1. Soil quality, microbial functions and tomato yield under cover crop mulching in the Mediterranean environment

• Authors:
  • Brunetti, P.
  • Mancinelli, R.
  • Marinari, S.
  • Campiglia, E.
• Source: SOIL & TILLAGE RESEARCH
• Volume: 145
• Year: 2015
• Summary: An experiment concerning the biological and chemical responses of soil to cover crop mulching was carried out in two adjacent experimental fields (2012 and 2013) under different climatic conditions in the Mediterranean environment (Central Italy). The Monthly Aridity Index was calculated in order to verify the relationship between soil properties and climatic factors under three different cover crop mulches: Vicia villosa Roth (HV), Phacelia tanacetifolia Benth. (LP), and Sinapis alba L. (WM). A conventional management was also included in the experimental fields as control (C). Soil samples were collected at 0-20cm depth after the transplanting and the harvesting of tomato (May and August, respectively), in order to assess the initial and residual effects of mulching on soil quality. In the two experimental years, the amount of precipitation from May to August was 110mm in 2012 and 172mm in 2013. The average values of AI were 18 and 49 in 2012 and 2013, respectively. LP mulching was sensitive to low precipitation levels in terms of aboveground decomposition rate (the variation of dry matter from May to August 2012 was -53% in LP, 64% in HV and 69% in WM) and a lower tomato yield compared to the control in 2012 (4.2kgm-2 in LP and 5.2kgm-2 in C). WM mulching was sensitive to low precipitation in terms of soil nutrient storage (from May to August 2012 the variation of soil C was 19% in WM., 6% in C, -5 % in LP and 10% in HV; the variation of soil N was 44% in WM, 2% in C, -2% in LP and 13% in HV). Soil microbial activity and functional diversity were strongly affected by the climatic conditions in all mulching treatments. In particular, precipitation influenced soil C availability, which enhanced microbial functional diversity. In short, the effects of lacy phacelia, white mustard and hairy vetch mulching on soil quality, microbial functions and tomato yield were influenced by summer precipitation and temperature in the Mediterranean environment. © 2014 Elsevier B.V.

2. Carbon balance, partitioning and photosynthetic acclimation in fruit-bearing grapevine (Vitis vinifera L. cv. Tempranillo) grown under simulated climate change (elevated CO2, elevated temperature and moderate drought) scenarios in temperature gradient greenhouses

• Authors:
  • Sánchez-Díaz, M.
  • Aguirreolea, J.
  • Sanz-Sáez, T.
  • Erice, G.
  • Pascual, I.
  • Aranjuelo, I.
  • Salazar-Parra, C.
  • Irigoyen, J. J.
  • Araus, J. L.
  • Morales, F.
• Source: Journal of plant physiology
• Volume: 174
• Year: 2015
• Summary: Although plant performance under elevated CO2 has been extensively studied in the past little is known about photosynthetic performance changing simultaneously CO2, water availability and temperature conditions. Moreover, despite of its relevancy in crop responsiveness to elevated CO2 conditions, plant level C balance is a topic that, comparatively, has received little attention. In order to test responsiveness of grapevine photosynthetic apparatus to predicted climate change conditions, grapevine (Vitis vinifera L. cv. Tempranillo) fruit-bearing cuttings were exposed to different CO2 (elevated, 700ppm vs. ambient, ca. 400ppm), temperature (ambient vs. elevated, ambient +4°C) and irrigation levels (partial vs. full irrigation). Carbon balance was followed monitoring net photosynthesis (AN, C gain), respiration (RD) and photorespiration (RL) (C losses). Modification of environment 13C isotopic composition (d13C) under elevated CO2 (from -10.30 to -24.93‰) enabled the further characterization of C partitioning into roots, cuttings, shoots, petioles, leaves, rachides and berries. Irrespective of irrigation level and temperature, exposure to elevated CO2 induced photosynthetic acclimation of plants. C/N imbalance reflected the inability of plants grown at 700ppm CO2 to develop strong C sinks. Partitioning of labeled C to storage organs (main stem and roots) did not avoid accumulation of labeled photoassimilates in leaves, affecting negatively Rubisco carboxylation activity. The study also revealed that, after 20 days of treatment, no oxidative damage to chlorophylls or carotenoids was observed, suggesting a protective role of CO2 either at current or elevated temperatures against the adverse effect of water stress.

