• Authors:
    • Makabe, S.
    • Kanazaki, N.
    • Ikeya, K.
    • Watanabe, A.
    • Sugiura, Y.
    • Shibata, A.
  • Source: Journal of Environmental Management
  • Volume: 144
  • Year: 2014
  • Summary: The application of char to agricultural land is recognized as a potential way to sequester atmospheric carbon (C) assimilated by plants in soil, thus decelerating global warming. Such a process would also be expected to improve plant growth and the physical and chemical properties of soil. However, field investigations of the effects of continuous char application have not been reported. In the present study, the effects of repetitive bamboo char application on CO 2, CH 4, and N 2O flux from soil, soil C content, and crop yield were investigated at two upland fields over five crop seasons. Three treatments: chemical fertilizer (CF) applied plots (Control plot); cattle manure (CM) (10 t ha -1) and CF applied plot (CM plot); and bamboo char (20 t ha -1), cattle manure (10 t ha -1), and CF applied plot (Char/CM plot), were arranged in each field. After three crop seasons, the fourth treatment with char was applied without CF (Char plot) was given to one of the fields. CM and/or char were applied every crop season. Gas fluxes were measured using the static chamber method. Seasonal variations in CO 2 flux and total CO 2 emissions were consistently similar between the CM and Char/CM plots and between the Char and Control plots. As such, the decomposition rate of bamboo char was quite small, and the positive or negative effect of char on CM decomposition was not significant in the fields. Soil C analysis provided confirmation of this. CM application enhanced N 2O emission mainly in the summer crop season. The differences in total N 2O emission between the Char/CM and CM plots as well as between the Char and Control plots were insignificant in most cases. Total CH 4 flux was negligibly small in all cases. Although the yield of winter crop (broccoli) in the Char/CM plots was twice observed to be higher than that in the Control and CM plots at one of the fields, in general, the char application had no effect on overall crop yield. Thus, the repeated application of bamboo char had no significant influence on greenhouse gas emissions and crop yields, but a high C accumulating function was found.
  • Authors:
    • Calegari, A.
    • Balota, E. L.
    • Nakatani, A. S.
    • Coyne, M. S.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 197
  • Year: 2014
  • Summary: Soil degradation in Brazil is a concern due to intensive agricultural production. Combining conservation practice, such as no-tillage, with winter cover crops may increase microbial activity and enhance soil quality more than either practice alone. This research evaluated the benefits of long-term (23 years) winter cover crops and reduced tillage on soil microbial quality indicators in an Oxisol from Parana State, Southern Brazil. The winter cover treatments were: fallow, black oat, wheat, radish, blue lupin, and hairy vetch in conventional (plow) or no-tillage management; the summer crop was a soybean/maize rotation. Soil quality parameters included organic C, microbial biomass C and N, total and labile polysaccharide, easily extractable and total glomalin-related soil protein, and enzyme activity. Winter crops increased soil microbial quality parameters compared to fallow in both tillage systems, with greater relative increase in conventional than no-tillage. No-tillage had higher microbial biomass, polysaccharide, glomalin-related soil protein, and soil enzyme activity than conventional tillage. Including legumes in the crop rotation was important for N balance in the soil-plant system, increasing soil organic C content, and enhancing soil quality parameters to a greater extent than grasses or radish. The microbial parameters proved to be more sensitive indicators of soil change than soil organic C. Cultivating winter cover crop with either tillage is a beneficial practice enhancing soil microbial quality and also soil organic C stocks.
  • Authors:
    • Burmester, C. H.
    • Balkcom, K. S.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 2
  • Year: 2014
  • Summary: Alabama wheat ( Triticum aestivum L.) farmers are changing management practices, which include using higher N fertilizer rates and planting wheat with no-tillage or other conservation tillage systems to maximize yields. Experiments were conducted to (i) determine the level of tillage necessary to optimize wheat yields across different regions of Alabama and (ii) determine if N requirements change across tillage systems and regions in Alabama at four locations resulting in 9 site-year comparisons. Each experiment consisted of a split-plot design with tillage as the main plot and 12 N fertilizer treatments as subplots, replicated four times to compare Zadoks' Growth Stage (GS)-30 tiller densities, tiller N concentrations, tiller biomass, GS-31 wheat biomass, biomass N concentration, wheat yields, and grain crude protein. Nitrogen treatments consisted of different rates across fall, GS-30, and GS-31 application times. Tillage systems had no effect on tiller density, tiller N concentration, or tiller biomass, but fall N increased tiller density 15% and tiller biomass 34% across Coastal Plain locations. Non-inversion tillage increased wheat yields 13% on Coastal Plain soils compared to conventional tillage. Fall N increased wheat yields 10%, and N applied at GS-30 improved yields 18% compared to delaying application until GS-31, indicating application of fall N and applying total N by GS-30 was imperative for successful wheat production on Coastal Plain soils. Neither tillage system nor N applications affected wheat production extensively across the Limestone Valley. Non-inversion tillage or no-tillage with current recommended N practices can be successfully used in Alabama wheat production.
