Fig. 2
From: Legume-based mixed intercropping systems may lower agricultural born N2O emissions
Top soil (0–15 cm soil section) NH4 + (a, c) and NO3 − (b, d) content 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)). Vertical arrows above the charts indicate application dates of mineral fertilizers. Error bars show the standard error of the mean of each treatment (n = 3)