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- Chongtham Iman, Raj, et al.
(författare)
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Exploring the inner workings of design-support experiments: Lessons from 11 multi-actor experimental networks for intercrop design
- 2023
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Ingår i: European Journal of Agronomy. - : Elsevier BV. - 1161-0301 .- 1873-7331. ; 144
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Tidskriftsartikel (refereegranskat)abstract
- New forms of field experimentation are currently emerging to support transitions towards sustainable agricul-ture, including "multi-actor experimental networks" (MAENs). Both in public policy and in academic research, such networks are increasingly presented as a promising approach for fostering sustainable farming system design. Many studies have inventoried, categorized and compared experimental processes to discuss them in relation to contemporary issues. However, to our knowledge, these studies have not considered how MAENs can be implemented, nor their various contributions to sustainable farming systems design. The present work therefore explores the mechanisms whereby MAENs, depending on the way they are managed, support partic-ipatory design processes. Drawing on concepts from the design sciences, we studied 11 MAENs established across Europe to support intercrop (IC) design for field crops. Data on the characteristics of these 11 MAENs and their contributions to IC design were collected through individual and group interviews with the network pilots, and the study of individual MAEN documents. The analysis provides three types of results. First, we identify nine generative functions, that is, various processes through which experiments contribute to IC design, including: (i) finding one best option or highlighting contrasts between different ICs; (ii) highlighting the conditions that must be met for an IC to achieve certain effects; (iii) discovering new ICs or properties of ICs; and (iv) supporting the emergence/continuation of collective action for IC design. Second, we highlight different ways to manage MAENs, in other words ways to manage several experiments (in space and time) with a view to supporting participatory IC design. We show that this involves (i) coordinating several objects under design within a network of experiments, (ii) managing the coexistence of experiments guided by different logics in the same geographical area, and (iii) developing interactions between the experiments at a given point in time and over time to support IC design. Third, based on the previous results, we show consistency between the various con-tributions of MAENs to IC design and the different ways in which the pilots managed them, and we highlight three strategies for managing MAENs to support IC design: MAENs supporting (i) R&D-led design; (ii) farmer-led design; and (iii) distributed design. All these results provide mechanisms, points of reference, MAEN types and characteristics to inspire and foster the reflexivity of R&D actors interested in developing such participatory networks in the future.
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- Dhamala, Nawa Raj, et al.
(författare)
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Intercropping of oat and pea to address field-scale soil heterogeneity
- 2021
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Ingår i: Aspects of Applied Biology. - 0265-1491. ; 146, s. 275-280
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Growing grain legumes is challenging due to a high spatial and temporal variability in yield caused by various biotic and abiotic factors, which may be compensated and/or minimised by intercropping (IC) with cereals. However, little is known about the effect of field-scale soil spatial variability on competitive interactions between the IC components, resource use and crop yield performance. A field experiment was conducted to determine how intercropping (IC) of oat (Avena sativa L.) and field pea (Pisum sativum L.) affects crop yield, and balances the field-scale heterogeneity in soil conditions compared to sole crops (SCs). The soil parameters and crop yields varied considerably across the field. The oat-pea IC showed less field-scale variability in yield and suppressed weeds more strongly than pea SC. The study will provide an important insight into how IC can address the issue of crop yield variability and weed growth arising from the variable soil conditions.
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| 4. |
- Jensen, Erik Steen, et al.
(författare)
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Diversifying European agricultural systems by intercropping grain legumes and cereals
- 2020
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Ingår i: INTERNATIONAL JOURNAL OF AGRICULTURE AND NATURAL RESOURCES. - : PONTIFICIA UNIV CATOLICA CHILE. - 2452-5731. ; 47:3
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Tidskriftsartikel (refereegranskat)abstract
- E.S. Jensen, I.R. Chongtham, N.R. Dhamala, C. Rodriguez, N. Carton, and G. Carlsson.2020. Diversifying European agricultural systems by intercropping grain legumesand cereals. Int. J. Agric. Nat. Resour. 174-186. Cropping system diversification is akey factor in developing more sustainable cropping and food systems. The agroecologicalpractice of intercropping, meaning the simultaneous cultivation of two or more species inthe same field, has recently gained renewed interest as a means of ecological intensificationin European agricultural research. We discuss some recent research developments regarding1) intercropping for ecological intensification in agroecological and conventional croppingsystems, 2) studies on nitrogen resource use by cereal-grain legume intercropping cultivation,3) the role of intercropping in the management of biotic stressors, especially weeds, and 4)intercropping as a means of creating cropping systems that are more resilient to the abioticand biotic stress associated with climate change. Finally, we propose methods for the greateradoption of intercropping in European agriculture by unlocking farming systems from upstreamand downstream barriers, with the aim of developing more sustainable agricultural and foodsystems.
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| 6. |
- Dhamala, Nawa Raj, et al.
