• Authors:
    • Crosson, E.
    • Bandaru, V.
    • West, T.
    • Andrews, A.
    • Lauvaux, T.
    • Davis, K.
    • Richardson, S.
    • Miles, N.
  • Source: Journal of Geophysical Research-Biogeosciences
  • Volume: 117
  • Issue: G1
  • Year: 2012
  • Summary: This study presents observations of atmospheric boundary layer CO2 mole fraction from a nine-tower regional network deployed during the North American Carbon Program's Mid-Continent Intensive (MCI) during 2007-2009. The MCI region is largely agricultural, with well-documented carbon exchange available via agricultural inventories. By combining vegetation maps and tower footprints, we show the fractional influence of corn, soy, grass, and forest biomes varies widely across the MCI. Differences in the magnitude of CO2 flux from each of these biomes lead to large spatial gradients in the monthly averaged CO2 mole fraction observed in the MCI. In other words, the monthly averaged gradients are tied to regional patterns in net ecosystem exchange (NEE). The daily scale gradients are more weakly connected to regional NEE, instead being governed by local weather and large-scale weather patterns. With this network of tower-based mole fraction measurements, we detect climate-driven interannual changes in crop growth that are confirmed by satellite and inventory methods. These observations show that regional-scale CO2 mole fraction networks yield large, coherent signals governed largely by regional sources and sinks of CO2.
  • Authors:
    • Inubushi, K.
    • Ohkubo, S.
    • Kato, S.
    • Nagano, H.
  • Source: Soil Science & Plant Nutrition
  • Volume: 58
  • Issue: 6
  • Year: 2012
  • Summary: Here we have investigated the emission of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from long- and short-term organic farming Andosols in Matsumoto city of Nagano, in central Japan. We focus on three upland plots in Matsumoto, distinguished by how long they had each experienced continuous organic farming (OF)in these three cases, since 1971, 2009, and 2010 (plots hereafter termed M39-OF, M1-OF, and M1F-OF, respectively). Since 2001, in M39-OF, mainly rye (Secale cereale L., as green manure) and soybeans [Glycine max (L.) Merril, as crop] were cultivated, in winter and summer respectively, without tillage, other fertilizers and agro-chemicals. In contrast, from 2001 to 2008 in M1-OF, and from 2001 to 2009 in M1F-OF, these plots underwent conventional farming of some vegetables with tillage, fertilizer and agro-chemicals. Soils sampled from M39-OF and M1-OF in August 2009 were incubated for 4 weeks in darkness at 25 degrees C. During these 4 weeks, M39-OF emitted 8.0 times more CO2 and 274 times more N2O than M1-OF. Less than 2?mu g carbon (C) kg1?dry soil of CH4 was emitted from both soils. From February 2010 until January 2011, CO2, CH4, and N2O emission rates of M39-OF and M1F-OF were measured almost monthly, using a closed-chamber method. Annual CO2, CH4, and N2O emissions were 317, 1.7, and 27?g CO2-C equivalent m2 in M39-OF, and 138, 0.2, and 21?g CO2-C equivalent m2 in M1F-OF, respectively. The rye yield in M39-OF was 334?g?C?m2. Soybeans in M39-OF and M1F-OF yielded 290 and 286?g?C?m2, and withdrew 230 and 224?g?C?m2, respectively. Greenhouse gas (GHG) balance was calculated at 52 and 97?g CO2-C equivalent m2 in M39-OF and M1F-OF, respectively. Negative GHG balance indicated that M39-OF was acting as a GHG sink, with higher CH4 absorption than M1F-OF. Further, this beneficial function for global warming was thought to be based on its cultivation system, which had included green manure application since 2001. The difference in gas exchange between incubation and field experiments was considered a reason for the difference in N2O emission between incubation and field experiments.
  • Authors:
    • Gramig, B.
