• Authors:
    • Romic, D.
    • Rengel, Z.
    • Ondrasek, G.
    • Savic, R.
  • Source: European Journal of Soil Science
  • Volume: 63
  • Issue: 5
  • Year: 2012
  • Summary: Soil degradation processes, such as organic matter (OM) depletion, accompanied by metal contamination and salinization are becoming a serious threat to crop production and human food security. A glasshouse study was conducted to assess a factorial combination of salinity (0, 20, 40 and 60 mm NaCl) and cadmium (Cd) (0.3, 2.5 and 5.4 mg Cd kg-1) in organic soil (>90% OM) and their influence on dissolved organic carbon (DOC) in the rhizosphere and phyto-accumulation in radish (Raphanus sativus L. var. sativus). A 34-day exposure to increasing NaCl salinity significantly decreased DOC concentration in the radish rhizosphere solution and increased trace element (copper, Cu; zinc, Zn; and Cd) concentrations in the rhizosphere as well as in leaf/fruit tissues of radish. Soil contamination by Cd progressively raised concentrations in soil solution, but markedly reduced total concentration of Cu and Zn in the rhizosphere and leaves of radish. The NICA-Donnan chemical speciation/distribution modelling confirmed the predominance of dissolved organic reactive surfaces (from fulvic acid for example) in Cu and Cd chemisorption/complexation processes over the whole range of applied NaCl and Cd treatments. In contrast, Zn speciation was dominated by an organically-complexed pool at low salinity (020 mm NaCl), and free Zn2+ was the most important species at increased salinity (=40 mm NaCl). In conclusion, because of the diminished pool of DOC under excessive salinity, the biogeochemistry of Cu, Zn and Cd in the rhizosphere can be affected in a way that would enhance solubility and phyto-accumulation of these trace metals in food crops.
  • Authors:
    • Bellotti, B.
    • Ridoutt, B.
    • Page, G.
  • Source: Journal of Cleaner Production
  • Volume: 32
  • Year: 2012
  • Summary: There is growing interest in carbon footprints of products but for horticulture water use can also be important, hence we studied both for fresh tomatoes supplied to the Sydney market. Carbon and water footprints for each kg of fresh tomato supplied to Sydney depend on the season and the type of production system (ranging from 0.39 to 1.97 kg CO(2)e; 5 to 53 L). Energy use of the systems was also reported which ranged from 6.16 to 27.42 MJ for each kg of fresh tomato supplied to Sydney. Tradeoffs exist within studied production systems such that a system which had higher carbon footprint had lower water footprint; this complicates setting priorities for overall environmental improvement. To address this limitation, life cycle impacts of greenhouse gas (GHG) emissions and water use were subsequently modelled using endpoint indicators and compared. The results indicated that in all cases the climate change impacts were most important representing 84-96% of the combined scores on damages to the environment. As such the vegetable industry's priority to reduce GHG emissions is confirmed. In case of field production, transportation of tomatoes to market was the hotspot in carbon footprint, while for the medium and high technology greenhouses it was artificial heating. Although the results indicated priority to reduce carbon footprint, further development and harmonisation of LCA impact assessment models for water use at the endpoint level is considered essential. (C) 2012 Elsevier Ltd. All rights reserved.
  • Authors:
    • Yao, J.
    • Mahmood, Q.
    • He, M.
    • Tian, G.
    • Wu, X.
    • Pan, D.
