• Authors:
    • Lubbers, I. M.
  • Source: Earthworms and the soil greenhouse gas balance
  • Year: 2014
  • Summary: Earthworms play an essential part in determining the greenhouse gas (GHG) balance of soils worldwide. Their activity affects both biotic and abiotic soil properties, which in turn influence soil GHG emissions, carbon (C) sequestration and plant growth. Yet, the balance of earthworms stimulating C sequestration on the one hand and increasing GHG emissions on the other has not been investigated. Indeed, much is still unclear about how earthworms interact with agricultural land use and soil management practices, making predictions on their effects in agro-ecosystems difficult. This thesis determines whether the extent of GHG mitigation by soil C sequestration as affected by earthworms is offset by earthworm-induced GHG emissions from agro-ecosystems under different types of management. To achieve this aim, mesocosm and field studies are combined, as well as meta-analytic methods to quantitatively synthesize the literature. Using meta-analysis, it is shown that, on average, earthworm activity leads to a 24% increase in aboveground biomass, a 33% increase in carbon dioxide (CO 2) emissions and a 42% increase in nitrous oxide (N 2O) emissions. The magnitude of these effects depends on soil factors (e.g., soil organic matter content), experimental factors (e.g., crop residue addition or fertilizer type and rate) and earthworm factors (e.g., earthworm ecological category and -density). Conducting both a mesocosm and a field study record that earthworm activity results in increased N 2O emissions from fertilized grasslands. Further, field conditions record an increase in earthworm-induced N 2O emissions in autumn but not in spring, suggesting that earthworm effects in the field depend on soil physicochemical parameters influenced by meteorological and seasonal dynamics. The unique two-year experiment with a simulated no-tillage (NT) system and a simulated conventional tillage (CT) system, record that earthworm presence increases GHG emissions in an NT system to the same level as in a CT system. This suggests that the GHG mitigation potential of NT agro-ecosystems is limited. When considering the C budget in the simulated NT system, it is demonstrated that over the course of the experiment earthworms increase cumulative CO 2 emissions by at least 25%, indicating a higher C loss compared to the situation without earthworms. Yet, in the presence of earthworms the incorporation of residue-derived C into all measured soil aggregate fractions also increased, indicating that earthworm activity can simultaneously enhance CO 2 emissions and C incorporation into aggregate fractions. In conclusion, the revealed dominance of GHG emissions over C sequestration as affected by earthworms implies that their presence in agro-ecosystems results in a negative impact on the soil greenhouse gas balance.
  • Authors:
    • Luis Arrue, J.
    • Alvaro-Fuentes, J.
    • Plaza-Bonilla, D.
    • Cantero-Martinez, C.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 189
  • Issue: May
  • Year: 2014
  • Summary: There is a strong need to identify the combination of tillage and N fertilization practices that reduce the amount of nitrous oxide (N2O) emissions while maintaining crop productivity in dryland Mediterranean areas. We measured the fluxes of N2O in two field experiments with 3 and 15 years since their establishment. In the long-term experiment, two types of tillage (NT, no-tillage, and CT, conventional intensive tillage) and three mineral N fertilization rates (0, 60 and 120 kg N ha(-1)) were compared. In the short-term experiment, the same tillage systems (CT and NT) and three N fertilization doses (0,75 and 150 kg N ha(-1)) and two types of fertilizers (mineral N and organic N with pig slurry) were compared. N2O emissions, water-filled pore space, soil mineral N content, grain yields, N-biomass inputs and soil total nitrogen (STN) stocks were quantified and the N2O yield-scaled ratio as kg of CO2 equivalents per kg of grain produced was calculated. In both experiments tillage treatments significantly affected the dynamics of N2O fluxes. Cumulative losses of N as N2O were similar between tillage treatments in the long-term field experiment. Contrarily, although not significant, cumulative N losses were about 35% greater under NT than CT in the short-term experiment. NT significantly increased the production of grain and the inputs of N to the soil as above-ground biomass in both experiments. Averaged across fertilizer treatments, CT emitted 0.362 and 0.104 kg CO2 equiv. kg grain(-1) in the long-term and the short-term experiment, respectively, significantly more than NT that emitted 0.033 and 0.056 kg CO2 equiv. kg grain(-1), respectively. Nitrogen fertilization rates did not affect the average N2O fluxes or the total N losses during the period of gas measurement in the long-term experiment. Contrarily, in the short-term experiment, N2O emissions increased with application rate for both mineral and organic fertilizers. The use of pig slurry increased grain production when compared with the mineral N treatment, thus reducing the yield-scaled emissions of N2O by 44%. Our results showed that in rainfed Mediterranean agroecosystems, the use of NT and pig slurry are effective means of yield-scaled N2O emissions reduction. (C) 2014 Elsevier B.V. All rights reserved.
