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Abstract. When soil nitrate levels are low, plants suffer nitrogen (N) deficiency but when the levels are excessive, soil nitrates can pollute surface and subsurface waters. Strategies to reduce the nitrate pollution are necessary to reach a sustainable use of resources such as soil, water and plant. Buffer strips and cover crops can contribute to the management of soil nitrates, but little is known of their effectiveness in semiarid vineyards plantations. The research was carried out in the south coast of Sicily (Italy) to evaluate nitrate trends in a vineyard managed both conventionally and using two different cover crops (Triticum durum and Vicia sativa cover crop). A 10 m-wide buffer strip was seeded with Lolium perenne at the bottom of the vineyard. Soil nitrate was measured monthly and nitrate movement was monitored by application of a 15 N tracer to a narrow strip between the bottom of vineyard and the buffer and non-buffer strips. Lolium perenne biomass yield in the buffer strips and its isotopic nitrogen content were monitored. Vicia sativa cover crop management contributed with an excess of nitrogen, and the soil management determined the nitrogen content at the buffer areas. A 6 m buffer strip reduced the nitrate by 42 % with and by 46 % with a 9 m buffer strip. Thanks to catch crops, farmers can manage the N content and its distribution into the soil over the year, can reduced fertilizer wastage and reduce N pollution of surface and groundwater.

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When soil nitrate levels are inadequate, plants suffer nitrogen deficiency but when the levels are excessive, nitrates (NO₃-N) can pollute surface and subsurface waters. Strategies to reduce the nitrate pollution are necessary to reach a sustainable use of resources such as soil, water and plant. Buffer strips and cover crops can contribute to the management of soil nitrates, but little is known of their effectiveness in semiarid vineyards plantations. The experimental site, a 10 m wide and 80 m long area at the bottom of a vineyard was selected in Sicily. The soil between vine rows and upslope of the buffer strip (seeded with Lolium perenne) and non-buffer strips (control) was managed conventionally and with one of two cover crops (Triticum durum and Vicia sativa cover crop). Soil nitrate was measured monthly and nitrate movement was monitored by application of a ¹⁵N tracer to a narrow strip between the bottom of vineyard and the buffer and non-buffer strips. L. perenne biomass yield in the buffer strips and its isotopic nitrogen content were monitored. V. sativa cover crop management contribute with an excess of nitrogen, and the soil management determined the nitrogen content at the buffer areas. A 6 m buffer strip reduce the nitrate by 42% with and by 46% with a 9 m buffer strip

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Keywords:δ 13 C natural abundance Soil organic matter Spatial and depth distribution Root turnover Land use change Carbon sequestration Mediterranean ecosystems are characterized by nearly complete replacement of natural vegetation by intensive croplands and orchards leading to strong soil degradation. Organic carbon is usually accumulated in soils under maquis leading to partial regeneration of fertility for future agricultural use. The aim of this work was to investigate the effect of land use change from maquis to agriculture on soil organic carbon (SOC) stock and its spatial distribution in a Mediterranean system. Three Mediterranean land use systems (seminatural vegetation, cactus pear crop and olive grove) were selected in Sicily and analysed for soil C stocks and their δ 13 C. Total SOC and δ 13 C were measured up to 75 cm soil depth within and between the rows of cactus pear and olive grove and along a similar transect in maquis, in order to evaluate the distribution of new and old C derived from roots. The land use change from Mediterranean maquis (C 3 plant) to cactus pear (CAM plant) lead to a SOC decrease of 65% after 28 years of cultivation, and a further decrease for 14% after 7 years after the change from cactus pear to olive grove (C 3 plant). Considering these SOC losses as well as the periods after the land use changes we calculated the mean residence time (MRT) of soil organic matter. The MRT of C under Mediterranean maquis was about 142 years, but was just 10 years under cactus pear. Root biomass of cactus pear was used for a new approach to estimate root turnover. The root turnover rate of cactus decreased along the soil profile from 7.1% per year in 0-15 cm to 3.7% in 60-75 cm soil depth. Along the transect, the average of root turnover values was highest in the middle of the intra-row. Root turnover and C input were correlated with SOC stocks to evaluate C sequestration potential of soils depending on land use and managements. We conclude that the SOC under maquis is higher and has longer residence time compared to permanent agricultural crops like cactus pear and olives.

This paper aimed to study the effect of temporary cover crop and vine pruning residue burial as alternative practices to conventional tillage on soil nitrate (NO3-N) availability and grapevine performance in the short term. The trial was carried out in a rain-fed vineyard (Vitis vinifera L., cv Grecanico dorato/140 Ruggeri) located in a traditional Mediterranean viticultural area (37°32′48′′ N; 13°00′15′′ E) in Sicily (Italy). Conventional tillage (CT) soil management was compared with winter cover crop (CC), conventional tillage plus buried pruning residue (CT + PR), and winter cover crop plus buried pruning residue (CC + PR) management treatments. Two fertilizer treatments (92 kg ha−1 of N as urea and 0 kg ha−1) were applied to the four soil management treatments. Vicia faba L. was the selected leguminous cover crop species, which was seeded in autumn and buried in spring at the same time as vine pruning residues. The soil NO3-N content was monitored, and vine vegetative growth, yield, and must quality were assessed over two seasons. Results showed that NO3-N availability strongly differed between fertilized (F) and unfertilized (UF) plots and years and among treatments. A positive effect of winter leguminous CC + PR on the Grecanico dorato grapevine performance was observed. In the UF vineyard, grape fertility, yield, Ravaz index, and total soluble solids were significantly higher in CC + PR vines than in other treatments, thus showing the reliability of reducing N mineral fertilization and related risks of excess nitrate in groundwater. The possibility of increasing the overall sustainability of rain-fed vineyards in a semiarid agro-ecosystem, without negative effects on grape and must quality, is also demonstrated.

Tillage is the main force of soil redistribution in agricultural land use and has been seen as more critical than water erosion. This study aims to evaluate the effect of tillage with standard disk in vineyards. A representative study area with grapevines was selected, and 39 inter-rows were selected to test the effect of slope and forward speed. In each inter-row, a strip of soil was collected, and mixed with 2 kg of coloured sand used as a tracer, then replaced in the strip, and shallow soil tillage was performed by means of a standard disk plough. Three soil subsamples were collected along the slope every 0.30 m from the coloured strip and the sand tracer was separated from the soil and weighed. The results show that the mean soil translocation distance ranged from 0.73 to 1.14 m along the upslope direction, and from 0.32 to 0.84 m along the downslope direction. The net translocation was −0.33 ± 0.12 m which indicate an upslope soil movement. Mean translocation distance was not significantly affected by the considered forward speeds. These results demonstrate that tillage can reallocate soil upslope and open new insights into the use of disk plough as sustainable management in vineyards.