Low-input cropping systems to reduce input dependency and environmental impacts in maize production: A multi-criteria assessment

Intensification of cropping systems in recent decades has increased their productivity but affected air, soil and water quality. These harmful environmental impacts are exacerbated in Maize Monoculture (MM) and hasten the need for solutions to overcome the trade off between crop yield and environmental impacts. In a three-year cropping systems experiment, a conventional intensive maize monoculture (MM_Conv), with a winter bare fallow, deep soil tillage, non-limiting irrigation was compared to three Low Input Cropping Systems (LI-CS) designed as alternatives to the conventional system. They were managed with decision-rules implemented to reach specific objectives of input reduction. The LI-CS designed with Integrated Weed Management (IWM) techniques and other sustainable cropping practices, were:(i) MM_LI—an IWM Low Input MM; (ii) MM_CT—a Conservation Tillage combined with cover crop MM; and (iii) Maize-MSW—an IWM maize grown in rotation with soybean and wheat. A comprehensive multi-criteria assessment was carried out to quantify the agronomic, economic, social, and environmental performances of each system. A canonical discriminant analysis of performance metrics revealed large differences between the four systems. Yields were significantly higher in MM_Conv (11.0 Mg ha⁻¹) and MM_LI (10.3 Mg ha⁻¹) than in Maize-MSW (8.6 Mg ha⁻¹) and MM_CT (7.8 Mg ha⁻¹). MM_CT had the largest weed infestation (density and biomass) despite the greatest use of herbicides. The Herbicide Treatment Frequency Index (HTFI), used to indicate differences in herbicide use, revealed that the MM_LI (HTFI = 1.0) and Maize-MSW (1.1) halved the herbicide use as compared to the MM_Conv (2.1), despite having similar weed abundance levels. The LI-CS, especially MM_CT, produced high biomass winter cover crops and then less nitrogen fertilization was required as compared to MM_Conv. Gross margins in the MM_LI (1254 € ha⁻¹) and MM_Conv (1252 € ha⁻¹) were higher than the MM_CT (637 € ha⁻¹) and Maize-MSW (928 € ha⁻¹). MM_LI and MM_Conv had similar labour requirements. Water drainage, pesticide leaching, energy use, and estimated greenhouse gas emissions were higher in MM_Conv than in the LI-CS in most years. Results from this research show good potential for the MM_LI to reduce the environmental impacts of MM_Conv while maintaining its economic and social performance.