• Authors:
    • Blanco-Canqui, H.
    • Schlegel, A. J.
  • Source: Web Of Knowledge
  • Volume: 42
  • Issue: 3
  • Year: 2013
  • Summary: Inorganic fertilizers are widely used for crop production, but their long-term impacts on soil organic carbon (SOC) pools and soil physical attributes are not fully understood. We studied how half a century of N application at 0, 45, 90, 134, 179, and 224 kg ha -1 and P application at 0, 20, and 40 kg ha -1 (since 1992) affected SOC pools and soil structural and hydraulic parameters in irrigated continuous corn ( Zea mays L.) under conventional till on an Aridic Haplustoll in the central Great Plains. Application of 45, 90, 134, 179, and 224 kg N ha -1 increased the SOC pool by 4.6, 6.8, 7.6, 7.9, and 9.7 Mg ha -1, respectively, relative to nonfertilized plots in the 0- to 45-cm depth. Application of 20 kg P ha -1 increased the SOC pool by 2.9 Mg ha -1 in the 0- to 30-cm depth. The highest N rate increased the SOC pool by 195 kg ha -1 yr -1. The C gains may be, however, offset by the C hidden costs of N fertilization. Application of >45 kg N ha -1 reduced the proportion of soil macroaggregates (>0.25 mm) in the 7.5- to 30-cm depth. Fertilization did not affect hydraulic properties, but application of ≥90 kg N ha -1 slightly increased aggregate water repellency. An increase in SOC concentration did not increase the mean weight diameter of wet aggregates ( r=0.1; P>0.10), but it slightly increased aggregate water repellency ( r=0.5; P<0.005). Overall, long-term inorganic fertilization to irrigated corn can increase SOC pool, but it may reduce soil structural stability.
  • Authors:
    • Gimeno, B. S.
    • Gattinger, A.
    • Lassaletta, L.
    • Aguilera, E.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 168
  • Year: 2013
  • Summary: Mediterranean croplands are seasonally dry agroecosystems with low soil organic carbon (SOC) content and high risk of land degradation and desertification. The increase in SOC is of special interest in these systems, as it can help to build resilience for climate change adaptation while contributing to mitigate global warming through the sequestration of atmospheric carbon (C). We compared SOC change and C sequestration under a number of recommended management practices (RMPs) with neighboring conventional plots under Mediterranean climate (174 data sets from 79 references). The highest response in C sequestration was achieved by those practices applying largest amounts of C inputs (land treatment and organic amendments). Conservation tillage practices (no-tillage and reduced tillage) induced lower effect sizes but significantly promoted C sequestration, whereas no effect and negative net sequestration rates were observed for slurry applications and unfertilized treatments, respectively. Practices combining external organic amendments with cover crops or conservation tillage (combined management practices and organic management) showed very good performance in C sequestration. We studied separately the changes in SOC under organic management, with 80 data sets from 30 references. The results also suggest that the degree of intensification in C input rate is the main driver behind the relative C accumulation in organic treatments. Thus, highest net C sequestration rates were observed in most eco-intensive groups, such as "irrigated", "horticulture" and controlled experiments ("plot scale"). (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Smart, D. R.
    • Fanton-Borges, A. C.
    • Alsina, M. M.
  • Source: Ecosphere
  • Volume: 4
  • Issue: 1
  • Year: 2013
  • Summary: Nitrogen fertilizer applied to soil is the primary source of the greenhouse gas (GHG) nitrous oxide (N2O). The assessment of N2O emissions, or net fluxes of the GHG methane (CH4), are lacking for upland, arid agricultural ecosystems worldwide. In California, where rates of application for nitrogen (N) can exceed 300 kg per hectare for N-intensive fruit and nut crops (>2 million acres), liquid N fertilizers applied through microirrigation systems (fertigation) represent the predominant method of N fertilization. Little information is available for how these concentrated and spatially discrete N solution applications influence N2O emissions and net CH4 fluxes (the sum of methanogenic and methanotrophic activity). In this study we examined soil N2O-N emissions and net CH4 fluxes for drip and stationary microsprinklers, two of the most widely used fertigation emitters, in an almond orchard where 235.5 kg N/ha were applied during the season of measurement (2009-2010). We accomplished this by modeling the spatial patterns of N2O and CH4 at the scale of meters and centimeters using simple mathematical approaches. For two applications of 33.6 kg/ha and three applications of 56.1 kg/ha targeted to the phenologic stages with highest tree N demand, the spatial patterns of N2O fluxes were similar to the emitter water distribution pattern and independent of temperature and fertilizer N form applied. Net CH4 fluxes were extremely low and there was no discernible spatial pattern, but areas kept dry (driveways between tree rows) generally consumed CH4 while it was produced in the microirrigation wet-up area. The N2O-N emissions for fertigation events at the scale of days, and over a season, were significantly higher from the drip irrigated orchard (1.6 +/- 0.7 kg N2O-N ha(-1) yr(-1)) than a microsprinkler irrigated orchard (0.6 +/- 0.3 kg N2O-N ha(-1) yr(-1)). N2O emissions and net CH4 fluxes were only significantly correlated with soil water filled pore space and not with mineral-N. The correlation was much better for N2O emissions. Our results greatly improve our ability to scale N2O production to the orchard level, and provide growers with a tool for lowering almond orchard carbon and nitrogen footprints.