    • Reeling, C.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 146
  • Issue: 1
  • Year: 2012
  • Summary: Agricultural ecosystems are a source of greenhouse gas (GHGs) emissions and losses of nutrients to waterways. Several studies have recognized this and have documented the potential to reduce GHG fluxes and nutrient loss to waterways by using carbon offsets to fund the implementation of land retirement and afforestation. However, the ability to use land for both agricultural production and environmental conservation is also important. This study develops a novel analytical framework that is used to examine the cross-media (water and air) environmental effects of implementing offset-funded conservation practices in a working-lands setting. The framework is applied to a case study which examines the extent to which carbon pricing can affect practice implementation costs and the optimal distribution of these practices throughout an agricultural watershed. Results indicate that carbon offsets can reduce conservation practice implementation costs and have the potential to reduce greater amounts of nonpoint source pollution for a given cost of implementation. This conclusion has significant implications for policymaking, particularly with regard to using markets for GHG emissions to achieve water quality improvements where water quality trading or government conservation programs have historically been unsuccessful. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Ort, D.
    • Gleadow, R.
    • Fauquet, C.
    • Cavagnaro, T.
    • Grennan, A.
    • Miller, R.
    • Slattery, R.
    • Rosenthal, D.
  • Source: Global Change Biology
  • Volume: 18
  • Issue: 8
  • Year: 2012
  • Summary: Globally, cassava is the second most important root crop after potatoes and the fifth most important crop overall in terms of human caloric intake. In addition to its growing global importance for feed, fuel, and starch, cassava has long been vital to food security in Sub-Saharan Africa. Climate change is expected to have its most severe impact on crops in food insecure regions, yet little is known about how cassava productivity will respond to climate change. The most important driver of climate change is globally increasing atmospheric CO2 concentration ([CO2]). However, the potential for cassava to enhance food security in an elevated [CO2] world is uncertain as greenhouse and open top chamber (OTC) study reports are ambiguous. Studies have yielded misleading results in the past regarding the effect of elevated [CO2] on crop productivity, particularly in cases where pots restricted sink growth. To resolve these conflicting results, we compare the response of cassava to growth at ambient (ca. 385 similar to ppm) and elevated [CO2] (585 similar to ppm) under field conditions and fully open air [CO2] elevation. After three and half months of growth at elevated [CO2], above ground biomass was 30% greater and cassava root tuber dry mass increased over 100% (fresh weight increased 89%). High photosynthetic rates and photosynthetic stimulation by elevated [CO2], larger canopies, and a large sink capacity all contributed to cassava's growth and yield stimulation. Cassava exhibited photosynthetic acclimation via decreased Rubisco capacity early in the season prior to root tuber initiation when sink capacity was smaller. Importantly, and in contrast to a greenhouse study, we found no evidence of increased leaf N or total cyanide concentration in elevated [CO2]. All of our results are consistent with theoretical expectations; however, the magnitude of the yield increase reported here surpasses all other C3 crops and thus exceeds expectations.
  • Authors:
    • Phillips, R. L.
    • Tanaka, D. L.
    • Hendrickson, J. R.
    • Liebig, M. A.
    • Schmer, M. R.
  • Source: Biomass and Bioenergy
  • Volume: 45
  • Issue: October
  • Year: 2012
  • Summary: Switchgrass (Panicum virgatum L.) is being evaluated as a bioenergy crop for the northern Great Plains. Field measurements of CO2, CH4, and N2O flux are needed to estimate the net greenhouse gas (GHG) balance of this biofeedstock. The study objective was to determine effects of recommended Nitrogen (N) fertilization (67 kg ha(-1) of N applied) and unfertilized switchgrass on growing season soil-atmosphere CO2, CH4, and N2O flux using static chamber methodology. Mean hourly CO2 flux was greatest during periods of active switchgrass growth and was similar between N fertilizer treatments (P = 0.09). Mean hourly N2O flux was consistently greater under N fertilization than without N throughout the growing season. Overall, N fertilization of switchgrass affected cumulative growing-season N2O flux (27.6 kg ha(-1) +/- 4.0 kg ha(-1) vs. 86.3 kg ha(-1) +/- 14.3 kg ha(-1) as CO2 equivalents (CO(2)eq) for 0 kg ha(-1) and 67 kg ha(-1) of N applied, respectively; P < 0.01), but not cumulative CO2 or CH4 flux (P = 0.08 and 0.51, respectively). Aboveground biomass production was greater with N application (6.8 Mg ha(-1) +/- 0.5 Mg ha(-1) dry matter) than without N (3.2 Mg ha(-1) +/- 0.5 Mg ha(-1)) (P < 0.05). Net greenhouse gas intensity (GHGI; kg GHG flux kg(-1) harvest yield as CO(2)eq) for switchgrass production was similar between N treatments (0.71 vs. 0.44 for 0 kg ha(-1) and 67 kg ha(-1) of N applied, respectively; P = 0.18). Published by Elsevier Ltd.
