• Authors:
    • Xiong, Z. Q.
    • Ma, Y. C.
    • Jia, J. X.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 150
  • Year: 2012
  • Summary: The net ecosystem carbon budget (NECB), global warming potential (GWP) and greenhouse gas intensity (GHGI) of vegetable ecosystems are not well documented. The net GWP and GHGI either including the carbon emissions from agricultural management (net mGWP/mGHGI) or not were estimated from an intensive vegetable production system in Nanjing, China between 2009 and 2010. The four typical consecutive rotations included celery-tung choy-baby bok choy-amaranth (C-T-Bb-A), choy sum-celery-tung choy-bok choy (Cs-C-T-Bc), garland chrysanthemum-tung choy-bok choy (G-T-Bc), and celery-choy sum-lettuce-bok choy (C-Cs-L-Bc). A net sink was observed and estimated at crop seasonal time scale for both the NECB and the soil organic carbon change (delta SOC) from the four vegetable rotation fields. The mGWP, net GWP, net mGWP. GHGI and mGHGI all showed nearly consistent changes among the rotations and among the vegetables within each rotation. The global warming potential ranged from 26 Mg CO2 equiv. ha(-1) to 109 Mg CO2 equiv. ha(-1) for net GWP and 36 Mg CO2 equiv. ha(-1) to 131 Mg CO2 equiv. ha(-1) for mGWP. The GHGI and mGHGI ranged from 0.17 kg CO2 equiv. kg(-1) vegetable to 0.41 kg CO2 equiv. kg(-1) vegetable and from 0.22 kg CO2 equiv.kg(-1) vegetable to 0.49 kg CO2 equiv. kg(-1) vegetable, respectively. The mGWP, net GWP, net mGWP, GHGI and mGHGI were dominated by the GWP resulting from N2O emissions. Annual cumulative direct N2O emissions were 374 kg N2O ha(-1) for G-T-Bc, 216 kg N2O ha(-1) for C-T-Bb-A, 159 kg N2O ha(-1) for Cs-C-T-Bc and 89 kg N2O ha(-1) for C-Cs-L-Bc, respectively. High N fertilizer input was likely responsible for the high N2O emissions. Increasing fertilizer use efficiency and adoption of best practices are effective measures for sustainable intensive vegetable production.
  • Authors:
    • Shan, W. H.
    • Jie, G. D.
    • Zhou, C. Z.
    • Mei, J. H.
  • Source: Acta Pedalogica Sinica
  • Volume: 49
  • Issue: 1
  • Year: 2012
  • Summary: Ammonia (NH 3) volatilization is a major pathway for gaseous nitrogen loss from fields applied with manure. To explore effects of topdressing of bio-digested manure slurry on ammonia volatilization, a field experiment was carried out in a vegetable greenhouse, applying bio-digested pig manure slurry (DPS) on winter vegetable, cress ( Oenanthe clecumbens L.) and radish ( Raphanus sativus L. Var. Radiculus pers.), and summer vegetable, pak choi ( Brassica chinensis L.) and crown daisy ( Chrysanthemum carinatum Schousb.). The topdressing rates of nitrogen were 72 kg hm -2, 54 kg hm -2, 42 kg hm -2 and 63 kg hm -2, respectively, during the growing periods of vegetables. Results showed that (1) topdressing of DPS led to explosion of ammonia volatilization within 48 h; (2) the accumulative ammonia release of the growing season reached 8.68 kg hm -2 and 9.90 kg hm -2 in cress and radish fields, respectively, which were significantly higher than those in the plots topdressing with chemical fertilizer (CF) (4.06 kg hm -2 and 5.59 kg hm -2); however, in the pak choi and crown daisy fields, the value was 10.40 kg hm -2 and 11.61 kg hm -2, respectively, which were not so significantly higher than those in the plots topdressing with CF (9.81 kg hm -2 and 10. 09 kg hm -2); (3) ammonia volatilization contributed 11.7% and 17.7% to the total N loss, respectively in the cress and radish plots topdressing with DPS in winter, and 23.3% and 26.8% in the pak choi and crown daisy plots in summer. The former was significantly lower than the latter; (4) temperature, water content, content of soluble organic carbon, form and concentration of nitrogen, biomass and activity of microbes in the surface soil at 0-10 cm depth were found to be the main contributors to ammonia volatilization. Application of bio-digested manure slurry in the vegetable field increased nitrogen loss through ammonia volatilization from DPS per se and its stimulative effect on decomposition of soil organic nitrogen. It is, therefore, essential to pay adequate attention to effects of temperature and application method in using bio-digested manure slurry as a soil amendment.
  • Authors:
    • Ozores-Hampton, M.
    • Fraisse, C. W.
    • Jones, C. D.
