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

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 Nmin (mineral N) test and rapid plant tests on N recommendation for winter wheat. The results showed that Nmin sollwert (NS, Nmin + 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 Nmin (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.