Department of Plant Sciences

Atmospheric N deposition is a serious problem in the North China Plain (NCP) because it imposes a considerable nutrient burden on the surrounding environment. A manual integrated total N input (ITNI) method was developed using 15N-labelled monitor plants grown in pots to obtain accurate measures of total N deposition to the agroecosystems in the NCP and improve N-fertilizer recommendations. Total airborne N input into the maize-wheat rotation system is 80-90 kg N ha-1 yr-1 in the NCP, and the plant available N from deposition for maize and wheat plants is c. 50 kg N ha-1 yr-1. While total airborne N input is measured at almost 100 kg N ha-1 yr-1 when ryegrass is used as the monitoring plant, and the plant available N from deposition for ryegrass is c. 76 kg N ha-1 yr-1, accounting for 77% of the total N deposition. Dry deposition is likely to be the major contributor to the total N deposition during wheat growing season in the dry and dusty NCP.