  • Source: Journal of Food, Agriculture & Environment
  • Volume: 10
  • Issue: 3-4
  • Year: 2012
  • Summary: A better comprehension of carbon dynamics during agricultural production requires an understanding of the CO2 and CH4 fluxes from an agro-ecosystem after fertilisation. The dynamics of CO2 and CH4 fluxes for plant-soil ecosystems in a ventilated transparent greenhouse were evaluated after a pig manure compost or inorganic fertiliser application at the rate of 150 kg N ha(-1) during Brassica chinensis growth from seedling to maturity. Gas samples for the plant-soil ecosystems were collected using a static chamber approach, and the concentrations of CO2 and CH4 were determined using gas chromatography. The results showed that CO2 was fixed by the plant-soil ecosystem during Brassica chinensis growth after fertilisation and the CO2 and CH4 fluxes were not significantly different among the treatments compared with the control. The ecosystem uptake of CO2 increased with the soil temperature and the variation was in agreement with a first-order exponential curve. The temperature sensitivity of the CO2 efflux at the ecosystem level for the pig manure compost, inorganic fertiliser and control treatments were 7.97, 9.82 and 8.88, respectively. There was a positive correlation between the soil microbial biomass carbon and the CO2 uptake for both fertiliser treatments, whereas the CO2 uptake for the control treatment was increased by the soil microbial biomass nitrogen. The plant-soil ecosystems were minor CH4 sinks and sources, and the CH4 flux ranged from -5.56 to 4.23 mg CH4 m(-2)h(-1) for all of the treatments. The CH4 consumption for the pig manure compost and inorganic fertiliser treatments were negatively correlated with the soil microbial biomass nitrogen, whereas that for the control treatment showed a significant negative correlation with the soil nitrate-N. The results indicate that a plant-soil ecosystem could be a carbon sink, and that fertiliser application had no significant effects on either the CO2 or the CH4 uptake in a plant-soil ecosystem.
  • Authors:
    • Ort, D.
    • Gleadow, R.
    • Fauquet, C.
    • Cavagnaro, T.
    • Grennan, A.
    • Miller, R.
    • Slattery, R.
    • Rosenthal, D.
  • Source: Global Change Biology
  • Volume: 18
  • Issue: 8
  • Year: 2012
  • Summary: Globally, cassava is the second most important root crop after potatoes and the fifth most important crop overall in terms of human caloric intake. In addition to its growing global importance for feed, fuel, and starch, cassava has long been vital to food security in Sub-Saharan Africa. Climate change is expected to have its most severe impact on crops in food insecure regions, yet little is known about how cassava productivity will respond to climate change. The most important driver of climate change is globally increasing atmospheric CO2 concentration ([CO2]). However, the potential for cassava to enhance food security in an elevated [CO2] world is uncertain as greenhouse and open top chamber (OTC) study reports are ambiguous. Studies have yielded misleading results in the past regarding the effect of elevated [CO2] on crop productivity, particularly in cases where pots restricted sink growth. To resolve these conflicting results, we compare the response of cassava to growth at ambient (ca. 385 similar to ppm) and elevated [CO2] (585 similar to ppm) under field conditions and fully open air [CO2] elevation. After three and half months of growth at elevated [CO2], above ground biomass was 30% greater and cassava root tuber dry mass increased over 100% (fresh weight increased 89%). High photosynthetic rates and photosynthetic stimulation by elevated [CO2], larger canopies, and a large sink capacity all contributed to cassava's growth and yield stimulation. Cassava exhibited photosynthetic acclimation via decreased Rubisco capacity early in the season prior to root tuber initiation when sink capacity was smaller. Importantly, and in contrast to a greenhouse study, we found no evidence of increased leaf N or total cyanide concentration in elevated [CO2]. All of our results are consistent with theoretical expectations; however, the magnitude of the yield increase reported here surpasses all other C3 crops and thus exceeds expectations.
  • Authors:
    • Hellweg, S.
    • Pfister, S.
    • Juraske, R.
    • Stoessel, F.
  • Source: Environmental Science & Technology
  • Volume: 46
  • Issue: 6
  • Year: 2012
  • Summary: Food production and consumption is known to have significant environmental impacts. In the present work, the life cycle assessment methodology is used for the environmental assessment of an assortment of 34 fruits and vegetables of a large Swiss retailer, with the aim of providing environmental decision-support to the retailer and establishing life cycle inventories (LCI) also applicable to other case studies. The LCI includes, among others, seedling production, farm machinery use, fuels for the heating of greenhouses, irrigation, fertilizers, pesticides, storage and transport to and within Switzerland. The results show that the largest reduction of environmental impacts can be achieved by consuming seasonal fruits and vegetables, followed by reduction of transport by airplane. Sourcing fruits and vegetables locally is only a good strategy to reduce the carbon footprint if no greenhouse heating with fossil fuels is involved. The impact of water consumption depends on the location of agricultural production. For some crops a trade-off between the carbon footprint and the induced water stress is observed. The results were used by the retailer to support the purchasing decisions and improve the supply chain management.
