Interpreting the Rate of Change in Nitrate‐Nitrogen in Sugarbeet Petioles¹

Abstract

Nitrate-nitrogen in sugarbeet petioles is used to evaluate current N status of sugarbeet crops. Since the NO,-N changes rapidly during the season, better relationships are needed to interpret these data relative to sugarbeet N nutrition.Sugarbeets (Beta vulgaris, L.) were grown at four N fertilization rates and two irrigation levels to determine the root yield, sucrose percentage, sucrose yield, and N uptake in relation to the NO,-N concentration in the petioles. NO,-N in beet petioles increased to a peak concentration and then decreased exponentially during the two growing seasons on all treatments. The exponential decrease after the peak enables prediction of the NO,-N in the petioles during the remainder of the growing season. This rate of change approach can be used to predict N needs when adding supplemental N for sugarbeets and to characterize the N status of soil-crop systems.Additional index words: Petiole analysis, Nitrogen uptake.

Phosphorus Relationships in Potato Plants1

“…1). The total P concentration of 3 Commercial names are shown for the benefit of the reader and do not imply endorsement or preferential treatment of the product listed. the tops increased about two-times faster than the soluble P concentration in the petiole up to about 3.0 g kg-1 total Pin the tops.…”

“…It should be possible to predict the time required for the petiole soluble P concentration to decrease to 1000 mg kg-1 if its decline follows a definite functional relationship. This approach was successful for NOrN concentrations in sugarbeet petioles (3). The equation used in that approach was N = N 0 ec 1 , where N was the N0 3 -N concentration at time(t), N 0 was the concentration at the first sampling date after the peak NOr N concentration occurred, and (c) was a constant for any treatment or grower's field.…”

“…A randomized complete block design was used with four or five replications for each experiment. Russet Burbank potato 3 were used in all experiments at 0.8 kg ha-1 (active ingredient, a.i.) and 3.3 kg ha-1 (a.i.…”

In‐Season Prediction of Sugarbeet Yield, Quality, and Nitrogen Status Using an Active Sensor

“…Petiole NO 3 testing can effectively measure N need but may be affected by high residual soil N levels (Shock et al, 2000) or low soil moisture (Marschner, 1995). Petiole NO 3 levels may be an effective indicator of crop N status (Carter et al, 1971) but in‐season NO 3 concentrations are not well related to sugarbeet yield or quality (Last and Tinker, 1968). As such, there has been only limited success thus far in developing a method to monitor sugarbeet growth and N status within the growing season.…”

Plant Analyses and Interpretation

“…The development of plant analysis for prognostic purposes and its successful application is difficult because of complex interactions in the biological system and unknown future climatic conditions. Carter et al (1971) and Westermann and Kleinkopf (1985) provide prognostic examples that predict future nutrient concentrations in petioles. Complex simulation models that consider crop growth processes in relationship to climatic conditions and the soil environment may eventually be able to predict nutrient concentrations to use as diagnostic tools (Mendham et al, 1997).…”