Water and living soil: improving infiltration
Rain benefits crops when water enters the soil instead of running off with soil and nutrients. Cover, living roots and soil organisms help create the structure enabling this pathway.
Soil life creates space for water
The Soil Biology Primer connects life with structure, erosion and water availability. Bacterial substances bind particles; fungal hyphae connect and stabilise aggregates. Pores between them allow water and air movement.
Growing roots create pathways. Earthworms make burrows, some connecting the surface with deeper layers. Biological activity can facilitate water entry and improve aeration.
Protection starts at the surface
Vegetation and residues protect against raindrop impact. Living roots feed microbes through exudates and sustain rhizosphere activity. Cover and reduced disturbance complement each other by protecting both surface and underlying structure.
What studies found
Andrea Basche and Marcia DeLonge’s 2019 meta-analysis of 89 studies examined how farming practices affect infiltration rate, the speed of water entry. Cover crops increased it by an average 34.8% relative to comparable uncovered land. Perennial systems, including perennial grasses and agroforestry, averaged 59.2% higher rates than annual crops. No-till alone did not produce a statistically significant overall increase.
These figures are averages across analysed studies. The central finding was the importance of cover and continuous living roots.
From infiltration to available moisture
Infiltration describes entry speed. Field capacity describes water retained after freely draining water has left. Crops also depend on the fraction accessible to roots. We examine entry, retention and root access together; structure, depth, organic matter and texture all contribute.
Our field work
We plan to monitor infiltration alongside structure and microbiology in olive groves, connecting cover, compost and liquid applications with repeated microscopic observations following our School training.
Sources and further reading
- Soil Biology Primer, USDA NRCS, Elaine R. Ingham, Andrew R. Moldenke, Clive A. Edwards
- Basche & DeLonge (2019), Comparing infiltration rates in soils managed with conventional and alternative farming methods: A meta-analysis
- Soil Health on Cropland, USDA NRCS
- Biocrust-linked changes in soil aggregate stability along a climatic gradient in the Chilean Coastal Range (2022)
- Distribution of populations of micro-organisms in different aggregate size classes in soil as affected by long-term liming management
- How Do Earthworms, Soil Texture and Plant Composition Affect Infiltration along an Experimental Plant Diversity Gradient in Grassland?
- Soil Health Assessment, USDA NRCS
- Role of Organic Matter, USDA NRCS