• Authors:
    • Tenhunen, J.
    • Huwe, B.
    • Kwon, H. J.
    • Arnhold, S.
    • Xue, W.
    • Lee, B.
    • Otieno, D.
    • Lindner, S.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 199
  • Year: 2015
  • Summary: The Asian agricultural landscape, which accounts for approximately 12.6% of the world's agricultural land, is highly heterogeneous due to the multicultural cropping system. Information regarding CO 2 exchange and carbon (C) balance of these agro-ecosystems is scarce, even though they are likely to immensely contribute to the global C budget. Net Ecosystem CO 2 Exchange (NEE) and Ecosystem respiration ( Reco) were measured between 2009 and 2010 on 5 dominant crops (potato, rice, radish, cabbage and bean) in the Haean catchment of South Korea, using a closed chamber system to quantify CO 2 fluxes in this agricultural landscape characteristic of the Asian cropping system. Parallel measurements were conducted on leaf area index (LAI), plant biomass and climatic variables, mainly photosynthetic active radiation (PAR), air temperature, soil temperature and soil moisture. Biomass and LAI development differed among the crops likely as a result of differences in light use efficiencies (alpha) and carbon allocation patterns. The peak total biomass for radish, cabbage, potato, rice and bean were 0.530.07, 0.550.12, 1.850.51, 2.540.35 and 1.010.26 kg m -2, respectively, while the respective maximum LAI were 2.8, 3.7, 6.4, 6.3 and 6.7 m 2 m -2. Variations in seasonal patterns, magnitudes and the timing of maximum NEE and gross primary production (GPP) among the crops were likely the result of differences in LAI and alpha. The lowest peak Reco rate was 3.80.5 mol m -2 s -1, measured on rice paddies while the highest was 34.44.3 mol m -2 s -1 measured on the cabbage fields. The maximum NEE rates were -29.40.4 and -38.76.6 mol m -2 s -1, measured in potato and cabbage fields, respectively. Peak GPP rates in potato and cabbage fields were 39.50.6 and 63.07.2 mol m -2 s -1, respectively. PAR explained more than 90% of the diurnal variations in GPP, while LAI and α determined the seasonal trends of maximum GPP. The timing of maximum CO 2 assimilation (GPP Max) differed among the crops, thus, even though maximum CO 2 uptake in the respective crops only lasted a couple of weeks, the effect of the staggered peak GPP resulted in extended period of high CO 2 uptake. These differences among crops were significant, hence, modeling approaches need to consider the heterogeneity in ecosystem CO 2 exchange associated with these multicultural agriculture landscapes.
  • Authors:
    • Valentine, T. A.
    • Hawes, C.
    • Squire, G. R.
    • Young, M. W.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 202
  • Year: 2015
  • Summary: Efforts to maintain or increase food production in developed agriculture would be compromised if current high-intensity production was degrading supporting ecosystem services, such as the ability of soil to function. The link between cropping intensity, defined by pesticide and fertiliser applications, and soil biophysical status was examined at 70 sites in a high-yielding region of the UK, in which cropping sequences covering a wide range of intensity had diverged from a common low-intensity origin in the 1970s. Two sequences of still low or moderate intensity based on spring cereals or a low frequency of winter cereals formed comparators for three high intensity sequences based on winter wheat and potato which together were associated with adverse effects of -30% on soil carbon content in the upper soil layer ( P<0.001), -11% on soil water holding capacity ( P<0.01) and +15% on soil bulk density ( P<0.001). Negative effects were also found in some high intensity sequences on soil macroporosity and penetrometer resistance. Even in this high-yielding region, therefore, current forms of intensification are associated with adverse trends in soil condition that may be detrimental to future production. The effects of these trends in soil condition on agricultural output now need to be quantified, and the economic burden accounted for, if fields reduce their capacity to yield or need reparation to keep them productive.
  • Authors:
    • Andersen, M. N.
    • Kirk, H. G.
    • Nielsen, K. L.
    • Korup, K.
    • Kaminski, K. P.
    • Topbjerg, H. B.
    • Liu, F. L.
