Nitrogen Fertilization and Clipping Effects on Green Needlegrass (Stipa viridula Trin.): I. Development, Growth, Yield, and Quality1
- Larry M. White,
- Clee S. Cooper and
- Jarvis H. Brown2
More information is needed about fertilization and management of green needlegrass (Stipa viridula Trin.) to increase its relative prevalence in the northern Great Plains. We applied N and imposed clipping treatments on green needlegrass to determine the effects of these treatments on the initiation and growth of tillers, and on the yield and quality of forage. Ammonium nitrate was broadcast at 0, 70, and 140 kg of N/ha in November 1968. The two clipping treatments were unclipped and clipped to a 5-cm height five times during 1969 at approximately 21-day intervals. Studies were conducted in 1969 and 1970 on a dryland site which normally receives 32.6 cm annual precipitation.
In 1969 N increased dry matter yield, percentages of crude protein and P, but did not affect the rate of successive plant development. Residual N in 1970 increased dry matter yield, decreased percentage of P, and had no effect on the percentage of crude protein. Doubling the N fertilization rate had little effect on the plant factors measured.
In 1969 clipping decreased dry matter yield, increased percentages of crude protein and P, and extended the plant growth period by 26 days. Clipping in 1969 reduced dry matter yield in 1970, but did not affect percentages of crude protein and P.
There were 30% floral and 70% vegetative tillers on nonfertilized plots, and two-thirds of the floral tillers present in July 1969 were initiated the previous autumn. Nitrogen fertilization increased the number of spring-initiated tillers, which were 15% floral and 85% vegetative and matured 4 weeks later than autumn-initiated tillers.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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