Forage Yield and Quality of Phalaris as Affected by N Fertilization and Defoliation Regimes
1978
Saibro, Joao C. | Hoveland, Carl S. | Williams, John C.
Phalaris (Phalaris aquatica L., also referred to as P. tuberosa L.) is a winter productive cool-season perennial grass species having potential in the southeastern U.S. The purpose of our study was to determine the effect of N fertilization rates and defoliation on forage yield, in vitro dry matter digestibility (IVDMD), total forage N and NO₃-N, and total non-structural carbohydrates (TNC) stored in conns. The synthetic, ‘AP-2’ phalaris, was fertilized at 100, 200, 300, and 400 kg N/ha/year and harvested at vegetative, inflorescence emergence, and seed stages of growth over a 2-year period in the field. Forage yield, total N, and NO₃-N concentration increased linearly with increasing N fertilization. Maximum dry forage yield was 10 metric tons/ha annually. Total N concentration ranged from 2.8 to 4.0%. Forage NO₃-N concentration was highest in autumn but less than that considered potentially toxic to ruminants. Harvesting at more advanced plant maturity increased forage yield while reducing NO₃-N and IVDMD. The IVDMD was relatively high, averaging 63% over the year. Corm reserves of TNC decreased with N fertilization but increased with plant maturity. TNC in corras remained low throughout the active growing season. Results of this study indicate that AP-2 phalaris can utilize up to 300 kg N/ha annually either under frequent defoliation or cutting at hay stage. This grass maintains relatively high IVDMD at a fairly advanced stage of maturity.
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