Reduced nitrate leaching and enhanced denitrifier activity and efficiency in organically fertilized soils

Kramer et al. 10.1073/pnas.0600359103.

Supporting Information

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Supporting Table 4
Supporting Figure 4
Supporting Figure 5
Supporting Table 5
Supporting Figure 6
Supporting Figure 7

Fig. 4. Nitrous oxide fluxes (ng of N₂O-N cm^–2· hr^–1) after fall fertilization of fertilized and control plots for each treatment. The lighter areas represent fluxes from unfertilized plots. Stars indicate significant differences between fertilized and control plots at P < 0.05 (least significant difference). Cumulative nitrous oxide emissions after fall fertilization (Table 2) were calculated by extrapolating over periods between sampling dates. Although fluxes vary on a short time scale, this method is commonly used for estimating relative annual or seasonal emissions among treatments (1).

1. Groffman, P. & Tiedje, J. (1989) Soil Biol. Biochem. 21, 621-626.

Fig. 5. Nitrous oxide fluxes (ng of N₂O-N cm^–2· hr^–1) after spring fertilization of fertilized and control plots for each treatment. The lighter areas represent fluxes from unfertilized plots. Stars indicate significant differences between fertilized and control plots at P < 0.05 (least significant difference). Cumulative nitrous oxide emissions after spring fertilization (Table 2) were calculated by extrapolating over periods between sampling dates.

Fig. 6. The 1.7-ha study area of four replicate plots for each of three apple production systems: Organic, integrated, and conventional. In May 1994, Reganold et al. (1) planted the study area with Golden Delicious apples (Malus x domestica Borkh.) on EMLA.9 rootstocks in a randomized complete block design. This research was part of a 20-ha commercial apple orchard in Zillah, Washington. Each plot in the study area contains four rows of approximately 80 trees per row trained on a two-wire trellis system. Trees were planted at a spacing of 1.4 m within rows and 3.2 m between rows for a density of 2,240 trees per ha. Because of russeting and market demand for newer cultivars, every other tree in the study area was top-grafted in 1999 from Golden Delicious to Galaxy Gala, with the remaining half grafted in 2000. The rootstock remained EMLA.9, with Golden Delicious as an interstock trunk for each tree. Within each of the 12 plots, three 4-m² subplots (six 4-m² subplots in the organic, which received two fertilizer treatments) were established and fertilized according to management practice at a rate of 67.3 kg N· ha^–1 on October 22, 2002, and 44.9 kg N· ha^–1 on 1 May 2003 as follows: Three subplots in each of the four conventional plots were fertilized with Ca(NO₃)₂ (15.5% N); three subplots in each of the four integrated plots were fertilized with a 50:50 combination of composted chicken manure and Ca(NO₃)₂; three subplots were fertilized with composted chicken manure (3% N) and another set of three subplots was fertilized with dried alfalfa meal (3% N) in each of the four organic plots. One unfertilized control subplot of 4 m² was also established in each of the 12 plots. Locations of fertilization subplots were selected randomly. Each 4-m² subplot was 2 ´ 2 m and engulfed two apple trees in a single row. Resin bags were installed in each subplot at 30- and 100-cm depth to monitor nitrate leaching. Studies have indicated that resin bags provide similar measurements of leached nitrogen to those obtained using other methods, such as suction lysimeters and soil sampling (2, 3). Static chamber bases were placed in each plot for gas sampling.

1. Reganold, J., Glover, J., Andrews, P. & Hinman, H. (2001) Nature 410, 926-930.

2. Schnabel, R. (1983) Soil Sci. Soc. Am. J. 47, 1041-1042.

3. Wyland, L. & Jackson, L. (1993) Soil Sci. Soc. Am. J. 57, 1208-1211.

Fig. 7. Soil nitrate availability in the top 10 cm of the soil profile for 1 month after fall (A) and spring fertilizations (B). Treatment plots were fertilized on October 22, 2002 and May 2, 2003 at rates of 67.3 and 44.9 kg N· ha^-1, respectively, according to management type.

