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Investigation:

TG-08 (Melillo / Cerri)

LBA Dataset ID:

TG08_SOIL_GAS_FERTILIZATION

Originator(s):

1. STEUDLER, P.A.
2. GARCIA-MONTIEL, D.C.
3. PICCOLO, M.C.
4. NEILL, C.
      5. MELILLO, J.M.
6. FEIGL, B.J.
7. CERRI, C.C.

Point(s) of Contact:

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Dataset Abstract:

This file contains measurements of nitric oxide, nitrous oxide, carbon dioxide emissions and soil moisture, N and P pools, net N mineralization and nitrification rates in response to nitrogen and phosphorus fertilization in a mature moist tropical forest and an 11-year pasture at Nova Vida in Rondonia, in the Brazilian Amazon. Six temporal measurements were made: just prior to fertilization, 1, 7, 14 days after fertilization in the wet season, 6 months after fertilization in the dry season, and 13 months after 2 additional fertilizer applications. Total N applied as either NH4Cl or NaNO3 was 100 kg N ha-1 yr-1. Total P applied as Na2HPO4 was 40 kg P ha-1 yr-1. Records in the data file represent flux measurements made in 3x3 m plots in 6 treatments of 3 randomized blocks in the pasture and forest site and the associated soil characteristics at 0-5 and 5-10 depths for these plots.

Beginning Date:

1998-02-18

Ending Date:

1999-03-10

Metadata Last Updated on:

2012-07-18

Data Status:

Archived

Access Constraints:

PUBLIC

Data Center URL:

http://daac.ornl.gov/

Distribution Contact(s):

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Access Instructions:

PUBLIC

Data Access:

IMPORTANT: The LBA-ECO Project website is no longer being supported. Links to external websites may be inactive. Final data products from the LBA project can be found at the ORNL DAAC. Please follow the fair use guidelines found in the dataset documentation when using or citing LBA data.
Datafile(s):

LBA-ECO TG-08 Soil Gas Flux after Forest and Pasture Fertilization, Rondonia, Brazil:  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1105

Documentation/Other Supporting Documents:

LBA-ECO TG-08 Soil Gas Flux after Forest and Pasture Fertilization, Rondonia, Brazil:  http://daac.ornl.gov/LBA/guides/TG08_Soil_Gas_Fertilization.html

Citation Information - Other Details:

Steudler, P.A., Garcia-Montiel, D.C., Piccolo, M.C., Neill, C., Melillo, J.M., Feigl, B.J., and C.C. Cerri. 2012. LBA-ECO TG-08 Soil Gas Flux after Forest and Pasture Fertilization, Rondonia, Brazil. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. http://dx.doi.org/10.3334/ORNLDAAC/1105

Keywords - Theme:

Parameter Topic Term Source Sensor
NITROGEN BIOSPHERE VEGETATION FIELD INVESTIGATION AUTOANALYZER
PHOSPHATE BIOSPHERE VEGETATION FIELD INVESTIGATION SPECTROPHOTOMETER
SOIL GAS/AIR BIOSPHERE VEGETATION FIELD INVESTIGATION CHEMILUMINESCENCE
SOIL GAS/AIR BIOSPHERE VEGETATION FIELD INVESTIGATION GC (GAS CHROMATOGRAPH)
SOIL GAS/AIR BIOSPHERE VEGETATION FIELD INVESTIGATION IRGA (INFRARED GAS ANALYZER)
SOIL MOISTURE/WATER CONTENT BIOSPHERE VEGETATION FIELD INVESTIGATION WEIGHING BALANCE

Uncontrolled Theme Keyword(s):  LAI, SOIL CHEMISTRY, SOIL GAS FLUX, SOIL PROPERTIES

Keywords - Place (with associated coordinates):

Region
(click to view profile)
Site
(click to view profile)
North South East West
Rondonia Fazenda Nova Vida -10.15600 -10.15600 -62.81100 -62.81100

Related Publication(s):

Steudler, P.A., Garcia-Montiel, D.C., Piccolo, M.C., Neill, C., Melillo, J.M., Feigl, B.J., and C.C. Cerri. 2002. Trace gas responses of tropical forest and pasture soils to N and P fertilization. Global Biochem. Cycles Vol 16, No.2, 10.1029/2001GB001394.