  • Authors:
    • Sauer, T.
    • Soolaneyakanahally, R.
    • de Gooijer, H.
    • Bentrup, G.
    • Schoeneberger, M.
    • Brendle, J.
    • Zhou, X.
    • Current, D.
  • Source: Journal of Soil and Water Conservation
  • Volume: 67
  • Issue: 5
  • Year: 2012
  • Authors:
    • McKone, T. E.
    • Horvath, A.
    • Santero, N. J.
    • Masanet, E.
    • Lobscheid, A. B.
    • Strogen, B.
    • Mishra, U.
    • Nazaroff, W. W.
    • Scown, C. D.
  • Source: Environmental Research Letters
  • Volume: 7
  • Issue: 1
  • Year: 2012
  • Summary: The Energy Independence and Security Act of 2007 set an annual US national production goal of 39.7 billion 1 of cellulosic ethanol by 2020. This paper explores the possibility of meeting that target by growing and processing Miscanthus x giganteus. We define and assess six production scenarios in which active cropland and/or Conservation Reserve Program land are used to grow to Miscanthus. The crop and biorefinery locations are chosen with consideration of economic, land-use, water management and greenhouse gas (GHG) emissions reduction objectives. Using lifecycle assessment, the net GHG footprint of each scenario is evaluated, providing insight into the climate costs and benefits associated with each scenario's objectives. Assuming that indirect land-use change is successfully minimized or mitigated, the results suggest two major drivers for overall GHG impact of cellulosic ethanol from Miscanthus: (a) net soil carbon sequestration or emissions during Miscanthus cultivation and (b) GHG offset credits for electricity exported by biorefineries to the grid. Without these factors, the GHG intensity of bioethanol from Miscanthus is calculated to be 11-13 g CO2-equivalent per MJ of fuel, which is 80-90% lower than gasoline. Including soil carbon sequestration and the power-offset credit results in net GHG sequestration up to 26 g CO2-equivalent per MJ of fuel.
  • Authors:
    • Lence, S.
    • Livingston, M.
    • Greene, C.
    • Chase, C.
    • Delate, K.
    • Singerman, A.
    • Hart, C.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 4
  • Year: 2012
  • Summary: Emphasis on reducing emissions from the greenhouse gases (GHG), carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) has increased in recent years in the USA, primarily for industry, transportation, energy and agricultural sectors. In this study, we utilized on-farm data collected by the USDA-National Agricultural Statistics Service (NASS) Agricultural Resource Management Survey (ARMS), secured under an agreement with the USDA-Economic Research Service (ERS) to analyze the profitability of organic and conventional soybean production, based on changes that 'green payments' in a cap-and-trade system would introduce in agricultural markets in the USA. In particular, the analysis focused on establishing whether organic producers would be better positioned to sequester carbon (C) and reap the benefits of the C-offset scheme compared to conventional producers, given the differences in costs, management practices and environmental benefits between organic and conventional production methods. We estimated several changes in profitability of soybean producers according to management practices, incentives for the generation of offset credits, and increase in energy input prices that a potential cap-and-trade system may introduce in future agricultural markets in the USA. Survey data suggested that even with lower yields, conventional producers could profit from converting to organic agriculture, given organic price premiums. In addition, taking into consideration both direct and indirect costs, average cost for conventional-till (CT) organic soybean production was approximately 9% lower than no-till (NT) conventional production. With a C market and payments for soil C sequestration through potential Clean Energy legislation, additional profit could be accrued by organic producers, because organic production would have 28% greater ton CO2 eq. acre(-1) yr(-1) sequestration than conventional NT. Thus, the environmental benefits from GHG reduction could incentivize increased conversion from conventional to organic production across the USA.
