Carbon footprint and yield performance assessment under plastic film mulching for winter wheat production

The rising population and food consumption, together with reduction in available land and other productive resources poses a significant challenge for the current agriculture to meet the increasing food demand. Achieving food security under recent production systems can only be met by increasing the grain yield per unit area substantially, while decreasing the environmental impacts on the planet. Agricultural production is a primary source of greenhouse gas (GHG) emissions and its impact on global climate change cannot be ignored. Carbon (C) footprint stands for a certain amount of gaseous emissions that are not only relevant to climate change but also associated with human production and consumption activities. It provides a wide platform for policy–makers, the general public and producer in solving the global challenges of promoting food production and concomitantly reducing the GHG emissions. Because of the growing environmental concerns and rising food demands, C footprint of production system must shrink dramatically. The adoption of water–saving cultivation techniques has been attracting increased attention worldwide. The plastic film mulching (PFM) system is one of the most widely applied water–saving strategies in arid and semi–arid areas. Although PFM practice can sustain a high–yielding performance, it may also stimulate negative impacts on environment and climate. However, to our knowledge none of the studies has attempted to explore the C footprint in PFM. The total GHG emission and C footprint of PFM in comparison with traditional flat cultivation in China is addressed in this article.

In this research, a 6–year field experiment was conducted to examine the effect of PFM, irrigation and N application rates on grain yield, total GHG emissions and C footprint of winter wheat. We hypothesized that PFM in combination with appropriate N rate and supplementary irrigation may reduce C footprint, while sustaining higher grain yield and greater water use efficiency (WUE) under dry semi–humid areas in comparison to traditional flat planting (CK).

We found that PFM increased grain yield and WUE significantly in winter wheat, compared with the conventional flat planting no mulch system (CK), due to the favorable soil hydrothermal conditions. The use of plastic film and supplementary irrigation decreased C footprint under the high N rate, but increased C footprint under lower N rate. Additional irrigation and higher N rate can be avoided under the CK, because of the inferior grain yield and severe environmental impacts. Under PFM, however, an increasing N rate higher than 75 kg N ha–1, and supplementary irrigation (in case of drought) could be considered. N fertilizer is the largest source for total GHG emissions, and increasing N rate enhanced the GHG emissions and C footprint significantly, which suggests that optimum N rate can substantially mitigate the GHG emissions and C footprint. In a nutshell, based on the improved yield performance, WUE and C footprint, the use of plastic film mulch, in collaboration with appropriate N rate and reasonable irrigation regime is an effective practice for winter wheat. However, the associated environmental concerns such as “white pollution” due to the accumulation of leftover plastic films should be considered seriously before making any recommendation.