  • Authors:
    • Lloveras, J.
    • Santiveri, F.
    • Biau, A.
  • Source: Agronomy Journal
  • Volume: 105
  • Issue: 5
  • Year: 2013
  • Summary: The incorporation of crop stover into the soil improves soil fertility and crop productivity by increasing C sequestration and reducing the emission of greenhouse gases among other parameters. Interactions between crop stover management and N fertilization could help to improve C sequestration while increasing productivity. The objective of this study was to evaluate the impact of incorporating or removing corn (Zea mays L.) stover, in combination with different N fertilization rates (0, 100, 200, and 300 kg N ha(-1)), on corn production, soil organic carbon (SOC), and soil mineral nitrogen (SMN) in high production areas. We performed two field experiments (Exp. 1 and 2) for 3 yr under sprinkler irrigation. Over the duration of the experiment (short-term period), stover management did not affect corn production or SMN levels, while high average grain yields were achieved (16-20 Mg ha(-1)) when N was applied. After 3 yr, removing the stover reduced SOC levels by approximately 0.82 and 1.06 g C m(-2) (0-30-cm depth) in 2012 in Exp. 1 and 2, respectively. The amounts of corn stover incorporated were higher than 16 Mg ha(-1) yr(-1) of dry matter. Our data suggest that returning stover to the soil has a positive short-term impact on soil quality without grain yield penalties. Although selling the stover provides a short-term economic advantage, continuous stover removal may cause significant soil degradation in the future.
  • Authors:
    • Yilmaz, G.
    • Bilgili, A. V.
    • Ikinci, A.
  • Source: Turkish Journal of Agriculture & Forestry
  • Volume: 37
  • Issue: 6
  • Year: 2013
  • Summary: Broad interest in reducing greenhouse gas emissions requires a better understanding of controls on carbon dioxide (CO2) release under different agricultural management practices. The objective of this study was to investigate and model seasonal variation of soil CO2 emissions from an apple orchard field (Malus domestica L. 'Starkrimson'). Soil CO2 emissions from an apple orchard managed with common practices were measured weekly over a 3-year period (May 2008 to May 2011) from both under the crowns of trees (CO2-UC) and between rows (CO2-BR) using a soda lime technique and were modeled using available environmental data. The study area is located in the Harran Plain of southeastern Turkey and has a semiarid climate. The weekly soil CO2 emissions ranged from 87.8 to 1428 kg week(-1) ha(-1), from 74.6 to 835 kg week(-1) ha(-1), and from 88.6 to 1087 kg week(-1) ha(-1) for CO2-UC, CO2-BR, and the average of both (CO2-AVG), respectively, and showed a pronounced seasonal pattern with the lowest emissions in winter (January and February) and the highest emissions during the growing season (April to December). Relative to 2008 emissions, 2009 CO2 emissions increased by approximately 75%, and 2010 emissions increased by approximately 88%. Comparison of 3 models (multiple linear regression, principal component regression, and multivariate adaptive regression splines) showed that multivariate adaptive regression splines provided the best performance in modeling soil CO2 emissions, explaining overall variation of 64%, 56%, 76%, and 53% in CO2-AVG for the first, second, third, and all three 3 periods, respectively. In conclusion, overall findings showed that soil CO2 emissions could be modeled by available environmental data such as air and soil temperature.
  • Authors:
    • Heinemann, A. B.
    • Moreira, J. A. A.
