• Authors:
    • Paustian, K.
    • Ngugi, M. K.
    • Suddick, E. C.
    • Six, J.
  • Source: California Agriculture
  • Volume: 67
  • Issue: 3
  • Year: 2013
  • Summary: California growers could reap financial benefits from the low-carbon economy and cap-and-trade system envisioned by the state's AB 32 law, which seeks to lower greenhouse gas emissions statewide. Growers could gain carbon credits by reducing greenhouse gas emissions and sequestering carbon through reduced tillage and increased biomass residue incorporation. First, however, baseline stocks of soil carbon need to be assessed for various cropping systems and management practices. We designed and set up a pilot soil carbon and land-use monitoring network at several perennial cropping systems in Northern California. We compared soil carbon content in two vineyards and two orchards (walnut and almond), looking at conventional and conservation management practices, as well as in native grassland and oak woodland. We then calculated baseline estimates of the total carbon in almond, wine grape and walnut acreages statewide. The organic walnut orchard had the highest total soil carbon, and no-till vineyards had 27% more carbon in the surface soil than tilled vineyards. We estimated wine grape vineyards are storing significantly more soil carbon per acre than almond and walnut orchards. The data can be used to provide accurate information about soil carbon stocks in perennial cropping systems for a future carbon trading system.
  • Authors:
    • Suddick, E. C.
    • Six, J.
  • Source: Science of the Total Environment
  • Volume: 465
  • Year: 2013
  • Summary: Agricultural soils are responsible for emitting large quantities of nitrous oxide (N2O). The controlled incomplete thermal decomposition of agricultural wastes to produce biochar, once amended to soils, have been hypothesized to increase crop yield, improve soil quality and reduce N2O emissions. To estimate crop yields, soil quality parameters and N2O emissions following the incorporation of a high temperature (900 degrees C) walnut shell (HTWS) biochar into soil, a one year field campaign with four treatments (control (CONT), biochar (B), compost (COM), and biochar+compost (B+C)) was conducted in a small scale vegetable rotation system in Northern California. Crop yields from five crops (lettuce, winter cover crop, lettuce, bell pepper and Swiss chard) were determined; there were no significant differences in yield between treatments. Biochar amended soils had significant increases in % total carbon (C) and the retention of potassium (K) and calcium (Ca). Annual cumulative N2O fluxes were not significantly different between the four treatments with emissions ranging from 0.91 to 1.12 kg N2O-N ha(-1) yr(-1). Distinct peaks of N2O occurred upon the application of N fertilizers and the greatest mean emissions, ranging from 67.04 to 151.41 g N2O-N ha(-1) day(-1), were observed following the incorporation of the winter cover crop. In conclusion, HTWS biochar application to soils had a pronounced effect on the retention of exchangeable cations such as K and Ca compared to un-amended soils and composted soils, which in turn could reduce leaching of these plant available cations and could thus improve soils with poor nutrient retention. However, HTWS biochar additions to soil had neither a positive or negative effect on crop yield nor cumulative annual emissions of N2O.
  • Authors:
    • Arena, C.
    • Amato, U.
    • Maglione, G.
    • Polimeno, F.
    • Ottaiano, L.
    • Vitale, L.
    • Di Tommasi, P.
    • Mori, M.
    • Magliulo, V.
  • Source: Plant, Soil and Environment
  • Volume: 59
  • Issue: 11
  • Year: 2013
  • Summary: The effect of the nitrification inhibitor 3,4-dimethylphyrazole phosphate (DMPP) on N-fertilized crop growth and soil N2O emissions were studied at two experimental sites in Southern Italy, characterised by a Mediterranean climate and different soil texture. The experiments were a randomized block design of two treatments: crop fertilized with NH4NO3 (considered the control treatment) or amended with DMPP plus NH4NO3 (considered the DMPP treatment). ANOVA was performed to assess differences between treatments and fertilization periods whereas simple and multiple linear regressions were performed in order to assess the effect of the soil-related independent variables on soil gases emissions. Growth of potato plants fertilized with DMPP-added nitrogen was enhanced compared to control plants, whereas no benefit on maize plants grown during summer was observed. N2O emissions measured from soil to potato after the first fertilization with DMPP-added nitrogen was reduced during winter, but was higher than control after the second fertilizer application in spring, leading to comparable N2O emission factors (EF1) between treatments. In maize N2O emissions and EF1 were lower for DMPP compared to control treatment. The effectiveness of reduction in soil N2O emission was influenced by soil temperature and water-filled pore space (WFPS) in both experimental sites. However, the overall effect of WFPS was contrasting as N2O emissions were decreased in potato and enhanced in maize.
