Rice Production with a Center Pivot Irrigation System.

Quantity of irrigation water needed to maintain flood on rice fields varies by region based on soil properties and weather.  Many rice farmers are concerned about water issues due to inadequate groundwater recharge, urban competition for water resources, and high energy costs for flood irrigating rice.  Experiments were conducted at Portageville, MO with rice irrigated with center pivot sprinkler irrigation. The objective was to reduce water use with sprinkler irrigated rice without using more nitrogen fertilizer or pesticides and produce equivalent or greater yields to flood irrigated rice. Rice cultivars and hybrids  were drill planted with 19-cm row spacings.  Nitrogen fertilizer treatments included broadcast urea dry applications and sprayed UAN solution followed immediately with irrigation to simulate fertigation.  Total N rates will be 0, 100, 151, and 202 kg N ha^-1. Applications were (1) all urea applied at first tiller growth stage, (2) 50% first tiller, with 10% in five weekly fertigations , and (3) 25% first tiller, with 15% in five weekly fertigations. Herbicide treatments included Acetolactase Synthase (ALS) herbicides. Results indicated a water usage savings of 28% compared to the traditional flooding of rice fields. This comparison was made using a side inlet flooding system which has been shown to be up to 60% more efficient than the conventional cascade method of flooding. The most difficult weed to control was Palmer Amaranth.  Plant measurements and rice yields showed that fertigation application of N was more efficient than dry fertilizer applications.