Data/hora: 12/06/2024 09:32:35

Provedor de dados: 	21	
País: 	Germany	
Título: 	Nitrogen fixation and transfer in grassclover leys under organic and conventional cropping systems	
Autores: 	Oberson, A.; Frossard, E.; Bühlmann, C.; Mayer, J.; Mäder, P.; Lüscher, A.	
Data: 	2013-03	
Ano: 	2013	
Palavras-chave: 	Nutrient turnover; Crop husbandry.	
Resumo: 	Background and aim  Symbiotic dinitrogen (N2) fixation is the most important external N source in organic systems. Our objective was to compare symbiotic N2 fixation of clover grown in organically and conventionally cropped grass-clover leys, while taking into account nutrient supply gradients.  Methods  We studied leys of a 30-year-old field experiment over 2 years in order to compare organic and conventional systems at two fertilization levels. Using 15N natural abundance methods, we determined the proportion of N derived from the atmosphere (PNdfa), the amount of Ndfa (ANdfa), and the transfer of clover N to grasses for both red clover (Trifolium pratense L.) and white clover (Trifolium repens L.).   Results  In all treatments and both years, PNdfa was high (83 to 91 %), indicating that the N2 fixation process is not constrained, even not in the strongly nutrient deficient non-fertilized control treatment.  Annual ANdfa in harvested clover biomass ranged from 6 to 16 gN m−2. At typical fertilizer input levels, lower sward yield in organic than those in conventional treatments had no effect on ANdfa because of organic treatments had greater clover proportions. In two-year-old leys, on average, 51 % of N taken up by grasses was transferred from clover.  Conclusion  Both, organically and conventionally cropped grass-clover leys profited from symbiotic N2 fixation, with high PNdfa, and important transfer of clover N to grasses, provided sufficient potassiumand phosphorus-availability to sustain clover biomass production.	
Tipo: 	Journal paper	
Identificador: 	http://orgprints.org/23228/1/Oberson-etal-2013-PlantansSoil-onlinefirst.pdf

Oberson, A.; Frossard, E.; Bühlmann, C.; Mayer, J.; Mäder, P. and Lüscher, A.   (2013) Nitrogen fixation and transfer in grassclover leys under organic and conventional cropping systems.   Plant and Soil,   (online),  - .	
Relação: 	http://orgprints.org/23228/	
Formato: 	application/pdf