  • Source: ACTA AGRICULTURAE SCANDINAVICA SECTION B-SOIL AND PLANT SCIENCE
  • Volume: 65
  • Issue: 5
  • Year: 2015
  • Summary: A drought screening experiment focusing on intrinsic water use efficiency (WUEi) was carried out among 132 clones belonging to a dihaploid potato mapping population. The clones were exposed to progressive soil drying during a five-day period in a greenhouse pot experiment. Analysis of the underlying variables was done based on a multivariate data analysis strategy. The strategy successfully divided the clones into WUEi performance categories. Differences between clonal WUEi responses were traced back to differences in the net photosynthetic rate. Stomatal conductance (g(s)) did not vary significantly between the clones. Leaf abscisic acid (ABA) concentration and leaf water potential were found to reflect known isohydric behaviour for potato, and a non-linear relationship could be established for g(s) and leaf ABA concentration across the WUEi groups. Similarly, a common non-linear relationship between leaf ABA concentration and soil water potential was found. The latter findings suggest that the investigated population did not harbour significant genetic variation as to ABA production as function of soil desiccation level or with respect to the sensitivity of stomatal aperture vis-a-vis leaf ABA concentration and soil water potential.
  • Authors:
    • Pethybridge, S. J.
    • Hay, F.
  • Source: Web Of Knowledge
  • Issue: 1073
  • Year: 2015
  • Summary: A desktop study was undertaken to assess the contribution of the pyrethrum industry in Tasmania, Australia to on-farm greenhouse gas (GHG) emissions in comparison to potato and onion. Pyrethrum used significantly less diesel in transport than potato or onion. This was mainly due to the lower weight of dried flowers harvested from pyrethrum crops in comparison to the weight of crop from potato and onion fields (60 t/ha). First harvest pyrethrum required a similar amount of diesel to potato and onion for tractor and harvester operations. However, older pyrethrum crops required only 41% of the diesel used in potato and onion crops due mainly to the perennial nature of pyrethrum and the absence of cultivation in years subsequent to planting. Pyrethrum required greater inputs (kg a.i./ha) of herbicides and lower inputs of fungicides than potato and onion. All three crops required little input of insecticides. Pyrethrum had substantially lower inputs of nitrogen (N) and phosphorus (P) than potato or onion. First-harvest pyrethrum required only 38 and 59% of the N required by potato and onion, respectively. Moreover, pyrethrum required lower potassium (K) than potato, but higher K than onion. The electricity consumption associated with irrigation of pyrethrum and onion were similar, and amounted to 39% that of potato, due to the higher irrigation requirement of potato (5.1 ML/ha) in comparison to pyrethrum and onion (2.0 ML/ha) in Tasmania. The global warming potential (GWP) per hectare associated with planting to harvest of first year pyrethrum (18 months) and subsequently from one harvest to another (12 months) was estimated at 4,128.8 and 2,184.7 kg CO 2-e/ha, respectively. By comparison the GWP resulting from planting to harvest of potato and onion in Tasmania (4 months) was estimated at 5,284.0 and 4,875.3 kg CO 2-e/ha. The GWP of first year pyrethrum was therefore 78% that of potato and 85% that of onion, while the annual GWP per hectare of older pyrethrum fields was 41% that of potato and 45% that of onion. This study was based on strict assumptions and on generic emission factors for greenhouse gases. Therefore caution is required with the absolute figure for GWP. However, this study indicated that the on-farm production of pyrethrum is a relatively low contributor to GHG production on a per hectare basis, in comparison to other annual crops often grown in rotation.
  • Authors:
    • Cayambe,J.
    • Iglesias,A.
    • de Jalón,S. G.
    • Chuquillanqui,C.
    • Riga,P.
  • Source: ITEA
  • Volume: 111
  • Issue: 2
  • Year: 2015
  • Summary: The temperature rise of the planet associated with anthropogenic greenhouse gas emissions promotes interest for strategies to mitigate them. Since agriculture is a sector responsible for nearly a fifth of global emissions, it is necessary to identify measures to be applied, what is their mitigation potential and the estimated cost of implementing each measure. Our study addresses these questions by comparing the production of potato in two distinct production systems and with actual field data. In a first step, this paper calculates in a modern agricultural system the carbon footprint of mechanization and energy use for irrigation (located in Spain) and in less productive systems that integrate less technologies (located in Peru) . The results show that in the case studies in both countries the nitrogen cycle represents the primary source of greenhouse gas emissions, followed by energy fuel for irrigation and mechanization. Subsequently this study evaluates economically the mitigation actions through Marginal Abatement Cost Curves. These results demonstrate that the management of nitrogen fertilizer is the best alternative to reduce the carbon footprint because of their greater potential to reduce greenhouse gas emissions and their lower equivalent mitigation costs. Finally, the study provides a methodological framework that can be easily applied to other crops. © 2015, Asociacion Interprofesional para el Desarrollo Agrario. All rights reserved.
