• Authors:
    • Robertson, M. J.
    • Pannell, D. J.
    • Kragt, M. E.
    • Thamo, T.
  • Source: Agricultural Systems
  • Volume: 112
  • Year: 2012
  • Summary: Carbon sequestration in agricultural soil has been identified as a potential strategy to offset greenhouse gas emissions. Within the public debate, it has been claimed that provision of positive incentives for farmers to change their land management will result in substantial carbon sequestration in agricultural soils at a low carbon price. However, there is little information about the costs or benefits of carbon sequestration in agricultural soils to test these claims. In this study, the costeffectiveness of alternative land-use and land-management practices that can increase soil carbon sequestration is analysed by integrating biophysical modelling of carbon sequestration with wholefarm economic modelling. Results suggest that, for a case study model of a crop-livestock farm in the Western Australian wheatbelt, sequestering higher levels of soil carbon by changing rotations (to include longer pasture phases) incur considerable opportunity costs. Under current commodity prices, farmers would forego more than $80 in profit for every additional tonne of CO2-e stored in soil, depending on their adoption of crop residue retention practices. This is much higher than the initial carbon price of $23 t(-1) in Australia's recently legislated carbon tax. This analysis does not incorporate the possibility that greenhouse gas emissions may increase as a result of including longer pasture phases. Accounting for emissions may substantially reduce the potential for net carbon sequestration at low carbon prices.
  • Authors:
    • Tian, C.
    • Chen, F.
    • Wang, X.
    • Zhang, R.
    • Li, Z.
  • Source: PLOS ONE
  • Volume: 7
  • Issue: 11
  • Year: 2012
  • Summary: There is much interest in the role that agricultural practices might play in sequestering carbon to help offset rising atmospheric CO2 concentrations. However, limited information exists regarding the potential for increased carbon sequestration of different management strategies. The objective of this study was to quantify and contrast carbon dioxide exchange in traditional non-mulching with flooding irrigation (TF) and plastic film mulching with drip irrigation (PM) cotton (Gossypium hirsutum L.) fields in northwest China. Net primary productivity (NPP), soil heterotrophic respiration (R-h) and net ecosystem productivity (NEP) were measured during the growing seasons in 2009 and 2010. As compared with TF, PM significantly increased the aboveground and belowground biomass and the NPP (340 g C m(-2) season(-1)) of cotton, and decreased the R-h (89 g C m(-2) season(-1)) (p < 0.05). In a growing season, PM had a higher carbon sequestration in terms of NEP of similar to 429 g C m(-2) season(-1) than the TF. These results demonstrate that conversion of this type of land use to mulching practices is an effective way to increase carbon sequestration in the short term in cotton systems of arid areas.
  • Authors:
    • Leon-Cofreces, C.
    • Garcia, M.
    • Calvo, R.
    • Miralles de Imperial, R.
    • Martin, J.
    • Delgado, M.
  • Source: Soil Research
  • Volume: 50
  • Issue: 3
  • Year: 2012
  • Summary: Soil has an important role in the greenhouse effect as a net source or net sink of greenhouse gases. This study compared CO2 emission from broiler poultry manure (PMB) and hen poultry manure (PMH) in two different soils. A laboratory experiment was conducted to evaluate the decomposition of poultry manure by analysing carbon mineralisation. Jars were filled with soil, sealed, and placed in an incubator for 60 days, with periodic CO2 analysis. Higher emissions were found in soil amended with PMH; cumulative carbon released as CO2 was 800 mg C/kg in soil amended with PMH, and 600 mg C/kg with PMB. Data for cumulative CO2-C released from unamended and amended soils were fitted to four different kinetic models. With poultry manure, there were significant differences in the model parameters that represent the amount of total potentially mineralisable carbon and the mineralisation rate constant. After 60 days, the percentages of organic carbon mineralised for PMH were 40% and 26% for each soil, whereas the percentages were 20% and 12% for PMB.
  • Authors:
    • Beyene, S.
    • Kebede, M.
  • Source: Journal of Environment and Earth Science
  • Volume: 2
  • Issue: 4
  • Year: 2012
  • Summary: Greenhouse experiments were conducted at DZARC on soil sampled from farmers' field to examine the influence of floriculture effluent on soil quality and crop performance, and to see the most likely trends. The sample was splitted into two; the first remained to be as it is while the second was subjected to sterilization and call it non-sterilized (NS) and sterilized (S) soil, respectively. Seven rates of effluent was used as a treatment and laid out in CRD with four replications. The effluent was found to have high pH, EC, N, P, S, exchangeable bases, low in micronutrients and very low in heavy metals. The shoot dry weight was reduced by 36.9 and 58.8% for NS and S soils respectively in the first harvest. The second round experiment further confirmed that it keeps decreasing due to effluent additions. However, at lower volumes, the non-sterilized soil showed benefit from the effluent and hence the value started to increase but later it followed the same trends with application of higher volumes. Chemical properties were highly influenced by effluent additions. The pH and EC continuously increased whereas OC and TN increased to some extent but decreased as the volume of effluent increased. Exchangeable bases and micro-nutrients were continuously increased. The trends indicated that dry weight on Fluvisols will decline corresponding to the decrease in soil organic matter while pH, CEC and ESP continuously increases ending in the shift of slight alkaline soil to sodic soil. Generally, the effluent was found to disturb the performance of the crop and soil quality parameters. Disturbance in terms of shoot dry weight and soil quality parameters revealed that it was much less for the NS owing to the presence of organism.