3. Energy and nutrient density of foods in relation to their carbon footprint.

• Authors:
  • Verger, E. O.
  • Martin, A.
  • Rehm, C. D.
  • Drewnowski, A.
  • Voinnesson, M.
  • Imbert, P.
• Source: AMERICAN JOURNAL OF CLINICAL NUTRITION
• Volume: 101
• Issue: 1
• Year: 2015
• Summary: Background: A carbon footprint is the sum of greenhouse gas emissions (GHGEs) associated with food production, processing, transporting, and retailing. Objective: We examined the relation between the energy and nutrient content of foods and associated GHGEs as expressed as g CO 2 equivalents. Design: GHGE values, which were calculated and provided by a French supermarket chain, were merged with the Composition Nutritionnelle des Aliments (French food-composition table) nutrient-composition data for 483 foods and beverages from the French Agency for Food, Environmental and Occupational Health and Safety. Foods were aggregated into 34 food categories and 5 major food groups as follows: meat and meat products, milk and dairy products, frozen and processed fruit and vegetables, grains, and sweets. Energy density was expressed as kcal/100 g. Nutrient density was determined by using 2 alternative nutrient-density scores, each based on the sum of the percentage of daily values for 6 or 15 nutrients, respectively. The energy and nutrient densities of foods were linked to log-transformed GHGE values expressed per 100 g or 100 kcal. Results: Grains and sweets had lowest GHGEs (per 100 g and 100 kcal) but had high energy density and a low nutrient content. The more-nutrient-dense animal products, including meat and dairy, had higher GHGE values per 100 g but much lower values per 100 kcal. In general, a higher nutrient density of foods was associated with higher GHGEs per 100 kcal, although the slopes of fitted lines varied for meat and dairy compared with fats and sweets. Conclusions: Considerations of the environmental impact of foods need to be linked to concerns about nutrient density and health. The point at which the higher carbon footprint of some nutrient-dense foods is offset by their higher nutritional value is a priority area for additional research.

4. In situ net N mineralisation and nitrification under organic and conventionally managed olive oil orchards

• Authors:
  • Garcia-Ruiz, R.
  • Hinojosa, M. B.
  • Gomez-Munoz, B.
• Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
• Volume: 101
• Issue: 2
• Year: 2015
• Summary: Olive oil orchard occupies a great percentage of the cropland in southern Spain. Thus, changes in nitrogen (N) fertilization might have a great effect on N dynamics at least at regional scale, which should be investigated for a sustainable N fertilization program. In situ net N mineralization (NM) and nitrification (NN) were investigated during a year in comparable organic (OR) and conventional (CV) olive oil orchards of two locations differing their N input. Soil samples were collected in two soil positions (under and between trees canopy) and both buried-bags and soil core techniques were used to quantify both microbial rates. There were differences in NM and NN between sites mainly due to differences in soil total N (TN), and potential mineralisable N (PMN). In all cases NM and NN were higher in soils under tree canopy. NM and NN were higher in OR than in CV managed orchards in the location with high soil TN. Soil TN and PMN explained together a 50 % of the variability in soil N availability, which suggests that these two variables are good predictors of the potential of a soil to provide available N. The highest rates of soil N availability were found in spring, when olive tree demand for N was at its maximum. Annual soil N availability in olive groves was in all cases higher or similar than tree demand suggesting that soil annual supply of N should be taken into account in order to develop sustainable N fertilisation strategies for olive crops.

5. Greenhouse gas emissions from conventional and organic cropping systems in Spain. II. Fruit tree orchards

• Authors:
  • Alonso, A.
  • Guzman, G.
  • Aguilera, E.
• Source: AGRONOMY FOR SUSTAINABLE DEVELOPMENT
• Volume: 35
• Issue: 2
• Year: 2015
• Summary: Fruit tree orchards have a historical and economic importance for Mediterranean agriculture, notably in Spain. Fruit tree orchards have the potential to mitigate global warming by sequestrating carbon (C) and providing renewable fuels. Actually, there is few information on the benefits of organic practices. Therefore, we analyzed the greenhouse gas contribution of 42 pairs of organic and conventional perennial cropping systems, including citrus, subtropical trees, other fruit trees, treenuts, vineyards, and olives, using life-cycle assessment (LCA). The assessment was based on management information from interviews and involved the estimation of soil carbon sequestration, specific Mediterranean N2O emission factors, and the consideration of coproducts. Results show on average a 56 % decrease of greenhouse gas emissions under organic versus conventional cropping, on an area basis. On a product basis, greenhouse gas emissions decreased by 39 % on average. These findings are explained mainly by C sequestration in soils, which is due in turn to higher C inputs by cover cropping and incorporation of pruning residues.