  • Authors:
    • Rashti,Mehran Rezaei
    • Wang,Weijin
    • Moody,Phil
    • Chen,Chengrong
    • Ghadiri,Hossein
  • Source: Atmospheric Environment
  • Volume: 112
  • Year: 2015
  • Summary: The emission of nitrous oxide (N2O) from vegetable fields contributes to the global greenhouse gases budget. However, reliable estimation of N2O emissions from vegetable production in the word has been lack. Vegetable cropping systems are characterised with high N application rates, irrigation, intensive production and multiple planting-harvest cycles during the year. Improved understanding of the key factors controlling N2O production is critical for developing effective mitigation strategies for vegetable cropping systems under different climate, soil type and management practices. Based on a comprehensive literature review and data analysis, we estimated the global N2O emission from vegetable production using seasonal fertiliser-induced emission factors (EFs) and examined the relationship of the seasonal emissions and EFs to possible controlling factors. The global average seasonal EF for vegetable fields is around 0.94% of applied N fertiliser, which is very similar to the Intergovernmental Panel on Climate Change (IPCC) annual emission factor of 1.0% for all cropping systems. The total N2O emission from global vegetable production is estimated to be 9.5 x 10(7) kg N2O N yr(-1), accounting for 9.0% of the total N2O emissions from synthetic fertilisers. Stepwise multiple regression analysis on the relationships of soil properties, climatic factors and N application rates to seasonal N2O emissions and N2O EFs showed that N fertiliser application rate is the main regulator of seasonal N2O emission from vegetable fields but the seasonal EFs are negatively related to soil organic carbon (SOC) content. In fields receiving >= 250 kg ha(-1) N fertiliser, 67% (n = 23, P <= 0.01) of the variation in seasonal emissions can be explained by the combined effects of N application rate, mean water-filled pore space (WFPS) and air temperature, while 59% (n = 23, P <= 0.01) of the variation in seasonal EFs relates to temperature, mean WFPS and soil pH. The result also shows that in vegetable fields with mean seasonal air temperature higher than 14 degrees C, increases in SOC decrease the seasonal EF and total N2O emissions from fertiliser N. (C) 2015 Elsevier Ltd. All rights reserved.
  • Authors:
    • Akhtar,Saqib Saleem
    • Andersen,Mathias Neumann
    • Liu,Fulai
  • Source: Agricultural Water Management
  • Volume: 158
  • Year: 2015
  • Summary: Salinity is one of the major threats to global food security. Biochar amendment could alleviate the negative impacts of salt stress in crop in the season. However, its long-term residual effect on reducing Na+ uptake in latter crops remains unknown. A pot experiment with wheat was conducted in a greenhouse. The soil used was from an earlier experiment on potato where the plants were irrigated with tap water (S0), 25 mM (S1) and 50 mM (S2) NaCl solutions and with 0 and 5% (w/w) biochar amendment. At onset of the experiment, three different EC levels at S0, S1 and S2 were established in the non-biochar control (2.3, 7.2 and 10.9 dS m(-1)) and the biochar amended (2.8, 8.1 and 11.8 dS m(-1)) soils, respectively. A column leaching experiment was also conducted in the greenhouse to study the adsorption capacity of biochar to Na+. The results indicated that biochar addition reduced plant sodium uptake by transient Na+ binding due to its high adsorption capacity, decreasing osmotic stress by enhancing soil moisture content, and by releasing mineral nutrients (particularly K+, Ca++, Mg++) into the soil solution. Growth, physiology and yield of wheat were affected positively with biochar amendment, particularly under high salinity level. It was concluded that addition of biochar had significant residual effect on reducing Na+ uptake in wheat under salinity stress. However, more detailed field studies should be carried out to evaluate the long-term residual effects of biochar for sustaining crop production in saline soils. (C) 2015 Elsevier B.V. All rights reserved.
  • Authors:
    • Brady,M. V.
    • Hedlund,K.
    • Rong-Gang Cong
    • Hemerik,L.
    • Hotes,S.
    • Machado,S.
    • Mattsson,L.
    • Schulz,E.