  • Authors:
    • Kuzyakov, Y.
    • Li, X.
    • Marschner, P.
    • Guo, J.
    • Fan, M.
    • Tian, J.
  • Source: European Journal of Soil Biology
  • Volume: 52
  • Issue: September–Octobe
  • Year: 2012
  • Summary: In the last three decades there has been a major shift in China's agriculture with the conversion from cereal fields to vegetable production, however little is known about the impact of this land use change on labile soil carbon and microbial community structure. We conducted a study to characterize dissolved organic carbon (DOC) and soil microbial community by comparing greenhouse vegetable fields with contrasting management intensity and adjacent cereal fields (wheat maize rotation) in Shouguang and Quzhou in North China. Compared with cereal fields, greenhouse vegetable cultivation increased soil organic carbon (SOC) and total nitrogen (TN), while it decreased the soil pH, particularly at the high-intensity site. The DOC concentration was significantly higher in greenhouse vegetable fields than in cereal fields, whereas DOC composition differed between greenhouse vegetable fields and cereal fields only at high management intensity. Chemical fractionation indicated that DOC from greenhouse vegetable fields with high management intensity was less decomposed than DOC from cereal fields, because the percentage of hydrophobic acid (HOA) as DOC was higher in vegetable fields. Vegetable production significantly changed the microbial community structure in comparison to cereal fields: high-intensity management increased total bacteria, G (+) bacteria and fungi, while low-intensity decreased fungi and increased bacteria-to-fungi ratio. The main factor affecting microbial community structure was soil pH in this study, accounting for 24% of the differences. (C) 2012 Elsevier Masson SAS. All rights reserved.
  • Authors:
    • Fitt, B. D. L.
    • Stevens, M.
    • Townsend, J. A.
    • West, J. S.
  • Source: European Journal of Plant Pathology
  • Volume: 133
  • Issue: 1
  • Year: 2012
  • Summary: This review describes environmental factors that influence severity of crop disease epidemics, especially in the UK and north-west Europe, in order to assess the effects of climate change on crop growth and yield and severity of disease epidemics. While work on some diseases, such as phoma stem canker of oilseed rape and fusarium ear blight of wheat, that combine crop growth, disease development and climate change models is described in detail, climate-change projections and predictions of the resulting biotic responses to them are complex to predict and detailed models linking climate, crop growth and disease development are not available for many crop-pathogen systems. This review uses a novel approach of comparing pathogen biology according to 'ecotype' (a categorization based on aspects such as epidemic type, dissemination method and infection biology), guided by detailed disease progress models where available to identify potential future research priorities for disease control. Consequences of projected climate change are assessed for factors driving elements of disease cycles of fungal pathogens (nine important pathogens are assessed in detail), viruses, bacteria and phytoplasmas. Other diseases classified according to 'ecotypes' were reviewed and likely changes in their severity used to guide comparable diseases about which less information is available. Both direct and indirect effects of climate change are discussed, with an emphasis on examples from the UK, and considered in the context of other factors that influence diseases and particularly emergence of new diseases, such as changes to farm practices and introductions of exotic material and effects of other environment changes such as elevated CO2. Good crop disease control will contribute to climate change mitigation by decreasing greenhouse gas emissions from agriculture while sustaining production. Strategies for adaptation to climate change are needed to maintain disease control and crop yields in north-west Europe.
  • Authors:
    • Six, J.
    • Tian,Jing
    • Kuzyakov, Y.
    • Lee, J.
    • Chen, H.
    • Christie, P.
    • Li, X.
    • Zhang, F.
    • Fan, M.
