Effects of Long-Term Green Manure Application on the Concentrations of Mineral Elements in Grain of Dryland Wheat in Northwest of China

Green manure is an important managing practice to secure high crop yield, improve soil fertility and nutrient efficiency. However, it was still not clear about the influence of long-term green manure incorporation on mineral elements concentrations in grain of dryland wheat. In this study, inductively coupled plasma mass spectrometry (ICP-MS) technique was applied to evaluate the impact of long-term green manure application on mineral elements of wheat grains which were collected from three experimental treatments including control of non fertilization, chemical fertilization and green manure at wheat harvest in a 25 year wheat experiment conducted in Wuwei, Gansu province. The results showed that most of the mineral elements content of wheat grain under green manure treatment showed an increase trend compared with non fertilization treatment. The elements of Si, Fe, and Ru showed the significant increase under green manure treatment. Besides, it was found the content of all heavy metals in wheat grains showed no significant difference compared with the non fertilization treatment. However, Ni element increased compared with the chemical fertilizer treatment. In conclusion, long-term green manure incorporation can improve some mineral nutrient elements in grain of dryland wheat, which may contribute to the grain nutritional quality while maintaining high wheat yield. However, the effects of green manure application on the behaviors of heavy metals in soil-plant system required further research.