SSS2.1

High majority of soil erosion studies focus on cereal croplands, vineyards, olive, avocado, citrus, almond, persimmon, apple, and apricot orchards. To date, there is a lack of information about the possible impacts of tillage management on soil properties and hydrological response in fig orchards. Understanding this will be crucial to design efficient soil conservation practices and degradation control. Therefore, the aim of this research was to study the initial soil erosion in fig plantations and temporal evolution of initial soil erosion after the tillage intervention on undeveloped, Calcic Fluvisol in Dalmatia, Croatia. The study was conducted by collecting undisturbed soil samples, followed by rainfall simulations (58 mm h^-1, during 30 min, over 0.785 m² plots) in eight repetitions per measurement 2 days, 1 month, and 3 months after the intensive tillage. The results showed a clear difference among soil properties trough time. Seasonal effect significantly modifies soil properties and hydrological response. Soil bulk density and mean weight diameter increase (p < 0.05), while water holding capacity, water stable aggregates, soil organic content, and available phosphorus decrease (p < 0.05) by time after tillage_. The highest runoff was measured 1 month (100.5 m³ ha^-1), followed by 3 months (82 m³ ha^-1), and 0 months (48.3 m³ ha^-1) after tillage. Sediment losses were highest at 3 months (3488.9 kg ha^-1), followed by 3.5 times lesser losses at 1 month (990.6 kg ha^-1), and 8.2 times lower right after the tillage (426.1 kg ha^-1). Temporal variations of soil erodibility in this study were under the influence of soil natural consolidation and precipitation. Fig orchards on young, undeveloped soils are highly erodible forms of land use and conservation practices need to be deploy in order to mitigate land degradation.

Keywords: soil physical properties, runoff, permanent plantation, short-term changes, undeveloped soil

Acknowledgments

This work was supported by Croatian Science Foundation through the project "Soil erosion and degradation in Croatia" (UIP-2017-05-7834) (SEDCRO).

How to cite: Bogunovic, I., Telak, L. J., Dugan, I., Ferreira, C. S. S., and Pereira, P.: Tillage-induced management impact on soil properties and initial soil erosion in degraded calcareous soils in Mediterranean fig orchard, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1309, https://doi.org/10.5194/egusphere-egu21-1309, 2021.

Soil quality indexes (SQIs) are very useful in assessing the status and edaphic health of soils. This is particularly the case in the Mediterranean area, where successive torrential rainfall episodes give rise to erosion and soil degradation processes; these are being exacerbated by the current climate crisis. The objective of this study was to analyze the soil quality in two contrasting Mediterranean watersheds in the province of Malaga (Spain): the middle and upper watersheds of the Rio Grande (sub-humid conditions) and the Benamargosa River (semi-arid conditions). Field soil sampling was carried out at representative sites, and the soils were subsequently analyzed for various edaphic properties in the laboratory. From the resulting data, the mean values ​​have been grouped and reclassified, and based on a multicriteria evaluation, a SQI for the study region was generated. The results show that there are major differences between the two watersheds, with optimal soil quality values being found in the Rio Grande watershed, but more unfavorable values occurring throughout most of the Benamargosa River watershed.

How to cite: Sillero-Medina, J. A., Hueso-Gonzalez, P., and Ruiz-Sinoga, J. D.: SQI: Development index and application for two contrasting mediterranean landscapes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15889, https://doi.org/10.5194/egusphere-egu21-15889, 2021.