    • Yan, Y.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 150
  • Year: 2012
  • Summary: The conversion from cereal fields to vegetable production in the last three decades represents a significant shift in land use in China. Here, we studied the effects of conversion form cereal fields to vegetable production in north China on soil organic carbon (SOC) and total nitrogen (TN) in both bulk soil and soil aggregates. We used two approaches: (1) measurements of paired soil samples from wheat (Triticum aestivum L) - maize (Zea mays L) fields and adjacent greenhouses vegetable fields in three vegetable production areas representing various management intensities in terms of C and N inputs and frequency of tillage: (2) fractionating soil to distinguish intra-aggregate particulate organic matter (iPOM) and organo-mineral complexes (silt + clay). Our results indicated that converting cereal fields to greenhouse vegetable production with intermediate and high management intensity led to increases in SOC and TN and decreases in C:N ratios in the top soil. The accumulation rates of C and N in the surface soil (0-30 cm) were estimated to be 1.37 Mg C ha(-1) yr(-1) and 0.21 Mg N ha(-1) yr(-1) over an average period of 8 years after cereal fields to greenhouse vegetable production conversion. At the soil aggregate level, only the coarse (>250 mu m) and fine (53-250 mu m) iPOM fraction contributed to the increases in soil C (e.g., 49% and 51% of total C increases, respectively), while the coarse and fine iPOM, and silt + clay fraction accounted for 22%, 30% and 48%, respectively, of total N increases. This illustrates how the addition of readily available C (manure) and N (manure and inorganic N) leads to a temporary stabilization of C in relatively labile SOM fractions, but to a preferential stabilization of N in organo-mineral SOM fractions. In conclusion, the conversion to highly intensive vegetable systems in China leads to marked differences in C and N stabilization dynamics.
  • Authors:
    • Takebe, M.
    • Karasawa, T.
  • Source: Plant and Soil
  • Volume: 353
  • Issue: 1-2
  • Year: 2012
  • Summary: Aims A field experiment was conducted where maintenance of indigenous arbuscular mycorrhizal (AM) fungal populations was attempted using AM host cover crops arranged temporally or spatially during growth of nonmycorrhizal crops. Methods To arrange AM hosts temporally, sunflower or oat was grown as a cover crop after non-host cropping (cabbage) or fallowing. In order to arrange AM hosts spatially, red clover, white clover or vetch was intercropped during growth of non-host cabbage. Results The AM colonization and growth of maize with previously introduced sunflower or oat were much greater than those without introduction of cover crops or those with introduction of non-host cover crops. The AM colonization and yield of winter wheat grown after cabbage with AM host intercropping were greater than those after cabbage only cropping, suggesting that arrangement of AM hosts between cabbage rows is effective for maintaining the AM fungal population in soil during non-host cropping. Conclusions Mycorrhizal hosts cropped after or during non-host cropping is an effective means to increase indigenous AM fungal populations. The results show that AM colonization, P uptake and productivity of crops after cultivation of nonmycorrhizal crops can be improved by arranging AM hosts temporally or spatially as cover crops.
  • Authors:
    • Haeberli, M.
    • Keiser, A.
    • Stamp, P.
  • Source: Field Crops Research
  • Volume: 128
  • Year: 2012
  • Summary: Today over 90% of the potatoes for the fresh market are washed; therefore consumers already object to minor external quality deficiencies. The quality assessment performed by potato traders does not distinguish in detail between quality deficiencies and potential links to the farming systems and site parameters are unknown. Thus, the cause for the observed increase of external quality problems is unknown. From 2001 to 2003 the extent and the potential causes of quality deficiencies were studied on totally 278 fields on conventional, integrated and organic farms in the wet and cool climate of Switzerland. Just before harvest samples consisting of 810 tubers were collected on each field in a standardised sampling pattern. Wireworms, slugs and drycore were responsible for important economic losses in all farming systems. In the organic farming system the quality damage was higher for all three deficiencies. While wireworm and slug damage were of general importance, drycore was significantly most severe in the organic farming system in all three years. Crass clover ley in the years preceding potatoes increased the risk for all three quality deficiencies. Slug damage increased with soil cover (catch crops) and with the percentage of crops favourable to slugs in the crop rotation (e.g. vegetables). Seed tubers without black scurf infestation reduced the occurrence of black scurf and drycore on harvested tubers. Fungicide seed treatment reduced black scurf significantly if seed tubers were infested. Insecticide seed treatment for cereals preceding potatoes as well as molluscicide treatments in the potato crop had a beneficial but not always sufficient effect. (C) 2012 Elsevier B.V. All rights reserved.