| 1. |
- Lindberg, T., et al.
(författare)
-
Distribution of15N in the soil-plant system during a four-year field lysimeter study with barley (Hordeum distichum L.) and perennial meadow fescue (Festuca pratensis Huds.)
- 1989
-
Ingår i: Plant and Soil. - Dordrecht, Netherlands : Kluwer Academic Publishers. - 0032-079X .- 1573-5036. ; 119:1, s. 25-37
-
Tidskriftsartikel (refereegranskat)abstract
- An annual cereal, barley, and a perennial grass ley, meadow fescue, were grown in field lysimeters in Sweden and fertilized with 12 and 20g Ca(NO3)2-N m-2 yr-1, respectively. Isotope-labeled (15N) fertilizer was added during year 1 of the study, whereafter similar amounts of unlabeled N were added during years 2 and 3. The grass ley lysimeters were ploughed after the growing season of year 3 and sown with barley during year 4. The barley harvest in year 1 removed 59% of the added fertilizer N, while the fertilizer N export by two meadow fescue harvests in year 1 was 65%. The labeled N export decreased rapidly after year 1, especially in the barley, but increased slightly after ploughing of the grass ley.The microbial biomass, measured with the chloroform fumigation method, incorporated a maximum of 1.4-1.7% of the labeled N during the first seven weeks after application. Later on, the incorporation stabilized at less than 1% in both cropping systems.The susceptibility of the residual labeled N to mineralization was evaluated three years after application by means of long-term laboratory incubations. The curves of cumulative mineralized N were described by a two-component first-order regression model that differentiated between an available and a more recalcitrant fraction of potentially mineralizable N. There was no difference in the amounts of potentially mineralizable N between the cropping systems. The labeled N comprised 5 and 2% of the amounts of potentially mineralizable N in the available and more recalcitrant fraction, respectively. The mineralization rate constants for the labeled N were almost twice as high as for the total potentially mineralizable N. The available fraction of the total potentially mineralizable N was 12%, while twice that proportion of the labeled N was available.It was concluded that the short-term ley did not differ from the annual crop with respect to the early disposition of the fertilizer N and the behaviour of the residual organic N.
|
|
| 2. |
- Schnürer, Johan, 1957-, et al.
(författare)
-
Mineralization of nitrogen from15N labelled fungi, soil microbial biomass and roots and its uptake by barley plants
- 1987
-
Ingår i: Plant and Soil. - Dordrecht, Netherlands : Kluwer Academic Publishers. - 0032-079X .- 1573-5036. ; 102:1, s. 71-78
-
Tidskriftsartikel (refereegranskat)abstract
- The availability of nitrogen in15N labelled fungi, soil microbial biomass (Ca(15NO3)2 immobilized by addition of glucose), barley roots and Ca(NO3)2 to barley plants was investigated in a greenhouse experiment. Samples of above-ground plant biomass were taken five times during 76 days. During this time, and at the start of the experiment, the C and N contents of the soil microbial biomass were determined. Microbial biomass-C decreased during the first 41 days, and then increased back to pre-treatment levels. Only 2% of the total soil15N was found in the microbial biomass two days after additions of Ca(15NO3)2. At the final sampling 76 days later, 17% of the15N remaining in soil was found in the microbial biomass. In the other tratments, microbial biomass-N accounted for 20% of remaining soil15N in the one that had received fungi, 29% in the one with barley roots and 35% in the Ca(NO3)2 plus glucose treatment. At harvest, 38% of the soil15N at day 0 added as Ca(NO3)2-N, 29% of fungal-N, 10% of N immobilized in the soil microbial biomass and 7% of N in barley roots was recovered in the above-ground plant biomass.It can be concluded that nitrogen in the native soil biomass is resistant to mineralization and plant uptake. The use of laboratory grown organisms for mineralization studies will overestimate the plant availability of nitrogen in soil microorganisms.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
-
BILAVGASER och SKOGSDÖD
- 1985
-
Samlingsverk (redaktörskap) (refereegranskat)abstract
- Lokala skogsskador orsakade av luftföroreningar har länge varit kända. De stora regionala skadorna är emellertid ett nytt och mycket större problem.Uppskattningsvis beror mellan 30 och 70% av de svenska luftföroreningsbetingade skogsskadorna på bilavgasutsläpp.Forskarna underströk att även om man inte vetenskapligt helt kan förklara varför träden skadas, så vet man tillräckligt mycket för att klart kunna motivera minskade utsläpp.En längre sammanfattning ges i rapporten.
|
|
| 10. |
|
|
