Assessing the effects of cover crops on cash crop yields

Cover crops (CCs) provide an opportunity to reduce the environmental externalities of farming (Blanco-Canqui et al. 2015; Daryanto et al. 2018). However, CCs have been found to have positive, negative, or no effect on following crop yields (Table 1, Alvarez et al. 2017; Chahal and Van Eerd 2021, 2023; Daryanto et al. 2018; Deines et al. 2022; Nielsen et al. 2016; Sanchez et al. 2019; Tonitto et al. 2006; Qin et al. 2021). The conflicting results among the studies can be attributed to soil, agronomic, and climatic factors such as soil texture and fertility, CC species, main crop type, CC and main crop management, precipitation, and temperature, to name a few (Blanco-Canqui et al. 2015; Malone et al. 2022; Nielsen et al. 2016). A better understanding of contributing factors of CC effects on main crop yield is therefore needed. In this chapter, we will review the agronomic and pedoclimatic variables under which CCs either enhance or decrease crop yield. We will also highlight some of the potential mechanisms of CC-induced impacts on the subsequent crop yield along with five case studies from the USA and Canada that highlight regional differences of CC effects on crop yields.