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Previous research on late-season N fertilization of pecans [Carya illinoinensis (Wangehn) K. Koch] has shown significant uptake and storage of N in perennial tissues (roots, trunk, and shoots) that was used in subsequent years. The objectives of this study were to follow the fate of ¹⁵N applied at three different stages during pecan kernel fill in both the soil and tree components. In August and September 2002, ¹⁵N-labeled ammonium sulfate (9.94% ¹⁵N atom excess) was applied (56 kg N/ha) to nine pecan research trees during the early [3 days into kernel fill (DIK)], middle (25 DIK), and late (38 DIK) stages of pecan kernel fill near Las Cruces, N.M. In November 2002, about 67% of applied ¹⁵N was recovered from the soil and 13% from tree components. More ¹⁵N was recovered in nuts from the early treatment than middle or late treatments. Recoveries for May 2003 were 27% and 60% for tissues and soils, respectively. Leaf recovery increased an average of 14% in May 2003 over November 2002 leaves. More ¹⁵N was recovered from the late treatment in all tree components for May 2003 than early or middle treatments. The primary source of N for spring growth was ¹⁵N stored in perennial tissues. Fifteen months after ¹⁵N fertilizer was applied during kernel fill in 2002 about 24% remained in the soil, 28% had been used by the tree, and 48% was lost to the environment.

Field studies were conducted in 1995 and 1996 at Las Cruces, New Mexico, and Alcalde, New Mexico, to compare direct seeding to transplanting for stand establishment and yield estimates of calendula (Calendula officinalis), catnip (Nepeta cataria), lemon balm (Melissa officinalis), stinging nettle (Urtica dioica), and globemallow (Sphaeralcea spp.). Calendula established well from seed or transplants at both sites. Transplanting increased establishment of lemon balm, catnip, stinging nettle, and globemallow. Lemon balm establishment was increased by 230% to 400% at Las Cruces, and catnip establishment was increased by 84% to 100% at Alcalde by transplanting. Direct seeding resulted in little or no stand establishment for stinging nettle and globemallow at Alcalde. In 1996, transplants increased lemon balm and stinging nettle dry weight yields by a factor of three or more at both sites. Dry weight yields of transplanted catnip were 4.86 t·ha⁻¹ in 1995 and 7.90 t·ha⁻¹ in 1996 in Las Cruces. Alcalde yields for transplanted dried catnip were 2.43 t·ha⁻¹ in 1995 and 5.12 t·ha⁻¹ in 1996. Transplanted globemallow dry weight yields were 6.04 t·ha⁻¹ in 1995 and 9.17 t·ha⁻¹ in 1996 for Las Cruces. Transplanted stinging nettle yield in Alcalde was 5.91 t·ha⁻¹ for plants that overwintered and were harvested in the second season. Transplanting versus direct seeding medicinal herbs has the potential to substantially increase stand establishment and yield in New Mexico, particularly in the more northern and cooler part of the state.

Field studies were conducted to determine the production potential of echinacea (Echinacea purpurea), valerian (Valeriana officinalis), mullein (Verbascum thapsus) and yerba mansa (Anemopsis californica) medicinal herbs at two sites in New Mexico. Las Cruces, N.M., is at an elevation of 3,891 ft (1,186 m) and has an average of 220 frost free days per year, whereas Alcalde, N.M., is at an elevation of 5,719 ft (1,743 m) and averages 152 frost-free days per year. In-row plant spacings of 12, 18 and 24 inches (30.5, 45.7, and 61.0 cm) were compared at both locations. The corresponding plant densities for the 12, 18 and 24 inch spacings were 14,520 plants/acre (35,878 plants/ha), 9,680 plants/acre (23,919 plants/ha), and 7,260 plants/acre (17,939 plants/ha), respectively. Data were collected on growth rates, fresh yield, and dry yield for the herbs grown at each site. All crops at both sites had highest plot yields at the 12-inch spacing, suggesting that optimum in-row plant spacings are at or below the 12-inch spacing. Yields of 1.94 ton/acre (4.349 t·ha^-1) of dried yerba mansa root, 0.99 ton/acre (2.219 t·ha^-1) of dried echinacea root, and 2.30 ton/acre (5.156 t·ha^-1) of dried mullein leaves were realized at the 12-inch spacing at Las Cruces in southern New Mexico. Yields of 1.16 ton/acre (2.600 t·ha^-1) of dried valerian root, 0.93 ton/acre (2.085 t·ha^-1) of dried echinacea root, and 0.51 ton/acre (1.143 t·ha^-1) of dried mullein leaves were harvested at the 12-inch spacing at Alcalde in northern New Mexico. Yields of fresh echinacea flowers were 1.56 ton/acre (3.497 t·ha^-1) in Las Cruces. Yields of dried mullein flowers were 0.68 ton/acre (1.524 t·ha^-1) in Las Cruces and 0.66 ton/acre (1.479 t·ha^-1) in Alcalde.