Phosphorus fertilizer management for sugarbeet in the Bighorn Basin of Wyoming and Sidney, Montana

Phosphorus (P) is a necessary plant nutrient but local recommendations for P application to sugarbeet in the Big Horn Basin of Wyoming are needed. The objectives of this study were to determine the effect of P fertilizer placement and rates on sugarbeet root and sugar yield, and also to determine the optimum rate for banded and broadcast applications of P in the Bighorn Basin of Wyoming and Sidney, Montana. The study was established under furrow irrigation in 2012 and 2013 at the University of Wyoming Research and Extension Center located in Powell, Wyoming and 2013 at the Montana State University Eastern Agricultural Research Center located in Sidney, Montana. Treatments consisted of five fertilizer products, and seven fertilizer rates in a randomized complete block design split-plot array with four replications; fertilizer product was the main plot, and fertilizer rate was the subplot. Dry monoammonium phosphate (MAP: 11-52-0) was broadcast in spring on tilled plots at rates of 0, 34, 67, 135, 202, 269, and 336 kg P2O5 ha -1. Liquid ammonium polyphosphate (APP: 10-34-0) was banded at a depth of 5 cm directly below and beside seeds at planting, at the same rates as the broadcast fertilizer applications. Syngenta HM 9120RRRTM and CrystalRTM RR052 sugarbeet seeds were planted in Powell and Sidney, respectively. Pre-planting P soil tests were from 9 mg kg -1 to 23 mg kg-1. Sugarbeet root yield was from 33 Mt ha-1 to 86 Mt ha-1. Higher P2O5 rates corresponded to slightly higher yield. Mean sugar yield was about 13% of root yield and ranged from 4 to 14.33 Mt ha-1 across years and location. Sugar loss to molasses (SLM) was between 0.88% and 1.5%. All parameters were not affected by P application rate or formulation. Both broadcast and banding of the P fertilizers produced equal root and sugar yield.