Pagliai et al. Soil management and sustainable agriculture

Marcello Pagliai*, Nadia Vignozzi and Sergio Pellegrini
Consiglio per la Ricerca e la sperimentazione in Agricoltura, Centro di ricerca per l’agrobiologia e la pedologia (CRA-ABP), Firenze

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Key words: Soil thematic strategies, soil functions, soil quality, soil structure, soil erosion, soil compaction, soil crusting.

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Abstract

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Soil degradation is a major environmental problem worldwide, and there is strong evidence that the soil degradation processes are an immediate threat to both biomass and economic returns, as well as a long-term threat to future crop yields. The vulnerability of the European soils to the degradation processes is certainly high and it strongly increases in the Italian soils due to the higher variability of the environment. In Italy, for example the 21.3% of the national soil cover is at risk of desertification (41.1% in centre and south Italy). Main soil degradation processes are erosion, sealing, aridity and salinisation. Soil degradation during the last 40 years caused a decrease of about 30% in its water holding capacity and a proportional shortening of the return time of catastrophic events. Soil degradation has also caused an impairment of several other eco-services, e.g., quality of foods and landscape. The main aspects of environmental degradation can be ascribed to soil processes (erosion, soil compaction, soil crusting, deterioration of soil structure, flooding, losses of organic matter, salinisation, onsite and offsite damages, etc.) following the impact of human activities. Since conventional production systems have resulted in excessive erosion and soil degradation, there is need to control and reduce the occurrence of such degradation. Agricultural management systems can play an important role in preventing soil degradation provided that appropriate management practices are adopted. Long-term field experiments in different types of soils have shown that alternative tillage systems (e.g. no tillage, minimum tillage, ripper subsoiling, etc.) improve the soil structural quality. The continuous conventional tillage causes a decrease of soil organic mat ter content that is associated to a decrease of aggregate stability, leading, as a consequence, to the formation of surface crusts, with an increase of runoff and erosion risks. Other aspects of dangerous soil degradation (erosion) in the hilly environments are represented by land levelling and scraping. After levelling, slopes being prepared for plantation (particularly vineyard) are almost always characterised by the presence of large amounts of incoherent earth materials accumulated with scraper, very vulnerable to water erosion and landsliding. Subsoil compaction is strongly under evaluated, even though the presence of a ploughpan at the lower limit of cultivation is largely widespread in the alluvial soils of the plains cultivated by monoculture and it is responsible of the frequent flooding of such plains in occasion of heavy rains concentrated in a short time (rainstorm), because the presence of this compact layer strongly reduced drainage. Alternative tillage practices, like ripper subsoiling, are able to avoiding the formation of such a compact layer.

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