Do organic farming practices improve soil physical properties?

Authors: BLANCO-CANQUI, HUMBERTO - University Of Nebraska; Ruis, Sabrina; FRANCIS, CHARLES - University Of Nebraska

Submitted to: Soil Use and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2023
Publication Date: 11/27/2023
Citation: Blanco-Canqui, H., Ruis, S.J., Francis, C.A. 2023. Do organic farming practices improve soil physical properties? Soil Use and Management. 40. https://doi.org/10.1111/sum.12999.
DOI: https://doi.org/10.1111/sum.12999

Interpretive Summary: The impacts of organic farming (OF) on soil physical properties are not well understood across regions and management strategies. This study is unique because it provides a global understanding of the differences in soil physical properties between conventional and organic farming. Organic farming can improve soil structural quality and increase water infiltration and storage in many cases, but it has variable effects on soil compaction. The improvement in these physical properties suggests OF could enhance crop yields and resilience of agricultural systems to extreme weather events. On one hand, there can be reduced potential for soil erosion and increased water intake under high rainfall events. On the other hand, the increased water holding capacity can potentially contribute to improved adaptation to drought conditions. Studies that were under OF for >10 yr, used animal manure as an amendment, and were on silt loam or loam soils were common. However, these characteristics and management selections are not true of all organic farms, suggesting future research should include more diverse sites and management choices. The positive impact of OF on soil physical properties highlights OF’s potential for improved sustainability and resilience to extreme weather events. This information will be valuable to scientists and natural resource managers to understand how and in what timeframe OF can impact soil physical properties.

Technical Abstract: Organic farming (OF) is a reemerging farming system that could address food security and adverse environmental footprints of conventional farming (CF). However, how OF affects the soil physical environment, an essential pillar for soil ecosystem service delivery, is not well understood. This paper: 1) reviews global literature published through Jan 10, 2023 regarding impacts of OF on soil physical properties compared with CF, 2) discusses OF adoption challenges and opportunities, and 3) underlines research needs. Overall the literature indicates that OF generally improves soil physical properties relative to CF. Organic farming increased wet aggregate stability, saturated hydraulic conductivity, and plant available water in 55-56% of studies, and mesoporosity (5-250 µm) and cumulative water infiltration in the few studies available. Thus, OF can improve soil structural and hydraulic properties in many cases. However, OF had mixed or no effects on soil compaction indicators (i.e., bulk density and penetration resistance). Organic farming likely improved soil physical properties by increasing soil C concentration, although OF-induced increases in soil C did not always equate with improved physical properties, possibly due to frequent tillage in the data reviewed. Factors tended to affect OF impacts on physical properties in this order: amendment type > duration > soil texture > others. Most OF studies were long-term (>10 yr), used animal manure amendment, and were conducted in medium textured soils, which highlight the need for more comprehensive assessments of OF and soil physical properties under different management conditions. In general, OF positively impacted the soil physical environment, which can contribute to OF sustainability, expansion, and outreach that informs farmers about long-term OF benefits.