19602015
  • Authors:
    • Riseman, A.
    • Chapagain, T.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 101
  • Issue: 1
  • Year: 2015
  • Summary: Enhancing soil organic carbon (SOC), nitrogen (N) and water use efficiency (WUE) are significant challenges in intensive wheat production. An intercropping system combining wheat and grain legumes may help maintain SOC, soil mineral N and WUE while also providing an opportunity to sequester carbon (C) in low input organic systems. We grew wheat (Triticum aestivum cv. 'Scarlet') as a monoculture and intercropped with either common bean (Phaseolus vulgaris cv. 'Red Kidney', or cv. 'Black Turtle'), or fava bean (Vicia faba cv. 'Bell') in rows of 1:1, 2 wheat: 1 bean or broadcast arrangement without fertilizers for 2 years to assess the effects of genotype and spatial arrangement on biological nitrogen fixation and seasonal transfer, WUE, gross ecosystem photosynthesis (GEP), and net ecosystem productivity (NEP). Stable isotope methods (C-13 and N-15 natural abundance) were used to quantify C and N within the plant and soil system. Field CO2 exchange measurements used a dynamic closed transparent chamber connected to a portable CO2 analyzer. Intercropped plots had higher percent N derived from symbiotic N-2 fixation, and increased C and N accumulation compared to monocultured wheat. The fava bean cv. Bell intercrops showed increased nodulation (60-80 % more nodules) and percent N derived from symbiotic N-2 fixation (10-12 % higher) compared to common beans resulting in the fixation of 74 kg N ha(-1) biologically from the 1:1 arrangement. The highest rate of N-transfer (13 %) was observed in the wheat-fava bean cv. Bell combination when planted in the 1:1 arrangement. All intercrops accumulated more N in shoot biomass compared to monoculture wheat with wheat-fava bean cv. Bell (1:1 arrangement) accumulating the highest N (34 kg N ha(-1), i.e., 176 % higher) and C (214 g C m(-2) year(-1), i.e., 26 % higher). All plots fixed the most CO2 (i.e., greatest GEP) during mid-growth stage (50 days after seeding i.e., prior to flowering) however, wheat-fava bean cv. Bell in the 1:1 arrangement displayed the greatest NEP sequestering C at the seasonal daytime average rate of 208 mg C m(-2) h(-1) (i.e., 7 % higher than wheat monoculture plots). Intrinsic WUE of wheat, as indicated by delta C-13, was also improved when grown with fava bean cv. Bell or common bean cv. Red Kidney. This study demonstrated that intercropping wheat and fava bean is an effective strategy to achieve greater nitrogen fixation and transfer to the wheat counterparts, higher WUE, and ecosystem productivity than wheat monocultures in areas with low soil N and C. Furthermore, the wheat-fava bean cv. Bell (1:1 arrangement) was more productive than either the 2:1 or mixed planting arrangements.
  • Authors:
    • Lv, Y. Z.
    • Huang, F.
    • Zhao, N.
    • Yang, Z. C.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 146
  • Issue: Pt. A
  • Year: 2015
  • Summary: The aim of the study is to analyze the effects of different fertilization of organic and inorganic fertilizers on soil organic carbon (SOC) sequestration and crop yields after a 22 years long-term field experiment. The crop yields and SOC were investigated from 1981 to 2003 in Dry-Land Farming Research Institute of Hebei Academy of Agricultural and Forestry Sciences, Hebei Province, China. The dominant cropping systems are winter wheat-summer corn rotation. There were totally sixteen treatments applied to both wheat and corn seasons: inorganic fertilizers as main plots and corn stalks as subplots and the main plots and subplots all have four levels. The results revealed: after 22 years, mixed application of inorganic fertilizers and crop residuals, the SOC and crop yields substantially increased. Higher fertilizer application rates resulted in greater crop yields improvement. In 2002-2003, wheat and corn for the highest fertilizer inputs had the highest yield level, 6400kgha-1 and 8600kgha-1, respectively. However, the SOC decreased as the excessive inorganic fertilizer input and increased with the rising application of corn stalks. The treatment of the second-highest inorganic fertilizer and the highest corn stalks had the highest SOC concentration (8.64gCkg-1). Pearson correlation analysis shows that corn and winter wheat yields and the mineralization amount of SOC have significant correlation with SOC at p<0.05 level.
  • Authors:
    • Medina, E.
    • Aragüés, R.
    • Zribi. W.
    • Faci, J. M.