Data Characteristics (Entity and Attribute Overview):

Data Characteristics:

Data are available in one comma separated ASCII file: TG08_Fertilization_fluxes.csv



The file is organized as follows:



File name:,TG08_Fertilization_fluxes.csv,,,,,,,,,,,,,,,,,,,,,,,,,

File date:,16-Dec-11,,,,,,,,,,,,,,,,,,,,,,,,,

Associated LME file:,TG08_Trace_Gas_Response_N_P_Fert,,,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,

Column,Column_heading,Units/format,Explanation,,,,,,,,,,,,,,,,,,,,,,,

----1,State,,State in which study was done,,,,,,,,,,,,,,,,,,,,,,,

----2,Location,,Location of the study: all data were collected at Fazenda Nova Vida,,,,,,,,,,,,,,,,,,,,,,,

----3,Year,,Year in which measurements were made,,,,,,,,,,,,,,,,,,,,,,,

----4,Month,,Month in which measurements were made,,,,,,,,,,,,,,,,,,,,,,,

----5,Day,,Day of the month on which measurements were made,,,,,,,,,,,,,,,,,,,,

----6,Chronosequence,,Chronosequence id,,,,,,,,,,,,,,,,,,,,,,,

----7,Landuse,,Type of landuse: either pasture or forest,,,,,,,,,,,,,,,,,,,,,,,

----8,Yr_formed,,Year in which the pasture area was converted from forest into pasture,,,,,,,,,,,,,,,,,,,,,,,

----9,Days_since_fert,,Days since fertilizer treatment was applied; negative values indicate sampling done prior to treatment,,,,,,,,,,,,,,,,,,,,,,,

---10,Number_fertilizations,,Number of fertilization events either 1 or 3. Fertilizer was applied one time prior to the short-term or intermediate term (180 day) measurements; two additional fertilizations were applied in August and November prior to the 395 day measurements,,,,,,,,,,,,,,,,,,,,,,,

---11,Block,,Experimental block identification,,,,,,,,,,,,,,,,,,,,,,,

---12,Plot,,Experimental plot identification,,,,,,,,,,,,,,,,,,,,,,,

---13,Treatment,,Control=unfertilized; NH4=fertilized with NH4Cl at 100 kg N ha-1 yr-1 ; NO3=fertilized with NaNO3 at 100 kg N ha-1 yr-1; PO4=fertilized with Na2HPO4 at 40 kg P ha-1 yr-1,,,,,,,,,,,,,,,,,,,,,,,

---14,Sampling_depth,cm,Soil depth from which samples were collected: 000-005 represents 0-5 cm depth while 005-010 represents 5-10 cm,,,,,,,,,,,,,,,,,,,,,,,

---15,Soil_water_content,percent,Soil water content calculated as (soil fresh weight- soil dry weight)/ soil dry weight,,,,,,,,,,,,,,,,,,,,,,,

---16,Bulk_density,g per cm3,Values areaverage soil bulk density for appropriate landuse, chronosequence, and soil depth from previous study (Neill et al. 1995),,,,,,,,,,,,,,,,,,,,,,,

---17,Particle_density,g per cm3,Values for the appropriate pasture age and landuse from Steudler et al. 1996 are applied to this study,,,,,,,,,,,,,,,,,,,,

---18,WFPS,percent,Water filled pore space calculated as Soil water content*(bulkdensity/total porosity%) where total porosity%= [1-(bulk density /particle density)]*100 ,,,,,,,,,,,,,,,,,,,,,,,

