Quick nitrate test for hybrid sudangrass and pearlmillet Hays

Abstract

Hybrid sudangrass and pearlmillet are noted as having a high potential for accumulating nitrate (NO₃) and poisoning cattle. Hay samples can be accurately tested for NO₃ content in the laboratory, however, this may take considerable time for farmers to obtain their results. This study was conducted to evaluate applicability of a quick Nitrate Meter for in‐field testing of forage NO₃ in the plant sap and to study the effects of nitrogen (N) fertilization on forage NO₃ accumulation. Nitrate readings taken from the sap were highly correlated with those using the conventional laboratory method (R²=0.85–0.95 for hybrid sudangrass and 0.91–0.94 for pearlmillet). Nitrate concentrations varied with plant height, growing stages, locations in the test plots, N rates and sources, and environmental conditions. Nitrate concentrations in the whole plant decreased with plant height and plant maturity. Higher NO₃ levels were correlated with higher rates of N fertilizers. Nitrate accumulation was also enhanced by drought stress. The quick NO₃test method is easy to use and usually takes less than 20 minutes to obtain results. This methodology allows increased management flexibility for farmers who use warm‐season annual grasses in their production systems.

Notes

Corresponding author (e‐mail address: [email protected]).

Current address: Department of Soil and Crop Sciences, Texas A&M University, Overton, TX 75684.