  • Authors:
    • Asam, Z.-u.-Z.
    • Zhang, W.
    • Li, D.
    • Xu, X.
    • Luo, Y.
    • Kumar, S.
    • Rafique, R.
  • Source: Global and Planetary Change
  • Volume: 118
  • Issue: July
  • Year: 2014
  • Summary: Greenhouse gas (GHG) emissions play an important role in regulating the Earth surface temperature. GHG emissions from soils are sensitive to climate change and land management practices. According to general circulation model (GCM) predictions, the Earth will experience a combination of increased temperature and altered precipitation regimes which may result in an increase or a decrease of GHG exchange. The effect of climate change on GHG emissions can be examined through both experiments and by applying process-based models, which have become more popular. The performance of those models can be improved significantly by appropriate calibration procedures. The objectives of this study are to: (i) calibrate the DAYCENT model using advance parameter estimation (PEST) software and to (ii) examine simulated GHG dynamics at daily and seasonal time-scales under a climate change scenario of increased temperature (2 degrees C) and a precipitation regime change where 40% of precipitation during the dry season was redistributed to the wet season. The algorithmic calibration improved the model performance by reducing the sum of weighted squared residual differences by up to 223% (decreased from 1635 to 505 g N2O-N ha(-1) d(-1)) for N2O and 22% (decreased from 623 to 507% WFPS) for water filled pore space (WFPS) simulation results. In the altered climate scenario, total N2O and CO2 fluxes decreased by 9% (from 231 to 2.10 kg N2O-N ha(-1) yr(-1)) and 38% (from 1134.08 to 699.56 kg CO2 ha-1 yr-1) respectively, whereas CH4 fluxes increased by 10% (from 1.62 to 1.80 kg CH4 ha-1 yr-1). Our results show a larger impact of altered climate on CO2 as compared to N2O and CH4 emissions. The main difference in all GHG emissions was observed in summer period due to drought conditions created by reduced precipitation and increased temperatures. However, the GHG dynamics can also be attributed to no-till practices which play an important role in changing the soil moisture conditions for aerobic and anaerobic microsites. These results are based on a process-based model, therefore, we suggest performing experimental studies to examine the GHG emissions under increased temperature and especially under altered precipitation regimes. (C) 2014 Elsevier B.V. All rights reserved.
  • Authors:
    • Sawchik, J.
    • Franzluebbers, A. J.
    • Taboada, M. A.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 190
  • Year: 2014
  • Summary: Agriculture has become increasingly specialized in response to political, regulatory, sociological, and economic pressures to meet market demands of an ever-larger food and fiber processing sector. However, there is a growing concern with specialized agricultural systems, because of increasingly negative responses on the environment from declining soil quality to eutrophication of water bodies and enhanced greenhouse gas emissions. Literature from North and South America was reviewed that showed (i) strong positive production outcomes of crops grown following pastures, (ii) enhancement of soil organic matter with perennial pastures, particularly in the surface soil, (iii) improvement in water infiltration and water quality, and (iv) synergies between crop and livestock systems in system-wide evaluations of production and environmental quality. Therefore, agricultural soils would benefit from the re-introduction of perennial grasses and legumes into the landscape (i.e. temporally and/or spatially) by regaining soil organic matter and strengthening their capacity for long-term productivity and environmental resiliency. Published by Elsevier B.V.
  • Authors:
    • Zhang, W.
    • Li, D. J.
    • Xu, X. L.
    • Luo, Y. Q.
    • Kumar, S.
    • Rafique, R.
    • Asam, Z. U.
  • Source: Global and Planetary Change
  • Volume: 118
  • Year: 2014
  • Summary: Greenhouse gas (GHG) emissions play an important role in regulating the Earth surface temperature. GHG emissions from soils are sensitive to climate change and land management practices. According to general circulation model (GCM) predictions, the Earth will experience a combination of increased temperature and altered precipitation regimes which may result in an increase or a decrease of GHG exchange. The effect of climate change on GHG emissions can be examined through both experiments and by applying process-based models, which have become more popular. The performance of those models can be improved significantly by appropriate calibration procedures. The objectives of this study are to: (i) calibrate the DAYCENT model using advance parameter estimation (PEST) software and to (ii) examine simulated GHG dynamics at daily and seasonal time-scales under a climate change scenario of increased temperature (2°C) and a precipitation regime change where 40% of precipitation during the dry season was redistributed to the wet season. The algorithmic calibration improved the model performance by reducing the sum of weighted squared residual differences by up to 223% (decreased from 1635 to 505 g N 2O-N ha -1 d -1) for N 2O and 22% (decreased from 623 to 507% WFPS) for water filled pore space (WFPS) simulation results. In the altered climate scenario, total N2O and CO2 fluxes decreased by 9% (from 2.31 to 2.10 kg N2O-N ha -1 yr -1) and 38% (from 1134.08 to 699.56 kg CO2 ha -1 yr -1) respectively, whereas CH4 fluxes increased by 10% (from 1.62 to 1.80 kg CH4 ha -1 yr -1). Our results show a larger impact of altered climate on CO2 as compared to N2O and CH4 emissions. The main difference in all GHG emissions was observed in summer period due to drought conditions created by reduced precipitation and increased temperatures. However, the GHG dynamics can also be attributed to no-till practices which play an important role in changing the soil moisture conditions for aerobic and anaerobic microsites. These results are based on a process-based model, therefore, we suggest performing experimental studies to examine the GHG emissions under increased temperature and especially under altered precipitation regimes.