  • Authors:
    • Mahanta, S. K.
    • Ghosh, P. K.
  • Source: Invited Article
  • Volume: 35
  • Issue: 2
  • Year: 2014
  • Summary: Globally soils contain around twice the amount of carbon in the atmosphere and thrice in vegetation. Therefore, soil is both 'a source and a sink' for greenhouse gases and balance between the functions is very delicate. The gases move continuously from one pool to another maintaining balance in different pools of the ecosystem. Appropriate management of soil offers to the potential to provide solutions for each of the challenges related to food security and climate change. The estimated carbon sequestration potential of world soils lies between 0.4 to 1.2 Gt per year which includes 0.01-0.30 Gt per year from grasslands. Carbon sequestration can be enhanced in grasslands through grazing management, sowing favorable forage species, fertilizer application and irrigation, restoration of degraded grasslands etc. However, there are certain limitations that hinder in adopting the practices for enhancing carbon sequestration in grasslands. The limitations include continuous degradation of grasslands, changing climate, paucity of information on carbon stock of grasslands from developing countries, disagreement on systems for documenting carbon stock changes over a period of time, hindrance in policy implementations etc.
  • Authors:
    • Fumagalli,M.
  • Source: Italian Journal of Agrometeorology
  • Volume: 20
  • Issue: 1
  • Year: 2014
  • Summary: Intensive maize production in Lombardy region (northern Italy) is widespread and requires big amounts of input, especially nitrogen (N), thus leading to potential environmental risks. Starting from farm survey data the current work aims to evaluate how alternative N management options for reducing losses can be effective in climate change mitigation. Under current management (ACT) of typical continuous maize cropping systems across the region, the greenhouse gases (GHG) emissions from the production of inorganic fertilisers and from direct and indirect N2O released after N application accounted for, on average, 67% of the total GHG emissions. The adoption of the best N management plans (FERT scenario), reduced GHG emissions and C-footprint (expressed per unit of agricultural product) by 27 and 26%, respectively. Furthermore, the double cropping system (two crops harvested in 12 months - ROT scenario) strongly increased GHG emissions in comparison with the only cultivation of a summer crop. However, the high productivity of this system, led to a C-footprint lower than the ACT one and still higher than the FERT one. The current work highlights the opportunities for carbon mitigation offered by changes on field N management, without significantly impact the yield. © 2015, Patron Editore S.r.l. All rights reserved.
  • Authors:
    • Asano,Maki
    • Wagai,Rota
  • Source: Geoferma
  • Volume: 216
  • Year: 2014
  • Summary: Aggregate hierarchy, a fundamental soil feature controlling various physical and biogeochemical processes, is well-studied for soils dominated by crystalline minerals but not for the soils rich in poorly-crystalline or short-range-order (SRO) minerals. We examined the presence and nature of aggregate hierarchy in the surface horizon of an Andisol which is characterized by high concentrations of organic matter and SRO minerals (esp.allophane/imogolite). Several pretreatments were tested to achieve maximum dispersion and the particle-size fractions isolated (53 mu m) were characterized by SEM, XRD, and elemental analyses. Mass distribution as well as physical and chemical characteristics among the isolated size fractions were strongly influenced by the dispersion level, indicating the importance to find optimal dispersion level. Upon minimum dispersion (wet sieving), over 95% of total C was present as >53 mu m aggregates and the C concentration and C:N ratio remained constant across all size fractions. Even after mechanical shaking, >53 mu m and 2-53 mu m fractions accounted for 37% and 41% of total C, respectively. Maximum dispersion was achieved only after sodium saturation pretreatment followed by the sonication at the energy level 5-10 folds higher than normally required for non-volcanic soils (5 kJ While dissolving minor levels of organic matter and metals, the maximum dispersion treatment liberated large amounts of small particles (<2 mu m) that were enriched in N-rich organic matter, SRO mineral, and organo-metallic complex and that accounted for 48% of total mass, 63% of C, N, and 72 to 91% of extractable phases of Al, Si, and Fe by pyrophosphate and acid-oxalate. The step-wise breakdown of macro- and micro-aggregates with concurrent liberation of micron- to submicron-size particles upon the increased levels of dispersion, therefore, represents clear evidence of aggregate hierarchy on this soil type. Due to their abundance and chemistry, the small particles (<02 and 0.2-2.0 mu m fractions) likely acted as strong binding agents to form both micro- and macro-aggregates. Significant positive correlation of organic matter concentration and C:N ratio against the extractable metal concentrations was found when samples of all size fractions and dispersion treatments were combined. We proposed a simple conceptual model for Artdisol aggregate hierarchy to explain the observed variation in the abundance and chemistry of isolated fractions. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Ziadi, N.