  • Authors:
    • Moriondo,M.
    • Jones,G. V.
    • Bois,B.
    • Dibari,C.
    • Ferrise,R.
    • Trombi,G.
    • Bindi,M.
  • Source: Climatic Change
  • Volume: 119
  • Issue: 3-4
  • Year: 2013
  • Summary: This research simulates the impact of climate change on the distribution of the most important European wine regions using a comprehensive suite of spatially informative layers, including bioclimatic indices and water deficit, as predictor variables. More specifically, a machine learning approach (Random Forest, RF) was first calibrated for the present period and applied to future climate conditions as simulated by HadCM3 General Circulation Model (GCM) to predict the possible spatial expansion and/or shift in potential grapevine cultivated area in 2020 and 2050 under A2 and B2 SRES scenarios. Projected changes in climate depicted by the GCM and SRES scenarios results in a progressive warming in all bioclimatic indices as well as increasing water deficit over the European domain, altering the climatic profile of each of the grapevine cultivated areas. The two main responses to these warmer and drier conditions are 1) progressive shifts of existing grapevine cultivated area to the north-northwest of their original ranges, and 2) expansion or contraction of the wine regions due to changes in within region suitability for grapevine cultivation. Wine regions with climatic conditions from the Mediterranean basin today (e.g., the Languedoc, Provence, Ctes Rhne M,ridionales, etc.) were shown to potentially shift the most over time. Overall the results show the potential for a dramatic change in the landscape for winegrape production in Europe due to changes in climate.
  • Authors:
    • Novara,Agata
    • Gristina,Luciano
    • La Mantia,Tommaso
    • Ruehl,Juliane
  • Source: Geoderma
  • Volume: 193-194
  • Year: 2013
  • Summary: Clarifying which factors cause an increase or decrease in soil organic carbon (SOC) after agricultural abandonment requires integration of data on the temporal dynamics of the plant community and SOC. A chronosequence of abandoned vineyards was studied on a volcanic island (Pantelleria, Italy). Vegetation in the abandoned fields was initially dominated by annual and perennial herbs, then by Hyparrhenia hirta (L.) Stapf, and finally by woody communities. As a consequence, the dominant photosynthetic pathway changed from C-3 to C-4 and then back to C-3. Conversion of a plant community dominated by one photosynthetic pathway to another changes the C-13/C-12 ratio of inputs to SOC. Using the time since abandonment and the shift in belowground delta C-13 of SOC relative to the aboveground delta C-13 plant community, we estimated C-3-C and C-4-C changes during secondary succession. SOC content (g kg(-1)) increased linearly (R-2=0.89 and 0.73 for 0-15 and 15-30 cm soil depth) with the age of abandonment, increasing from 12 g kg(-1) in cultivated vineyards to as high as 26 g kg(-1) in the last stage of the succession. delta C-13 increased in the bulk soil and its three aggregate fractions (> 250,250-25, and < 25 mu m) during succession, but the effect of soil depth and its interaction with succession age were significant only for soil aggregate fractions. Polynomial curves described the change in delta C-13 over the chronosequence for both depths. delta C-13 in the bulk soil had increased from -28 parts per thousand. to -24 parts per thousand. by 35 years after abandonment for both depths but then decreased to -26 parts per thousand. at 60 years after abandonment (corresponding with maturity of the woody plant community). Overall, the results indicate that abandoned vineyards on volcanic soil in a semi-arid environment are C sinks and that C storage in these soils is closely related to plant succession. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Holden, Z. A.
    • Abatzoglou, J. T.
    • Luce, C. H.
