Prediction of soil nitrogen supply and maize yields with the relative chlorophyll contents of leaves under different climates and soil conditions

Chlorophyll meters are often used to evaluate nitrogen status of crops and soils. Soil replacement experiments were carried out in fields to evaluate the promising application of Chlorophyll meter to different climate zones, which represents three different soils, namely, Phaeozem, Cambisol and Acrisol in Hailun (middle temperate zone), Fengqiu (warm temperate zone) and Yingtan (Mid-subtropical zone) Agricultural Experimental Stations, respectively. The relationships between chlorophyll meter readings of maize leaves and soil inorganic nitrogen contents and maize yields were studied. The results show that there are significant correlations between chlorophyll meter (SPAD) readings and soil nitrate nitrogen contents, soil inorganic nitrogen and maize yields at the prosperous stage of maize. These results indicate the chlorophyll meter can be used to evaluate soil nitrogen availability and corn yields at corn prosperous stage, which are not affected by climate and soil variety.