NIVEP: Minimizing Nitrogen Environmental Impacts in Intensive Greenhouse Vegetable Production Systems of China

Vegetable production is very intensive, and often relies on greenhouses as this allows to extend the vegetation period and increase yields. Worldwide the total area covered by greenhouses approx. 5.6 million ha, with 4.67 million ha or 83% being found in China. The most prominent center of vegetable production in China is the coastal Shouguang county of Shandong province, where 65% of the entire agriculture land is used for vegetable production in solar greenhouses.
Fertilizer use by Chinese farmers in greenhouse vegetable production systems by far exceed crop demand i.e. >2000 kg N ha^-1 yr^-1, with N inputs being 4-7 times higher as crop requirements. The excessive use of fertilizers has been causing tremendous environmental problems such as gaseous N losses (N₂O, N₂, NO, NH₃), N leaching (NO₃^-, NH₄⁺, DON), acidification and heavy metal accumulation in soils and crops.
The project aims at:

• Quantification of the temporal dynamics of topsoil (0-1 m) and subsoil (1-3 m soil depth) changes in C and N stocks of solar greenhouse soils using a Chrono sequence approach.
• Quantification of changes in actual and potential denitrification rates in soil profiles of intensively managed solar greenhouse vegetable systems as affected by management and land use history
• Assessment of the effectiveness of anaerobic soil infestation and DOC additions to subsoils for removing excess NO₃^- from top- and subsoils. Thereby, tracing the fate of subsoil produced N₂O for its possible contribution to soil-atmosphere N₂O fluxes
• Identification of the potential of different solar greenhouse soil restoration measures and management methods such as biochar and/or straw application as well as fertigation for its effectiveness in increasing soil health, soil N retention potentials and NUE efficiency as well as reducing greenhouse gas emission of greenhouse vegetable production.