Optimization of Irrigation Efficiency and Water Retention in Agroecological Systems Through Organic Matter Management

Water scarcity poses a critical constraint to sustainable agriculture, particularly in small-scale systems that rely on traditional irrigation methods. Although organic matter (OM) is known to enhance soil structure and water-holding capacity, quantitative evidence regarding optimal OM levels and their interaction with microbial activity in agroecological contexts remains limited. This study evaluates the effect of different OM contents (2.37%, 3.42%, 5.55%, 7.89%, and 9.43%) on infiltration, moisture retention, and microbiological dynamics in 129 agroecological plots located in the northern highlands of Ecuador. Field and laboratory assessments revealed that intermediate OM levels (between 3.42% and 5.55%) optimize available water retention (up to 14.78%) and stabilize infiltration. In contrast, excessive OM levels (>7.9%) decrease retention efficiency and increase leaching risk. Microbial activity showed a positive correlation with OM up to a certain threshold, beyond which fungal and yeast activity declined under field conditions. The results underscore the importance of managing OM within an optimal functional range to improve irrigation efficiency, enhance microbial resilience, and support water sustainability in agroecological production systems.