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Roots below one meters depth are important for nitrate uptake by annual crops

Kristensen, Hanne L. and Thorup-Kristensen, Kristian (2008) Roots below one meters depth are important for nitrate uptake by annual crops. [Rødder under én meters dybde er vigtige for et-årige afgrøder's optagelse af nitrat.] In: Ma, L.; Ahuja, L.R. and Bruulsema, T.W. (Eds.) Quantififying and understanding plant Nitrogen uptake for systems modeling (ISBN 13:978-1-4200-5295-4). CRC Press, chapter 11, pp. 245-258.

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Summary

The root depths of annual crops vary from 0.2 m to more than 2 m depending on root growth rate and length of growing season. However, studies of root growth and N uptake are often restricted to a depth of 1 m or less, as root biomass is assumed to be negligible below this depth. We have studied the importance of root growth and N uptake to a depth of 2.5 m in fully grown field vegetables and cover crops by use of minirhizotrons and deep point placement of 15N. These data were used for calculation of the potential rate of nitrate uptake below 1 m depth. The rate was found to be significant for the six crops studied. The effect of root depth on soil N left by an annual crop was simulated with the EU-rotate N model. The results showed that deep rooted crops exploit deep N when it is available and thereby reduce the amount of nitrate that is prone to leaching. Therefore deep roots and N uptake need to be considered to understand and model N cycling in agro-ecosystems.


EPrint Type:Book chapter
Subjects: Soil > Nutrient turnover
Crop husbandry > Crop combinations and interactions
Crop husbandry > Production systems > Vegetables
Research affiliation: Denmark > DARCOF III (2005-2010) > VEGQURE - Organic cropping Systems for Vegetable production
Denmark > AU - Aarhus University > AU, DJF - Faculty of Agricultural Sciences
Deposited By: Kristensen, Ph.D. Hanne L.
ID Code:11459
Deposited On:28 Nov 2007
Last Modified:12 Apr 2010 07:35
Document Language:English
Status:Published
Refereed:Not peer-reviewed

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