Nitrogen Recommendation for Winter Wheat Using N_min Test and Rapid Plant Tests in North China Plain

Abstract

Nitrogen (N) over‐fertilization is a common phenomenon in cereal crop production in North China Plain in order to meet the food requirement by increasing population. It is of significance to optimize N fertilization in winter wheat according to crop N need using suitable N recommendation methods. Thus a field experiment with split‐plot design was carried out in this region to evaluate the role of N_min (mineral N) test and rapid plant tests on N recommendation for winter wheat. The results showed that N_min sollwert (NS, N_min + fertilizer N) 90 kg N ha^− 1 at regreening stage (early March) and N rate 90 kg N ha^− 1 at shooting stage (middle April) could meet N requirement of winter wheat with the target yield of 6000 kg ha^− 1. Plant nitrate concentration in the stem base of wheat as well as SPAD readings (using SPAD‐502 chlorophyll meter from Minolta, Japan) of wheat functional leaves positively correlated with the NS levels at shooting stage, indicating that plant nitrate and SPAD tests could reflect the N nutritional status at this stage. Under treatment of NS 90 + 90, the 0–90 cm soil residual N_min (53.2 kg N ha^− 1) and apparent N loss (12.4 kg N ha^− 1) were controlled at the environmental safe levels without yield loss compared with other treatments with higher N rates, suggesting total N supply of 180 kg N ha^− 1 may be the optimal fertilization under the experimental condition.

Keywords:

• Winter wheat
• Nitrogen application
• Nmin method
• Nitrate
• SPAD tests
• China

Acknowledgments

This research work was a part of Sino‐German Cooperative Project “Sustainable Agriculture in North China Plain.” The authors thank the support of the Major State Basic Research Development Programme of the People's Republic of China (Project No. 1999011707) and National Natural Scientific Foundation of China (Grant No. 39870479), and Ministry of Education and Science & Technology of Germany (BMBF). The authors also thank Dr. Meg Walsh of Colorado State University for her careful revision on the manuscript.