    • Zhang, J.
    • Qin, S.
    • Xiang, J.
    • Ding, W.
    • Fan, J.
  • Source: Geoderma
  • Volume: 230-231
  • Year: 2014
  • Summary: Understanding the balance between soil organic carbon (SOC) accumulation and depletion under different fertilization regimes is important for improving soil quality and crop productivity and for mitigating climate change. A long-term field experiment established in 1989 was used to monitor the influence of organic and inorganic fertilizers on the SOC stock in a soil depth of 0-60 cm under an intensive wheat-maize cropping system in the North China Plain. The study involved seven treatments with four replicates: CM, compost; HCM, half compost nitrogen (N) plus half fertilizer N; NPK, fertilizer N, phosphorus (P), and potassium (K); NP, fertilizer N and P; NK, fertilizer N and K; PK, fertilizer P and K; and CK, control without fertilization. Soil samples were collected and analyzed for SOC content in the 0-20 cm layer each year and in the 20-40 cm and 40-60 cm layers every five years. The SOC stock in the 0-60 cm depth displayed a net decrease over 20 years under treatments without fertilizer P or N, and in contrast, increased by proportions ranging from 3.7% to 31.1% under the addition of compost and fertilizer N and P. The stabilization rate of exogenous organic carbon (C) into SOC was only 1.5% in NPK-treated soil but amounted to 8.7% to 14.1% in compost-amended soils (CM and HCM). The total quantities of sequestered SOC were linearly related (P < 0.01) to cumulative C inputs to the soil, and a critical input amount of 2.04 Mg C ha(-1) yr(-1) was found to be required to maintain the SOC stock level (zero change due to cropping). However, the organic C sequestration rate in the 0-60 cm depth decreased from 0.41 to 0.29 Mg C ha(-1) yr(-1) for HCM and from 0.90 to 0.29 Mg C ha(-1) yr(-1) for CM from the period of 1989-1994 to the period of 2004-.2009, indicating that the SOC stock was getting to saturation after the long-term application of compost. The estimated SOC saturation level in the 0-60 cm depth for CM was 61.31 Mg C ha(-1), which was 1.52 and 1.14 times the levels for NPK and HCM, respectively. These results show that SOC sequestration in the North China Plain may mainly depend on the application of organic fertilizer. Furthermore, the SOC sequestration potential in the 0-20 cm layer accounted for 40.3% to 44.6% of the total amount in the 0-60 cm depth for NPK, HCM, and CM, indicating that the SOC sequestration potential would be underestimated using topsoil only and that improving the depth distribution may be a practical way to achieve C sequestration. (C) 2014 Elsevier B.V. All rights reserved.
  • Authors:
    • Bishop, T. F. A.
    • Karunaratne, S. B.
    • Baldock, J. A.
    • Odeh, I. O. A.
  • Source: Science Article
  • Volume: 219-220
  • Year: 2014
  • Summary: This study aims to map the measurable fractions of soil organic carbon related to the RothC carbon model at the catchment scale and to assess the model and prediction quality. It also discusses how the outputs can be used to provide initial pool estimates for process modelling of soil carbon in a spatial context. The study was carried out in Cox's Creek catchment in northern New South Wales, Australia. Samples were collected in 2010 using a design-based sampling scheme. The measurable fractions of the RothC soil carbon model considered in this study were resistant organic carbon, humus organic carbon and particulate organic carbon. It has been reported that these measurable fractions of soil organic carbon can successfully substitute for the conceptual pools of carbon in the RothC soil carbon model. All the samples were scanned to create MIR spectra and recently developed spectroscopic models by Commonwealth Scientific and Industrial Research Organisation (CSIRO) under the national soil carbon research programme (2009-2012) were used to carry out the prediction of respective fractions. We used linear mixed models to create a model for mapping the measurable fractions of soil organic carbon across the catchment. The cross validation results revealed that the highest Lin's concordance correlation between measured and predicted values was recorded for resistant organic carbon (0.78), followed by humus organic carbon (0.74) and particulate organic carbon (0.58). Finally, to assess the uncertainty of the predictions we carded out conditional sequential Gaussian simulations. We demonstrated that measurable fractions of carbon related to the RothC model can be mapped at catchment scale with reasonable accuracy. The derived maps could be used in future studies to initialize the RothC model at any location across the landscape with quantified uncertainties. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • He, W.