---19,N_min,ug (N03-+NH4)-N gm dry soil-1 day-1,Nitrogen mineralization rate reported as the change in micrograms of inorganic N (ammonium + nitrate) per gram dry weight of soil per day,,,,,,,,,,,,,,,,,,,,,,,

---20,Nitrification,ug NO3-N gm dry soil-1day-1,Nitrogen nitrification rate reported as the change in micrograms of nitrogen in the form of nitrate per gram dry weight of soil per day,,,,,,,,,,,,,,,,,,,,,,,

---21,Soil_NH4_conc,ug NH4-N per gm dry soil,Soil ammonium concentration measured after extraction with 2M KCl,,,,,,,,,,,,,,,,,,,,,,,

---22,Soil_NO3_conc,,Soil nitrate concentration measured after extraction with 2M KCl,,,,,,,,,,,,,,,,,,,,,,,

---23,Soil_PO4_conc,,Soil phosphate concentration measured after extraction with anion exchange resin,,,,,,,,,,,,,,,,,,,,,,,

---24,NO_flux,ug NO-N m-2 hr-1,Flux of nitric oxide measured as micrograms of N in the form of nitric oxide per meter squared of soil per hour. Positive values represent a net flux from the soil to the atmosphere and negative values a net flux from the atmosphere to the soil.,,,,,,,,,,,,,,,,,,,,,,,

---25,CO2_flux,mg CO2-C m-2 hr-1,Flux of carbon dioxide measured as milligrams of carbon dioxide per meter squared of soil per hour. Positive values represent a net flux from the soil to the atmosphere and negative values a net flux from the atmosphere to the soil.,,,,,,,,,,,,,,,,,,,,,,,

---26,N2O_flux,ug NO2-N m-2 hr-1,Flux of nitrous oxide measured as micrograms of N in the form of nitrous oxide per meter squared of soil per hour. Positive values represent a net flux from the soil to the atmosphere and negative values a net flux from the atmosphere to the soil.,,,,,,,,,,,,,,,,,,,,,,,

---27,NO_N2O_flux,ug NO-N + N2O-N m-2 hr-1,N-oxide flux calculated as the sum of NO and N2O fluxes,,,,,,,,,,,,,,,,,,,,,,,

,,,,,,,,,,,,,,,,,,,,,,,,,,

,Missing data are represented by -9999,,,,,,,,,,,,,,,,,,,,,,,,,



Sample data:

State,Location,Year,Month,Day,Chronosequence,Landuse,Yr_formed,Days_since_fert,Number_fertilizations,Block,Plot,Treatment,Sampling_depth,Soil_water,Bulk_density,Particle_density,WFPS,N_min,Nitrification,Soil_NH4_Conc,Soil_NO3_conc,Soil_PO4_conc,NO_flux,CO2_flux,N2O_flux,NO_N2O_flux

RONDONIA,NOVAVIDA,1998,2,18,PVA1,FOREST,0,-1,1,1,23,CONTROL,000-005,15.7685,1.1950, 2.6326,34.51,0.01,-0.06,0.47,0.47,5.30,37.93,352.72,13.44,51.38

RONDONIA,NOVAVIDA,1998,2,20,PVA1,FOREST,0,-1,1,2,27,CONTROL,000-005,16.0612,1.1950, 2.6326,35.15,1.18,1.23,0.75,0.75,7.33,27.90,505.86,86.71,114.62

RONDONIA,NOVAVIDA,1998,2,21,PVA1,FOREST,0,-1,1,3,35,CONTROL,000-005,17.1937,1.1950, 2.6326,37.63,1.67,2.08,3.01,3.01,5.46,29.55,450.59,31.70,61.25

RONDONIA,NOVAVIDA,1998,2,18,PVA1,FOREST,0,-1,1,1,20,NH4, 000-005,16.5289,1.1950,

2.6326,36.17,1.90,2.00,1.65,1.65,5.02,11.47,317.76,69.81,81.28

RONDONIA,NOVAVIDA,1998,2,20,PVA1,FOREST,0,-1,1,2,29,NH4,000-005,18.7629,1.1950, 2.6326,41.06,-0.12,4.41,31.74,31.74,7.12,65.49,408.03,5.94,71.43

