• Authors:
    • Lee,Hyunok
    • Sumner,Daniel A.
  • Source: Climatic Change
  • Volume: 132
  • Issue: 4
  • Year: 2015
  • Summary: This article establishes quantitative relationships between the evolution of climate and cropland using daily climate data for a century and data on allocation of land across crops for six decades in a specific agro-climatic region of California. These relationships are applied to project how climate scenarios reported by the Intergovernmental Panel on Climate Change would drive cropland patterns into 2050. Projections of warmer winters, particularly from 2035 to 2050, cause lower wheat area and more alfalfa and tomato area. Only marginal changes in area were projected for tree and vine crops, in part because although lower, chill hours remain above critical values.
  • Authors:
    • Siles,J. A.
    • Cajthaml,T.
    • Hernandez,P.
    • Perez-Mendoza,D.
    • Garcia-Romera,I.
    • Sampedro,I.
  • Source: Microbial Ecology
  • Volume: 70
  • Issue: 1
  • Year: 2015
  • Summary: Dry olive residue (DOR) is a waste product derived from olive oil extraction and has been proposed as an organic amendment. However, it has been demonstrated that a pre-treatment, such as its transformation by saprophytic fungi, is required before DOR soil application. A greenhouse experiment was designed where 0 and 50 g kg -1 of raw DOR (DOR), Coriolopsis floccosa-transformed DOR (CORDOR) and Fusarium oxysporum-transformed DOR (FUSDOR) were added to soil. Analyses of the soil chemical properties as well as the structure and relative abundance of bacterial and actinobacterial communities were conducted after 0, 30 and 60 days following amendment. The different amendments produced a slight decrease in soil pH and significant increases in carbon fractions, C/N ratios, phenols and K, with these increases being more significant after DOR application. Quantitative PCR assays of the 16S rRNA gene and PLFA analyses showed that all amendments favoured bacterial growth at 30 and 60 days, although actinobacterial proliferation was more evident after CORDOR and FUSDOR application at 60 days. Bacterial and actinobacterial DGGE multivariate analyses showed that the amendments produced structural changes in both communities, especially after 60 days of amendment. PLFA data analysis identified changes in soil microbial communities according to the amendment considered, with FUSDOR and CORDOR being less disruptive than DOR. Finally, integrated analysis of all data monitored in the present study enabled us to conclude that the greatest impact on soil properties was caused by DOR at 30 days and that soil showed some degree of resilience after this time.
  • Authors:
    • Aengelo Rodrigues,M.
    • Dimande,Paulo
    • Pereira,Ermelinda L.
    • Ferreira,Isabel Q.
    • Freitas,Sara
    • Correia,Carlos M.
    • Moutinho-Pereira,Jose
    • Arrobas,Margarida
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 103
  • Issue: 2
  • Year: 2015
  • Summary: Cover cropping is a major challenge in the sustainable management of rainfed olive orchards. From a 5 year study (2009-2014), the effect of a mixture of early-maturing and self-reseeding annual legumes (Legs) grown as a cover crop in a rainfed olive orchard was compared with a cover of natural vegetation fertilized with 60 kg nitrogen (N) ha(-1) year(-1) (NV +N), and a cover of natural vegetation not fertilized (NV -N). The study took place in NE Portugal. The following were assessed: (1) the performance of the covers by measuring ground cover percentages, dry matter yields and N content in aboveground biomass; (2) the soil fertility through chemical and microbiological assays and by growing plants in pot experiments; and (3) the nutritional status of olive trees and olive yields. Legumes gave higher ground-cover percentages, produced more biomass and accumulated more N in shoots in comparison to natural vegetation, whether fertilized or not. The results showed intense biological activity [microbial carbon (C) and N, CO2-C evolved in a laboratory incubation, metabolic quotient, total culturable fungi and bacteria, and acid phosphatase activity] in the 0-10 cm soil layer of the treatments producing more biomass (Legs and NV +N). However, soil available N was greater in soil samples from the Legs plot. N recoveries by turnip (Brassica rapa var. rapa L.) and rye (Secale cereale L.) grown in pot experiments were 84.4 and 60.2 mg pot(-1) in soil samples from the Legs treatment and 29.4 and 27.1 mg pot(-1) and 14.2 and 13.6 mg pot(-1), respectively in NV +N and NV -N plots. Sown legumes appeared less effective in increasing organic C than natural vegetation. Nevertheless, in the Legs plot the increase of easily mineralizable C was proportionally higher than the increase of total organic C, which may mean that a more reactive pool of organic C is created, which may reduce the turnover of organic C and N in the soil. In the 10-20 cm soil layer, total organic C was significantly lower in Legs (14.0 g kg(-1)) than in NV -N (22.1 g kg(-1)) and N +NV (25.2 g kg(-1)) treatments, likely due to a priming effect caused by mineral N coming from the surface layer. Two years after the trial started, the N nutritional status of the olive trees was significantly higher in Legs than in natural vegetation plots even when 60 kg N ha(-1) year(-1) was applied. The cumulative olive yields in NV -N and NV +N plots were only 58.6 and 77.7 % in comparison to those found in the Legs plot, if only the last four harvests were considered, which were those influenced by the ground-cover treatments (2010-2013).