  • Source: Soil and Tillage Research
  • Volume: 148
  • Year: 2015
  • Summary: Soil evaporation is an important component of the water balance in irrigated agriculture. Mulching can be an effective technique to reduce soil evaporation but its efficiency depends on meteorological conditions and the characteristics of the different mulching materials. The objective of this work was to assess the effectiveness of inorganic (plastic) and organic (pine bark, vine pruning residues, geotextile, and wheat straw) mulching materials for soil evaporation control during the energy-limited and falling-rate evaporation stages. Soil evaporation rates (ER) were quantified through consecutive weighings of initially wet soils placed in trays in the laboratory and in microlysimeters in the field. ER depended on meteorological and experimental conditions, stage of evaporation and type of mulching material. In the falling-rate stage, ERs decreased linearly ( p<. 0.001) with decreases in GWC, and for long drying periods the ERs were low and similar among treatments, implying that soil mulching will be ineffective for soil evaporation control in low-frequency irrigation systems. In the energy-limited stage, all mulching materials decreased the ERs in relation to the bare soil, but the plastic, vine residues and pine bark materials had lower ERs than the rest of mulching materials. These materials will be therefore recommended for soil evaporation control in high-frequency irrigation systems where the soil surface remains wet most of the time.
  • Authors:
    • Ippolito, J. A.
    • Barbarick, K. A.
    • McDaniel, J.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY
  • Volume: 44
  • Issue: 1
  • Year: 2015
  • Summary: The USEPA adapted a risk assessment approach in biosolids regulations that includes the use of an uptake coefficient (UC) (i.e., the ratio of plant concentration to quantity of element added) to determine limitations on selected elemental additions. The nature of the risk assessment requires UCs to be constants. Our hypothesis was that the UC for Cu, Fe, Mo, Ni, P, and Zn for biosolids-amended dryland winter wheat ( Triticum aestivum L.) decreases with multiple biosolids applications at the same location. We applied up to 10 applications to two sites (designated North Bennett A and B) in eastern Colorado at rates from 2.24 to 11.2 Mg ha -1 per application from 1993 to 2013. Results indicated that grain concentrations for all six elements followed no discernible trend as the number of biosolids applications increased. The UC values for these elements compared with the number of biosolids applications followed exponential decay models ( R2 ranged from 0.329 to 0.879). Consequently, UC values will likely not provide constants for risk assessment where multiple biosolids applications are made on the same site. We found that the slope between cumulative elemental removal by grain (kg ha -1) to the cumulative amount of element added with biosolids (kg ha -1) provides a constant over the number of biosolids additions ( R2 ranged from 0.471 to 0.990). As compared with the USEPA approach, our strategy of looking at cumulative changes may provide better estimations of wheat-grain concentrations for risk assessment of biosolids-borne elements.
  • Authors:
    • Menendez, S.
    • Maria Estavillo, J.
    • Gonzalez-Murua, C.
    • Dunabeitia, M. K.
    • Fuertes-Mendizabal, T.
    • Huerfano, X.
  • Source: EUROPEAN JOURNAL OF AGRONOMY
  • Volume: 64
  • Year: 2015
  • Summary: Wheat is among the most widely grown cereals in the world. In order to enhance its production, its management is based on the addition of nitrogen (N) fertilizers. Nevertheless, its application could increase nitrous oxide (N2O) emissions, which effects are very pernicious to the environment, being a strong greenhouse gas (GHG). Regarding GHG, soil processes can also produce or consume carbon dioxide (CO2) and methane (CH4). Nitrification inhibitors (NI) have been developed with the aim of decreasing fertilizer-induced N losses and increase N efficiency. The fact that the application of a NI enhances N use efficiency is a good reason to think that more N should be also available for increasing the grain N concentration of wheat plants. If the application of NI means an increase in N use efficiency, it is plausible to consider that more N would be available, hence, increasing the grain N concentration of wheat. We present a two-year field-experiment to evaluate the influence of the NI 3,4-dimethylpyrazol phosphate (DMPP) on grain yield, grain quality and GHG emissions. Fertilizer dose, with and without DMPP, was 180 kg N ha(-1) applied as ammonium sulfate nitrate (ASN) splitted in two applications of 60 kg N ha(-1) and 120 kg N ha(-1), respectively. A treatment with a non-splitted application of ASN with DMPP and an unfertilized treatment were also included. The splitted application of ASN with DMPP was able to reduce N2O emissions, without affecting yield and its components. The alternative management of a non-splitted application of DMPP was more efficient mitigating N2O emissions, whilst keeping yield and slightly reducing grain protein content. In consequence of the low N2O fluxes from our soils, the EF applied in our region should be lower than the default value of 1% proposed by IPCC.
