Soil conservation and ecosystem services from agroforestry systems: a GIS-based approach for soil erosion in Central Italy

Preserving natural resources, such as soil, is one of the major challenge for agriculture, in the view of developing sustainable adaptation strategies to climate change. Soil loss by water erosion is a critical issue in the Mediterra - nean region due to high rainfall erosivity caused by the increased frequency of extreme precipitation events. In Tuscany, the risk of soil erosion is exacerbated on arable soil of hilly areas, where the persistent application of conventional tillage is associated with: (i) long periods with bare soils within the crop rotation, (ii) poor herba- ceous vegetation cover due to low biomass productivity and (iii) scarce presence of trees on farmland. Agrofore - stry systems - “the practice of deliberately integrating woody vegetation (trees or shrubs) with crop and/or ani- mal systems to benefit from the resulting ecological and economic interactions” - can reduce soil erosion risk by enhancing cover-management factor. In this study the (R)USLE (Revised Universal Soil Loss Equation) was im- plemented on a GIS-based model in order to assess the potential of diferent agroforestry systems in decreasing soil erosion risk on arable land below the tolerance threshold (11 Mg ha-1 yr-1). The JRC-EU map proposed by Pa- nagos et al. (2015) was used for rainfall erosivity, whereas the agroforestry P-factor values were derived from Delgado & Canter (2012). The reference scenario, based in current soil uses (Corine Land Cover 2012) allowed to determine the baseline of potential soil losses on arable land in Tuscany and to identify areas characterized by the highest risk of erosion. About 50% of the cropland in the study area, 450,000 ha, has a severe soil erosion risk, more than 33 Mg ha-1 yr-1 of soil loss.The development of alternative scenarios, based on the possible implemen- tation of agroforestry systems, allowed to highlight that: (i) alley cropping systems (P-factor from 0.1 to 0.5) would reduce soil loss rate under the tolerance threshold on 60 % of the arable land of Tuscany; (ii) the 11% of the arable land would urgently need high conservative agroforestry practices (P-factor less than 0.1) in order to reduce soil loss below the tolerance threshold

Increase globe artichoke cropping sustainability using sub-surface drip-irrigation systems in a Mediterranean coastal area for reducing groundwater withdrawal

During the last decades in coastal areas of the Mediterranean basin, human growth posed severe stresses on freshwater resources due to increasing demand by agricultural, industrial and civil activities, in particular on groundwater. This in turn led to worsening of water quality, loss/reduction of wetlands, up to soil salinization and abandonment of agricultural areas. Within the EU LIFE REWAT project a number of demonstration measures will take place in the lower Cornia valley (Livorno, Italy), both structural (pilot) and non-structural (education, dissemination and capacity building), aiming at achieving sustainable and participated water management. In particular, the five demonstration actions are related to: (1) set up of a managed aquifer recharge facility, (2) restoration of a Cornia river reach, (3) water saving in the civil water supply sector, (4) water saving in agriculture, (5) reuse of treated wastewater for irrigation purposes. Thus, the REWAT project general objective is to develop a new model of governance for sustainable development of the lower Cornia valley based on the water asset at its core. As per water use in agriculture, the lower Cornia valley is well known for the horticultural production. In this regard, globe artichoke (Cynara cardunculus L. var. scolymus L. (Fiori)) crops, a perennial cool-season vegetable, cover a surface of about 600 ha. In order to increase stability and productivity of the crop, about 2000 – 4000 m3 ha-1 yr-1 of irrigation water is required. Recent studies demonstrated that yield of different crops increases using Sub-surface Drip-Irrigation (SDI) system under high frequency irrigation management enhancing water use efficiency. In the SDI systems, the irrigation water is delivered to the plant root zone, below the soil surface by buried plastic tubes containing embedded emitters located at regular spacing. Within the LIFE REWAT, the specific objectives of the pilot on irrigation efficiency is to (i) demonstrate the suitability of SDI for globe artichoke cultivation, reducing the water consumption, while maintaining (or even increasing) crop production and (ii) assess the crop water use efficiency respect to surface drip-irrigation. The field test is located in Venturina (Italy) and it covers a surface of 4 ha. The soil is characterized by sandy-loam texture, 1.72% of organic matter at 7.81 pH. Groundwater is the main source of supply for irrigation. By the chemical point of view, a monitoring campaign in spring 2016 showed a neutral pH of 7.2, electrical conductivity of 1363 μS/cm, 373 and 243 mg/l of total sulphate and carbonate, respectively, thus demonstrating the suitability of groundwater for SDI application. The SDI system was implemented at the beginning of September 2016. The sub-surface buried pipelines, were placed at 0.25 m depth, with emitters spaced 0.5 m. The distance between pipelines was 1.5 m, according to globe artichoke layout (1.5 m between rows, 1 m in-row spacing). Surface-buried tubes were placed in an area about 0.75 ha wide for the comparison with SDI. Artichoke var. Terom were transplanted after the SDI operation test. In the next 3 years, both crop productivity and water use will be assessed. Results will be presented and discussed with the whole farmer’s community. Acknowledgement This paper is presented within the framework of the project LIFE REWAT, which has received funding from the LIFE Programme of the European Union Grant Agreement LIFE14 ENV/IT/001290