  • Source: Agricultural Systems
  • Volume: 113
  • Year: 2012
  • Summary: Agriculture is a significant contributor to rising atmospheric greenhouse gas (GHG) levels, which is expected to result in sea level rise and increased frequency of extreme weather events and is of increasing global concern. Tomatoes are an important agricultural commodity in Florida, accounting for 40% of the fresh market production in the United States. Quantification of GHG emissions from typical tomato production in Florida could improve understanding of the impact of different GHG emissions sources and identification of areas for potential GHG emissions reductions. A practical methodology was implemented to calculate a representative GHG emissions estimate using production inputs and practices used by the Florida tomato industry. Experts and grower surveys were used to characterize typical Florida tomato production practices. Existing methodologies were used to convert material use and farm operations into GHG emissions estimates. Results indicated that, depending on irrigation system type and water source, the overall average estimates of GHG emissions associated with a growing season ranged from 16,183 kg CO2-eq ha(-1) (0.19 kg CO2-eq kg fruit(-1)) to 22,426 kg CO2-eq ha(-1) (0.27 kg CO2-eq kg fruit(-1)). Irrigation and nitrogen (N) fertilizer accounted for the most emissions, with irrigation accounting for between 2.8% and 26.6% of average GHG emissions and N fertilizer accounting for between 17.7% and 22.8%. It was concluded that increased efficiency in irrigation and N use, and improved methods for polyethylene mulch use and disposal, were the best areas for GHG emissions reductions.
  • Authors:
    • Kim, D.
  • Source: Agroforestry Systems
  • Volume: 86
  • Issue: 2
  • Year: 2012
  • Summary: Nitrogen (N)-fixing tree and crop intercropping systems can be a sustainable agricultural practice in sub-Saharan Africa and can also contribute to resolving climate change through enhancing soil carbon (C) sequestration. A study conducted by Makumba et al. (Agric Ecosyst Environ 118:237-243, 2007) on the N-fixing tree gliricidia and maize intercropping system in southern Malawi provides a rare dataset of both sequestered soil C and C loss as soil carbon dioxide (CO2) emissions. However, no soil C gain and loss estimates were made so the study failed to show the net gain of soil C. Also absent from this study was potential benefit or negative impact related to the other greenhouse gas, nitrous oxide (N2O) and methane (CH4) emissions from the intercropping system. Using the data provided in Makumba et al. (Agric Ecosyst Environ 118:237-243, 2007) a C loss as soil CO2 emissions (51.2 +/- A 0.4 Mg C ha(-1)) was estimated, amounting to 67.4% of the sequestered soil C (76 +/- A 8.6 Mg C ha(-1) in 0-2 m soil depth) for the first 7 years in the intercropping system. An annual net gain of soil C of 3.5 Mg C ha(-1) year(-1) was estimated from soil C sequestered and lost. Inclusion of the potential for N2O mitigation [0.12-1.97 kg N2O-N ha(-1) year(-1), 0.036-0.59 Mg CO2 equivalents (eq.) ha(-1) year(-1)] within this intercropping system mitigation as CO2 eq. basis was estimated to be 3.5-4.1 Mg CO2 eq. ha(-1) year(-1). These results suggest that reducing N2O emission can significantly increase the overall mitigation benefit from the intercropping system. However, significant uncertainties are associated with estimating the effect of intercropping on soil N2O and CH4 emissions. These results stress the importance of including consideration of quantifying soil CO2, N2O and CH4 emissions when quantifying the C sequestration potential in intercropping system.
  • Authors:
    • De Figueiredo, E. B.
    • La Scala Junior, N.
    • Panosso, A. R.
  • Source: Brazilian Journal of Biology
  • Volume: 72
  • Issue: 3
  • Year: 2012
  • Summary: Agricultural areas deal with enormous CO2 intake fluxes offering an opportunity for greenhouse effect mitigation. In this work we studied the potential of soil carbon sequestration due to the management conversion in major agricultural activities in Brazil. Data from several studies indicate that in soybean/maize, and related rotation systems, a significant soil carbon sequestration was observed over the year of conversion from conventional to no-till practices, with a mean rate of 0.41 Mg C ha(-1) year(-1). The same effect was observed in sugarcane fields, but with a much higher accumulation of carbon in soil stocks, when sugarcane fields are converted from burned to mechanised based harvest, where large amounts of sugarcane residues remain on the soil surface (1.8 Mg C ha(-1) year(-1)). The higher sequestration potential of sugarcane crops, when compared to the others, has a direct relation to the primary production of this crop. Nevertheless, much of this mitigation potential of soil carbon accumulation in sugarcane fields is lost once areas are reformed, or intensive tillage is applied. Pasture lands have shown soil carbon depletion once natural areas are converted to livestock use, while integration of those areas with agriculture use has shown an improvement in soil carbon stocks. Those works have shown that the main crop systems of Brazil have a huge mitigation potential, especially in soil carbon form, being an opportunity for future mitigation strategies.
  • Authors:
    • de Barros Viana Hissa, L.
    • Soares-Filho, B. S.
    • Costa, M. H.
    • Leite, C. C.