  • Authors:
    • Jabro, J. D.
    • Benjamin, J. G.
    • Hergert, G. W.
    • Mikha, M. M.
    • Nielsen, R. A.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 79
  • Issue: 2
  • Year: 2015
  • Summary: Long-term studies document that soil properties influenced by management practices occur slowly. The objectives of this study were to evaluate 70 yr of manure (M) and commercial fertilizer (F) additions and moldboard plowing on soil organic C (SOC), soil total N (STN), water-stable aggregates (WSA), and aggregate-associated C and N. The Knorr-Holden plots have been in furrow irrigated continuous corn (Zea mays L.) since 1912 on a Tripp sandy loam (coarse-silty, mixed, superactive, mesic Aridic Haplustoll). Soil samples were collected from the 0- to 5-, 5- to 10-, 10- to 15-, and 15- to 30-cm depths in 2011. Soils were fractionated by wet sieving into four aggregate-size classes (>1000, 500-1000, 250-500, and 53-250 mm). Continuous M amendment increased the SOC in the 0- to 30-cm depth approximately 1.7-fold compared with the F treatment. The combination of F + M further increased SOC in the 0- to 15-cm depth by approximately 36% for the M treatment receiving 90 kg N ha-1 of F (90 + M) and by 16% for the M treatment receiving 180 kg N ha-1 of F (180 + M) compared with the 15- to 30-cm depth. Macroaggregates increased with M and F + M when compared with F with the corresponding increase in microaggregate quantities associated with the F and no-N treatment. In the 0- to 30-cm depth, microaggregates were approximately 1.8 to 4.9 times greater than the macroaggregates. Aggregate-associated C masses were greater in microaggregates than in macroaggregates, which reflects greater amounts of microaggregates present in the soil. A significant, positive correlation was observed between SOC and aggregate-associated C. Overall, the addition of manure-based amendments, with or without F, increased SOC and enhanced aggregate stability.
  • Authors:
    • Bramley, H.
    • Siddique, K. H. M.
    • Oliveira, E. A. D. de
    • Stefanova, K.
    • Palta, J. A.
  • Source: GLOBAL CHANGE BIOLOGY
  • Volume: 21
  • Issue: 2
  • Year: 2015
  • Summary: The response of wheat to the variables of climate change includes elevated CO 2, high temperature, and drought which vary according to the levels of each variable and genotype. Independently, elevated CO 2, high temperature, and terminal drought affect wheat biomass and grain yield, but the interactive effects of these three variables are not well known. The aim of this study was to determine the effects of elevated CO 2 when combined with high temperature and terminal drought on the high-yielding traits of restricted-tillering and vigorous growth. It was hypothesized that elevated CO 2 alone, rather than combined with high temperature, ameliorates the effects of terminal drought on wheat biomass and grain yield. It was also hypothesized that wheat genotypes with more sink capacity (e.g. high-tillering capacity and leaf area) have more grain yield under combined elevated CO 2, high temperature, and terminal drought. Two pairs of sister lines with contrasting tillering and vigorous growth were grown in poly-tunnels in a four-factor completely randomized split-plot design with elevated CO 2 (700 L L -1), high day time temperature (3°C above ambient), and drought (induced from anthesis) in all combinations to test whether elevated CO 2 ameliorates the effects of high temperature and terminal drought on biomass accumulation and grain yield. For biomass and grain yield, only main effects for climate change variables were significant. Elevated CO 2 significantly increased grain yield by 24-35% in all four lines and terminal drought significantly reduced grain yield by 16-17% in all four lines, while high temperature (3°C above the ambient) had no significant effect. A trade-off between yield components limited grain yield in lines with greater sink capacity (free-tillering lines). This response suggests that any positive response to predicted changes in climate will not overcome the limitations imposed by the trade-off in yield components.
  • Authors:
    • Rosenqvist, E.
    • Ottosen, C. O.
    • Andersen, S. B.
    • Sharma, D. K.
