|Vories, Earl - Earl|
Submitted to: Crop Management
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/24/2011
Publication Date: 10/21/2011
Citation: Rhine, M.D., Stevens, W.E., Heiser, J.W., Vories, E.D. 2011. Nitrogen fertilization on center pivot sprinkler irrigated rice. Crop Management. DOI:10.1094/CM-2011-1021-01-RS. Interpretive Summary: Farmers in the US and internationally are interested in producing rice with center pivot irrigation as a way to save water or produce rice on fields not suited to flooded culture. Experiments were conducted to determine the effects of nitrogen (N) form and timing of application on growth and yield of rice grown under a center pivot irrigation system on a soil not suitable for flood irrigation. Varying rates and timings of dry urea and fluid N were tested and compared to rice grown on a flooded Sharkey clay soil. Fertigation, or applying fluid N with irrigation, was shown to be a suitable application method and no differences were found between liquid and dry N applications on sprinkler irrigated rice. Similar yields were observed between flood and sprinkler irrigation for N rates typically applied to rice. This information will benefit farmers by giving them additional options for producing rice and everyone will benefit from efficient use of water and fertilizer in agriculture.
Technical Abstract: Three rice (Oryza sativa) experiments were conducted to determine the effects of nitrogen (N) form and timing of application on growth and yield of sprinkler irrigated rice compared to flood irrigated rice. Three rice cultivars (two conventional, one hybrid) were grown under a center pivot irrigation system on an upland soil with areas of high sand content, a field not suitable for flood irrigation. The first experiment on this field was fertilized with varying rates of dry urea (46 percent N) at V4, followed by five weekly applications of fluid N in the form of Urea – Ammonium Nitrate (UAN 32 percent N) at various rates. Fluid N applications were applied as either 50 or 75 percent of the total N application. Experiment two was fertilized with dry urea at varying rates during the V4 and R0 growth stages. The third experiment was conducted on a flooded Sharkey clay soil, and was fertilized with dry urea, mirroring the applications of experiment two. Yields with fertigation increased up to 150 kg N ha-1, with conventional yields averaging 6717 kg ha-1 and hybrid cultivars averaging 8737 kg ha-1. Rice yields also increased when 75 percent of the total N was applied as weekly fertigations compared to 50 percent. Across years, no significant differences were found between liquid and dry N applications on sprinkler irrigated rice. Flood irrigation yielded higher than sprinkler irrigation at N rates below 100 kg N ha-1. This may have been due to N volatilization losses becoming more critical at low N rates. When N rates were above 100 kg N ha-1, no significant differences were found between flood and sprinkler irrigation. Within irrigation treatments, no differences were found between N rates excluding the unfertilized check.