חיפוש מתקדם
Biology and Fertility of Soils
Steffens, D., Institute of Plant Nutrition, Justus-Liebig University, Südanlage 6, D-35390 Gieisen, Germany
Pfanschilling, R., Institute of Plant Nutrition, Justus-Liebig University, Südanlage 6, D-35390 Gieisen, Germany
Feigenbaum, S., Institute of Soils and Water, Volcani Center, P.O.B. 6, Bet-Dagan 50250, Israel
Management of N fertilization depends not only on the mineral N measured at the beginning of the growing season but also on the status of the low- molecular-weight organic-N fraction. Our study was conducted to analyze how much of the 15N applied in labeled cornshoot tissue would be recovered in 0.01 M CaCl2-extractable 15N fractions and wheter a decrease in the CaCl2-extractable 15N fraction quantitatively followed the trend in net mineralization of the 15N applied in corn-shoot tissue during an incubation period. The effects of adding 15N-labeled young corn-shoot tissue to a sandy soil and a clay soil were investigated for 46 days in an aerobic incubation experiment at 25°C. The application of 80 mg N kg-1 soil in the form of labeled corn-shoot tissue (24.62 mg 15N kg-1 soil) resulted in a significant initial increase, followed by a decrease the labeled organic-N fraction in comparison with the untreated soils during the incubation. The labeled organic-N fraction was significantly higher in the sandy soil than in the clay soil until the 4th day of incubation. The decrease in labeled organic N in the sandy soil resulted in a subsequent increase in 15NO3/- during the incubation. Ammonification of applied plant N resulted in a significant increase in the 1 M HCl extractable non-exchangeable 15NH4/+ fraction in the clay soil, owing to the vermiculite content. The 15N recovery was analyzed by the 0.01 M CaCl2 extraction method; at the beginning of the incubation experiment, recovery was 37.0% in the sandy soil and 36.7% in the clay soil. After 46 days of incubation, recovery increased to 47.2 and 43.8% in the sandy and clay soils, respectively. Net mineralization of the 15N applied in corn-shoot tissue determined after the 46-day incubation was 6.60 mg 15N kg-1 soil (=34.9% of the applied organic15N) and 4.37 mg 15N kg-1 soil (=23.1% of the applied organic15N) in the sandy and the clay soils, respectively. The decrease in the labeled organic-N fraction extracted by 0.01 M CaCl2 over the whole incubation period was 3.14 and 2.33 mg 15N kg-1 soil in the sandy and clay soil, respectively. These results indicate that net mineralization of 15N was not consistent with the decrease in the labeled organic- N fraction. This may have been due to the inability of 0.01 M CaCl2 to extract or desorb all of the applied organic 15N that was mineralized during the incubation period.
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הספר "אוצר וולקני"
אודות
תנאי שימוש
Extractability of 15N-labeled corn-shoot tissue in a sandy and a clay soil by 0.01 M CaCl2 method in laboratory incubation experiments
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Steffens, D., Institute of Plant Nutrition, Justus-Liebig University, Südanlage 6, D-35390 Gieisen, Germany
Pfanschilling, R., Institute of Plant Nutrition, Justus-Liebig University, Südanlage 6, D-35390 Gieisen, Germany
Feigenbaum, S., Institute of Soils and Water, Volcani Center, P.O.B. 6, Bet-Dagan 50250, Israel
Extractability of 15N-labeled corn-shoot tissue in a sandy and a clay soil by 0.01 M CaCl2 method in laboratory incubation experiments
Management of N fertilization depends not only on the mineral N measured at the beginning of the growing season but also on the status of the low- molecular-weight organic-N fraction. Our study was conducted to analyze how much of the 15N applied in labeled cornshoot tissue would be recovered in 0.01 M CaCl2-extractable 15N fractions and wheter a decrease in the CaCl2-extractable 15N fraction quantitatively followed the trend in net mineralization of the 15N applied in corn-shoot tissue during an incubation period. The effects of adding 15N-labeled young corn-shoot tissue to a sandy soil and a clay soil were investigated for 46 days in an aerobic incubation experiment at 25°C. The application of 80 mg N kg-1 soil in the form of labeled corn-shoot tissue (24.62 mg 15N kg-1 soil) resulted in a significant initial increase, followed by a decrease the labeled organic-N fraction in comparison with the untreated soils during the incubation. The labeled organic-N fraction was significantly higher in the sandy soil than in the clay soil until the 4th day of incubation. The decrease in labeled organic N in the sandy soil resulted in a subsequent increase in 15NO3/- during the incubation. Ammonification of applied plant N resulted in a significant increase in the 1 M HCl extractable non-exchangeable 15NH4/+ fraction in the clay soil, owing to the vermiculite content. The 15N recovery was analyzed by the 0.01 M CaCl2 extraction method; at the beginning of the incubation experiment, recovery was 37.0% in the sandy soil and 36.7% in the clay soil. After 46 days of incubation, recovery increased to 47.2 and 43.8% in the sandy and clay soils, respectively. Net mineralization of the 15N applied in corn-shoot tissue determined after the 46-day incubation was 6.60 mg 15N kg-1 soil (=34.9% of the applied organic15N) and 4.37 mg 15N kg-1 soil (=23.1% of the applied organic15N) in the sandy and the clay soils, respectively. The decrease in the labeled organic-N fraction extracted by 0.01 M CaCl2 over the whole incubation period was 3.14 and 2.33 mg 15N kg-1 soil in the sandy and clay soil, respectively. These results indicate that net mineralization of 15N was not consistent with the decrease in the labeled organic- N fraction. This may have been due to the inability of 0.01 M CaCl2 to extract or desorb all of the applied organic 15N that was mineralized during the incubation period.
Scientific Publication
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