    • Silveira, P. M. da
    • Machado, P. L. O. de A.
    • Costa, A. R. da
    • Leal, W. G. de O.
    • Madari, B. E.
    • Carvalho, M. T. de M.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 48
  • Issue: 5
  • Year: 2013
  • Summary: The objective of this work was to measure the fluxes of N2O‑N and NH3‑N throughout the growing season of irrigated common‑bean (Phaseolus vulgaris), as affected by mulching and mineral fertilization. Fluxes of N2O‑N and NH3‑N were evaluated in areas with or without Congo signal grass mulching (Urochloa ruziziensis) or mineral fertilization. Fluxes of N were also measured in a native Cerrado area, which served as reference. Total N2O‑N and NH3‑N emissions were positively related to the increasing concentrations of moisture, ammonium, and nitrate in the crop system, within 0.5 m soil depth. Carbon content in the substrate and microbial biomass within 0.1 m soil depth were favoured by Congo signal grass and related to higher emissions of N2O‑N, regardless of N fertilization. Emission factors (N losses from the applied mineral nitrogen) for N2O‑N (0.01-0.02%) and NH3‑N (0.3-0.6%) were lower than the default value recognized by the Intergovernmental Panel on Climate Change. Mulch of Congo signal grass benefits N2O‑N emission regardless of N fertilization.
  • Authors:
    • Alves Moreira, J. A.
    • da Silveira, P. M.
    • Oliveira de Almeida Machado, P. L.
    • da Costa, A. R.
    • de Oliveira Leal, W. G.
    • Madari, B. E.
    • de Melo Carvalho, M. T.
    • Heinemann, A. B.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 48
  • Issue: 5
  • Year: 2013
  • Summary: The objective of this work was to measure the fluxes of N2O-N and NH3-N throughout the growing season of irrigated common-bean (Phaseolus vulgaris), as affected by mulching and mineral fertilization. Fluxes of N2O-N and NH3-N were evaluated in areas with or without Congo signal grass mulching (Urochloa ruziziensis) or mineral fertilization. Fluxes of N were also measured in a native Cerrado area, which served as reference. Total N2O-N and NH3-N emissions were positively related to the increasing concentrations of moisture, ammonium, and nitrate in the crop system, within 0.5 m soil depth. Carbon content in the substrate and microbial biomass within 0.1 m soil depth were favoured by Congo signal grass and related to higher emissions of N2O-N, regardless of N fertilization. Emission factors (N losses from the applied mineral nitrogen) for N2O-N (0.01-0.02%) and NH3-N (0.3-0.6%) were lower than the default value recognized by the Intergovernmental Panel on Climate Change. Mulch of Congo signal grass benefits N2O-N emission regardless of N fertilization.
  • Authors:
    • Mahanta, D.
    • Tuti, M. D.
    • Gupta, H. S.
    • Bhatt, J. C.
    • Bisht, J. K.
    • Pandey, S. C.
    • Bhattacharyya, R.
    • Mina, B. L.
    • Singh, R. D.
    • Chandra, S.
    • Srivastva, A. K.
    • Kundu, S.
  • Source: Agronomy Journal
  • Volume: 105
  • Issue: 1
  • Year: 2013
  • Summary: Carbon retention is a critical issue in arable farming of the Indian Himalayas. This study, conducted from 2001 through 2010 on a sandy clay loam soil, evaluated the effect of tillage alterations (conventional tillage [CT] and zero tillage [ZT]) and selected irrigation treatments (I1: pre-sowing, I2: pre-sowing + active tillering or crown root initiation, I3: pre-sowing + active tillering or crown root initiation + panicle initiation or flowering, and I4: pre-sowing + active tillering or crown root initiation + panicle initiation or flowering + grain filling), applied at the critical growth stages to rice ( Oryza sativa L.) and wheat ( Triticum aestivum L.) on soil organic C (SOC) retention and its pools, soil aggregation, and aggregate-associated C contents in the 0- to 30-cm soil layer. Results indicate that the plots under ZT had nearly 17 and 14% higher total SOC and particulate organic C contents compared with CT (~9.8 and 3.6 g kg -1 soil) in the 0- to 5-cm soil layer after 9 yr of cropping, despite similar mean aboveground biomass yields of both crops on both CT and ZT plots. Tillage had no effect on C pools in the subsurface layers. Irrigation had positive impact on SOC content in the 0- to 5- and 5- to 15-cm layers. Although the labile pools of SOC were positively affected by ZT, the recalcitrant pool was not. Plots under ZT and I4 also had higher large and small macroaggregates and macroaggregate-associated SOC. Thus, adoption of ZT is the better management option for soil C improvement than CT, and irrigation generally enhances the positive impacts.
