Ishita Ahuja
Postdoktor
(+47) 458 37 316
ishita.ahuja@nibio.no
Sted
Steinkjer
Besøksadresse
Innocamp Steinkjer, Skolegata 22, Bygg P 1. etasje, 7713 Steinkjer
Forfattere
Ishita Ahuja Inger Sundheim Fløistad Per Grande Øyvind Meland Edvardsen Adam O’Toole Arne SteffenremSammendrag
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Sammendrag
Fishbones contain significant amounts of plant nutrients. Fish residues may be preserved by acidification to pH < 4, which may affect the chemical extractability, and the plant availability of nutrients when applied as fertilisers. Grinded bone material from cod (Gadus morhua) heads was mixed with formic acid to investigate if this would increase the concentrations of ammonium lactate–acetate (AL)-extractable nutrients. Two degrees of fineness of fishbones (coarse 2–4 mm; fine < 0.71 mm) were compared at pH 3.0 and 4.0 plus a water control in a laboratory study over 55 days. Samples for measurement of AL-extractable P, Ca, Mg and K were taken on day 2, 15, 34 and 55. Whereas more formic acid and thereby lower pH clearly increased the concentrations of AL-extractable calcium (Ca-AL) and magnesium (Mg-AL), AL-extractable phosphorus (P-AL) was only significantly increased in finely grinded bones at pH 3. After 34 days at pH 3, 6% of the total content of P was extracted by AL in fine fishbones. In the water control, about 1% of the P was extracted, possibly from phospholipids. This P-AL concentration was well above P-AL extracted from acidified coarse fishbones (pH 3 and 4) and from fine fishbones acidified to pH 4. With acidification, about 30% of total Ca and 100% of total Mg were extracted by AL, and the Ca-AL and Mg-AL concentrations were closely correlated. A possible reason for lower P-AL in coarse fishbones at pH 3 and 4, and in fine fishbones at pH 4 than in water controls may be a precipitation of apatite from phospholipids and dissolved calcium.
Forfattere
Ishita AhujaSammendrag
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Forfattere
Ishita AhujaSammendrag
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Forfattere
Diego Abalos Tatiana Francischinelli Rittl Sylvie Recous Pascal Thiébeau Cairistiona F. E. Topp Kees Jan van Groenigen Klaus Butterbach-Bahl Rachel E. Thorman Kate E. Smith Ishita Ahuja Jørgen E. Olesen Marina Azzaroli Bleken Robert M. Rees Sissel HansenSammendrag
Crop residue incorporation is a common practice to increase or restore organic matter stocks in agricultural soils. However, this practice often increases emissions of the powerful greenhouse gas nitrous oxide (N2O). Previous meta-analyses have linked various biochemical properties of crop residues to N2O emissions, but the relationships between these properties have been overlooked, hampering our ability to predict N2O emissions from specific residues. Here we combine comprehensive databases for N2O emissions from crop residues and crop residue biochemical characteristics with a random-meta-forest approach, to develop a predictive framework of crop residue effects on N2O emissions. On average, crop residue incorporation increased soil N2O emissions by 43% compared to residue removal, however crop residues led to both increases and reductions in N2O emissions. Crop residue effects on N2O emissions were best predicted by easily degradable fractions (i.e. water soluble carbon, soluble Van Soest fraction (NDS)), structural fractions and N returned with crop residues. The relationship between these biochemical properties and N2O emissions differed widely in terms of form and direction. However, due to the strong correlations among these properties, we were able to develop a simplified classification for crop residues based on the stage of physiological maturity of the plant at which the residue was generated. This maturity criteria provided the most robust and yet simple approach to categorize crop residues according to their potential to regulate N2O emissions. Immature residues (high water soluble carbon, soluble NDS and total N concentration, low relative cellulose, hemicellulose, lignin fractions, and low C:N ratio) strongly stimulated N2O emissions, whereas mature residues with opposite characteristics had marginal effects on N2O. The most important crop types belonging to the immature residue group – cover crops, grasslands and vegetables – are important for the delivery of multiple ecosystem services. Thus, these residues should be managed properly to avoid their potentially high N2O emissions.
Forfattere
Ishita AhujaSammendrag
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Ishita AhujaSammendrag
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Maria Bjørkman Ishita Ahuja Annette Folkedal Schjøll Nicole Van Dam Atle M. Bones Richard MeadowSammendrag
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Ishita Ahuja Maria Björkman Annette Folkedal Schjøll Aysel Heydarova Ralph Kissen Nicole Van Dam Richard Meadow Atle M. BonesSammendrag
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Forfattere
Ishita Ahuja Nicole Van Dam Maria Björkman Eleanna Kazana Glen Powell Annette Folkedal Schjøll Ralph Kissen Aysel Heydarova Jens Rohloff Richard Meadow John Trevor Rossiter Atle M. BonesSammendrag
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Maria Björkman Ishita Ahuja Annette Folkedal Schjøll Nicole van Dam Atle M. Bones Richard MeadowSammendrag
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Forfattere
Maria Björkman Ishita Ahuja Annette Folkedal Schjøll Nicole Van Dam Atle M. Bones Richard MeadowSammendrag
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Forfattere
Birgit Hafeld Borgen Ishita Ahuja Ole Petter Thangstad Bjørn Ivar Honne Jens Rohloff John Trevor Rossiter Atle M. BonesSammendrag
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Forfattere
Ishita Ahuja Birgit Hafeld Borgen Magnor Kåre Hansen Bjørn Ivar Honne Caroline Müller Jens Rohloff John Trevor Rossiter Atle M. BonesSammendrag
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