Alfalfa (Medicago sativa l.) overseeding on mature switchgrass (panicum virgatum l.) stand: Biomass yield and nutritive value after the establishment year

Perennial crops can positively act on the environment providing a better inter-annual protection of soil cover from water erosion, limiting soil fertility degradation, the risk of nutrient leaching and the exploitation of water for irrigation. Switchgrass (Panicum virgatum L.), a warm-season grass native from North America, has been cultivated for decades as forage crop and only recently as bioenergy crop. Even if several studies reported a positive effect of nitrogen (N) supply on switchgrass yield and quality, potential indirect and direct environmental risks (e.g., eutrophication and greenhouse gas emission) are related to this practice. For this reason grass-legume intercropping can represent a sustainable practice able to increase biomass yield and quality, and at the same time to improve N use efficiency, soil structure and fertility. Based on this, the aim of this study was to evaluate the suitability of switchgrass to Mediterranean environment as forage crop and to improve biomass yield and its nutritional value by intercropping with alfalfa (Medicago sativa L). During spring 2013, in two switchgrass pure stands (varieties Alamo and Blackwell, respectively), alfalfa was established through direct seeding implementing a split-plot experimental design. Our first year results report a positive effect of the intercropping in increasing the total annual yield of the stand, of about 20% with respect to the pure switchgrass stand. However, the presence of alfalfa negatively affected switchgrass yield in the mixture. In both varieties, the crude protein content was higher in the mixture than in the pure switchgrass stands. Conversely, the neutral detergent fibre content in the mixture was lower than in pure switchgrass. Then, our results show that switchgrass-alfalfa intercropping leads to increase the profitability of grassland-based livestock production

Light reduction affected agronomic performance and nutritive value of temporary grassland swards in a Mediterranean rainfed plot trial

In Italy, traditional olive orchards are characterised by low tree density (100-300 ha-1) allowing the cultivation of forage and crops under the tree canopy (Paris et al., 2019). Eichhorn et al. (2006), reported that in Central Italy there are 20000 ha of farmland identified as a silvoarable olive orchard. The intercropping of perennial legumes and trees is a key strategy to improve nutrient cycle of silvoarable systems, due to the higher amount of nitrogen (N) accumulated in stable forms in soil due by biological nitrogen-fixation (Hernandez-Esteban et al., 2019; Sanna et al., 2019), leading to a request for reduction of inorganic N fertilisation. Perennial legumes can also provide a continuous soil cover during the entire year reducing soil loss risk (Vallebona et al., 2016). In the Mediterranean basin, the most important perennial legume is alfalfa (Medicago sativa L.). Previous studies reported that alfalfa nutritive value was not negatively affected by tree presence (Mantino et al., 2021), whereas legume production was reduced due the competition for resources such as water (Nasielski et al., 2015), nutrients (Isaac et al., 2014) and light (Mantino et al., 2021). In Tuscany, sulla (Hedysarum coronarium L.) an autochthonous biennial legume is appreciated for its rusticity, productivity, and quality and it is intercropped with Italian ryegrass (Lolium multiflorum Lam.) for a better utilisation as pasture. In 2019, a rainfed field plot trial was established to evaluate agronomic performance and nutritive value of different perennial forage species grown under different levels of light reduction, aiming to start a selection of shade tolerant forage crops. In October, the plot trial was established in Pisa, on a clay-loam soil with pH of 8.1 and 2.5 % w/w of organic matter content in the topsoil (0-0.3 m). Before sowing, 100 kg ha-1 of P2O5 were applied. The experimental layout complies with a two-factor randomized complete block design with four replicates (18 m2 sizing each plot). The first factor included five different swards: i) sulla cv. Silvan, (ii) ryegrass cv. Teanna, (iii) mix of sulla cv. Silvan and ryegrass, 50:50 (iv) mix of sulla cv. Silvan, sulla cv. Chiara Stella and sulla cv. Bellante 33:33:33 and (v) alfalfa cv. Messe. The second factor included three increasing shading levels: S0) the control representing full light availability, S25) and S50), corresponding to a reduction of potential light availability of 25 and 50% respectively. As previously tested by Varella et al. (2011), shading was provided by woody slats, N-S oriented, 2.0 m long and 0.10 m wide, with a distance between each slat of 0.10 m for S50 and 0.20 m for S25, covering a total surface of 4 m2. After sowing, slats were placed at 0.8 m above ground level. Yield and nutritive value of herbage mass and N2 fixation were evaluated for two consecutive years. Herbage biomass was not affected by the reduction of the 50% of light in ryegrass and ryegrass-sulla mixture while it was negatively affected in alfalfa and sulla. Conversely, the 25% of shade level had no effect on legume yield

