Long‐term organic management: Mitigating land use intensity drawbacks and enhancing soil microbial redundancy

• Published in: Journal of plant nutrition and soil science 2024-04, Vol.187 (2), p.287-294
• Main Authors: Paliaga, Sara, Muscarella, Sofia Maria, Lucia, Caterina, Pampinella, Daniela, Palazzolo, Eristanna, Badalucco, Luigi, Badagliacca, Giuseppe, Laudicina, Vito Armando
• Format: Article
• Language: English
• Subjects: Agricultural practices; Animal manures; bacteria; Biological activity; Biomass; Cover crops; Crops; enzyme activities; Farming; Farming systems; fungi; Land use; Land use management; Legumes; Manures; Microbial activity; microbial biomass; Microorganisms; Nitrogen; Organic farming; Organic soils; Pasture; Physical properties; Redundancy; Soil chemistry; Soil fertility; Soil improvement; Soil physical properties; Soil properties; Substrates; Tillage; Vegetables
• ISSN: 1436-8730; 1522-2624
• DOI: 10.1002/jpln.202300252

Background Soils under organic farming systems exhibit better quality and higher biological activity than conventional systems. Manure addition, especially coupled with reduced or no tillage, significantly enhances microbial biomass and activity by improving soil physical properties and providing carbon (C) and nitrogen (N) sources. While several studies have examined the effects of transitioning from conventional to organic farming on soil chemistry and biochemistry, limited research has explored the influence of land use variations on soil fertility within long‐term organic farming systems. Aims Therefore, the aim of this study was to assess how three different land uses—pasture, vegetable crops, and orchard—affected soil fertility under a long‐term organic farming system. Methods Soil samples were collected from the 0 to 15 cm layer of plots used for pasture, vegetable crops and orchard, being the latter cover cropped with legumes, and analyzed to determine chemical and biochemical soil parameters. Results Contrary to expectations, high land use intensity (vegetable crops and orchard soils) resulted in increased soil organic C and total N, compared to low intensity (pasture). Such an increase was ascribed to farmyard manure addition that counteracted the negative impact of tillage. Consequently, microbial biomass C and activity also increased. The greatest availability of organic substrates favored bacteria, particularly gram‐positive strains, shaping the microbial community. However, despite changes of microbial biomass and of the main microbial groups, microbial activity was only slightly affected, suggesting high functional redundancy of microorganisms in long‐term organic farming soil. Conclusions Results suggested that if land use intensification provides for organic supply, its negative impact on soil fertility may be mitigated.