  • Authors:
    • Davison, D. R.
    • Petersen, J. L.
    • Shaver, T. M.
    • Donk, S. J. van
  • Source: Transactions of the ASABE
  • Volume: 55
  • Issue: 1
  • Year: 2012
  • Summary: Reduced tillage, with more crop residue remaining on the soil surface, is believed to conserve water, especially in arid and semi-arid climates. However, the magnitude of water conservation is not clear. An experiment was conducted to study the effect of crop residue removal on soil water content, soil quality, and crop yield at North Platte, Nebraska. The same field plots were planted to soybean ( Glycine max) in 2009 and 2010. There were two treatments: residue-covered soil and bare soil. Residue (mostly corn residue in 2009 and mostly soybean residue in 2010) was removed every spring from the same plots using a flail chopper and subsequent hand-raking. The experiment consisted of eight, 12.2 m * 12.2 m, plots (two treatments with four replications each). Soybeans were sprinkler-irrigated, but purposely water-stressed, so that any water conservation in the residue-covered plots might translate into higher yields. After four years of residue removal, soil organic matter content and soil residual nitrate nitrogen were significantly smaller, and soil pH was significantly greater, in the bare-soil plots compared to the residue-covered plots. The residue-covered soil held approximately 90 mm more water in the top 1.83 m compared to the bare soil near the end of the 2009 growing season. In addition, mean soybean yield was 4.5 Mg ha -1 in the residue-covered plots, compared to 3.9 Mg ha -1 in the bare-soil plots. Using two crop production functions, it is estimated that between 74 and 91 mm of irrigation water would have been required to produce this extra 0.6 Mg ha -1. In 2010, mean soybean yield was 3.8 Mg ha -1 in the residue-covered plots, compared to 3.3 Mg ha -1 in the bare-soil plots. Between 64 and 79 mm of irrigation water would have been required to produce this extra 0.5 Mg ha -1. In both years, several processes may have contributed to the differences observed: (1) greater evaporation of water from the soil in the bare-soil treatment, and (2) greater transpiration by plants in the bare-soil treatment in the beginning of the growing season as a result of more vegetative growth due to higher soil temperatures in the bare-soil treatment.
  • Authors:
    • Muchaonyerwa, P.
    • Chiduza, C.
    • Dube, E.
  • Source: Soil & Tillage Research
  • Volume: 123
  • Year: 2012
  • Summary: A study was conducted to determine the effects of oat (Avena sativa) and grazing vetch (Vicia dasycapa) winter cover crops and fertilization regimes on soil organic matter (SOM) in an irrigated maize-based (Zea mays L.) conservation agriculture (CA) system following four years of continuous practice. Separate plots of oat and grazing vetch cover crops were grown in winter and then maize was planted in all plots in the following summer season. The four fertilization regimes used were: (i) fertilizer applied to the cover crops and the maize crop (F1), (ii) fertilizer applied to cover crops only (F2), (iii) fertilizer applied to the maize crop only (F3) and (iv) no fertilizer applied (F4). Control plots (weedy fallows) were included and the treatments were laid out in a randomized complete block design with three replications. Soil samples from 0-5, 5-20 and 20-50 cm depths were analyzed for total SOM, particulate organic matter (POM) fractions, hot water soluble C (HWC) and C-associated with water stable macro- and micro-aggregates (WSAC). While total SOM was more concentrated in the 0-5 cm soil depth across treatments, a lack of maize fertilization (F2 and F4 regimes) significantly (P
  • Authors:
    • Haghighi, B. J.
    • Miri, H. R.
    • Ebrahimi, S. M.
  • Source: Advances in Environmental Biology
  • Volume: 6
  • Issue: 4
  • Year: 2012
  • Summary: The purpose of this study was evaluating the growth and compare yield and water consumption of corn under treatments of conventional tillage, reduced tillage and no tillage during the different irrigation intervals. This study was conducted at Arsanjan city, southern Iran in 2009. The experiment was split plot in randomized completely blocks design with three tillage methods (conventional tillage without residues, minimum tillage and conservation residues, and no tillage and reserve residues) as main factor and irrigation intervals (8 days, 11 days and 14 days intervals) as sub factor with four replication. Result of this study showed that 8 days irrigation interval and conventional tillage produced the highest grain yield, biological yield, ear number, seed number and seed weight in comparison with other treatments. But, by increasing irrigation interval to 14 days and decreasing water usage, no tillage and reserve residue treatment could prevent reduction in grain yield. In general results showed that residues management by reserving residue as a surface cover and improves tillage method to minimum and no tillage can increase corn yield through improvement soil organic carbon which is the main goal in conservation agriculture. We can reach to economic corn yield by reducing irrigation times and saving water usage in warm and dry regions, so it is possible to plant corn in this area directly in residue of previous crop.