(författare)
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Effects of including forbs on N-2-fixation and N yield in red clover-ryegrass mixtures
- 2018
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 424, s. 525-537
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Tidskriftsartikel (refereegranskat)abstract
- Legume biological nitrogen (N-2)-fixation is stimulated by neighbouring non-fixing species, but studies of legume N-2-fixation in temporary grasslands including non-leguminous forage herb (forb) species are rare.We investigated N-2-fixation, N yield, and total herbage production in a range of species mixtures consisting of three forb species-chicory (Cichorium intybus L.), ribwort plantain (Plantago lanceolata L.), and caraway (Carum carvi L.)-mixed into a traditional red clover (Trifolium pratense L.) and perennial ryegrass (Lolium perenne L.) mixture at two fertilisation levels.The percentage of red clover N derived from the atmosphere (%Ndfa) was higher in mixtures containing non-legumes than in pure stand but, did not increase with inclusion of forbs. On a whole-seasonal basis, red clover in mixtures derived 90% or more of its N from fixation even when fertilised with 216 kg total N ha(-1). Forbs, in particular chicory, reduced the amount of N-2-fixation and total N yields by affecting the red clover proportion in the harvested biomass.Generally, inclusion of forbs in red clover-ryegrass mixtures had no negative effect on total herbage production and percentage of legume N-2-fixation. However, to maintain a high total N and N-2-fixation yields, mixtures should not include a high seeding proportion of chicory.
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| 7. |
- Dhamala, Nawa Raj, et al.
(författare)
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Highly productive forage legume stands show no positive biodiversity effect on yield and N2-fixation
- 2017
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 417, s. 169-182
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Tidskriftsartikel (refereegranskat)abstract
- While N-2-fixation in diversified grasslands including forage legumes and non-legumes has been widely studied, N-2-fixation in swards containing only forage legumes remains unclear. In this study, we investigated N-2-fixation in pure stands and mixtures of three forage legumes.N-2-fixation, dry matter (DM) and nitrogen (N) yields were quantified in a field experiment for red clover (Trifolium pratense L.), white clover (Trifolium repens L.) and lucerne (Medicago sativa L.) pure stands and mixtures using the isotope dilution method.All three forage legume species derived most (around 85%) of their N from atmospheric N-2-fixation (%Ndfa). However, no positive effect of species diversity was found in any of the mixtures. Species composition of the forage legume mixtures affected the amount of N from N-2-fixation by affecting DM production and N accumulation of the species, where the seasonal amount of N-2-fixation ranged from 370 to 500 kg N ha(-1); which was highest in the presence of red clover.We found that mixtures of the three forage legumes were highly productive, but did not show positive advantages compared to the red clover pure stands in terms of DM, N yield and %Ndfa.
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| 9. |
- Dhamala, Nawa Raj, et al.
(författare)
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N transfer in three-species grass-clover mixtures with chicory, ribwort plantain or caraway
- 2017
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 413, s. 217-230
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Tidskriftsartikel (refereegranskat)abstract
- There is substantial evidence that legume-derived Nitrogen (N) is transferred to neighboring non-legumes in grassland mixtures. However, there is sparse information about how deep rooted non-legume forage herbs (forbs) influence N transfer in multi-species grasslands.Red clover (Trifolium pretense L.) was grown together with perennial ryegrass (Lolium perenne L.) and one of three forb species: chicory (Cichorium intybus L.), ribwort plantain (Plantago lanceolata L.) or caraway (Carum carvi L.) in a field experiment. During the first year after the establishment, red clover leaves were labeled with N-15-urea to determine the N transfer from red clover to companion ryegrass and forbs.On an annual basis, up to 15 % of red clover N was transferred to the companion ryegrass and forbs, but predominantly to the grass. The forb species did not differ in their ability to take up clover N, but biomass production and soil N acquisition was higher in chicory and plantain than in caraway.Grass relied to a great extent on clover N, whereas forbs relied on soil N. Soil N-15-enrichment indicated that N transfer occurred in the upper soil layers and that a dependence on clover-derived N did not necessarily give grass a growth advantage.
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| 10. |
- Dhamala, Nawa Raj, et al.
(författare)
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Short-term residual N unaffected by forbs in grass-clover mixtures
- 2017
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Ingår i: Soil Use and Management. - : Wiley. - 0266-0032 .- 1475-2743. ; 33, s. 457-459
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Tidskriftsartikel (refereegranskat)abstract
- We determined the effect on residual nitrogen (N) of including forbs (chicory, ribwort plantain and caraway) in perennial ryegrass-red clover mixtures. Although soil N inputs during the grassland phase differed markedly between mixtures, in a pot experiment we found no differences in the potentially mineralizable N of the soil or in the dry matter production and N content of the spring barley test crop. The fertilizer value of the grassland mixtures corresponded to 10g N/m(2), irrespective of forb inclusion. Thus, the inclusion of nonlegume forbs did not negatively affect short-term residual N fertility of legume-based grasslands.
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