How climate change will affect soil functioning is a major concern, especially in Mediterranean agrosystems, where, according to climate change projections, the occurrence of extreme temperatures and drought events will be increased. The main objective of our experiment was to evaluate the effect of land management (tillage system) on soil resilience against a simulated dry-rewetting cycle. Soil samples were collected from an in-situ field experiment established in 2008 in the Guadalquivir Valley, where conservation agriculture practices have been tested. Three different land management practices under a typical Mediterranean wheat-legume rotation system were compared: 1) traditional tillage (TT), 2) minimum tillage (MT) and 3) no-tillage (NT). Following our hypothesis, conservation agriculture practices (reduced tillage and no-tillage) may allow a more mature soil microbial community by reducing soil perturbation, and this would result in higher resistance of soil functioning against drought periods. Soil enzyme activities (β-glucosidase, phosphatase, acetylglucosaminidase, aminopeptidase, and dehydrogenase activities), microbial functional diversity (Microresp method), and soil DNA concentration (as an index of microbial biomass) were analyzed in a base-line sampling. Afterwards, a dry-rewetting cycle was simulated under controlled conditions. 8 subsamples of 50g from each soil sample were hydrated to reach 70% of each soil water holding capacity (WHC) and kept in those conditions for a pre-incubation period of 15 days. After this period, half of the replicates were let dry for 12 days (drought), while the others were maintained at 70% WFC (controls). Finally, all replicates were rehydrated again to the initial water content during a 14 days rewetting period. During this cycle, soil respiration rates were periodically measured to study the evolution of soil microbial activity. Our results showed that initial respiration rates were slightly higher in MT compared to NT (p<0.1), likely due to higher organic C and N content in the MT soils. Drought extremely reduced respiration rates in the three treatments, but the results did not show a clear pattern among treatments. During the rewetting period, respiration rates were significantly higher in drought samples in comparison with the controls, while no significant differences were found for the land management treatments. Besides, land management practices did not have a significant effect on soil DNA concentration, functional diversity of the microbial community, or enzyme activities. To conclude, the absence of a clear effect of land management practices on soil resilience to drought may be due to the experimental conditions. An in-situ experiment will allow us to determine if tillage reduction enhances soil resilience to moisture stress.

How to cite: Morales, L., Domínguez, M. T., Herrador, M. B., Madejón, E., and Fernández-Boy, E.: Effect of conservation agriculture practices on the resilience of Mediterranean soils to the predicted seasonal drought events, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7994, https://doi.org/10.5194/egusphere-egu21-7994, 2021.

Steep slope viticulture is a common practice in the Mediterranean basin offering landscapes of considerable environmental and socio-economic value. However, these agricultural systems are very fragile. One of the main problems is soil erosion due to extreme rainfall, both for drop splash and water accumulation. This may cause a progressive reduction in soil fertility and the occurrence of instabilities and land degradation phenomena. To worsen this condition there is the soil compaction by mechanization and the intensification of severe weather events due to climate change (Tarolli and Straffelini, 2020).

Sustainable farming techniques may provide innovative solutions to reduce the risk of soil erosion. A virtuous approach involves the use of herbaceous coverings between the rows of vines, for many reasons. They provide active protection from the kinetic energy of water droplets; reduce the amount of water flowing on the surface positively affecting the infiltration capacity of the soil; improve ecosystem services in the vineyard.

This work aims to evaluate the effectiveness of different types of grass cover in terms of erosion and runoff generation in steep slope viticulture. The research is part of the SOiLUTION SYSTEM project (www.soilutionsystem.com) within the EU Rural Development Programme (Programma di Sviluppo Rurale per il Veneto 2014-2020); it is proposed to identify an integrated system of environmentally and economically sustainable interventions to reduce the risk of erosion and improve soil management in the terraced area of Soave (Veneto region), one of the two Italian GHIAS-FAO site. In particular, we have set up an experimental vineyard, where different managements are being tested, one for each inter-row of equal size and slope. Downstream of each of them, a water/sediment trap has been developed, obtaining continuous measurements of water volume and sediment concentration over two years. In this way, it is possible to compare the measures understanding the propensity of managements to generate runoff and soil erosion.

Specifically, many types of managements have been evaluated. (1) Continuous tillage, or a bare soil row; (2) Reference, a row where the farm's traditional grass cover is proposed; (3) Nectariferous, or a mix of herbaceous species capable of attracting insects and thus increasing biodiversity in the row; (3) Single tillage, or a row tilled once a year; (4) Native, or a row sown with native species of the place where the vineyard is located.

In combination with in-field experiments, an analysis was carried out on remote sensing data. The evolution of high-tech in topography permits low-cost tools and methodology to create high-resolution Digital Terrain Models (DTMs). For this purpose, we used a RPAS (Remotely Piloted Aircraft Systems) paired with Structure from Motion technique (RPAS-SfM). 3D reconstruction provides detailed knowledge of the terrain features, offering interesting insight to understand the processes that took place in the vineyard. The integrated implementation of in-field measures with remote sensing data opens new opportunities in runoff and soil erosion understanding, providing stakeholders with useful guidelines for sustainable management.