Table 4. Comparative nitrogen loss studies after fertilization with organic (including compost, dairy sludge, green manures, and biological nitrogen fixation) and mineral fertilizers

     The column labeled "Same N inputs: refers to whether overall nitrogen inputs were equalized among the treatments. The next four columns show variables measured in the present study. Shaded areas indicate that the variable was measured in the study, ORG means that the organic treatment was higher, CON is the conventional (mineral fertilizer), and SAME indicates no statistical difference between the fertilizer treatments. Lab rN₂O is the relative rate of nitrous oxide emissions (N₂O: N₂O + N₂) under ideal laboratory conditions, where the denitrifier community is provided with carbon and nitrate in an anaerobic environment (12). Field denitrification is overall gas losses from denitrification (N₂O + N₂) as determined using intact cores and acetylene (13). Field N₂O emissions are measured using chambers. Leaching refers to nitrate loss through the soil profile. The studies used various techniques, all of which enabled evaluation of relative nitrogen losses among treatments.

1. Paustian, K., Andren, O., Clarholm, M., Hansson, A., Johansson, G., Lagerlof, J., Lindberg, T., Petterson, R. & Sohlenius, B. (1990) J. Appl. Ecol. 27, 60-84.

2. Svensson, B., Klemedtsson, H., Simkins, S., Paustian, K. & Rosswall, T. (1991) Plant Soil 138, 257-272.

3. Yanan, T., Emteryd, O., Dianqing, L. & Grip, H. (1997) Nut. Cycling Agroecosyst. 48, 225-229.

4. Loro, P., Bergstrom, D. & Beauchamp, E. (1997) J. Environ. Qual. 26, 706-713.

5. Drinkwater, L., Wagoner, P. & Sarrantonio, M. (1998) Nature 396, 262-265.

6. Ellis, S., Yamulki, S., Dixon, E., Harrison, R. & Jarvis, S. (1998) Plant Soil 202, 15-25.

7. Di, H., Cameron, K., Moore, S. & Smith, N. (1998) New Zealand J. Ag. Res. 41, 263-270.

8. Arcara, P., Gamba, C., Bidini, D. & Marchetti, R. (1999) Biol. Fertil. Soils 29, 270-276.

9. van der Weerden, T., Sherlock, R., Williams, P. & Cameron, K. (2000) Biol. Fertil. Soils 31, 334-342.

10. Robertson, G.P., Paul, E. & Harwood, R. (2000) Science 289, 1922-1925.

11. Aulakh, M., Khera, T., Doran, J. & Bronson, K. (2001) Biol. Fertil. Soils 34, 375-389.

12. Cavigelli, M. & Robertson, G. P. (2000) Ecology 81, 1402-1414.

13. Mosier, A. R. & Klemedtsson, L. (1994) in Methods of Soil Analysis Part II: Microbiological and Biochemical Properties, eds., Weaver, R. W., Angle, J. S. & Bottomley, P. J. (Soil Sci. Soc. Am., Madison, WI), pp. 1047-1065.

Table 5. Nitrous oxide emission rates from various ecosystems

1. Robertson, G. P., Vitousek, P., Matson, P. & Tiedje, J. (1987) Plant Soil 97, 119-130.

2. Mummey, D., Smith, J. & Bolton, H., Jr. (1994) Soil Biol. Biochem. 26, 279-286.

3. Panek, J., Matson, P., Ortiz-Monasterio, I. & Brooks, P. (2000) Ecol. App. 10, 506-514.

4. Davidson, E., Matson, P. & Brooks, P. (1996) Soil Sci. Soc. Am. J. 60, 1145-1152.

5. Matson, P. & Vitousek, P. (1990) J. Geophys. Res. 95, 16789-16798.

6. Robertson, G. P., Paul, E. & Harwood, R. (2000) Science 289, 1922-1925.

 

Table 6. Fertility management practices for three apple production systems

     The organic, integrated, and conventional systems had similar total soil (ground) N inputs each year.

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