  • Source: Article
  • Volume: 342
  • Issue: 6164
  • Year: 2013
  • Summary: Trends in streamflow timing and volume in the Pacific Northwest United States have been attributed to increased temperatures, because trends in precipitation at lower-elevation stations were negligible. We demonstrate that observed streamflow declines are probably associated with declines in mountain precipitation, revealing previously unexplored differential trends. Lower-troposphere winter (November to March) westerlies are strongly correlated with high-elevation precipitation but weakly correlated with low-elevation precipitation. Decreases in lower-tropospheric winter westerlies across the region from 1950 to 2012 are hypothesized to have reduced orographic precipitation enhancement, yielding differential trends in precipitation across elevations and contributing to the decline in annual streamflow. Climate projections show weakened lower-troposphere zonal flow across the region under enhanced greenhouse forcing, highlighting an additional stressor that is relevant for climate change impacts on hydrology.
  • Authors:
    • Derpsch, R.
    • Basch, G.
    • Friedrich, T.
    • Kassam, A.
    • Lahmar, R.
    • Mrabet, R.
    • Serraj, R.
    • Gonzalez-Sanchez, E. J.
  • Source: Field Crops Research
  • Volume: 132
  • Year: 2012
  • Summary: The objective of this article is to review: (a) the principles that underpin conservation agriculture (CA) ecologically and operationally; (b) the potential benefits that can be harnessed through CA systems in the dry Mediterranean climate; (c) current status of adoption and spread of CA in the dry Mediterranean climate countries; and (d) opportunities for CA in the Central and West Asia and North Africa (CWANA) region. CA, comprising minimum mechanical soil disturbance and no-tillage seeding, organic mulch cover, and crop diversification is now practised on some 125 million ha, corresponding to about 9% of the global arable cropped land. The area under CA is spread across all continents and many agro-ecologies, including the dry Mediterranean climate. Empirical and scientific evidence is presented to show that significant productivity, economic, social and environmental benefits exist that can be harnessed through the adoption of CA in the dry Mediterranean climates, including those in the CWANA region. The benefits include: higher productivity and income; climate change adaptation and reduced vulnerability to the erratic rainfall distribution; and reduced greenhouse gas emissions. CA is now spread across several Mediterranean climate countries outside the Mediterranean basin particularly in South America, South Africa and Australia. In the CWANA region, CA is perceived to be a powerful tool of sustainable land management but it has not yet taken off in a serious manner except in Kazakhstan. Research on CA in the CWANA region has shown that there are opportunities for CA adoption in rainfed and irrigated farming systems involving arable and perennial crops as well as livestock.
  • Authors:
    • Luna, J. M.
    • Mitchell, J. P.
    • Shrestha, A.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 1
  • Year: 2012
  • Summary: Organic farming has been historically dependent on conventional tillage operations to convert perennial pasture leys to annual crop rotations, incorporate crop residues, compost and cover crops, as well as to mechanically kill existing vegetation. Conventional tillage, however, has long been known to lead to soil degradation and erosion. A recently developed no-till organic production system that uses a roller-crimper technology to mechanically kill cover crops was evaluated in two states in the western United States. In Washington, pumpkins ( Cucurbita spp.) grown in a no-till roller-crimper (NT-RC) system produced yields 80% of conventional tillage, but with fewer weeds. However, in California on-farm research trials in organic cotton ( Gossypium barbadense L.), tomato ( Lycopersicon esculentum Mill.), eggplant ( Solanum melongena L.) and cowpea ( Vigna unguiculata (L.) Walp.), the no-till system produced virtual crop failure, or yields less than 20% of the standard production method. The major problems associated with rolled cover crops in California included reduced crop seedling emergence, planter impediment with excessive residue, lack of moisture and delay in transplanting of vegetable crops due to continued growth of cover crops, in-season crop competition from cover crop regrowth and impracticability of using cultivators. Further, excessive dry residue during summer in California can present the risk of fire. In both California and Oregon, considerable success has been demonstrated with zone tillage (strip tillage) in conventionally produced field and vegetable crops. In a replicated Oregon trial, the organic strip tillage treatment produced 85% of the broccoli ( Brassica oleracea L.) yield compared to a conventional tillage treatment. Our studies suggest that the zone tillage concept may offer opportunities to overcome many of the agronomic challenges facing no-till.
