HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Cui, Z. Articles by Huang, S. Search for Related Content PubMed Articles by Cui, Z. Articles by Huang, S. Agricola Articles by Cui, Z. Articles by Huang, S. Related Collections Nutrient Management Plant Nutrition

NITROGEN MANAGEMENT

Regional Evaluation of Critical Nitrogen Concentrations in Winter Wheat Production of the North China Plain

^a Dep. of Plant Nutrition, College of Resources and Environ. Sci., China Agricultural Univ., Beijing 100094, China
^b School of Veterinary Medicine, Univ. of Pennsylvania, Kennett Square, PA 19348
^c College of Resources and Environ. Sci., Qingdao Agricultural Univ., Qingdao 266109, China
^d College of Resources and Environ. Sci., Henan Agricultural Univ., Zhengzhou 450000, China
^e Inst. of Soil Sci. and Fertilizer, Shanxi Academy of Agric. Sci., Taiyuan 030031, China
^f College of Resources and Environ. Sci., Shandong Agricultural Univ., Taian 271018, China
^g Institute of Soil Sci. and Fertilizer, Henan Academy of Agricultural Sci., Zhengzhou, 450000, China

^* Corresponding author (chenxp{at}cau.edu.cn).

Investigating critical nitrogen concentration (CNC) in grain and straw provides insights into N nutrition, and can serve as a guide to improved agricultural practice. This regional study evaluated the relationship between N fertilization rate and grain yield, N concentration, potential N loss, and determined critical grain and straw nitrogen concentrations (CGNC and CSNC) for winter wheat (Triticum aestivum L.) production in China. At the economically optimum nitrogen rate (EONR), grain N concentration was similar to the maximum value calculated using a linear plus plateau model, while straw N concentration was significantly less than the relevant maximum value. Soil nitrate N content after harvest and apparent N loss for maximum straw N concentration increased by 19 and 9 kg N ha^–1 compared to values at the EONR. Based on nine field experiments, CGNC and CSNC corresponding to optimal N rate were established to be 21.9 g kg^–1 (20.8–23.0 g kg^–1) and 6.8 g kg^–1 (6.5–7.1 g kg^–1), respectively. An evaluation of CGNC and CSNC across 111 on-farm sites indicated that while many sites had grain and straw N concentrations falling within the CGNC and CSNC, a substantial portion of the sites had grain and straw N concentrations falling outside of the CGNC and CSNC or falling within the critical ranges when N supply was deficient (0 N control) or excess (at farmer's N practice). This region-wide study provided evidence for the usefulness of CSNC, and particularly CGNC, as indicators of N deficiencies in wheat production; however, neither indicator provided information about excess N fertilization.

Abbreviations: CGNC, critical grain N concentration • CNC, critical N concentration • CSNC, critical straw N concentration • EONR, economically optimal N rate • NCP, North China Plain

All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher.

Received for publication March 31, 2008.