Enhancing Greenhouse Soil Quality Through Ecological Intensification (EI). A Case Study

Intensive greenhouse cultivation, characterized by high agrochemical inputs and minimal organic amendments, maximizes crop productivity but often leads to soil degradation and environmental harm, notably through nitrate leaching and increased nitrous oxide (N 2 O) emissions. To reduce agricultural inputs that may lead to soil degradation, this study evaluates an alternative fertilization strategy based in ecological intensification (EI). Specifically, a management system incorporating horticultural crop residues and organic amendments—with limited use of inorganic fertilizers—was compared to a conventional fertilization system (C) over a six-year period. Soil quality was assessed using physical and chemical indicators alongside microbial gene abundance (16s, ITS) and genes related to denitrification processes ( nirK , nirS , nosZ 1, and nosZ 2) measured by Real-Time PCR. The EI system enhanced soil organic matter and soil structure by enhancing macroporosity and aggregate stability. However, it also increased the risk of salinization. Fungal abundance and the key denitrification genes ( nosZ1 and nosZ2 ) were significantly higher under EI management. The fungal-to-bacterial ratio approached, but did not reach, statistical significance, and the nos/nir gene ratio—an indirect indicator of N 2 O emission potential—remained similar between treatments. These findings suggest a complex interaction between soil quality and denitrifier community dynamics that warrants further investigation, particularly to assess potential N 2 O emissions.