  • Authors:
    • Retore, M.
    • Silva, W. M.
    • Concenco, G.
    • Zanatta, J. A.
    • Tomazi, M.
    • Mercante, F. M.
    • Salton, J. C.
  • Source: Agriculture Ecosystems and Enviroment
  • Volume: 190
  • Issue: SI
  • Year: 2014
  • Summary: Performance of soil management systems was initiated in 1995 in a field experiment in Dourados, MS, Brazil, with the following systems: CS - conventional tillage; NTS - no-tillage; ICLS - integrated crop-livestock with soybean (Glycine max (L) Merr.) and pasture under no-till, rotating every two years, and PP - permanent pasture. Pastures (Brachiaria decumbens) were grazed by heifers with stocking rate adjusted to constant supply of forage. The hypothesis was that rotation of crops and pastures would be more efficient and present beneficial effects to the environment. More complex and diversified production systems may exhibit synergism between components to result in better soil physical structure, greater efficiency in use of nutrients by plants, greater accumulation of labile fractions of soil organic matter, greater diversity and biological activity in soil, and lower occurrence of nematodes and weeds. Better soil conditions in ICLS allowed greater resilience; over the years of assessment soybean and pasture yields were less affected by drought and frost. The ICLS was very efficient, accumulating soil C and reducing emissions of greenhouse gases. Soil quality was improved in integrated systems with larger number of components and greater interaction between these components (ICLS) compared to simple systems. Based on soil attributes, we affirmed in this long-term study that the ICLS system is agronomically and environmentally efficient and sustainable. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Sakalauskas, A.
    • Avizienyte, D.
    • Romaneckas, K.
    • Masilionyte, L.
    • Buragiene, S.
    • Sarauskis, E.
  • Source: Energy
  • Volume: 69
  • Issue: SI
  • Year: 2014
  • Summary: To achieve energy independence, Lithuania and other Baltic countries are searching for new ways to produce energy. Maize is a crop that is suitable for both food and forage, as well as for the production of bioenergy. The objective of this work was to assess the energy efficiency of maize cultivation technologies in different systems of reduced tillage. The experimental research and energy assessment was carried out for five different tillage systems: DP (deep ploughing), SP (), DC (deep cultivation), SC (shallow cultivation) and NT (no tillage). The assessment of the fuel inputs for these systems revealed that the greatest amount of diesel fuel (67.2 l ha -1) was used in the traditional DP system. The reduced tillage systems required 12-58% less fuel. Lower fuel consumption reduces the costs of technological operations and reduces CO 2 emissions, which are associated with the greenhouse effect. The agricultural machinery used in reduced tillage technologies emits 107-223 kg ha -1 of CO 2 gas into the environment, whereas DP emits 253 kg ha -1 of CO 2. The energy analysis conducted in this study showed that the greatest total energy input (approximately 18.1 GJ ha -1) was associated with the conventional deep-ploughing tillage technology. The energy inputs associated with the reduced-tillage technologies, namely SP, DC and SC, ranged from 17.1 to 17.6 GJ ha -1. The lowest energy input (16.2 GJ ha -1) was associated with the NT technology. Energy efficiency ratios for the various technologies were calculated as a function of the yield of maize grain and biomass. The best energy balance and the highest energy efficiency ratio (14.0) in maize cultivation was achieved with the NT technology. The energy efficiency ratios for DP, SP, DC and SC were 12.4, 13.4, 11.3 and 12.0, respectively.
  • Authors:
    • Cecagno, D.
    • Costa, S. E. V. G. de A.
    • Martins, A. P.
    • Anghinoni, I.
    • Assmann, J. M.
    • Carlos, F. S.
    • Carvalho, P. C. de F.