  • Authors:
    • Ortega, J. F.
    • Montoya, F.
    • Camargo, D. C.
    • Corcoles, J. I.
  • Source: Web Of Knowledge
  • Volume: 107
  • Issue: 6
  • Year: 2015
  • Summary: Potato ( Solanum tuberosum L.) yield is sensitive to water stress in the semiarid regions of Spain. This study was conducted to determine the effect of four irrigation treatments on potato tuber yield under one-quarter (4.9 ha) of the total irrigation area (18.4 ha) of a center pivot system in Albacete, Spain, during 2011 and 2012. Four irrigation treatments were applied, representing 60, 80, 100, and 120% of potato crop water requirement (CWR). In 2011, crop yield differed between the 60% irrigation treatment and the other treatments, whereas in 2012, yield differed between irrigation treatments with high (100 and 120%) and low (60 and 80%) water supply. Water use efficiency (WUE) ranged from 8.6 to 11.6 kg m -3 in 2011 and 7.1 to 8.4 kg m -3 in 2012, with significant differences among treatments in 2011. Differences in harvest index (HI) were observed between the irrigation seasons due to weather conditions of the second year. The 80% treatment was more efficient or equally efficient compared with the unstressed treatments and therefore represents a viable option when there are limited water supplies or high water costs.
  • Authors:
    • Almagro, M.
    • Albaladejo, J.
    • Garcia-Franco, N.
    • Martínez-Mena, M.
  • Source: Research Article
  • Volume: 153
  • Issue: 153
  • Year: 2015
  • Summary: Semiarid Mediterranean agroecosystems need the implementation of sustainable land management (SLM) practices in order to maintain acceptable levels of soil organic matter (SOM). The application of SLM practices helps to maintain soil structure and physical-chemical protection of soil organic carbon (SOC), hence improving soil carbon sequestration and mitigating CO2 emissions to the atmosphere. In an organic, rain-fed almond (Prunus dulcis Mill., var. Ferragnes) orchard under reduced tillage (RT), as the habitual management practice during the 14 years immediately preceding the experiment, we studied the effect of two agricultural management practices on soil aggregate distribution and SOC stabilization after four years of implementation. The implemented practices were (1) reduced tillage with a mix of Vicia sativa L. and Avena sativa L. as green manure (RTG) and (2) no-tillage (NT). Four aggregate size classes were differentiated by wet sieving (large and small macroaggregates, microaggregates, and the silt plus clay fraction), and the microaggregates occluded within small macroaggregates (SMm) were isolated. In addition, three organic C fractions were separated within the small macroaggregates and microaggregates, using a density fractionation method: free light fraction (free LF-C), intra-aggregate particulate OM (iPOM-C), and organic C associated with the mineral fraction (mineral-C). The results show that the combination of reduced tillage plus green manure (RTG) was the most-efficient SLM practice for SOC sequestration. The total SOC increased by about 14% in the surface layer (0-5cm depth) when compared to RT. Furthermore, green manure counteracted the effect of tillage on soil aggregate rupture. The plant residue inputs from green manure and their incorporation into the soil by reduced tillage promoted the formation of new aggregates and activated the subsequent physical-chemical protection of OC. The latter mechanism occurred mainly in the fine iPOM-C occluded within microaggregates and mineral-C occluded within small macroaggregates fractions, which together contributed to an increase of up to 30% in the OC concentration in the bulk soil. No-tillage favored the OC accumulation in the mineral-C within the small macroaggregates and in the fine iPOM-C occluded within microaggregates in the surface layer, and in the mineral-C occluded within the small macroaggregates and microaggregates at 5-15cm depth, but four years of cessation of tillage were not enough to significantly increase the total OC in the bulk soil. © 2015 Elsevier B.V..