RONDONIA,NOVAVIDA,1998,2,21,PVA1,FOREST,0,-1,1,3,34,NH4,000-005,16.1616,1.1950, 2.6326,35.37,2.72,2.88,2.89,2.89,4.42,34.92,261.50,38.40,73.32

RONDONIA,NOVAVIDA,1998,2,18,PVA1,FOREST,0,-1,1,1,24,NH4+PO4,000-005,19.1781,1.1950, 2.6326,41.97,8.01,5.64,15.45,15.45,8.25,61.13,446.60,118.99,180.12

RONDONIA,NOVAVIDA,1998,2,20,PVA1,FOREST,0,-1,1,2,30,NH4+PO4,000-005,16.7598,1.1950, 2.6326,36.68,1.47,1.52,0.75,0.75,6.07,23.90,348.01,113.36,137.26

RONDONIA,NOVAVIDA,1998,2,21,PVA1,FOREST,0,-1,1,3,31,NH4+PO4,000-005,14.6199,1.1950, 2.6326,31.99,2.67,3.18,5.01,5.01,6.75,25.13,840.67,687.10,712.23

RONDONIA,NOVAVIDA,1998,2,18,PVA1,FOREST,0,-1,1,1,22,NO3,000-005,16.7308,1.1950, 2.6326,36.61,0.87,1.19,2.28,2.28,4.40,16.14,146.54,13.80,29.94

RONDONIA,NOVAVIDA,1998,2,20,PVA1,FOREST,0,-1,1,2,25,NO3,000-005,16.3424,1.1950, 2.6326,35.76,0.80,0.87,0.75,0.75,3.44,4.85,114.12,-7.23,-2.39

RONDONIA,NOVAVIDA,1998,2,21,PVA1,FOREST,0,-1,1,3,33,NO3,000-005,16.6344,1.1950, 2.6326,36.40,1.37,1.56,1.34,1.34,6.66,20.53,623.04,54.63,75.16

Data Application and Derivation:

Trace gas fluxes from tropical forests are important components of the global carbon and nitrogen budgets. The relative importance of the land-use change and soil nutrient dynamics on emissions in the seasonal and annual budgets of these gases us poorly understood. These data improve our understanding of the effects of land-use change and soil nutrient availability on the dynamics of soil-atmosphere gas exchange of NO, N2O and CO2.

Quality Assessment (Data Quality Attribute Accuracy Report):

Quality Assessment:

Gas fluxes:



A 1.032 ppmv NO standard in O2-free N2 (Scott- Marrin, Riverside, California) was diluted with NO/NO2-free air to produce a number of NO calibration standards, usually 49.2 ppbv. Ambient air was passed sequentially through scrubbers containing drierite and ascarite to produce NO/NO2-free air (less than 0.06 ppbv NO). The analyzer was calibrated before and after each daily field sampling and varied by less than ±10 between calibrations.



A certified standard of 826 ppmv CO2 in air from Scott Specialty Gases of was used to calibrate the IRGA. The analyzer was calibrated before and after each daily field sampling and varied by less than ±1% between calibrations.



A Scott certified standard of 0.985 ppmv N2O in N2 was used for calibration. Prior calibrations with multiple standards showed that the detector response was linear from 0.310 ppmv (ambient) to at least 1.00 ppmv.

Process Description:

Data Acquisition Materials and Methods:

Field site description:

This study was conducted at Fazenda Nova Vida, located at km 472 of highway BR-364 in central Rondonia. Climate of the area is characteristic of humid tropical forest, with an annual precipitation of 2270 mm distributed seasonally with a dry season extending from June through September. Mean annual maximum and minimum temperatures are 25.6 and 18.8 degrees C, respectively, with a seasonal variation of approximately 4 degrees C (Bastos and Diniz 1982).

