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Reed canarygrass yield under two-cut management

Our objective was to evaluate yield and stand persistence of reed canarygrass under two-harvest management and low availability of soil K. Three N and three K fertilizer treatments were applied to reed canarygrass for five years at two sites in central New York State. Reed canarygrass persisted under all treatments throughout the experiment, although K deficiency symptoms appeared in the high N, low K fertilizer combination. Stands receiving 200 lbs actual N/acre/season had reduced yields in 1997, due to very low soil K. Forage K levels for the high N treatment were under 1% K. Nitrogen fertilization decreased forage K concentration, but significantly increased total K uptake. Potassium fertilization had essentially no effect on forage K concentration, total DM yield, or total K uptake in the absence of N fertilizer. Potassium fertilization with constant N fertilization resulted in increased forage K concentration, yield of DM and annual K uptake.

Conclusions:

  • At the high N fertilizer rate, DM yield increased linearly with increased K fertilizer rate, while K fertilizer did not influence yield in the absence of N fertilizer.
  • Nitrogen-fertilized reed canarygrass under a two-harvest management with no K fertilization produced adequate forage yield.
  • The high N, low K, fertilizer combination did produce K deficiency symptoms.
  • Although reed canarygrass stand persistence in this study did not appear to be affected by prolonged K deficiency, it is prudent to maintain harvested grass forage K concentration above 12 g kg-1 DM to minimize risk to stand persistence.