  • Authors:
    • Kuzyakov, Y.
    • Li, X.
    • Marschner, P.
    • Guo, J.
    • Fan, M.
    • Tian, J.
  • Source: European Journal of Soil Biology
  • Volume: 52
  • Issue: September–Octobe
  • Year: 2012
  • Summary: In the last three decades there has been a major shift in China's agriculture with the conversion from cereal fields to vegetable production, however little is known about the impact of this land use change on labile soil carbon and microbial community structure. We conducted a study to characterize dissolved organic carbon (DOC) and soil microbial community by comparing greenhouse vegetable fields with contrasting management intensity and adjacent cereal fields (wheat maize rotation) in Shouguang and Quzhou in North China. Compared with cereal fields, greenhouse vegetable cultivation increased soil organic carbon (SOC) and total nitrogen (TN), while it decreased the soil pH, particularly at the high-intensity site. The DOC concentration was significantly higher in greenhouse vegetable fields than in cereal fields, whereas DOC composition differed between greenhouse vegetable fields and cereal fields only at high management intensity. Chemical fractionation indicated that DOC from greenhouse vegetable fields with high management intensity was less decomposed than DOC from cereal fields, because the percentage of hydrophobic acid (HOA) as DOC was higher in vegetable fields. Vegetable production significantly changed the microbial community structure in comparison to cereal fields: high-intensity management increased total bacteria, G (+) bacteria and fungi, while low-intensity decreased fungi and increased bacteria-to-fungi ratio. The main factor affecting microbial community structure was soil pH in this study, accounting for 24% of the differences. (C) 2012 Elsevier Masson SAS. All rights reserved.
  • Authors:
    • Chi, S.
    • Li, Z.
    • Han, H.
    • Li, N.
    • Wang, B.
    • Zhao, H.
    • Ning, T.
    • Tian, S.
  • Source: Web Of Knowledge
  • Volume: 7
  • Issue: 12
  • Year: 2012
  • Summary: The objective of this study was to quantify soil methane (CH4) and nitrous oxide (N2O) emissions when converting from minimum and no-tillage systems to subsoiling (tilled soil to a depth of 40 cm to 45 cm) in the North China Plain. The relationships between CH4 and N2O flux and soil temperature, moisture, NH4+-N, organic carbon (SOC) and pH were investigated over 18 months using a split-plot design. The soil absorption of CH4 appeared to increase after conversion from no-tillage (NT) to subsoiling (NTS), from harrow tillage (HT) to subsoiling (HTS) and from rotary tillage (RT) to subsoiling (RTS). N2O emissions also increased after conversion. Furthermore, after conversion to subsoiling, the combined global warming potential (GWP) of CH4 and N2O increased by approximately 0.05 kg CO2 ha(-1) for HTS, 0.02 kg CO2 ha(-1) for RTS and 0.23 kg CO2 ha(-1) for NTS. Soil temperature, moisture, SOC, NH4+-N and pH also changed after conversion to subsoiling. These changes were correlated with CH4 uptake and N2O emissions. However, there was no significant correlation between N2O emissions and soil temperature in this study. The grain yields of wheat improved after conversion to subsoiling. Under HTS, RTS and NTS, the average grain yield was elevated by approximately 42.5%, 27.8% and 60.3% respectively. Our findings indicate that RTS and HTS would be ideal rotation tillage systems to balance GWP decreases and grain yield improvements in the North China Plain region. Citation: Tian S, Ning T, Zhao H, Wang B, Li N, et al. (2012) Response of CH4 and N2O Emissions and Wheat Yields to Tillage Method Changes in the North China Plain. PLoS ONE 7(12): e51206. doi:10.1371/journal.pone.0051206