Effects of conservation agriculture on physicochemical soil health in 20 maize‐based trials in different agro‐ecological regions across Mexico
Maize (Zea mays L.) is Mexico’s primary staple food, but the Country’s degrading soils and climate variability limit its productivity. Conservation agriculture (CA), a management technique that combines minimal tillage, permanent soil cover, and crop diversification, could reduce soil degradation and help improve soil health. There is however a lack of information about the effects of CA on soil health in the diverse agroecological conditions in Mexico. This study reports results of a field trial network established to adapt CA to Mexico’s diverse cropping systems and local conditions. Physicochemical soil health, also referred to as soil quality, was studied in 20 trials in agro‐ecologies ranging from handplanted traditional systems to intensive irrigated systems, initiated between 1991 and 2016. Soil in CA was compared to the local conventional practice (CP), which commonly involves tillage, residue removal, and continuous maize production. Across the sites, organic matter and nitrates were higher in the top (0–5 cm) layer of soil and soil aggregate stability was greater under CA than under CPs. For other soil health parameters, such as nutrient content, pH or penetration resistance, the effects of management varied widely across sites and soil types and most were determined more by local soil type than by management. CA increased maize yields at most sites and on average by 0.85 ± 1.80 t ha−1. Given the significant variation across agro‐ecologies, local adaptive trials are important to assess the effects of CA on soil health and fit the practice to local conditions.