  • Source: Global Biogeochemical Cycles
  • Volume: 26
  • Issue: 2
  • Year: 2012
  • Summary: The evaluation of impacts of land use change is in general limited by the knowledge of past land use conditions. Most publications on the field present only a vague description of the earlier patterns of land use, which is usually insufficient for more comprehensive studies. Here we present the first spatially explicit reconstruction of historical land use patterns in Brazil, including both croplands and pasturelands, for the period between 1940 and 1995. This reconstruction was obtained by merging satellite imagery with census data, and provides a 5' x 5' yearly data set of land use for three different categories (cropland, natural pastureland and planted pastureland) for Brazil. The results show that important land use changes occurred in Brazil. Natural pasture dominated in the 1950s and 1960s, but since the beginning of 1970s it has been gradually replaced by planted pasture, especially in southeast and center west of Brazil. The croplands began its expansion in the 1960s reaching extensive areas in almost all states in 1980. Carbon emissions from historical land use changes were calculated by superimposing a composite biomass map on grids of a weighted average of the fractions of the vegetation types and the replacement land uses. Net emissions from land use changes between 1940 and 1995 totaled 17.2 +/- 9.0 Pg-C (90% confidence range), averaging 0.31 +/- 0.16 Pg-C yr(-1), but reaching up to 0.47 +/- 0.25 Pg-C yr(-1) during the 1960s and through 1986-1995. Despite international concerns about Amazon deforestation emissions, 72% of Brazil's carbon emissions during the period actually came from deforestation in the Atlantic Forest and Cerrado biomes. Brazil's carbon emissions from land use change are about 11 times larger than its emissions from fossil fuel burning, although only about 18.1% of the native biomass has been lost due to agricultural expansion, which is similar to the global mean (17.7%).
  • Authors:
    • Williams, S.
    • Easter, M.
    • Paustian, K.
    • Lokupitiya, E.
    • Andren, O.
    • Katterer, T.
  • Source: Biogeochemistry
  • Volume: 107
  • Issue: 1-3
  • Year: 2012
  • Summary: Carbon (C) added to soil as organic matter in crop residues and carbon emitted to the atmosphere as CO(2) in soil respiration are key determinants of the C balance in cropland ecosystems. We used complete and comprehensive county-level yields and area data to estimate and analyze the spatial and temporal variability of regional and national scale residue C inputs, net primary productivity (NPP), and C stocks in US croplands from 1982 to 1997. Annual residue C inputs were highest in the North Central and Central and Northern Plains regions that comprise similar to 70% of US cropland. Average residue C inputs ranged from 1.8 (Delta States) to 3.0 (North Central region) Mg C ha(-1) year(-1), and average NPP ranged from 3.1 (Delta States) to 5.4 (Far West region) Mg C ha(-1) year(-1). Residue C inputs tended to be inversely proportional to the mean growing season temperature. A quadratic relationship incorporating the growing season mean temperature and total precipitation closely predicted the variation in residue C inputs in the North Central region and Central and Northern Plains. We analyzed the soil C balance using the crop residue database and the Introductory Carbon Balance regional Model (ICBMr). Soil C stocks (0-20 cm) on permanent cropland ranged between 3.07 and 3.1 Pg during the study period, with an average increase of similar to 4 Tg C year(-1), during the 1990s. Interannual variability in soil C stocks ranged from 0 to 20 Tg C (across a mean C stock of 3.08 +/- A 0.01 Pg) during the study period; interannual variability in residue C inputs varied between 1 and 43 Tg C (across a mean input of 220 +/- A 19 Tg). Such interannual variation has implications for national estimates of CO(2) emissions from cropland soils needed for implementation of greenhouse gas (GHG) mitigation strategies involving agriculture.
  • Authors:
    • Reardon-Smith, K.
    • Mushtaq, S.
    • Maraseni, T. N.
  • Source: Journal of Environmental Management
  • Volume: 111
  • Year: 2012
  • Summary: The Australian Government is meeting the challenge of water scarcity and climate change through significant on-farm infrastructure investment to increase water use efficiency and productivity, and secure longer term water supplies. However, it is likely that on-farm infrastructure investment will alter energy consumption and therefore generate considerable greenhouse gas (GHG) emissions, suggesting potential conflicts in terms of mitigation and adaptation policies. In particular, the introduction of a price on carbon may influence the extent to which new irrigation technologies are adopted. This study evaluated trade-offs between water savings, GHG emissions and economic gain associated with the conversion of a sprinkler (hand shift) irrigation system to a drip (trickle) irrigation system for a lettuce production system in the Lockyer Valley, one of the major vegetable producing regions in Australia. Surprisingly, instead of trade-offs, this study found positive synergies - a win-win situation. The conversion of the old hand-shift sprinkler irrigation system to a drip irrigation system resulted in significant water savings of almost 2 ML/ha, as well as an overall reduction in GHG emissions. Economic modelling, at a carbon price of $ 30/t CO(2)e, indicated that there was a net benefit of adoption of the drip irrigation system of about $ 4620/ML/year. We suggest priority should be given, in the implementation of on-farm infrastructure investment policy, to replacing older inefficient and energy-intensive sprinkler irrigation systems such as hand shift and roll-line. The findings of the study support the use of an integrated approach to avoid possible conflicts in designing national climate change mitigation and adaptation policies, both of which are being developed in Australia.
  • 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.