Fig. 4
From: Legume-based mixed intercropping systems may lower agricultural born N2O emissions
Cumulative mean N2O emission rates of the non-fertilized mono-crops (wheat (WT), faba bean (FB), poplar (PL), and Robinia (RB)), N-fertilized mono-crops (80 kg N ha−1 in the form of calcium-ammonium-nitrate; wheat (NWT) and poplar (NPL)) and non-fertilized mixed crops (wheat with faba bean (WFB) and poplar with Robinia (PRB)). Upper graphs (a) show the agro-forestry treatments, and lower graphs (b) show the crop domains during the period from May–September 2014 (vegetation period of spring crops) and November 2014 to August 2015. Error bars show the standard error of the mean of each treatment (n = 3). Means within each crop followed by the same letter (A, B) are not significantly different (p > 0.05). n.s. not significant