We used a forest and a pasture created in 1987 and the other in 1972. At the time of this study the pasture was 11 years old. These sites were part of previous studies of the effect of the conversion of forest to pasture on C, N, and P stocks and dynamics (Neill et al. (1995, 1997); Garcia-Montiel et al. 2000) and trace gas fluxes (Feigl et al. 1995; Steudler et al. 1996; Garcia-Montiel et al. 2001; Melillo et al. 2001; Steudler et al. 2002).

Forest vegetation consisted of open moist tropical forest with a large number of palm trees. This forest was altered by selective logging, which removed 1 to 3 trees/ha between 1982 and 1992. The pasture was formed by slash and burning of the original forest with no intermediate cropping phase, soil tilling, chemical fertilization or liming and planted with Brachiaria brizantha (Hochst) Stapf. Both sites used in this study were in areas at an elevation of approximately 150 m with minimal relief. Soils contained between 230 to 30% clay and were classified as redyellow podzolic latosol in the Brazilian classification and as Kandiudult in the U.S. classification (Moraes et al. 1995).



Experimental design:

We established a total of three blocks per site (forest or pasture), and within each block six treatments were randomly assigned to 3 by 3 m plots for a total of three replicates by treatment, or 18 plots per site.



The six fertilization treatments were ammonium, nitrate, ammonium plus phosphate, nitrate plus phosphate, phosphate, and control. Ammonium was applied as NH4Cl at 100 kg N per ha per yr and nitrate as NaNO3 at the same annual rate as ammonium. Phosphate was applied as Na2HPO4 at 40 kg P per ha per yr. Fertilizer was applied in three equal amounts spaced throughout the year (March, August, and November 1998). At each application fertilizer was mixed with 150 g of acid-washed dry sand so it could be distributed evenly in

the plots.



Measurements were conducted 2 or 3 days before and 1, 7, and 14, 180 (6 months) and 395 days (13 months) after fertilization to examine the short-, intermediate-, and long-term responses. We measured the gas fluxes and the soil properties, shaded air, and soil temperatures (surface and 2, 5, and 10 cm depths), soil moisture, net N mineralization, and net nitrification rates and N pools at each sampling date. Resin P pools were measured pre-fertilization and at 7 and 14 days after fertilization. Fertilizer was applied dry to one block in the forest and pasture and the next rain event was allowed to wash the fertilizer into the soil. Measurements were then begun 18 to 24 hours after the rain ceased. The other two blocks were fertilized and measured sequentially in the same manner over the next 7 days. The short-term measurements were made during the wet season, and the intermediate-term measurements at 6 months after fertilization during the dry season. Final long-term measurements were made 13 months (and 2 fertilization events) after the original measurements.





Gas flux measurements:

Soil fluxes of NO, N2O, and CO2 were measured simultaneously using a recirculating chamber design similar to the systems developed by Davidson et al. (1991), Sundquist et al. (1992) and Verchot et al. (1999). We used a modified two-piece chamber design (Bowden et al., 1990) where the lower portion of the PVC chamber (anchor) was inserted into the soil several days in advance of the first measurement and left in place for the duration of the

experiment to allow repeated sampling at the same locations. One anchor was located in the central area of each plot. This effectively left a 0.5-m buffer zone along the plot edges to avoid any edge effects. During each flux measurement the chamber top (8.38 L or 5.94 L) was placed on the anchor and the changes in headspace-gas concentrations were measured over a 15- to 20-min incubation time. The chamber top was also equipped with a luer lock sampling port for collecting headspace-gas samples for N2O analysis. Gas

fluxes and soil parameters were measured in the forest between 0900 and 1100 (Local time which is GMT -4) and in the pasture between 1200 and 1500 (Local time).