    • Thomsen,I. K.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Soil biodiversity through its delivery of ecosystem functions and attendant supporting ecosystem services - benefits soil organisms generate for farmers - underpins agricultural production. Yet lack of practical methods to value the long-term effects of current farming practices results, inevitably, in short-sighted management decisions. We present a method for valuing changes in supporting soil ecosystem services and associated soil natural capital - the value of the stock of soil organisms - in agriculture, based on resultant changes in future farm income streams. We assume that a relative change in soil organic C (SOC) concentration is correlated with changes in soil biodiversity and the generation of supporting ecosystem services. To quantify the effects of changes in supporting services on agricultural productivity, we fitted production functions to data from long-term field experiments in Europe and the United States. The different agricultural treatments at each site resulted in significant changes in SOC concentrations with time. Declines in associated services are shown to reduce both maximum yield and fertilizer-use efficiency in the future. The average depreciation of soil natural capital, for a 1% relative reduction in SOC concentration, was 144 Euro ha -1 (SD 47 Euro ha -1) when discounting future values to their current value at 3%; the variation was explained by site-specific factors and the current SOC concentration. Moreover, the results show that soil ecosystem services cannot be fully replaced by purchased inputs; they are imperfect substitutes. We anticipate that our results will both encourage and make it possible to include the value of soil natural capital in decisions.
  • Authors:
    • Yan Jiao
    • Hou JianHua
    • Zhao JiangHong
    • Yang WenZhu
  • Source: Acta Agriculturae Scandinavica: Section B, Soil & Plant Science
  • Volume: 65
  • Issue: 6
  • Year: 2015
  • Summary: The effects of soil properties and cropland age on atmospheric nitrous oxide (N2O) emissions following the conversion of grassland to cropland in temperate grassland ecosystems are uncertain. In this study, N2O emissions were compared among grassland and cropland soils in the agro-pastoral ecotone of Inner Mongolia over three growing seasons. Four adjacent sites with different land-use histories were selected, including grassland and croplands cultivated for 5, 10, and 50 years after conversion. N2O flux measurements were obtained using a closed-chamber method and were performed continuously during vegetation periods. After the conversion of grassland to cropland, N2O emission initially decreased and thereafter increased in the study sites. The cumulative N2O emissions of the cropland soils 5 and 10 years in age were 10-50% less than those of the grassland, and the N2O emissions from the cropland soil 50 years in age were 10-30% greater than the grassland. When the seasonal emissions were correlated against single soil parameter, the key soil parameter that affected N2O emissions over the entire growing season was the soil moisture content. When the interactions among soil parameters were considered, the amount of N2O emissions could be quantitatively described by a linear combination of two soil variables, the soil ammonium nitrogen (NH4+-N) and moisture concentrations. This study demonstrates how the time of land use conversion from grassland to cropland can positively or negatively affect N2O emission.
  • Authors:
    • Yunusa,Isa A. M.
    • Blair,Graeme
    • Zerihun,Ayalsew
    • Yang,Shenjiao
    • Wilson,Susan C.
    • Young,Iain M.
  • Source: Acta Agriculturae Scandinavica, Section B — Soil & Plant Science
  • Volume: 131
  • Issue: 4
  • Year: 2015
  • Summary: Coal-fired power generation and agriculture account for more than half of global greenhouse gas emissions, but the coal fly ash (CFA) produced in the former can be a resource for reducing emissions from agriculture to minimise environmental footprints in both industries. Our aim in this study was to test how acidic and alkaline CFA addition could minimise loss of C and N from acidic soil, with or without added manure. We determined composition and structural characteristics of acidic and alkaline CFA for their capacity to adsorb organic carbon, but observed poor adsorption because of low concentrations of cenospheres and unburnt carbon as the primary absorbents in the ash. Addition of CFA had no impact on the loss of carbon or nitrogen from unmanured soil in which concentrations of these nutrients were low. Loss of carbon from manured soil was reduced by 36 % with alkaline ashes and by 3-fold with acidic ashes; while loss of N was 30-50 % lower with acidic ashes, but 28 % higher with alkaline ashes, compared with no ash treatment. The increases in C sparing with CFA addition were achieved not by direct C absorption but by restraining microbial population and respiration, and potentially emissions. Alkaline CFA increased soil pH and if used to substitute just 10 % of lime for ameliorating soil acidity would reduce CO2 emission associated with the mining of the lime and its eventual dissolution in soil by 2.66 Tg or 2.8 % of Australia's annual agricultural emissions. High concentrations of oxides of phosphorus, silicon, titanium and clay particles in acidic ashes, and oxides of cations in alkaline ashes, were associated with potential for promoting C storage and acidity amelioration in soil.