• Authors:
    • Montanarella, L.
    • Panagos, P.
    • Bampa, F.
    • Lugato, E.
    • Jones, A.
  • Source: GLOBAL CHANGE BIOLOGY
  • Volume: 20
  • Issue: 11
  • Year: 2014
  • Summary: Bottom-up estimates from long-term field experiments and modelling are the most commonly used approaches to estimate the carbon (C) sequestration potential of the agricultural sector. However, when data are required at European level, important margins of uncertainty still exist due to the representativeness of local data at large scale or different assumptions and information utilized for running models. In this context, a pan-European (EU+Serbia, Bosnia and Herzegovina, Montenegro, Albania, Former Yugoslav Republic of Macedonia and Norway) simulation platform with high spatial resolution and harmonized data sets was developed to provide consistent scenarios in support of possible carbon sequestration policies. Using the CENTURY agroecosystem model, six alternative management practices (AMP) scenarios were assessed as alternatives to the business as usual situation (BAU). These consisted of the conversion of arable land to grassland (and vice versa), straw incorporation, reduced tillage, straw incorporation combined with reduced tillage, ley cropping system and cover crops. The conversion into grassland showed the highest soil organic carbon (SOC) sequestration rates, ranging between 0.4 and 0.8 t C ha -1 yr -1, while the opposite extreme scenario (100% of grassland conversion into arable) gave cumulated losses of up to 2 Gt of C by 2100. Among the other practices, ley cropping systems and cover crops gave better performances than straw incorporation and reduced tillage. The allocation of 12 to 28% of the European arable land to different AMP combinations resulted in a potential SOC sequestration of 101-336 Mt CO 2 eq. by 2020 and 549-2141 Mt CO 2 eq. by 2100. Modelled carbon sequestration rates compared with values from an ad hoc meta-analysis confirmed the robustness of these estimates.
  • Authors:
    • Van Santen, E.
    • Arriaga, F. J.
    • Balkcom, K. S.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 77
  • Issue: 5
  • Year: 2013
  • Summary: Tillage systems that promote minimal surface disturbance combined with high residue cover crops can sequester C, but additional research to quantify carbon sequestration with conservation agricultural systems is needed for modelers, policymakers, and landowners. A factorial arrangement of conservation tillage (no-till, fall paratill, spring paratill, and spring strip-till) and winter cover crops (no cover, rye [Secale cereale L], and wheat [Triticum aestivum L.]) were established in a corn/cotton (Zea mays L./Gossypium hirsutum L.) rotation from 2004 to 2009 to (i) evaluate cover crop biomass production and associated changes in soil organic carbon (SOC) to 15 cm, (ii) evaluate the potential of conservation systems to sequester SOC after years of conventional tillage, and (iii) compare measured changes in SOC to predicted soil conditioning index (SCI) values. Carbon returned to the soil each year averaged 2500 and 1340 kg C ha-1 for cover crops and corn residue, respectively. The average SOC sequestration rate in the top 15 cm was 926 ± 344 kg C ha-1 yr-1. Soil organic C values measured after 6 yr related well with predicted SCI values (r2 = 0.81; P = 0.0004). However, discrepancies between SCI and SOC values for conservation systems highlighted the need to improve the SCI for the Southeast U.S. Conservation systems following years of conventional monocropping were equivalent in their ability to sequester considerable amounts of C that will improve soil quality in the Coastal Plain of the southeastern USA. © Soil Science Society of America, All rights reserved.
  • Authors:
    • Rosolem, C. A.
    • Li, Y.