We used a Unisearch Associates LMA-4 NO2 analyzer to measure NO concentrations and a LICOR model 6252 infrared gas analyzer (IRGA) to measure CO2 concentrations. Our design used the LICOR pumping system to circulate air at 1 L min_1 through 0.25-inch Teflon lines connected to the chamber top. The internal NO analyzer pump subsampled this airflow at about 400 ml per min and returned the air to circulating sample stream. A Campbell data logger was used to record the outputs from the NO and CO2 analyzers at 5-s intervals. Incubations were initiated by collecting ambient air concentration data for at least 1 min prior to placing the chamber top on the anchor to ensure initial conditions were stable and representative. The Unisearch NO2 analyzer determines NO concentrations using a Luminol chemiluminescent technique with a CrO3 converter to oxidize NO to NO2. We modified the analyzer to increase

the efficiency of water removal from the analyzer sample air stream by increasing the pressure differential across the stock Nafion dryer and by connecting an inline silica gel drying tube to the outer shell of the drier. This modification resulted in stable converter efficiencies for at least 50 hours of use under 25 to 30 degrees C temperature and approximately 90% relative humidity conditions. We also added a 0.25-inch Teflon line to return the exhaust from the analyzer air pump back to the circulating sample air stream.



For NO flux calculation we used data collected 2 min after chamber closure. This procedure allowed deposition of ambient NO2 and O3 to the soil surface (Davidson et al., 1991). When we measured a very rapid increase in NO concentration, such as in the NH4+ containing fertilized plots, the deposition period was reduced to about 1 min.



CO2 emissions were calculated using the steepest portion of the concentration data against incubation time from the first 2�4 min after the chamber was closed.



Headspace-gas samples were collected using 10-ml Becton Dickinson syringes equipped with stopcocks for determination of N2O concentrations at the beginning and at 2 or 3 times during the 15-min chamber incubation. Nitrous oxide concentrations were determined using electron capture gas chromatography with a detector temperature of 310 degrees C (Bowden et al., 1990). Gas samples were analyzed on site within 12 hours of collection. Nitrous oxide fluxes were calculated using the linear change in N2O concentration against incubation time.





Quality control:

A 1.032 ppmv NO standard in O2-free N2 (Scott- Marrin, Riverside, California) was diluted with NO/NO2-free air to produce a number of NO calibration standards, usually 49.2 ppbv. Ambient air was passed sequentially through scrubbers containing drierite and ascarite to produce NO/NO2-free air (less than 0.06 ppbv NO). The analyzer was calibrated before and after each daily field sampling and varied by less than ±10 between calibrations.



A certified standard of 826 ppmv CO2 in air from Scott Specialty Gases of was used to calibrate the IRGA. The analyzer was calibrated before and after each daily field sampling and varied by less than ±1% between calibrations.



A Scott certified standard of 0.985 ppmv N2O in N2 was used for calibration. Prior calibrations with multiple standards showed that the detector response was linear from 0.310 ppmv (ambient) to at least 1.00 ppmv.



Soil nutrient concentrations:

At the same time that gas measurements were conducted, we also collected three 2.5-cm-diameter soil cores from the 0�5 and 5�10 cm depths in each plot and then composited these by depth. These samples were used for determinations of gravimetric soil moisture, inorganic N and P pools, and net rates of N mineralization and nitrification in each plot. Ammonium and

NO3- pools were measured by extraction with 2 N KCl. Net N mineralization

and net nitrification rates were measured with 7-day aerobic laboratory incubation (Neill et al., 1995). Soil P pools were determined only in the 0�5 cm of soil depth by the resin extractable P method used in the first step of the sequential P fractionation procedure described by Tiessen and Moir (1993).

Soil moisture content was converted to percent water-filled pore space (WFPS) using soil porosity for these sites (Steudler et al., 1996).

References:

Bastos T.X. and Diniz T.D.de A.S. 1982. Avaliacao de clima do Estado de Rondonia para desenvolvimento agricola. EMBRAPA-CPATU, Belem, Brazil, Boletim de Pesquisa 44.