An on-farm rotational grazing trial: restricting access time to pasture did not affect the productivity of a dairy sheep flock in spring

In the Mediterranean area, semi-extensive mixed farming systems characterise the inland landscape and guarantee the maintenance of several agroecosystem services. Rationed and rotational grazing have been proposed as efficient agroecological practices for sustainable intensification. Previous studies have highlighted that, during spring, restricted access time to pasture of below four hours per day decreases herbage intake and milk production of rotationally stoked ewes. The aim of this study was to assess the effect of restricted access time on daily herbage intake and milk productivity of Sarda ewes under rotational grazing management in a real farm located in southern Tuscany. The entire flock of 145 lactating ewes was allotted two homogenous groups and rotationally stoked on a grass-legume mixed pasture and fed about 1.7 kg of DM ewe(-1) d(-1) of supplementation. Each group was then assigned to the following treatments: two hours per day of access time to pasture, from 10:00 to 12:00 CET, and four hours per day of access time to pasture, from 10:00 to 14:00 CET. Data on herbage yield and quality, dry matter intake and milk yield were collected from April 5 to May 10, 2018. The rotational grazing schedule was conducted allowing for abundant herbage and exploiting high-nutritive biomass of the upper horizon sward. The results of our on-farm experiment showed that restricting daily access time to pasture down two hours did not reduce the potential daily herbage intake and the milk performance of dairy ewes rotationally stocked on a mixed pasture in spring. Our study also highlighted the capacity of ewes to self-regulate the herbage intake in order to meet their energy requirements, when neutral detergent fibre is not a limiting factor. Our outcomes should encourage researchers and farmers to co-design further on-farm experiments

Carbon Budget of an Agroforestry System after Being Converted from a Poplar Short Rotation Coppice

Poplar (Populus L. spp.) Short Rotation Coppice systems (SRCs) for bioenergy production are being converted back to arable land. Transitioning to Alley Cropping Systems (ACSs) could be a suitable strategy for integrating former tree rows and arable crops. A field trial (Pisa, Central Italy) was set up with the aim of assessing the C storage of an ACS system based on hybrid poplar and sorghum (Sorghum bicolor L. Moench) and comparing it with that of an SRC cultivation system. The carbon budget at the agroecosystem scale was assessed in the first year of the transition using the net biome production (NBP) approach with a simplified method. The overall NBP for the SRC was positive (96 40 g C m2 year1), highlighting that the system was a net carbon sink (i.e., NBP > 0). However, the ACS registered a net C loss (i.e., NBP < 0), since the NBP was 93 56 g C m2 year1. In the first year of the transition, converting the SRC into an ACS counteracted the potential beneficial eect of C storage in tree belowground biomass due to the high heterotrophic respiration rate recorded in the ACS, which was fostered by the incorporation of residues and tillage disturbance in the alley. Additional years of heterotrophic respiration measurements could allow for an estimate of the speed and extent of C losses