  • Authors:
    • Sparks, R.
    • Dillon, M.
    • Delgado, J. A.
    • Essah, S. Y. C.
  • Source: HortTechnology
  • Volume: 22
  • Issue: 2
  • Year: 2012
  • Summary: There is the need to develop potato (Solanum tuberosum) cropping systems with higher yields and crop quality. Field studies were conducted with cover crops grown under limited irrigation (
  • Authors:
    • Khamseh, A. R. M.
    • Ghotbi, M.
    • Dehaghi, M. A.
    • Rouhi, H. R.
    • Ghotbi, M.
    • Wahsha, M.
  • Source: International Journal of AgriScience
  • Volume: 2
  • Issue: 1
  • Year: 2012
  • Summary: Growing cover crops with allopathic characteristics is a way to biologically control the weed P. aegyptiaca. Allelochemicals are present in almost all plants and in many plant tissues including leaves, stems, flowers, fruits, seeds and roots. This experiment was conducted to compare effects of allopathic crops on the germination rate of P. aegyptiaca seeds. Weed infestations were tested in Polyethylene (PE) bags and pot experiments. 27 crops, of different families, were grown in 2-Kg pots containing sterile soil infested with 0.6 g of seed. The control pots contained only 0.6 g of P. aegyptiaca seeds. Two month-old plants were incorporated into the soil from the surface and then tomato seedlings ( Lycopersicum esculentum Mill.) were planted in the pots. Cotton (Malvaceae family) was among the cultured plants, used as a trap crop to thoroughly eradicate the threat of P. aegyptiaca. The most significant reduction in broomrape shoot and capsule number was demonstrated in those pots that contained cotton and sorghum, and in those that contained tomato; tomato dry weight significantly augmented. The results from the PE bags were in parallel with those of the pots. The germination rates of P. aegyptiaca (%) next to the plants in PE bags ranged from 8.333% to 55.333% respectively in millet and pepper. Except for sunflower, vetch, soy bean, chick pea, sainfoin, alfalfa, zucchini and sesame, which demonstrated catch crop, activity, the other cultivated plants; corn, oat, beet, sugar beet, triticale, caster-oil plant, millet, fiber flax, pepper, cotton and sorghum were determined as trap crops for the weed P. aegyptiaca.
  • Authors:
    • Carbonell-Bojollo, R.
    • Ordóñez-Fernández, R.
    • Veroz-González, O.
    • González-Sáncheza, E. J.
    • Gil-Ribes, J. A.
  • Source: Soil & Tillage Research
  • Volume: 122
  • Year: 2012
  • Summary: Conservation agriculture (CA) helps to mitigate climate change. Firstly, the modifications introduced by CA on the carbon dynamics in the soil directly result in an increase of the carbon (C) in the soil fraction. Secondly, CA drastically reduces C oxidation processes by diminishing the mechanical manipulation of the soil. Spain's position in relation to the Kyoto Protocol must be improved, as is one of the European countries in a non-compliance situation. With the aim of providing knowledge about the potential of CA as C sink in Spain, 29 articles on this subject were reviewed. According to 2010 CA uptake, the results demonstrated that conservation practices have the potential to promote the fixation in soil of about 2 Gg year(-1) more C than traditional tillage (TT) systems. As indicated by Tebrugge (2001), 3.7 Mg of CO2 are generated from 1 Mg of C through microbial oxidation processes taking place in the ground, meaning that through CA almost 7.5 Gg of CO2 could be sequestered from the atmosphere every year until the equilibrium is reached. C fixation was found to be irregular over time. C fixation rates were high in newly implemented systems during the first 10 years, reaching top values of 0.85 Mg ha(-1) year(-1) for no-tillage (NT) and 1.54 Mg ha(-1) year(-1) for cover crops (CC) implemented in-between perennial tree rows. After those first 10 years, it followed a period of lower but steady growth until equilibrium was reached. Nevertheless, C decreases of 0.16 Mg ha(-1) year(-1) in the first 10 years may be expected when practicing minimum tillage (MT). C sequestration rate resulted higher in case farmers do crop rotations in NT and MT rather than monoculture. In woody crops, studies reported higher C fixation values for native species when compared to sowed CC. Also, climate conditions seem to affect C sequestration rate in Spain. Although in NT differences observed between maritime and continental climates are not pronounced, as approximately 25% of the values recorded in both climates are equal, in the case of MT about 75% of maritime climate values result higher than the continental situation. (c) 2012 Elsevier B.V. All rights reserved.