for cultivars Templeton, CL 171, and RiceTec RTCLXL729 was a 38 kg N ha-1 dry urea application at first tiller growth stage followed by five 22.7 kg N ha-1 fertigations spaced in 1 week intervals for a total of 151 kg N ha-1. Irrigation has been a learning process. The field where the pivot test is located has silt loam soil intermingled with large sandy areas. In 2007, irrigation timing was based on the visual appearance and feel of the surface soil. In 2009, the Arkansas Irrigation Scheduling Program was modified to include an experimental water-use function for rice and used to schedule irrigation throughout the season. In addition, soil moisture sensors were installed at 15 and 30-cm depths and transmitted to a computer server for the internet. Dr. John Travlos at MU-Columbia set an electronic alarm system to call cell phones if the soil became too dry.