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Nitrogen dynamics in crop sequences with winter oilseed rape and winter wheat

Engström, Lena (2010). Nitrogen dynamics in crop sequences with winter oilseed rape and winter wheat. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2010:92
ISBN 978-91-576-7537-8
[Doctoral thesis]

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With the aim of improving fertiliser nitrogen (N) strategies and reducing N leaching, seasonal changes in soil N supply in crop sequences with winter wheat after winter oilseed rape were examined through field experiments. Break crop effects on wheat after oilseed rape, compared with after peas and oats, were determined as regards residual N, yield and optimum N rate (Opt-N). The impact of residues of the previous crops on net N mineralisation-immobilisation during autumn and winter was studied in field incubation experiments. The influence of spring N fertilisation on winter wheat yields was investigated. Nitrate leaching under winter oilseed rape, peas and oats, and under subsequent wheat was quantified, and measures against leaching were studied. Opt-N to winter wheat was 25 and 15 kg ha-1 lower after winter oilseed rape and peas, respectively, than after oats, despite a yield increase of 700 kg ha-1 after both. The uptake of soil N by wheat until maturity was 26 and 20 kg N ha-1 larger after oilseed rape and peas. Net N mineralisation (Nnet) between spring and maturity was higher after oilseed rape and peas than after oats. Nnet corresponded to 84% of the uptake (or supply) of soil N. The variations in wheat yield at optimum, together with either uptake of soil N or Nnet, explained 70% of the variation in Opt-N. Thus predicting wheat yield and supply of soil N, or Nnet, after previous crops is crucial for the calculation of Opt-N. Due to the large N uptake of winter oilseed rape during the autumn, N leaching during the following winter was lower than during the winter with subsequent winter wheat. More soil mineral N was found at harvest of winter oilseed rape and peas than after oats, affecting later leaching. Above-ground residues of oilseed rape, peas and oats incorporated into soil in September caused N immobilisation during autumn and winter, with the shortest duration for peas. Thus the residue N did not increase leaching risks. Perennial ryegrass as a catch crop undersown in spring in oilseed rape and peas reduced N leaching during winter, whereas direct drilling of winter wheat did not. Fertilisation of oilseed rape above Opt-N enhanced leaching by 0.5 kg N ha-1 per kg fertiliser N. It was concluded that optimising the spring N rate to winter oilseed rape was the most important measure against leaching under subsequent wheat.

Authors/Creators:Engström, Lena
Title:Nitrogen dynamics in crop sequences with winter oilseed rape and winter wheat
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2010
Number of Pages:64
ALLI. Engström, L & Lindén, B. 2009. Importance of soil mineral N in early spring and subsequent net N mineralisation for winter wheat following winter oilseed rape and peas in a milder climate. Acta Agriculturae Scandinavica Section B – Soil and Plant Science 59, 402-413. II. Engström, L & Bergkvist, G. 2009.The effects of three N strategies on tillering and yield of low shoot density winter wheat. Acta Agriculturae Scandinavica Section B – Soil and Plant Science 59, 536-543. III. Engström, L & Lindén, B. 2010. Temporal course of net N mineralisation-immobilisation in topsoil following incorporation of crop residues of winter oilseed rape, peas and oats in a northern climate. (Manuscript submitted) IV. Engström, L., Stenberg, M., Aronsson, H. & Lindén, B. 2010. Reducing nitrate leaching after winter oilseed rape and peas in mild and cold winters. Agronomy for Sustainable Development. Published on line: 24 September 2010. DOI: 10.1051/agro/2010035.
Place of Publication:Uppsala
ISBN for printed version:978-91-576-7537-8
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:nitrogen, mineralization, leaching, brassica napus, triticum, winter crops, pisum sativum, catch crops, fertilizer application, soil fertility, soil breaking, residual effects, field experimentation, sweden
Keywords:Shoot increase, optimum N fertiliser rate, residual N effect, C:N ratio, topsoil, root residues, ryegrass catch crop, direct drilling, excess N fertilisation
Permanent URL:
ID Code:2413
Department:(NL, NJ) > Dept. of Soil and Environment
(S) > Dept. of Soil and Environment
Deposited By: lena engström
Deposited On:24 Nov 2010 00:00
Metadata Last Modified:02 Dec 2014 10:18

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