• Authors:
    • Shennan, C.
    • Muramoto, J.
    • Albano, J. P.
    • Kokalis-Burelle, N.
    • Rosskopf, E. N.
    • Butler, D. M.
  • Source: PLANT AND SOIL
  • Volume: 355
  • Issue: 1-2
  • Year: 2012
  • Summary: Anaerobic soil disinfestation (ASD) has been shown to be an effective strategy for controlling soilborne plant pathogens and plant-parasitic nematodes in vegetable and other specialty crop production systems. Anaerobic soil disinfestation is based upon supplying labile carbon (C) to stimulate microbially-driven anaerobic soil conditions in moist soils covered with polyethylene mulch. To test the effectiveness of warm-season cover crops as C sources for ASD, a greenhouse study was conducted using a sandy field soil in which several warm-season legumes and grasses were grown and incorporated and compared to molasses-amended and no C source controls. Greenhouse pots were irrigated to fill soil porosity and covered with a transparent polyethylene mulch to initiate a 3-week ASD treatment prior to planting tomatoes. Soilborne plant pathogen inoculum packets, yellow nutsedge (Cyperus esculentus L.) tubers, and Southern root-knot nematode (Meloidogyne incognita (Kofoid & White) Chitwood; M.i.) eggs and juveniles were introduced at cover crop incorporation. In nearly all cases, ASD treatment utilizing cover crops as a C source resulted in soil anaerobicity values that were equal to the molasses-amended fallow control and greater than the no C source fallow control. In trial 1, Fusarium oxysporum Schlechtend.:Fr. (F.o.) survival was reduced by more than 97% in all C source treatments compared to the no C source control but there was no effect of C source in Trial 2. Carbon source treatments were inconsistent in their effects on survival of Sclerotium rolfsii Sacc. (S.r). In general, the number of M.i. extracted from tomato root tissue and root gall ratings were low in all treatments with cover crop C source, molasses C source, or composted poultry litter. Germination of yellow nutsedge tubers was highest in the no C source control (76%), lowest in the molasses control (31%), and intermediate from cover crop treatments (49% to 61%). Warm-season cover crops have potential to serve as a C source for ASD in vegetable and other crop production systems, but more work is needed to improve consistency and further elucidate mechanisms of control of soilborne plant pathogens and weeds during ASD treatment utilizing cover crops.
  • Authors:
    • Moudry, J.
    • Jelinkova, Z.
    • Moudry, J.,Jr.
    • Konvalina, P.
  • Source: Lucrari Stiintifice, Universitatea de Stiinte Agricole Si Medicina Veterinara "Ion Ionescu de la Brad" Iasi, Seria Agronomie
  • Volume: 55
  • Issue: 2
  • Year: 2012
  • Summary: Potatoes are cultivated in conventional as well as in organic farming systems and although the production area itself is not large as compared to other crops (e.g. 1.17% of arable land in the Czech Republic, 2.14% in Germany, but also 14.89% in the Netherlands), in terms of production and subsequent food usage they belong to the most important crops not only in Europe. Farming system, which is used for their cultivation, can be one of the main factors affecting the production of greenhouse gases. The work is focused on monitoring and calculating the value of emissions expressed in CO 2 equivalent (CO 2-eqv=1x CO 2+23x CH 4+298x N 2O) which is produced within the cultivation of potatoes in conventional and organic farming system. The results show that when comparing emission load within the agricultural production of potatoes there is an evident difference between conventional and organic farming systems, while different values can be observed in all parameters (field emission, planting, fertilizing, agrotechnical operations, pesticides). Although agrotechnical procedures themselves, including fertilization, are very similar in conventional and organic farming, the emission load produced per one kilogram of conventional potatoes is 0.145 kg CO 2e while the load produced per one kilogram of ecological potatoes is for the amount of 0.126 kg CO 2e by around 13% lower.
  • Authors:
    • Juszczak, R.
    • Sakowska, K.
    • Uzdzicka, B.
    • Olejnik, J.
  • Source: Woda Srodowisko Obszary Wiejskie
  • Volume: 12
  • Issue: 38
  • Year: 2012
  • Summary: One of the methods to study the exchange of mass and energy between the atmosphere and the surface of various terrestrial ecosystems is direct measurement of the fluxes of greenhouse gases. Particular attention is focussed on carbon dioxide whose concentration in the atmosphere dramatically increases [Urbaniak 2006]. The paper presents results of the measurements of carbon dioxide exchange conducted on 29th of June 2011 on three experimental plots (alfalfa, winter wheat and potato crops) situated in Agricultural Experimental Station in Brody (Wielkopolskie Province) and modeled values of ecosystem respiration ( Reco ), net ecosystem exchange ( NEE) and gross ecosystem production ( GEP). Measurements were carried out by means of closed dynamic chamber system. Reco measured on 29th of June 2011 ranged from 3.61 to 16.62 mol CO 2.m -2.s -1 and measured NEE - from 4.22 to -24.08 mol CO 2.m -2.s -1. Modeled values of the ecosystem respiration ( Reco ) for particular crops obtained with the LLOYD and Taylor [1994] function did not differ from measured values by more than 4% on average. The results of NEE modeling indicate that selected model [Michaelis, Menten 1913] worked well for sites with alfalfa and winter wheat crops (mean absolute percentage error - MAPE was 25.0 and 7.3%, respectively). NEE predictions for the site with potato crop differed largely ( MAPE=98.5%) from measured values and hence there is a need for looking for a model that would consider, apart from PPFD, also other environmental factors driving photosynthesis.
