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Intercropping of legumes and cereals is an important management method for improving yield stability, especially in organic farming systems. However, knowledge is restricted on the relevance of different nutrient transfer pathways. The objective of the study was to quantify nitrogen (N) and carbon (C) transfer from peas to triticale by (1) direct root contact (= R), (2) arbuscular mycorrhizal fungi (AMF; = A), and (3) diffusion (= D). Pea (Pisum sativum cv. Frisson and P2) and triticale (Triticum × Secale cv. Benetto) plants as intercrop were grown for 105 days. Treatment ADR enabled all transfer paths between the two crops. Treatment AD with root exclusion enabled AMF and diffusion transfer between peas and triticale. Treatment A with a diffusion gap barrier only allowed AMF transfer. Pea plants were labelled every 14 days with a 13C glucose and 15N urea solution, using the cotton wick technique. Direct root contact resulted in the highest pea rhizodeposition and thus the largest absolute amounts of N and C transfer to triticale. Root exclusion generally changed composition of rhizodeposits from fine root residues towards root exudates. Pea plant-N consisted of 17% N derived from rhizodeposition (NdfR) in treatment ADR but only 8% in the treatments AD and A, independently of pea variety, whereas pea plant-C consisted of 13% C derived from rhizodeposition (CdfR), without pea variety and transfer path treatment effects. Averaging all transfer path treatments, 6.7% of NdfR and 2.7% of CdfR was transferred from Frisson and P2 to triticale plants. Approximately 90% of this NdfR was transferred by direct root contact from Frisson to triticale and only 10% by AMF, whereas only 55% of CdfR was transferred to triticale by direct root contact, 40% by AMF and 5% by diffusion. Similar percentages were transferred from mutant P2 to triticale. Root exclusion generally changed RD composition from fine root residues towards root exudates. [ABSTRACT FROM AUTHOR]

Aims: More sustainable agricultural systems, which contribute to C sequestration and biological N fixation, require accurate quantification of plant C and N inputs into soils. This has to be conducted under field conditions, as there are serious shortcomings to pot-based experiments, which have dominated studies on rhizodeposition estimation in the past. Therefore, amounts of below-ground plant C, N, and especially the rhizodeposition of peas were quantified in the field more accurately, with particular emphasis on their transfer into different soil compartments during vegetation. Methods: Pea (Pisum sativum L.) plants were labelled with multiple pulses of 13C-glucose and 15N urea using the cotton wick method. Plants were harvested at four dates depending on plant development. Representative soil samples were taken at harvest with a special drilling tool, considering the spatial distribution of pea roots. Results: Our results indicate that the quantity of C and N rhizodeposition did not change between flowering and maturity. About one third of the C and N rhizodeposits were present in microbial biomass and extractable C or the inorganic N pool of soil. When comparing this field study to a former pot experiment, a higher root-to-shoot ratio was detected; also the rhizodeposition-to-root ratio was altered in the field, questioning the assumption that results from pot experiments can be transferred to field conditions. Conclusions: Due to a higher below-ground C (BGC) and N (BGN) input compared to pot experiments, studies aiming at quantifying BGC and BGN input will have to be conducted under field conditions. [ABSTRACT FROM AUTHOR]

Aims: The current study quantified the carbon (C) and nitrogen (N) transfer from peas to oats under field conditions to assess the effects of intercropping. The data obtained were compared with previously published pot and field experiments.Pea (Pisum sativum L. cv. Santana) and oat (Avena sativa L. cv Dominik) plants were grown as intercrops for 105 days. Pea plants were labelled with a solution of 2% 13C glucose (99 atom%) and 0.5% 15N urea (95 atom%), using the cotton wick technique.Pea rhizodeposits reached 540 kg C ha−1 and 17 kg N ha−1. CdfR (C derived from rhizodeposition) and NdfR corresponded to a proportion of 18.2 and 12.7%, respectively, of total pea biomass C and N. In the intercropped oat plants, only 0.6% of the total pea CdfR amount was found, but nearly 30% of the total pea NdfR amount.CdfR and NdfR as proportion of total pea biomass C and N, respectively, were 2.5 times higher in peas intercropped with oat plants than in sole-cropped pea plants, comparing the current results with those from previously published pot and field experiments. Future studies on intercropping should consider root formation and rhizodeposition more often.Methods: The current study quantified the carbon (C) and nitrogen (N) transfer from peas to oats under field conditions to assess the effects of intercropping. The data obtained were compared with previously published pot and field experiments.Pea (Pisum sativum L. cv. Santana) and oat (Avena sativa L. cv Dominik) plants were grown as intercrops for 105 days. Pea plants were labelled with a solution of 2% 13C glucose (99 atom%) and 0.5% 15N urea (95 atom%), using the cotton wick technique.Pea rhizodeposits reached 540 kg C ha−1 and 17 kg N ha−1. CdfR (C derived from rhizodeposition) and NdfR corresponded to a proportion of 18.2 and 12.7%, respectively, of total pea biomass C and N. In the intercropped oat plants, only 0.6% of the total pea CdfR amount was found, but nearly 30% of the total pea NdfR amount.CdfR and NdfR as proportion of total pea biomass C and N, respectively, were 2.5 times higher in peas intercropped with oat plants than in sole-cropped pea plants, comparing the current results with those from previously published pot and field experiments. Future studies on intercropping should consider root formation and rhizodeposition more often.Results: The current study quantified the carbon (C) and nitrogen (N) transfer from peas to oats under field conditions to assess the effects of intercropping. The data obtained were compared with previously published pot and field experiments.Pea (Pisum sativum L. cv. Santana) and oat (Avena sativa L. cv Dominik) plants were grown as intercrops for 105 days. Pea plants were labelled with a solution of 2% 13C glucose (99 atom%) and 0.5% 15N urea (95 atom%), using the cotton wick technique.Pea rhizodeposits reached 540 kg C ha−1 and 17 kg N ha−1. CdfR (C derived from rhizodeposition) and NdfR corresponded to a proportion of 18.2 and 12.7%, respectively, of total pea biomass C and N. In the intercropped oat plants, only 0.6% of the total pea CdfR amount was found, but nearly 30% of the total pea NdfR amount.CdfR and NdfR as proportion of total pea biomass C and N, respectively, were 2.5 times higher in peas intercropped with oat plants than in sole-cropped pea plants, comparing the current results with those from previously published pot and field experiments. Future studies on intercropping should consider root formation and rhizodeposition more often.Conclusions: The current study quantified the carbon (C) and nitrogen (N) transfer from peas to oats under field conditions to assess the effects of intercropping. The data obtained were compared with previously published pot and field experiments.Pea (Pisum sativum L. cv. Santana) and oat (Avena sativa L. cv Dominik) plants were grown as intercrops for 105 days. Pea plants were labelled with a solution of 2% 13C glucose (99 atom%) and 0.5% 15N urea (95 atom%), using the cotton wick technique.Pea rhizodeposits reached 540 kg C ha−1 and 17 kg N ha−1. CdfR (C derived from rhizodeposition) and NdfR corresponded to a proportion of 18.2 and 12.7%, respectively, of total pea biomass C and N. In the intercropped oat plants, only 0.6% of the total pea CdfR amount was found, but nearly 30% of the total pea NdfR amount.CdfR and NdfR as proportion of total pea biomass C and N, respectively, were 2.5 times higher in peas intercropped with oat plants than in sole-cropped pea plants, comparing the current results with those from previously published pot and field experiments. Future studies on intercropping should consider root formation and rhizodeposition more often. [ABSTRACT FROM AUTHOR]