Design, treatments, and vegetation measurements
This study was conducted on the Jornada Experimental Range (JER) in
1986. The objective of this study was to measure plant tissue
nutrients at mesquite (Prosopis glandulosa) dune sites of different
habitat types. Four habitat types were sampled: (1) playa, within a
dense stand
of large (3-5 m tall) mesquite growing along the edge of a large
playa;(2) arroyo, with widely spaced mesquite trees (3-5 m
tall)along the margin of temporary water courses; (3) dunes, which
are dominated by low-growing coppice mesquite, and (4) grassland, at
the base of a watershed with widely scattered mesquite, 2-3 m tall,
many of the plants being multiple-stemmed. The dune site is located
on the USDA Jornada Experimental Range, while the other three sites
arelocated on the New Mexico State University College Ranch.
Mesquite tissues (leaf, stem, flowers, pods) were collected in
conjunction with phenology studies and natural abundance of N15
during 1986 and 1987. These were digested and analyzed for total
nitrogen (Kjeldahl) and total phosphorous. Plant tissue was
oven-dried at 60o C and ground to 20 mesh in a Wiley mill. One-tenth
gram samples were weighed into 75ml Kjeldahl tubes and digested on a
block digestor (40 tubes at a time). The digest was a micro-
Kjeldahl sulfuric acid digest (Hg catalyst). An autoanalyzer was
used to determine NH4 (TKN-Total Kjeldahl Nitrogen) and PO4-P
(TP-Total Phosphorus).
REFERENCES
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Bremner, J.M., and C.S. Mulvaney. 1982. Nitrogen--Total. In A.L.
Page, R.H. Miller, and D. R. Keeney (eds.). Methods of soil
analysis. Part 2 - Chemical and microbiological properties. Agronomy
9 (2):595-624. Am. Soc. of Agron., Madison, Wis.