Long-Term Rye-Wheat-Ryegrass Forage Yields as Affected by Rate and Date of Applied Nitrogen

摘要

Forage yield and quality can be affected by time and rate of N application. This study was conducted to evaluate the long-term impacts of time and rate of applied N on rye (Secale cereale L.,)-wheat (Triticum aestivum L.)-ryegrass (Loliam multiflorumLam.) forage yield and protein considering seasonal (fall-winter and spring) production differences. Rye-wheat-ryegrass mixtures have been commonly used to extend the forage production season. A long-term experiment was initiated in 1919 to evaluate theeffects of N timing (all N applied preplant in the fall, all N applied in the spring, or split applied in the fail and spring), N rate (0, 50, 75, 100, 150, and 200 lb N/acre) and applied lime (no lime or single application of 2 tons/acre). Harvests were classified into two groups, fall-winter (November through February) and spring (March through June) with 5 March being the separation date between the two groups. An average of five harvests were obtained each year (two in the fall-winter and threein the spring). No differences in fall-winter, spring, or total forage production and forage protein were observed as a result of applied lime. In general a linear response to applied N up to 200 lb of N/acre was observed in fall-winter, spring, and total forage yields. Fall-winter forage production was higher when N was applied in the fall. Similarly, spring forage production was higher when N was applied in the spring. No differences in total forage production were observed over this 14-yr period between fall, spring, and split applied N. Forage protein was much higher in fall-winter harvests (before 5 March) than spring harvests. Total forage N removed (fall-winter plus spring production) tended to be somewhat higher when all fertilizer N was applied in the fall compared with split and spring N applications. Estimated N use efficiencies did not decrease with increasing N applied as has been reported in grain production systems. Forage production systems may have lower plant gaseous N loss (improved N use efficiency) because the plant is never allowed to approach flowering when N losses have been found to be greater.