Dissimilarity in yield components of maize grown in different fertility fields and effect of nitrogen application on maize in low fertility fields

【Objectives】 Crop yields are affected by both soil fertility and fertilizer application. Thus it is necessary to evaluate the productivity under different soil fertility conditions and fertilizer application. 【Methods】 Two field experiments were conducted consecutively in three years. Three fields with different basic fertility and yield levels were selected which named field A, B and C, and the soil fertility sequence was field ABC. Same crop management practice was applied in the three fields. Three nitrogen treatments were designed in field C with the lowest soil fertility. The treatments included conventional treatment (nitrogen application 210 kg/hm2), and the treatments with 40 kg/hm2 and 80 kg/hm2 more nitrogen input at the jointing stage of maize. Nitrate contents at 0-20 cm soil layers, biomass accumulation and LAI at critical growth stages, yield and its components, and soil basic properties were measured. 【Results】 Permanent mineral nitrogen had the highest correlation coefficient with maize yield compared with other soil properties. There were no significant differences of the nitrate contents in fields with different fertility. The nitrate contents in the treatments with more nitrogen input were significantly higher than that in the conventional treatment in the field C at the jointing stage, and the nitrate content difference was greatest at the tasseling stage. The yield, ears numbers, kennel numbers per ear and thousand kennel weight were all increased as the soil fertility promoted. The yield, ear numbers, kennel numbers per ear and thousand kennel weight in field A were 20.3%, 5.7%, 5.2% and 7.8% higher than those in field C. When more nitrogen was input in the lower soil fertility field, the yield, ear numbers, kennel numbers per ear were increased, while the harvest index was decreased. The yield, ear numbers, kennel numbers per ear and harvest index in the treatment with 80 kg/hm2 more nitrogen input were 17.1%, 9.2%, 4.6% and -8.2% higher than those in the conventional treatment in the field C. 【Conclusions】 More mineral nitrogen used for maize uptake was mineralized, and the yield was promoted through the increase of ear numbers, kennel numbers per ear and thousand kennel weight in the higher soil fertility field. The methods of input more nitrogen at the jointing stage can significantly increase the soil nitrate contents from the jointing stage to tasseling stage, which was helpful to the ear growth in the lower soil fertility field. So the yield was promoted through the increase of ear numbers and kennel numbers per ear. However, the yield still cannot reach the level of the high fertility field, and harvest index was decreased. What is more, environmental pollution risk was increased when the soil nitrate content was increased. Generally, both soil basic fertility improvement and optional fertilizer input should be considered for high yield maize cultivation.