Bowden, R.D., P.A. Steudler, J.M. Melillo, and J.D. Aber. 1990. Annual nitrous oxide fluxes from temperate forest soils in the northeastern United States. J. Geophys. Res. 95: 13,997-14,005.



Davidson, E. A. 1991. Fluxes of nitrous oxide and nitric oxide from terrestrial ecosystems, in Microbial Production and Consumption of Greenhouse Gases: Methane, Nitrogen Oxides, and Halomethanes, edited by J.E. Rogers and W.B. Whitman, pp. 219-235. Am. Soc. for Microbiol., Washington D.C.



Feigl B.J., Steudler P.A. and Cerri C.C. 1995. Effects of pasture introduction on soil CO2 emissions during the dry season in the State of Rondonia, Brazil. Biogeochemistry 31: 1-14.



Garcia-Montiel D.C., Neill C., Melillo J., Thomas S., Steudler P.A. and Cerri C.C. 2000. Soil phosphorus transformations following forest clearing for pasture in the Brazilian Amazon. Soil. Sci. Soc. Am. J. 64: 1792-1804.



Garcia-Montiel D.C., Steudler P.A., Piccolo M.C., Melillo J., Neill C. and Cerri C.C. 2001. Controls on soil nitrogen oxide emissions from forest and pastures in the Amazon. Global Biochem. Cycles 15:1021-1030.



Melillo J., Steudler P.A., Feigl B.J., Neill C., Garcia-Montiel D.C., Piccolo M.C. et al. 2001. Nitrous oxide emissions from forest and pastures of various ages in the Brazilian Amazon. J. Geophys. Res. 24: 34,179-34,188.



Moraes J.F.L., Volkoff B., Cerri C.C. and Bernoux M. 1995. Soil properties under Amazon forest and changes due to pasture installation in Rondonia, Brazil. Geoderma 70: 63-81.



Murphy, J. and J.P. Riley, 1962. A modified single solution method for the determination of phosphate in natural waters. Anal. chim. Acta 27:31-36.



Neill, C., M.C. Piccolo, P.A. Steudler, J. M. Melillo, B.J. Feigle, and C.C. Cerii. 1995. Nitrogen dynamics in soils of forests and active pastures in the western Brazilian Amazon Basin. Soil Biol. Biochem. 27: 1167-1175.



Neill C., Melillo J.M., Steudler P.A., Cerri C.C., Moraes J.F.L., Piccolo M.C. et al. 1997. Soil carbon and nitrogen stocks following forest clearing for pasture in the southwestern Brazilian Amazon. Ecol. Applic. 7: 1216 to 1225.



Steudler, P.A., J.M. Melillo, B.R. Feigle, C. Neill, M.C. Piccolo, and C.C. Cerri. 1996. Consequence of forest-to-pasture conversion on CH4 fluxes in the Brazilian Amazon Basin. J. Geophys. Res. 101: 18.547-18.554.



Steudler, P.A., Garcia-Montiel D.C., Piccolo M.C., Neill C., Melillo J.M., Feigl B.J. et al. 2002. Trace gas responses of tropical forest and pasture soils to N and P fertilization. Global Biochem. Cycles Vol. 16, No. 2, 10.1029/2001GB001394.



Sundquist, E. T., A. B. Shortlidge, and G. C. Winston. 1992. Diurnal variations in soil CO2 fluxes measured by a non-invasive chamber technique at Sleepers

River, Vermont, Eos Trans. AGU, 73:186.



Tiessen, H., and J.O. Moir. 1993. Characterization of available P by sequential extraction, In Soil sampling and methods of analyses, in Canadian Society of Soil Science, edited by M.R. Carter, pp. 5-76. Lewis, Boca Raton, Fla.



Verchot, L. V., E. A. Davidson, J. H. Cattanio, I. L. Ackerman, H. E.

Erickson, and M. Keller. 1999. Land use change and biogeochemical controls

of nitrogen oxide emissions from soils in eastern Amazonia, Global

Biogeochem. Cycles., 13: 31-46.

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