6. Biochar increases vineyard productivity without affecting grape quality: results from a four years field experiment in Tuscany.

• Authors:
  • Baronti, S.
  • Miglietta, F.
  • Genesio, L.
  • Vaccari, F. P.
• Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
• Volume: 201
• Year: 2015
• Summary: Biochar application to agricultural soils has proved to substantially modify the plant-soil-water relationship and lead mostly to a quantitative increase in agricultural production through physical, chemical and biological mechanisms. Nevertheless, the impact of biochar on qualitative traits of agricultural production needs to be further assessed. The effect of biochar application on vine yield and grape quality parameters is here investigated in a non-irrigated vineyard in Tuscany (central Italy). Results from four harvest-years showed a higher productivity, up to 66%, of treated plots with respect to their controls, while no significant differences were observed in grape quality parameters. The observed increase in productivity was inversely correlated with rainfall in the vegetative period, confirming the key role of biochar in regulating plant water availability. These findings support the feasibility of a biochar-based strategy as an effective adaptation measure to reduce the impact of water stress periods with no negative effects on grape quality.

7. Organic mulching, irrigation and fertilization affect soil CO2 emission and C storage in tomato crop in the Mediterranean environment

• Authors:
  • Radicetti, E.
  • Brunetti, P.
  • Marinari, S.
  • Mancinelli, R.
  • Campiglia, E.
• Source: Soil and Tillage Research
• Volume: 152
• Year: 2015
• Summary: Carbon stock and CO2 emissions in agricultural systems are highly affected by the management of applied practices in arable farms, such as fertilizer use, irrigation, soil tillage, cover crop management, etc. This study evaluated the effects of various organic mulches, nitrogen fertilization and irrigation levels on soil CO2 emissions, soil carbon sequestration and processing tomato production in the Mediterranean environment. The field experiment was carried out with five main treatments, three cover crops of hairy vetch (HV), lacy phacelia (LF) and white mustard (WM) transplanted in autumn and cut in May to be used as mulches, plus barley straw mulch (BS) and conventional (C) (bare soil). After tomato transplanting, the main plots were split into two nitrogen fertilization treatments (0 and 100kgNha-1) and the sub-plots were then split again into three irrigation levels (irrigation water 100%, 75%, 50% of evapotranspiration). In all treatments, a general effect was observed in the temporal fluctuations of soil CO2 emissions throughout the observation period which were significantly influenced by soil temperature and water content. The temporal fluctuations of the soil CO2 emissions were attributed to climatic conditions and the peaks achieved optimal conditions of soil temperature and water content for soil respiration. A larger amount of TOC was observed in the mulching treatments than in the control after tomato harvesting (on average 1.44% vs 1.33%, respectively and on average 1.43% in HV trastment), probably due to the residual biomass of the cover crops and a greater growth of the tomato. Although the soil carbon output as cumulated CO2 emissions did not show statistically significant differences between the treatments, the soil carbon balance enabled us to estimate the highest net carbon contribution to the soil in HV determined by inputs and input/output ratio. However, except for the BS in 2013, the input/output ratios were ≥1 in all mulch treatments. In the Mediterranean environment, agronomical practices, such as the use of hairy vetch mulch on notilled soil, a slight reduction of irrigation water (-25%) and a rationalized use of N fertilizer potentially could shift the C balance in favor of soil C accumulation.

8. Flooding and soil temperature affect water relations and photosynthesis of citrus rootstock leaves.

• Authors:
  • Syvertsen, J. P.
  • Goni, C.
  • Otero, A.
• Source: Acta Horticulturae
• Issue: 1065
• Year: 2015
• Summary: We evaluated the effects of the soil temperature (15, 25 and 35°C) and soil anoxia from flooding for 20 days on citrus rootstock seedlings of CT33 trifoliate, Carrizo citrange and Troyer citrange along with Tucuman, Pomeroy and Rubidoux trifoliates in a greenhouse. Flooding had no effect on shoot water potential (Psi s) at 25°C but at 15°C and 35°C, there were differences from non-flooded trees. Carrizo and Troyer had higher Psi s than CT33, and Tucuman had the highest Psi s among the trifoliates. Soil temperature was more important than flooding in determining plant water relations. At 35°C, ACO 2 was reduced up to 14% of non-flooded plants in 4 days, particularly in CT33. In flooded seedlings, across the three genotypes, the decrease of F v/F m was highest at 35°C. Troyer rootstock maintained lower ACO 2 at 35°C Based on leaf net gas exchange, chlorophyll fluorescence and water relations, above optimal soil temperature accelerates seedling deterioration. CT33 was less tolerant than Carrizo and Troyer at 35°C, whereas Tucuman, Pomeroy and Rubidoux had similar tolerance to anoxia regardless of soil temperature.