  • Source: PHYSIOLOGIA PLANTARUM
  • Volume: 153
  • Issue: 2
  • Year: 2015
  • Summary: The chlorophyll fluorescence parameter F v/F m reflects the maximum quantum efficiency of photosystem II (PSII) photochemistry and has been widely used for early stress detection in plants. Previously, we have used a three-tiered approach of phenotyping by F v/F m to identify naturally existing genetic variation for tolerance to severe heat stress (3 days at 40°C in controlled conditions) in wheat ( Triticum aestivum L.). Here we investigated the performance of the previously selected cultivars (high and low group based on F v/F m value) in terms of growth and photosynthetic traits under moderate heat stress (1 week at 36/30°C day/night temperature in greenhouse) closer to natural heat waves in North-Western Europe. Dry matter accumulation after 7 days of heat stress was positively correlated to F v/F m. The high F v/F m group maintained significantly higher total chlorophyll and net photosynthetic rate (P N) than the low group, accompanied by higher stomatal conductance (g s), transpiration rate (E) and evaporative cooling of the leaf (DeltaT). The difference in P N between the groups was not caused by differences in PSII capacity or g s as the variation in F v/F m and intracellular CO 2 (C i) was non-significant under the given heat stress. This study validated that our three-tiered approach of phenotyping by F v/F m performed under increasing severity of heat was successful in identifying wheat cultivars differing in photosynthesis under moderate and agronomically more relevant heat stress. The identified cultivars may serve as a valuable resource for further studies to understand the physiological mechanisms underlying the genetic variability in heat sensitivity of photosynthesis.
  • Authors:
    • Dalal, R. C.
    • Wang, W.
  • Source: European Journal of Agronomy
  • Volume: 66
  • Year: 2015
  • Summary: Farm management affects the global greenhouse gas (GHG) budget by changing not only soil organic carbon (SOC) stocks and nitrous oxide (N2O) emissions but also other pre-farm, on-farm and off-site emissions. The life cycle assessment (LCA) approach has been widely adopted to assess the "carbon footprint" of agricultural products, but rarely used as a tool to identify effective mitigation strategies. In this study, the global warming impacts of no-till (NT) vs. conventional till (CT), stubble retention (SR) vs. stubble burning (SB), and N fertilization (NF) vs. no N fertilization (N0) in an Australian wheat cropping system were assessed using in situ measurements of N2O fluxes over three years, SOC changes over forty years and including other supply chain GHG sources and sinks. The results demonstrated the importance of full GHG accounting compared to considering SOC changes or N2O emissions alone for assessing the global warming impacts of different management practices, and highlighted the significance of accurately accounting for SOC changes and N2O emissions in LCAs. The GHG footprints of wheat production were on averaged 475kg carbon dioxide equivalent (CO2-e) ha-1 (or 186kg CO2-e t-1 grain) higher under NF than N0. Where fertilizer N was applied (70kgNha-1), the life cycle emissions were 200kg CO2-e ha-1 (or 87t-1 grain) lower under NT than CT and 364kg CO2-e ha-1 (or 155t-1 grain) lower under SR than SB. Classification of the emission sources/sinks and re-calculation of published data indicated that under the common practices of SR combined with NT, N-related GHG emissions contributed 60-95% of the life cycle emissions in the predominantly rain-fed wheat production systems in Australia. Therefore, future mitigation efforts should aim to improve N use efficiency, explore non-synthetic N sources, and most importantly avoid excessive N fertilizer use whilst practising NT and SR.
  • Authors:
    • Zamberlan, J. F.
    • Reichardt, K.
    • Fiorin, J. E.
    • Roberti, D.
    • Keller, C.
    • Nora, D. D.
    • Amado, T. J. C.
    • Bortolotto, R. P.
    • Pasini, M. P. B.
    • Nicoloso, R. da S.
  • Source: African Journal of Agricultural Research
  • Volume: 10
  • Issue: 6
  • Year: 2015
  • Summary: Soil carbon dioxide flux is a complex process which depends on variations of different factors related to climate and soil. The objective of this study was identifying the abiotic factors that most contributed to this flux during different phonologic stages of the sequence black oat-vetch, cultivated under the no tillage system, in the winter, and find out the most important factors. Soil carbon fluxes were measured every 15 min with a LI-COR "long-term" (stationary) chamber, installed on the no tillage site of the rotation: soybean/black oat/soybean/black oat+vetch/corn/turnip/wheat. The factor that mostly influenced soil carbon fluxes was soil temperature, explaining 57% of the flux variation during the cycles of the crops and 80% from tillering to the begin of the elongation stage of the black oat. The phonologic stages of the black oat in the consortium black oat+vetch that mostly contributed to the carbon soil flux were from the begin of the tillering to the begin of the elongation, and from the elongation to massive grain of the black oat.