Tarolli, P., & Straffelini, E. (2020). Agriculture in Hilly and Mountainous Landscapes: Threats, Monitoring and Sustainable Management. Geography and Sustainability, 1 (1) (2020), pp. 70-76. https://doi.org/10.1016/j.geosus.2020.03.003

How to cite: Straffelini, E., Otto, S., Pijl, A., Marchesini, E., Gottardi, S., Tormen, N., Pitacco, A., Tezza, L., and Tarolli, P.: The role of inter-row grass cover in steep viticulture: understanding soil erosion combining in-field observation and remote sensing, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2158, https://doi.org/10.5194/egusphere-egu21-2158, 2021.

Maintenance of ground cover vegetation in olive orchards has been shown to reduce soil and runoff losses as compared to bare soil. However, extrapolation of its impact at hillslope scale under different conditions still challenging for several reasons. One is the limited duration of available experiments, usually shorter than 3 years, which can´t capture the annual variability in precipitation typical of Mediterranean type of climate. A second reason is the small scale in which many experiments are carried out, which do not capture all the relevant erosion processes at hillslope scale. A third reason, hardly discussed, is the use of the runoff plots that limits traffic resulting in conditions that might not be fully representative of actual orchards.

For evaluating the effect of temporary cover crops on water erosion processes in olives at hillslope scale, runoff and soil losses have been monitored from 2008 to 2019 in La Conchuela. This is an olive farm located in Southern Spain, where average annual precipitation is 655 mm, on Typic Haploxerert (clay content > 50%). Six runoff plots (14x24 m) delimited by steel beams on concrete foundation were established in a 13.4 % slope, containing 3 rows of 4 trees. This allows normal farm operations. Since 2008-2009, two soil management systems, conventional tillage (CT) and temporary cover crops (CC), were tested. In the two CT plots ground vegetation was controlled by 2-3chisel ploughing passes during the year. CC in the other four plots consisted of sowing manually in mid Fall a grass or a mix with grasses every 1 to 3 years without disturbing the soil surface, been mowed in early Spring. The aim of this cover crop was to be grown up spontaneously from seed produced the previous year. Weeds along the tree rows are controlled by herbicides in both cases.

No significant differences were detected (p < 0.05) for the whole period, although CC showed lower runoff and soil losses values. Runoff data ranged from 157.7 ± 61.2 to 144.5 ± 46.4 mm, and soil losses varied from 24.3 ± 9.1 to 16.4 ± 7.0 t·ha^-1 at the CT and CC treatments respectively. The lack of statistical differences can be explained by the large variability recorded in the measurements at the six plots, especially at the CC due to the specific weather and traffic conditions. Our experiment shows how in a crop, olives, subject to intense traffic during the harvesting season (happening in late fall or early winter, rainy season) and in an orchard on heavy soils, maintenance of a good cover crop is challenging in many years. Our results call for caution when extrapolating the benefits of cover crops in olives from the experimental plots to real world conditions. It also highlights the need for improved soil management under these conditions (e.g. controlled traffic, combination with inert mulch, …) to improve soil and water conservation in intensively cultivated olive orchards in heavy soils.

How to cite: Gomez, J. A. and Guzman, G.: Long-term evaluation of cover crops on soil and runoff losses under trafficked conditions in olive orchards, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-606, https://doi.org/10.5194/egusphere-egu21-606, 2021.

In Portugal, grain corn is the main cereal produced, comprising 56% of total cereal yield. It is grown in intensive monoculture cropping systems that may have negative effects on soil quality, affecting long-term fertility and productivity, and therefore the sustainability of production. A promising management practice to mitigate soil degradation is to grow a cover crop during the usual fallow period. This study examined in which extend six species of legume cover crops (forage pea (pisum sativum L), yellow lupin (lupinus luteus), crimson clover (trifolium incarnatum), balansa clover (trifolium michelianum), persian clover (trifolium suaveolens), and arrowleaf clover (trifolium vesiculosum) are suitable to mitigate soil threats in grain corn systems specifically in the Mediterranean region. Specific objectives were to identify the effectiveness of the legume 6 species in improving soil fertility (i.e., soil organic matter content), mitigating nutrient leaching, nutrient recycling, and weed control. The study was performed in the lower Mondego valley in central Portugal. It covered two autumn to spring periods of cover crop cultivation, and assessed changes in soil fertility, dry biomass yield of legumes and weeds, and their associated nutrient content (total nitrogen-phosphorus-potassium).

