Use of Irrigation to Extend the Seeding Window for Final Reclamation at Yucca Mountain, Nevada
The U.S. Department of Energy has implemented a program to investigate the feasibility of various techniques for reclaiming lands disturbed during site characterization at Yucca Mountain. As part of this program, two studies were conducted in 1997 to assess the effects of combinations of seeding date (date that seeds are planted) and supplemental irrigation on densities of native plant species at Yucca Mountain. Study objectives were to (1) determine whether the traditional seeding window (October-December) could be extended through combinations of seeding date and irrigation date, (2) determine which combination of seeding date and irrigation was most successful, and (3) assess the effects of irrigation versus natural precipitation on seedling establishment. In the first study, a multi-species seed mix of 16 native species was sown into plots on four dates (12/96, 2/97, 3/97, and 4/97). Irrigation treatments were control (no irrigation) or addition of 80 mm of supplemental water applied over a one month period. Plant densities were sampled in August and again in October, 1997. In the second study, Larrea tridentata and Lycium andersonii, two species that are common at Yucca Mountain, but difficult to establish from seed, were sown together into plots in January and August, 1997. Half the plots were irrigated with approximately 250 mm of water between August 18 and September 11, while the remaining plots received no irrigation (control). Plant densities were sampled in October, 1997. The August census for the multi-species mix study showed irrigated plots that were sown in February, March and April had higher plant densities and more species than plots that were not irrigated. Irrigation had no effect on plant densities on plots that were seeded in December. Plots were used again in October following 18 mm of precipitation in September. Densities of three species, Ambrosia dumosa, Hymenoclea salsola, and L. tridentata, (warm-season species) were lower on irrigated plots sown in December, February, and March, and showed no response to irrigation on plots sown in April. Therefore, early spring irrigation did not facilitate establishment of warm-season species. These results suggest that these species are dependent upon precipitation while temperatures are warm in late summer or fall. However, control plots that were seeded in December had acceptable densities of these species. A more practical approach might be to avoid irrigation costs by seeding in December and waiting for fall precipitation. The remaining species (cool-season species) showed an opposite response to supplemental water with greater densities on irrigated plots sown in February, March, and April, and no response to irrigation on plots sown in December. While these results show that irrigation can extend the seeding window for cool-season species should it be necessary, it was also apparent that if seeds are sown by late December, irrigation is not necessary to achieve acceptable plant densities.
- Research Organization:
- Yucca Mountain Project, Las Vegas, NV (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- NA
- OSTI ID:
- 893529
- Report Number(s):
- TDR-MGR-EV-000007 Rev 00; MOL.20010227.0039, DC# 23954; TRN: US0606015
- Country of Publication:
- United States
- Language:
- English
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