  • Authors:
    • Rhinhart, K.
    • Machado, S.
    • Ghimire, R.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 6
  • Year: 2015
  • Summary: Intensive cultivation of native grassland for dryland agriculture continuously depleted soil organic carbon (SOC) and nutrients. In 2010, we evaluated the influence of 80 yr of crop residue and nutrient management practices on SOC and N in 0- to 60-cm soil depth profiles in conventionally tilled winter wheat ( Triticum aestivum L.)-summer fallow (WW-SF) system. Residue and N treatments, no N addition with fall burning (FB0), spring burning (SB0), and no burning (NB0), 45 kg N ha -1 with SB (SB45) and NB (NB45), 90 kg N ha -1 with SB (SB90) and NB (NB90), manure (MN, 5.32 Mg dry mass ha -1 yr -1), and pea vines (PV, 0.99 Mg dry mass ha -1 yr -1), were in ordered arrangement, and an undisturbed grassland (GP) was used as a reference. All WW-SF treatments had less SOC and N stocks than GP. The SOC stocks were lowest under FB0 with 50% less SOC than GP. The WW-SF treatments have depleted up to 63 and 26% of SOC and N from surface soil since 1931. Fall burning and MN treatments depleted SOC at rates of 0.64 and 0.17 Mg ha -1 yr -1. Nitrogen stocks decreased at a rate of 0.02 Mg ha -1 yr -1 in FB, SB, and NB treatments, and 0.01 Mg ha -1 yr -1 in PV treatment. Reduction in tillage, application of low C/N ratio residues, and elimination of burning can improve sustainability of winter wheat production in the summer fallow region of the Pacific Northwest (PNW).
  • Authors:
    • González-Ubierna, S.
    • Casermeiro, M. A.
    • Cruz, M. T.
  • Source: Research Article
  • Volume: 153
  • Year: 2015
  • Summary: Soil respiration is the main carbon flux in the second largest terrestrial carbon pool, soil environment. Emissions of CO2 from soils are five times higher than from anthropogenic emissions (USDOE, 2008). Despite increasing atmospheric CO2 concentrations, the dynamics and driving forces for soil CO2 emissions are not well understood. This work investigates the evolution of soil respiration (Rs) in a semiarid Mediterranean agro-ecosystem after the application of three different biodegradable organic residues (BOR): municipal solid waste compost (MSWC), anaerobically (ANSS) and aerobically (AESS) digested sewage sludge. We also studied how these amendments affect the relationship between Rs and soil climate variables. The results showed a clear increase in Rs at very short time after the application, especially in AESS-treated soils. Annual evolution of Rs was highly correlated with the carbon fractions of the BORs applied, with the highest effect seen in AESS-treated soils after the application, and a moderate but more persistent effect in MSWC. ANSS showed an intermediate behaviour. The type of amendment explained 54.7% of Rs variability. The application of BOR also changed the relationship between Rs and soil climate conditions. The results showed that BOR application produced an increase in Rs positive dependence on soil temperature (Ts) and the Birch effect, and a decrease in the negative dependence on soil moisture (Ms). In untreated soils (CONT) Ts-Ms interaction was the main factor which drove Rs evolution. The results suggest using highly composted wastes (MSWC) as the best option of those analysed for medium-term carbon management in agricultural practices. © 2015 Elsevier B.V..
  • Authors:
    • Dunfield, P.
    • Dubey, G.
    • Kollah, B.
    • Mohanty, S. R.