  • Authors:
    • Bakken, L.
    • Budai, A.
    • Chen, R.
    • Senbayram, M.
    • Dittert, K.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 147
  • Issue: January
  • Year: 2012
  • Summary: Amending agricultural soils with organic residues is frequently recommended to improve soil fertility and to sequester carbon for counteracting global warming. However, such amendments will enhance microbial respiration, hence denitrification. Therefore, the assessment of effects on global warming must take N2O emission and the N2O/(N2O + N-2) product ratio of denitrification into account. There are some indications that the product ratio of denitrification is positively correlated with the ratio of available NO3- and available organic C in soils, but more research is needed to unravel quantitative relationships in well defined experiments. We conducted two laboratory incubation experiments, with the objective (i) to test the impact of the application of various N containing organic substrates including biogas residue on the denitrification rate and on N2O emission, and (ii) to investigate the effect of various NO3- concentrations on the denitrification rate and the N2O/(N2O + N-2) product ratio under standardized anoxic conditions in soils collected from long-term organic or inorganic fertilizer plots. In experiment 1, we found that biogas residue was more recalcitrant than maize straw, despite a high concentration of soluble organic C. High respiration (treatments with maize straw and sucrose) resulted in a transient peak in N2O emission, declining rapidly towards zero as nitrate concentrations reached less than 20 mg NO3--N kg(-1) dry soil. Application of biogas residue had a more moderate effect on soil respiration and denitrification, and resulted in a more long lasting peak in N2O emission. The results were interpreted as a result of a gradual increase in the relative activity of N2O reductase (thus lowering of the N2O/(N2O + N-2) product ratio of denitrification) throughout the incubation, most likely controlled by concentration of available NO3- in soil. In the second experiment, we found low N2O/(N2O N-2) product ratios for the treatment where NO3- concentrations were = 10 mM NO3-, and the ratios were remarkably independent of the soil's fertilizer history. We conclude that (i) in N-fertilized agricultural soils, application of organic matter with high contents of labile C may trigger denitrification-derived N2O emission whereas (ii) in soils with low NO3- contents such application may substantially lower the N2O/(N2O + N-2) product ratio and hence N2O emission. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Walker, M. B.
    • Faber, A.
    • Syp, A.
  • Source: Journal of Food, Agriculture & Environment
  • Volume: 10
  • Issue: 3-4
  • Year: 2012
  • Summary: In this paper, simulations with a Denitrification -Decomposition (DNDC) model were used to evaluate the impact of different management options on carbon (C) sequestration and emission of greenhouse gases: methane (CH 4) and nitrous oxide (N2O). Two cropping systems were analyzed. The first included potato, winter wheat, spring barley and forage maize (P-W-B-M). The second included potato, winter wheat, spring barley with clover and grass mixture (P-W-B-C). In both cropping systems, different farmyard manure (FYM) rates were applied. The application of additional nitrogen (N) using FYM increased the C sequestration, as well as N2O emissions and had a little effect on CH 4 uptake. An estimate into the average annual increases in N2O emissions, which were converted into carbon dioxide (CO2) equivalent emissions with 100-year global warming potential (GWP) multipliers, were offset by 56-144% of the C sequestration, depending on the management option. After 16 years of the experiment, the accumulation of C and N per hectare increased in the soil organic matter (SOM) pool. In P-W-B-M rotation, with manure applied at 325 kg N ha(-1), the accumulation of C increased to 5,760 and N 585 kg ha(-1), respectively. In P-W-B-C rotation, where a higher rate of manure was applied, the increase of C was at 10,796 and N 740 kg ha(-1). The highest influence in the rise of C and N accumulation was in humates. The high value of C sequestration in soil outweighs the emissions of N2O. In P-W-B-M rotations, the rate of applied FYM switched its average annual net GWP balance from net losses to a net sink. In P-W-B-C rotations, the applied FYM increased the annual rate of GHG emissions by 3%. The average annual N2O emissions increased by 44% under P-W-B-C rotation and by 142% under P-W-B-M rotations. Increases in the soil organic carbon (SOC) were by 234% and 408%, respectively, for P-W-B-C and P-W-B-M rotations. Our study showed that usage of FYM should be managed correctly, because applications at high rates have a negative impact on environment.
  • Authors:
    • Blicher-Mathiesen, G.
    • Hoffmann, C. C.
    • Gorres, C. M.
    • Elsgaard, L.
    • Schelde, K.
    • Petersen, S. O.