    • Liu, S.
    • Gu, R.
    • Yu, J.
    • Yan, C.
    • Teclemariam, S.
    • Liu, E.
    • Liu, Q.
  • Source: Geoderma
  • Volume: 213
  • Year: 2014
  • Summary: The influence of different tillage practices on soil organic carbon levels is more significant under long-term tillage compared to short-term tillage. Despite the great interest in the effect of no-tillage (NT) management practice on carbon sequestration, the long-term effect of NT practice on soil organic carbon and its fractions in northern China remain unclear. We evaluated the long-term effects (after 17 years) of NT and conventional tillage (CT) practices on soil organic carbon and its fractions at different depths ranging from 0 to 60 cm using a cinnamon soil in Shanxi, China. A randomised block design with three replications was used to evaluate both the tillage and its effects on the yield performance of winter wheat (Triticum aestivum L.). After 17 years, the soil organic carbon (SOC) concentration in the NT soil was greater than that of the CT soil, but only in the layer that was located between 0 and 10 cm. There was a significant accumulation of SOC (0-60 cm) in the NT soil (50.2 Mg C ha(-1)) compared to that observed in the CT soil (46.3 Mg C ha(-1)). The particulate organic matter C (POM-C), dissolved organic C (DOC), and microbial biomass C (MBC) levels in the 0-5 cm layer under NT treatment were 155%, 232%, and 63% greater, respectively, compared to the CT treatment. The POM-C, DOC, and MBC in the 5-10 cm layer under NT treatment were 67%, 123%, and 63% greater, respectively, compared to the CT treatment. Below 10 cm, the labile carbon observed in the NT treatment did not differ from that of the CT treatment. Significantly positive correlations were observed between the SOC and the labile organic C fractions. Moreover, the winter wheat (T. aestivum L) yield increased 28.9% in the NT treatment compared to the CT treatment. The data show that NT is an effective and sustainable management practice that improves carbon sequestration and increases soil fertility, resulting in higher winter wheat yields in the rainfed dryland farming areas of northern China. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Siegfried, W.
    • Rohr, C.
    • Riemann, D.
    • Retso, D.
    • Pribyl, K.
    • Nordl, O.
    • Litzenburger, L.
    • Limanowka, D.
    • Labbe, T.
    • Kotyza, O.
    • Kiss, A.
    • Himmelsbach, I.
    • Glaser, R.
    • Dobrovolny, P.
    • Contino, A.
    • Camenisch, C.
    • Burmeister, K.
    • Brazdil, R.
    • Bieber, U.
    • Barriendos, M.
    • Alcoforado, M.
    • Luterbacher, J.
    • Gruenewald, U.
    • Herget, J.
    • Seneviratne, S.
    • Wagner, S.
    • Zorita, E.
    • Werner, J.
    • Pfister, C.
    • Wetter, O.
    • Soderberg, J.
    • Spring, J.
  • Source: Climatic Change
  • Volume: 125
  • Issue: 3-4
  • Year: 2014
  • Summary: The heat waves of 2003 in Western Europe and 2010 in Russia, commonly labelled as rare climatic anomalies outside of previous experience, are often taken as harbingers of more frequent extremes in the global warming-influenced future. However, a recent reconstruction of spring-summer temperatures for WE resulted in the likelihood of significantly higher temperatures in 1540. In order to check the plausibility of this result we investigated the severity of the 1540 drought by putting forward the argument of the known soil desiccation-temperature feedback. Based on more than 300 first-hand documentary weather report sources originating from an area of 2 to 3 million km(2), we show that Europe was affected by an unprecedented 11-month-long Megadrought. The estimated number of precipitation days and precipitation amount for Central and Western Europe in 1540 is significantly lower than the 100-year minima of the instrumental measurement period for spring, summer and autumn. This result is supported by independent documentary evidence about extremely low river flows and Europe-wide wild-, forest- and settlement fires. We found that an event of this severity cannot be simulated by state-of-the-art climate models.