In general, the six legume cover crops (LCC) species showed good adaptation to Mediterranean conditions, yielding large amounts of biomass (up to 8 ton/ha for clovers species). At the short term, LCC incorporation into the soil had no clear effect in soil organic matter content. The median uptake of NPK macronutrients for all species was high respectively 176-20-172 kg/ha, due to their generally high biomass production, highlighting their great potential to mitigate nutrient leaching. The capacity of the LCC to provide green manure services enabled a median reduction of 40% of N, 60% of P, and 100% of K supplied by mineral fertilizers necessary to attain a corn grain yield of 12t/ha. LCC showed a good effectiveness in weeds control, although only in the second year of the study. Three clover species (crimson, balansa, arrowleaf) performed best in terms of weed control maintaining weed production below 0.5 ton/ha, vs 3-4 ton/ha in control plots, due to early establishment and/or high biomass production in later growth stages, and avoiding the first application of herbicide in pre-emergent herbicide for grain corn cultivation.

How to cite: Boulet, A. K., Alarcão, C., Ferreira, C., Veiga, A., Campos, L., Ferreira, A., and Hessel, R.: Introduction of legume cover crops practice in intensive grain corn crop system to mitigate soil threats in the Mediterranean region, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6199, https://doi.org/10.5194/egusphere-egu21-6199, 2021.

This paper investigates the use of plant trait analysis on cover crop species, and the impact selected species had on soil chemistry in a Spanish olive orchard. Farmers with hillside orchards in Spain frequently remove vegetation between tree rows due to concerns about water competition in the semi-arid environment. However, this increases the vulnerability of the soil to water erosion. Despite research showing that annual cover crops control soil loss, there has been little uptake of this form of management by farmers.

Ten species, native to southern Spain which had previously been used in cover crop experiments, and for which the seed was low cost, were assessed with plant trait analysis. Above and below ground traits, including specific leaf area, total biomass, root diameter and root volume, were examined to indicate the potential of the plants to reduce splash erosion, runoff and soil detachment. Four of the species were then selected and used in monocultures and mixes in an olive orchard set up in collaboration with CSIC in Cordoba. Soil moisture, rainfall, temperature and soil cover data was collected. Chemical analysis of plant and soil samples is to take place in January 2021.

Brachypodium distachyon, Calendula arvensis, Medicago sativa and Medicago truncatula had the most potential as cover crop species. In the field, the treatment with the greatest number of species (two grasses, one legume and one forb) had the highest mean soil cover at 78 ± 16%. It is hypothesised that the plots in which the greatest cover was established would show the greatest change in soil chemistry and that, where the legume was planted there will be higher nitrogen in the soil.

This presentation will outline the plant traits analysed, the outcomes of this analysis and the impact selected plants had on plant and soil chemistry in the field.

How to cite: Ripley, H., Stevens, C., and Quinton, J.: Plant trait analysis to determine effective annual cover crops for Spanish orchards, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-91, https://doi.org/10.5194/egusphere-egu21-91, 2021.

Low Density Polyethylene is the most applied plastic mulch in agriculture, for decreasing water evaporation, increasing soil temperature, or preventing weeds. Incomplete removal of polyethylene mulch causes plastic pollution in agricultural soils. In conventional agriculture the use of plastic mulch is combined with the use of pesticides. Little is known about the long term effects on soils of plastic debris accumulations in relation with pesticides residues.

We studied 18 parcels in vegetable farms, under organic or conventional management, where plastic mulch has been used for 5 to 20 years in Cartagena’s country side (SE Spain). We sampled soil at two depths: 0-10 cm and 10-30 cm. We compared the macro and micro plastic debris contents, the pesticides residue levels and the soil physiochemical properties between parcels. The ribosomal 16S and ITS DNA regions were sequenced to study shifts in bacterial and fungal communities, respectively. Soils under conventional management contained on average more than 6 different pesticides residues and soils in both managements contained on average 0.2±0.26 g/kg plastic debris. This study also showed how plastic and pesticides interact in soils and affect the microbial community. We identified the most sensitive groups which can act as bioindicators for plastic and pesticide pollution in soils.

How to cite: Beriot, N., Zornoza, R., Zomer, P., Ozbolat, O., Lloret, E., Ortega, R., Miralles, I., Huerta Lwanga, E., and Geissen, V.: Plastic mulch in agriculture: the case of low density polyethylene and its interactions with pesticides and soil microbiota, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7408, https://doi.org/10.5194/egusphere-egu21-7408, 2021.