  • Authors:
    • Mailapalli, D. R.
    • Horwath, W. R.
    • Wallender, W. W.
    • Burger, M.
  • Source: Journal of Irrigation and Drainage Engineering
  • Volume: 138
  • Issue: 1
  • Year: 2012
  • Summary: Development of best management practices (BMPs) such as conservation tillage and winter cover crop to mitigate runoff and reduce dissolved chemicals in irrigation runoff is an important objective for controlling surface water pollution attributable to agricultural activities. In this study, the effect of standard tillage (ST), ST with winter cover cropping (STCC), and no-till (NT) management practices on infiltration, runoff, and dissolved organic carbon (DOC) export from furrow-irrigated fields of 244-m length was investigated for summer 2007 and 2008 irrigations. The practices were implemented for 2 years. The average surface residue cover was 11, 44, and 32% for ST, STCC, and NT, respectively, for 2007 and 11, 59, and 61%, respectively, in the following year of the study. Two irrigations in each year were considered for the analysis. The runoff samples were collected from each tillage treatment using ISCO autosamplers at regular time intervals. The infiltration and runoff were estimated using a volume balance model (VBM) by considering a 0.2-m irrigation requirement. Converting from ST to STCC increased the infiltration by 14 and 43% and reduced the runoff by 48 and 43% in 2007 and 2008 irrigations, respectively; whereas, converting ST to NT enhanced the infiltration by 4% in both years and decreased the runoff by 19 and 23% in 2007 and 2008 irrigations, respectively. The authors observed only slightly higher DOC concentrations in STCC, but there was a 24% increase for NT in 2007 irrigations, and both compared to with ST ranged from 3.98 to 5.46 mg/L. The DOC concentration was not significantly different among the treatments in 2008 irrigations (3.48 to 4.6 mg/L). Combining the runoff and DOC concentration effects, the DOC export for STCC was decreased by 55% in both years; whereas, it was decreased by 4 and 27% for NT in 2007 and 2008 irrigations, respectively, compared with ST. Although STCC and NT have higher concentrations, the reduction in export in these treatments is attributable to lower runoff. These results suggest that DOC export can be controlled with STCC practice. No-till showed the same trend, although these results must be confirmed after extended implementation of this practice.
  • Authors:
    • Martiniello, P.
  • Source: Agricultural Sciences
  • Volume: 3
  • Issue: 1
  • Year: 2012
  • Summary: Agricultural systems based on crop rotations favour sustainability of cultivation and productivity of the crops. Wheat-forage crops rotations (annual winter binary mixture and perennial alfalfa meadow) combined with irrigation are the agronomical techniques able to better exploit the weather resources in Mediterranean environments. The experiment aimed to study the effect of 18 years of combined effect of irrigation and continuous durum wheat and wheat-forage rotations on productivities of crops and organic matter of topsoil. The experiments were established through 1991-2008 under rainfed and irrigated treatments and emphasized on the effect of irrigation and continuous wheat and wheat-forage crop rotations on water use efficiency and sustainability of organic matter. The effect of irrigation increased 49.1% and 66.9% the dry matter of mixture and meadow, respectively. Continuous wheat rotation reduced seed yield, stability of production, crude protein characteristics of kernel and soil organic matter. The yearly gain in wheat after forage crops was 0.04 t (ha yr) 1 under rainfed and 0.07 t (ha yr) -1 under irrigation treatments. The crude protein and soil organic matter of wheat rotations, compared to those of continuous wheat under rainfed and irrigated was increase in term of point percentage by 0.8 and 0.5 in crude protein and 5.1 and 4.4 in organic matter, respectively. The rotations of mixture and meadow under both irrigated treatments increased the point of percentage of organic matter over continuous wheat (9.3.and 8.5 in mixture and 12.5 and 9.5 meadow under rainfed and irrigation, respectively). Irrigation reduce the impact of weather on crop growing reducing water use efficiency (mean over rotations) for dry matter production (15.5 in meadow and 17.5 in mixture [L water (kg dry matter) -1]) and wheat seed yield. The effect of agronomic advantages achieved by forage crops in topsoil expire its effect after three years of continuous wheat rotation.