Soil nutrient distribution in long-term NPP plots- 1989

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Soil nutrient distribution beneath and between plant canopies in the Mesquite, Grassland, Playa, Creosotebush, and Tarbush plant communities. The LTER plant biomass plots was sampled in June 1989. A total of 750 soil samples were collected from 5 depths (0- 10, 10-20, 20-40, 40-60, 60-100 cm), 2 locations (under and between shrubs), within 5 vegetation zones (Mesquite, Grassland, Playa, Creosotebush, Tarbush), 3 sites per zone (site with low, medium, and high biomass, ranked based on FALL-89 biomass), and 5 directions per site (in buffer zone just outside of NPP plots N, S, E, W, and in the center of NPP plots C). Samples were analyzed for pH, CaCO3, NaHCO3- extractable P, KCl-extractable NH4 and NO3, total kjeldahl N, Saturation extrac cations, and DTPA-extractable micronutrients.

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data sheets, electronic spreadsheet (Microsoft Excel 2.2)

Sampling: A total of 750 soil cores were collected in June 1989 beneath the shrub canopy, and between shrubs at 5 depths (0-10, 10-20, 20-40, 40-60, 60-100 cm), 5 directions (In buffer zone just outside NPP plots North, South, East, West, and Center of NPP plot), within 5 zones (Mesquite, Grassland, Playa, Creosotebush, and Tarbush), on 3 sites per zone (sites with low, medium, and high biomass), on the Jornada LTER II site approximately 40 km NNE of Las Cruces, NM. Samples were analyzed for pH, CaCO3, NaHCO3-extractable P, KCl-extractable NH4 and NO3, total kjeldahl N, Saturation extrac cations, and DTPA-extractable micronutrients. % organic carbon was sampled at all directions only at the three grassland sites and only at 0-10cm and 10-20cm depth; one site per vegetation type was sampled at all depths for CU (center-under) location only. Nutrient Analysis: Soil samples were air-dryed in a glasshouse and ground to pass a 2-mm seive. Total N (and TP) was digested by Kjeldahl digestion block techniques (Bremner and Mulvaney, 1982). Digest NH4-N was analysed using an automated salicylate procedure (Technicon Industrial Method No. 329-74W/B). Inorganic N (NH4-N and NO3 + NO2-N) was extracted with 2M KCl (Keeney and Nelson, 1982). Ammonium-N in the extracts was analyzed colorimetrically (indophenol blue) in an automated procedure (Technicon Industrial Method No. 154-71) and NO3 + NO2-N was measured by an automated Cd reduction colorimetric procedure (Technicon Industrial Method No. 100- 70W/). Available P was analyzed as NaHCO3-extractable (PO4) P (Olsen and Sommers, 1982) %H2O--gravimetric-- (wt water/wt dry soil) Soluble cations (K, Na, Ca, Mg) were extracted using saturation extract methods (Rhoades 1982, Richards 1954), and analyzed as following: EC read on Yellow Springs Instruments (YSI) model 32 conductance meter Na, Ca, Mg read on Perkin Elmer ICP/6500 (inductively coupled plasma) K read on Perkin Elmer Model 5000 Atomic Absorption Spectrophotometer using emission mode, acetylene flame DTPA extractable micronutrients (Zn, Mn, Cu,. and Fe) were extracted using DTPA extraction method (Lindsay and Norvell, 1978), and analyzed using inductively coupled plasma atomic emmission spectrophotometry. Organic C was determined using a modified Mebius method (J.C. Yeomans and J.M. Bremner, 1988).

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5 vegetation communities with 3 sites in each zone: creosotebush scrub: CALI, GRAV, SAND tarbush flats: EAST, TAYL, WEST grassland: BASN, IBPE, SUMM mesquite dunes: NORT, RABB, WELL playa: COLL, SMAL, TOBO See attached site map.


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