  • Source: Article
  • Volume: 20
  • Issue: 8
  • Year: 2015
  • Summary: Experiments were carried out to determine how the incorporation of biomass from the bioenergy crop Jatropha curcas into a tropical vertisol affects the biogeochemical processes important for greenhouse gas (GHG) fluxes, specifically methane (CH4) production, carbon dioxide (CO2) production, and CH4 consumption. Leaf biomass of J. curcas was incorporated at 0.1, 0.5, and 1 % (w/w) into soil maintained under 60 % of moisture-holding capacity (MHC). Biomass addition significantly stimulated potential CH4 and CO2 production while inhibiting potential CH4 consumption. When 1 % of J. curcas biomass was added to soil, potential CH4 production increased nearly 50-fold over 60 days, from 2.45 µg CH4 g-1 soil day-1 in unamended soil to 115 µg g-1 day-1 in soil containing leaf biomass. Soil CO2 production also doubled when the J. curcas biomass was added. The potential CH4 consumption rate of soil was inhibited almost completely by 1 % of added biomass. The culturable methanotroph population was positively correlated with the CH4 consumption rate (r = 0.961, p < 0.0001) and was inhibited 20-fold by 1 % of biomass addition. In contrast, the total population of aerobic heterotrophs culturable on a complex medium increased from 11 to 59 × 106 of colony-forming units (CFU) g-1 of soil after biomass addition. Significant positive correlation was observed between the total heterotroph population and both CH4 production (r = 0.861, p = 0.0003) and CO2 production (r = 0.863, p = 0.0002). Our study shows that biomass from the bioenergy crop J. curcas can affect soil biogeochemical processes that control GHG emissions. We propose that a high incorporation of J. curcas biomass could dramatically change the CH4 flux in tropical soil by simultaneously increasing CH4 production and decreasing CH4 consumption, and we therefore recommend that biomass incorporation to soil be minimized (<0.1 %) as a strategy to mitigate GHG emission. © 2014, Springer Science+Business Media Dordrecht.
  • Authors:
    • Monti, A.
    • Fernando, A. L.
    • Schmidt, T.
    • Rettenmaier, N.
  • Source: Research Article
  • Volume: 8
  • Issue: 4
  • Year: 2015
  • Summary: Agricultural systems in the Mediterranean region are increasingly getting under pressure due to both global warming and the aggravating competition for agricultural land. Perennial grasses have the potential to tackle both challenges: they are drought-resistant crops and considered not to compete for high-productivity agricultural land because they can be grown on marginal land. This paper presents the outcome of a screening life cycle assessment (LCA) conducted as part of an integrated sustainability assessment within the EU-funded project ‘Optimization of Perennial Grasses for Biomass Production’ (OPTIMA). The project aims at optimised production of Miscanthus (Miscanthus × giganteus), giant reed (Arundo donax L.), switchgrass (Panicum virgatum L.) and cardoon (Cynara cardunculus L.) on marginal land in the Mediterranean region. Different cultivation and use options were investigated by comparing the entire life cycles of bioenergy and bio-based products to equivalent conventional products. The LCA results show that the cultivation of perennial grasses on marginal land and their use for stationary heat and power generation can achieve substantial greenhouse gas emission and non-renewable energy savings, with Miscanthus allowing for savings ranging up to 13 t CO2 eq./(ha · year) and 230 GJ/(ha · year), respectively. Negative environmental impacts are less pronounced. Significant parameters include irrigation needs and moisture content at harvest, which determines energy demand for technical drying. We conclude that the cultivation of perennial grasses on marginal land in the Mediterranean region provides potentials for climate change mitigation together with comparatively low other environmental impacts, if several boundary conditions and recommendations are met. © 2015, Springer Science+Business Media New York.
  • Authors:
    • Peridy, N.
    • Zouabi, O.
  • Source: Article
  • Volume: 133
  • Issue: 2
  • Year: 2015
  • Summary: North African countries (NACs) are particularly concerned with climate change because of their geographical position (close to deserts) and their economic dependence on agriculture. We aim to provide additional insight into the impact of climate on agriculture for NACs, through the example of Tunisia. We first use disaggregated data, both at the geographical level (for 24 regions in Tunisia) and at the product level (cereals, olives, citrus fruit, tomatoes, potatoes and palm trees). Second, through spatial panel data analysis, we explore both the time and spatial dimensions of the data. This makes it possible to consider spatial interactions in agricultural production and the role of climate in these spatial spillover effects. Finally, the model not only includes direct climate variables, such as temperature and precipitation, but also indirect climate-related variables such as the stock of water in dams and groundwater. Results show that Tunisian agriculture is strongly dependent on the direct effects of temperature and precipitation for all the products considered at the regional level. The presence of dams and groundwater generally has a positive effect on agricultural production for irrigated crops with interesting spillover effects with neighboring regions. However, this impact is still considerably lessened in the case of detrimental climate conditions (indirect effect). These results raise the question of the sustainability of the growth in agricultural production in Tunisia in the case of significant climate change.