9. Consideration of total available N supply reduces N fertilizer requirement and potential for nitrate leaching loss in tomato production.

• Authors:
  • Pena-Fleitas, M. T.
  • Thompson, R. B.
  • Gallardo, M.
  • Soto, F.
  • Padilla, F. M.
• Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
• Volume: 200
• Year: 2015
• Summary: Effects of increasing total available N (TAN) on agronomic performance, apparent recovery of TAN (AR TAN), NO 3- leaching and soil mineral N accumulation were examined in two tomato crops. Total available N was considered to be the sum of soil mineral N at planting, N mineralized from organic material (soil organic matter and manure), and mineral N fertilizer applied by fertigation. In each crop, four different mineral N fertilizer rates were applied as different N concentrations (N1: 0.6-1.1 mM, N2: 4.4-5.2 mM, N3: 13.4-13.6 mM, N4 20.5-21.7 mM) in nutrient solutions applied in all irrigations every 1-4 days throughout the crop. N3 treatments corresponded to local commercial practice. The first crop was grown in autumn-winter 2010 (AW-2010) and the second in spring 2011 (S-2011). For the two crops, TAN values were 165-215 kg N ha -1 in N1, 287-361 kg N ha -1 in N2, 563-667 kg N ha -1 in N3 and 847-976 kg N ha -1 in N4. In both crops, maximum fruit production was obtained with the N2 treatments. AR TAN decreased exponentially as TAN increased, from values of close to 1.0 for N1 treatments to approximately 0.3 for N4 treatments. The linear relationship between NO 3- leaching and TAN had a shallow slope, with a maximum leaching loss of 36-40 kg N ha -1 in the N4 treatments; NO 3- leaching loss was limited by small drainage volumes associated with good irrigation management. There was an exponential increase in residual soil mineral N with increasing TAN. For N3 treatments, corresponding to common local management practices, residual soil mineral N was 234-262 kg N ha -1, and for N4 treatments was 484-490 kg N ha -1. Therefore, increasing TAN very strongly increased the potential for subsequent N loss. Where TAN was excessive to crop N requirements, limiting NO 3- leaching loss (measured using lysimeters) by good irrigation practices was considered to only delay NO 3- leaching loss. The N3 treatments of 13-14 mM of N that corresponded to local practice were associated with a large potential N loss. Based on TAN, the optimal treatment was N2 of 4-5 mM which was associated with maximum fruit production and a relatively very small potential loss of N. The results demonstrated that by considering (i) TAN rather than just fertilizer N, and (ii) mineral N fertilizer as a supplement to other N sources, that maximum production can be achieved with high AR TAN and with a much reduced risk of N loss to the environment.

10. Carbon footprints of the horticultural products strawberries, asparagus, roses and orchids in Germany

• Authors:
  • Weber-Blaschke, G.
  • Lampert, P.
  • Soode, E.
  • Richter, K.
• Source: Agriculture Article
• Volume: 87
• Year: 2015
• Summary: Global climate change problem can be linked to production efficiency and everyday consumption patterns by calculating the greenhouse gas emissions resulting from each product. This is usually referred to as product carbon footprint (PCF). Only limited information is available about the PCF of German horticultural products. We measured the cradle-to-grave PCF of German strawberries, asparagus, roses and orchids in different production systems and compared it to the PCF of the same products grown in other countries. For the production and customer stage we collected primary data, for the comparison with products in other countries we used literature data. The results showed that the average consumer stage constitutes 3-71% of the PCF, the best case consumer scenario 1-39% and the worst case 60-99%. The consumer shopping trip was a hotspot in all analysed systems where a private car was used. Electricity for production, fuel use for soil management, and cooking and washing dishes were also among the most often identified hotspots. German open field strawberries perform better, German open field roses and asparagus are on the similar level with the same products produced abroad. However, asparagus transported by plane, and strawberries and roses grown in greenhouses have several times higher PCF regardless of the producing country. Consumers as well as producers are responsible for reducing the climate impact of horticultural products. Shopping trip on foot or by bike and using renewable energy can reduce the PCF significantly. We recommend extending the analysis to the life cycle assessment or product environmental footprint to consider more indicators to identify which products are less harmful to the environment.