  • Authors:
    • Payero, J.
    • Rowlings, D. W.
    • Grace, P. R.
    • Scheer, C.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 95
  • Issue: 1
  • Year: 2013
  • Summary: Irrigation is known to stimulate soil microbial carbon and nitrogen turnover and potentially the emissions of nitrous oxide (N2O) and carbon dioxide (CO2). We conducted a study to evaluate the effect of three different irrigation intensities on soil N2O and CO2 fluxes and to determine if irrigation management can be used to mitigate N2O emissions from irrigated cotton on black vertisols in South-Eastern Queensland, Australia. Fluxes were measured over the entire 2009/2010 cotton growing season with a fully automated chamber system that measured emissions on a sub-daily basis. Irrigation intensity had a significant effect on CO2 emission. More frequent irrigation stimulated soil respiration and seasonal CO2 fluxes ranged from 2.7 to 4.1 Mg-C ha(-1) for the treatments with the lowest and highest irrigation frequency, respectively. N2O emission happened episodic with highest emissions when heavy rainfall or irrigation coincided with elevated soil mineral N levels and seasonal emissions ranged from 0.80 to 1.07 kg N2O-N ha(-1) for the different treatments. Emission factors (EF = proportion of N fertilizer emitted as N2O) over the cotton cropping season, uncorrected for background emissions, ranged from 0.40 to 0.53 % of total N applied for the different treatments. There was no significant effect of the different irrigation treatments on soil N2O fluxes because highest emission happened in all treatments following heavy rainfall caused by a series of summer thunderstorms which overrode the effect of the irrigation treatment. However, higher irrigation intensity increased the cotton yield and therefore reduced the N2O intensity (N2O emission per lint yield) of this cropping system. Our data suggest that there is only limited scope to reduce absolute N2O emissions by different irrigation intensities in irrigated cotton systems with summer dominated rainfall. However, the significant impact of the irrigation treatments on the N2O intensity clearly shows that irrigation can easily be used to optimize the N2O intensity of such a system.
  • Authors:
    • Hulugalle, N. R.
  • Source: Crop and Pasture Science
  • Volume: 64
  • Issue: 8
  • Year: 2013
  • Summary: Partial mitigation of global warming caused by accelerated emissions of greenhouse gases such as carbon dioxide may be possible by storing atmospheric carbon in soils. Carbon storage is influenced by processes and properties that affect soil aggregation, such as clay and silt concentrations and mineralogy, intensity and frequency of wet/dry cycles, and microbial activity. Microbial activity, in turn, is influenced by factors such as temperature, nutrient and water availability, and residue quality. The objective of this study was to assess the influence of average annual maximum temperature on soil carbon storage in Vertosols under cotton-based farming systems. This paper reports a re-evaluation of results obtained from a series of experiments on cotton-farming systems conducted in eastern Australia between 1993 and 2010. The experimental sites were in the Macquarie and Namoi Valleys of New South Wales, and the Darling Downs and Central Highlands of Queensland. Average soil organic carbon storage in the 0-0.6m depth was highest in a Black Vertosol in Central Queensland and lowest in a Grey Vertosol that was irrigated with treated sewage effluent at Narrabri. At other sites, average values were generally comparable and ranged from 65 to 85 t C/ha. Climatic parameters such as ambient maximum temperature, T-max, and rainfall at rainfed sites (but not irrigated sites) were also related to soil organic carbon storage. At most sites, variations in carbon storage with average ambient maximum temperature were described by Gaussian models or bell-shaped curves, which are characteristic of microbial decomposition. Carbon storage occurred at peak rates only for a very limited temperature range at any one site, with these temperatures increasing with decreasing distance from the equator. The exception was a site near Narrabri that was irrigated with treated sewage effluent, where the relationship between soil organic carbon and T-max was linear. The decrease or absence of change in soil carbon storage with time reported in many Australian studies of annual cropping systems may be due to carbon storage occurring within a limited temperature range, whereas intra-seasonal average maximum temperatures can range widely. Further research needs to be conducted under field conditions to confirm these observations.