  • Source: Web Of Knowledge
  • Volume: 190
  • Year: 2014
  • Summary: Managing grazing stocks in integrated crop-livestock (ICL) systems under no-tillage is a key variable for reaching equilibrium in soil C and N budgets. Understanding how different plant and animal residues affect soil C and N stocks in these systems goes beyond soil dynamics since these elements are crucial for the functioning of the soil-plant-atmosphere system. The objective of this research was to determine soil C and N fractions, stocks, budgets and the carbon management index as affected by nine years of ICL with grazing intensities under no-tillage conditions. The experiment established in May 2001 in a Rhodic Hapludult (Oxisol) of southern Brazil was composed of black oat ( Avena sativa) plus ryegrass ( Lolium multiflorum) pasture in winter and soybean ( Glycine max) crop in summer. Treatments were regulated by grazing pressures to maintain forage at 10, 20, 30 and 40 cm high (G10, G20, G30 and G40, respectively). Non-grazed (NG) treatment was the control. Changes in soil C and N stocks and fractions (particulate and mineral-associated) were assessed in the ninth year of the experiment. Moderate and light grazing intensities (G20, G30 and G40) resulted in similar increases in total organic C, particulate organic C, total N, and particulate organic N compared with NG treatment. Soil C additions ranged from 0.54 to 8.68 Mg ha -1 from NG to the other grazing treatments. The G10 led to a soil N loss of 1.17 Mg ha -1 due to soil organic matter degradation. The carbon management index (CMI) values, compared with native forest (NF) as a reference, indicated soil quality loss and degradation under high grazing intensity (G10). For a positive contribution to the soil system, ICL must be managed with moderate grazing intensities and adjustment of N additions through N fixation or fertilization.
  • Authors:
    • Bandyopadhyay, K. K.
    • Lal, R.
  • Source: Geoderma
  • Volume: 232/234
  • Year: 2014
  • Summary: Soils can be a source or sink for the atmospheric greenhouse gases (GHGs) depending on the land use management, which needs to be understood properly for devising management strategies to mitigate climate change. It is hypothesized that the aggregate size distribution under different land use management practices and the C and N concentration in these aggregates may influence GHG (CO 2, N 2O and CH 4) emissions from soil. To test this hypothesis, a laboratory incubation study was conducted using soils from a 16-year old tillage experiment on corn ( Zea mays L.) and the adjoining forest on a Crosby silt loam soil (Haplic Luvisols) at the Waterman Agricultural and Natural Resource Laboratory of the Ohio State University (OSU), Columbus, Ohio. It was observed that in forest soil, cumulative CO 2 and N 2O emissions were significantly higher than those from the cultivated soil by 81.2 and 100%, respectively. However, there was no significant difference between conventional tillage (CT) and no till (NT) with respect to the cumulative CO 2 and N 2O emissions. Emissions were significantly higher from the large macro-aggregates than from other aggregate size fractions. There was net CH 4 uptake by the soil during the incubation period. The cumulative CO 2 and N 2O emissions and CH 4 uptake from different aggregate size fractions accounted for 59, 56, and 47% of the emissions/uptake of these gases from the bulk soil, respectively. The contributions of the large macro-aggregates towards the bulk soil CO 2 (39%) and N 2O (37.9%) emissions and CH 4 uptake (49.7%) were significantly higher than those of the micro-aggregates and mineral fraction. Total soil carbon, nitrogen, particulate carbon and nitrogen, and mineral associated carbon and nitrogen accounted for 87, 87 and 66% variation in the cumulative CO 2 and N 2O emissions and CH 4 uptake, respectively.
  • Authors:
    • Stahlman, P. W.
    • Benjamin, J. G.
    • Mikha, M. M.
    • Geier, P. W.
  • Source: Agronomy Journal
  • Volume: 106
  • Issue: 1
  • Year: 2014
  • Summary: Nutrient dynamics in the calcareous eroded soils of the western United States may react differently than the acid soils in the eastern United States. The objectives of this study were to evaluate the impact of tillage practices and N treatments on changes in soil nutrient constituents. The eroded study was initiated in 2006 at the Agriculture Research Center, Hays, KS, on an Armo silt loam (fine-loamy, mixed, mesic Entic Haplustolls). Tillage practices were no-tillage (NT) and conventional tillage (CT). Beef manure (M) and urea, as commercial fertilizer (F) at low (L) and high (H) rates were applied as N sources. The control (C) treatment, with no N added, was included under both tillage practices. Annually (2006-2011) spring soil samples were taken at 0- to 15-cm and 15- to 30-cm depths. Soil chemical properties were influenced by N treatments and sampling depths, but not by tillage. Soil acidity (pH) was reduced in 2011 compared with 2006. Relative to control, more reduction in soil pH was observed with HM (21%) compared with HF treatment. Soil EC with HM and HF was approximately 2.2 times greater than LM and LF. Soil extractable P with HM substantially increased, 45.9 mg kg -1, compared with LM, 18.3 mg kg -1, at the surface 0 to 15 cm. The change in soil organic carbon (DeltaSOC) associated with M was 36-fold higher than F treatments. In general, the use of M as N source improved soil nutrient dynamics in this eroded site compared with F.