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Monitoring soil mineral nitrogen concentration in Germany: Preliminary results and some methodical challenges P. Schweigert* and R.R. van der Ploeg Institute.

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Presentation on theme: "Monitoring soil mineral nitrogen concentration in Germany: Preliminary results and some methodical challenges P. Schweigert* and R.R. van der Ploeg Institute."— Presentation transcript:

1 Monitoring soil mineral nitrogen concentration in Germany: Preliminary results and some methodical challenges P. Schweigert* and R.R. van der Ploeg Institute of Soil Science, University of Hannover, Hannover, Germany

2 N surplus of agricultural land in Germany

3 Soil mineral nitrogen increased Consequences of N surplus

4 Soil mineral nitrogen increased Nitrate leaching increased Consequences of N surplus

5 Soil mineral nitrogen increased Nitrate leaching increased Nitrate concentration in groundwater often increased over 50 mg l -1 Problem for drinking water supliers, because: 50 mg l -1 is the upper limit in drinking water Consequences of N surplus

6 Soil mineral nitrogen increased Nitrate leaching increased Nitrate concentration in groundwater often increased over 50 mg l -1 Problem for drinking water supliers, because: 50 mg l -1 is the upper limit in drinking water 80 % of the drinking water comes from groundwater Consequences of N surplus

7 Prevention of overfertilization Promotion of cover crop cultivation during fall Measures to reduce nitrate leaching

8 In drinking water catchments Soil mineral nitrogen (NO 3 -N) in 0-90 cm depth In fall before leaching begins Result check: Monitoring programs

9 Baden-Württemberg : - Since First program in Germany samples per year Result check: Monitoring programs

10 Trend of soil mineral nitrogen in Baden-Württemberg

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13 Preliminary result - Soil nitrate concentration decreases - Nitrate leaching probably decreases

14 Are there still problems, that should be solved? Are there anyhow methodical challenges? Methodical challenges?

15 Trend of soil mineral nitrogen in Baden-Wuerttemberg

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17 Quantification of the influences of the weather on the mineral N content of the soils Methodical challenge:

18 Result check: Monitoring programs Liebenau - Since samples per year

19 Soil mineral nitrogen in Liebenau

20 Soil mineral nitrogen and the precipitation until sampling date

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25 Soil mineral nitrogen as a function of precipitation until sampling date

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27 Simple regression with 1 variable NO 3 -N = mean NO 3 -N fall content of all soils (kg ha -1 ), 0-90 cm depth P 10 = Precipitation since 1. October, until date of sampling (mm) NO 3 -N = P r 2 = 0.46 *

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31 Multiple regression with 2 variables NO 3 -N = mean NO 3 -N fall content of all soils (kg ha -1 ), 0-90 cm depth P 10 = Precipitation since 1. October, until date of sampling (mm) Y = Year (1992 = 0; 1993 = 1; 1994 = 2; etc.), temporal trend NO 3 -N = P Y r r 2 = 0.86 ***

32 Multiple regression with 2 variables NO 3 -N = mean NO 3 -N fall content of all soils (kg ha -1 ), 0-90 cm depth P 10 = Precipitation since 1. October, until date of sampling (mm) Y = Year (1992 = 0; 1993 = 1; 1994 = 2; etc.), temporal trend NO 3 -N = P Y r 2 = 0.86 ***

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34 Multiple regression with 4 variables NO 3 -N= mean NO 3 -N fall content of all soils (kg ha -1 ), 0-90 cm depth Y= Year (1992 = 0; 1993 = 1; 1994 = 2; etc.), temporal trend P 10 = Precipitation since 1. October until date of sampling (mm) P 9 = Precipitation of September (mm) T 10 = Mean air temperature at 2 p.m. in October (° C) NO 3 -N = P Y P T r 2 = 0.97 ***

35 Multiple regression with 4 variables NO 3 -N= mean NO 3 -N fall content of all soils (kg ha -1 ), 0-90 cm depth Y= Year (1992 = 0; 1993 = 1; 1994 = 2; etc.), temporal trend P 10 = Precipitation since 1. October until date of sampling (mm) P 9 = Precipitation of September (mm) T 10 = Mean air temperature at 2 p.m. in October (° C) NO 3 -N = P Y P T r 2 = 0.97 ***

36 Multiple regression with 4 variables NO 3 -N= mean NO 3 -N fall content of all soils (kg ha -1 ), 0-90 cm depth Y= Year (1992 = 0; 1993 = 1; 1994 = 2; etc.), temporal trend P 10 = Precipitation since 1. October until date of sampling (mm) P 9 = Precipitation of September (mm) T 10 = Mean air temperature at 2 p.m. in October (° C) NO 3 -N = P Y P T r 2 = 0.97 ***

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38 Decrease of nitrate in groundwater

39 Preliminary results: - Measures to reduce the nitrate leaching are successful Conclusions

40 Methodical challenge: - Values of soil nitrate are superimposed by atmospheric influences Conclusions

41 Methodical challenge: - Values of soil nitrate are superimposed by atmospheric influences - Multiple regression models can detect these influences Conclusions


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