  • Source: Agriculture Ecosystems & Enviroment
  • Volume: 162
  • Year: 2012
  • Summary: This study presents the first annual estimates of net ecosystem exchange (NEE) of CO 2 and net ecosystem carbon balances (NECB) of contrasting Danish agricultural peatlands. Studies were done at eight sites representing permanent grasslands (PG) and rotational (RT) arable soils cropped to barley, potato or forage grasses in three geo-regional settings. Using an advanced flux-chamber technique, NEE was derived from modelling of ecosystem respiration (ER) and gross primary production (GPP) with temperature and photosynthetically active radiation as driving variables. At PG ( n=3) and RT ( n=5) sites, NEE (meanstandard error, SE) was 5.10.9 and 8.62.0 Mg C ha -1 yr -1, respectively, but with the overall lowest value observed for potato cropping (3.5 Mg C ha -1 yr -1). This was partly attributed to a short-duration vegetation period and drying of the soil especially in potato ridges. NECB, derived from NEE and C-removal in harvested biomass, was equivalent to 8.41.0 and 11.52.0 Mg C ha -1 for the PG and RT land-use types, respectively. Means were not significantly different, P=0.214, and were comparable to a wider range of high-end emission factors for managed organic soils in boreal and temperate climate zones. It was stressed that evaluation of emission factors should explicitly differentiate between data representing net C balance from a soil perspective and CO 2-C balance from an atmospheric perspective. Modelling of inter-annual variability in NEE for three selected sites during a 21-year meteorological period indicated a range of 18-67% (coefficients of variation). Yet, the robustness of these estimates and their importance for the derived emission factors needs to be substantiated experimentally.
  • 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.
  • Authors:
    • Al-Amoud, A. I.
    • Alabdulkader, A. M.
    • Awad, F. S.
  • Source: Agricultural Economics – Czech
  • Volume: 58
  • Issue: 2
  • Year: 2012
  • Summary: A mathematical sector model has been formulated to optimize the cropping pattern in Saudi Arabia aiming at maximizing the net annual return of the agricultural sector in the country and ensuring the efficient allocation of the scarce water resources and arable land among the competing crops. The results showed the potential for Saudi Arabia to optimize its cropping pattern and to generate an estimated net return equivalent to about 2.42 billion US$ per year. The optimized cropping pattern in Saudi Arabia has been coupled with about 53% saving in water use and about 48% reduction in the arable land use compared to the base-year cropping pattern. Comparable weights was given to different crop groups by allocating about 48.4%, 35.4%, 13.1%, and 3.2% to grow cereals, fruits, forages, and vegetables, respectively. These findings are in line with the national strategy to rationalize the cultivation of water-intensive crops in favour of highly water-efficient crops.
  • Authors:
    • Darshana
    • Pandey, A.
    • Pandey, R. P.
    • Ostrowski, M.
  • Source: Irrigation and Drainage
  • Volume: 61
  • Issue: 2
  • Year: 2012
  • Summary: In this study, simulation and optimization models were assembled for the optimization of irrigation systems and their operation. The simulation model CROPWAT was used for estimation of the crop water requirement, time and depth. The evolutionary algorithm (GANetXL) was used for the optimal planning of cropping pattern, maximization of net benefits and minimization of irrigation water requirements for the study area of Holeta catchment, Ethiopia. The study area encompasses three command areas, i.e. farm A, farm B and Tsedey State Farm, and five different type of crops, i.e. potato, tomato, apple, peach and winter wheat. The simulation results of the CROPWAT model illustrated that crop water requirement for apple was highest (993 mm), followed by peach (908 mm), tomato (470 mm), potato (443 mm) and wheat (294 mm). The study reveals that fruit crops have more crop water requirements than cereals. The results of the GANetXL show that when the cropped area and water allocated was varied between extreme values, 23% of water can be saved. The total benefit from the study area can be enhanced by USD 34 ha -1 and can be helpful in improving the economic conditions of the farmers.
  • Authors:
    • Connell, T.
    • Knuteson, D. L.
    • MacGuidwin, A. E.
    • Bland, W. L.
    • Bartelt, K. D.
  • Source: Phytopathology
  • Volume: 102
  • Issue: 5
  • Year: 2012
  • Summary: We used cover crops with demonstrated efficacy against Verticillium dahliae and Pratylenchus penetrans in combination with the biocidal practice of solarization to determine the importance of targeting both organisms for managing potato early dying, an issue relevant to the search for alternatives to soil fumigation. Two experiments were conducted in commercial fields using a split-plot design with cover crop treatments of rapeseed, marigold, forage pearl millet, sorghum-sudangrass, and corn as the main plot factor and solarization as the subplot factor. Cover crops were grown and solarization applied in year one, followed by potato in year two. The main effect of solarization was significant for reduced inoculum levels of both organisms in year two and increased tuber yields. The main effect of cover crop was also significant with lower population densities of P. penetrans following the marigold and millet treatments and of V. dahliae following rape and sorghum-sudangrass. The cover crop treatments influenced yield in only one of the experiments in the absence of solarization. The combinatorial effect of cover crops and solarization resulted in a wide range of pathogen population densities. Mean soil inoculum levels were negatively related to yield for V. dahliae in experiment 1, and for P. penetrans and the P. penetrans x V. dahliae interaction in both experiments.