    • Garcia, R. A.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 77
  • Issue: 5
  • Year: 2013
  • Summary: Growing cover crops in systems under no tillage affects different pools of soil organic matter, and eventually soil physical attributes are modified. The objective of this study was to evaluate changes in soil organic matter and their relationship with soil physical attributes as affected by plant species grown in rotation with soybean [Glycine max (L.) Merr.] under no-till for 3 yr. Crop rotations included grain sorghum [Sorghum bicolor (L.) Moench], ruzigrass [Urochloa ruziziensis (R. Germ, and CM. Evard) Crins] and sorghum mixed with ruzigrass, all grown in fall/winter, followed by pearl millet [Pennisetum americanum (L.) Leeke], sunn hemp (Crotalaria juncea L.) and sorghum-sudangrass [S. bicolor × S. sudanense (Piper) Stapf] grown during the spring, plus a fallow check plot. Soybean was grown as the summer crop. Millet and sorghum-sudangrass cropped in spring showed higher root and shoot production as spring cropping. In fall/winter, sorghum mixed with ruzigrass yielded higher phytomass compared with sole cropping. Soil physical attributes and organic matter fractioning were positively affected by cropping millet and sorghum-sudangrass whereas intermediate effects were observed after sunn hemp. Maintaining fallow in spring had negative effects on soil organic matter and physical properties. Ruzigrass and sorghum mixed with ruzigrass cropped in fall/winter resulted in better soil quality. Spring cover crops were more efficient in changing soil bulk density, porosity, and aggregates down to 0 to 10 cm; on the other hand, fall/winter cropping showed significant effects on bulk density in the uppermost soil layer. Total C levels in soil were increased after a 3-yr rotation period due to poor initial physical conditions. Fractions of particulate organic C, microbial C, and C in macroaggregates were the most affected by crop rotations, and showed high relation with improved soil physical attributes (porosity, density, and aggregates larger than 2 mm). © Soil Science Society of America, All rights reserved.
  • Authors:
    • Steinriede Jr., R. W.
    • Zablotowicz, R. M.
    • Locke, M. A.
    • Testa, S.
    • Reddy, K. N.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 77
  • Issue: 3
  • Year: 2013
  • Summary: Conservation practices are increasingly important components of sustainable management systems, and information about their influence on soil characteristics is needed. Soil parameters were assessed in no-till (NT) or minimum tillage (MT) cotton (Gossypium hirsutum L.) production near Stoneville, MS, Mississippi Delta region, that included cover crop (rye [Secale cereal L.] or Balansa clover [Trifolium michelianum Savi var. balansae (Boiss.) Azn.]) vs. no cover crop. Soils (0-2, 2-5, and 5-15 cm) were sampled (2001-2006) before cotton planting. Independent of tillage, both cover crops accumulated more soil C than no cover, and N was greatest under clover. Soils (0-15 cm) under clover had greater aggregate stability than rye or no cover. The major factor influencing bulk density and infiltration was proximity to crop row bed and wheel traffic, but infiltration rates were sixfold greater under MT than NT (P rye or no cover). Moderate tillage slightly increased abundance of both reniform nematodes and earthworms, but neither was affected by cover crop. Fluorescein diacetate hydrolytic activity was higher in clover (50%) and rye (20%) in surface soil than with no cover. Soil microbial community structure (total fatty acid methyl ester analysis) (2005-2006) indicated a significant cover crop effect but no tillage effect. Mycorrhizal bioindicator (16:1 w5c) was greater in soil with rye than clover or no cover; however, cotton mycorrhizal infection was 40% greater in fibrous roots from rye or clover plots than roots from plots with no cover. Collectively, cotton production with a cover crop and reduced tillage resulted in soil conditions indicative of soil quality.
  • Authors:
    • Evans, R. G.
    • Stevens, W. B.
    • Sainju, U. M.
    • Iversen, W. M.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 77
  • Issue: 4
  • Year: 2013
  • Summary: Irrigation and tillage systems may affect surface residue and soil C and N fractions by influencing crop biomass yield, residue placement, and movement of water soluble C and N in the soil. We studied the effects of irrigation (mid-elevation spray application [MESA] and low energy precision application [LEPA ]) and tillage (conventional [CT] and strip-tillage [ST]) systems on crop biomass (stems and leaves) yield, surface residue, and soil C and N fractions at the 0- to 20-cm depth from 2004 to 2007 in a Savage clay loam (fine, smectitic, frigid Vertic Argiustolls) in Sidney, MT. Soil C and N fractions were soil organic carbon (SOC) and total nitrogen (STN), particulate organic carbon and nitrogen (POC and PON), microbial biomass carbon and nitrogen (MBC and MBN), potential carbon and nitrogen mineralization (PCM and PNM), NH4-N, and NO3-N. While crop biomass across treatments increased from 2004 to 2007, surface residue was greater with ST than with CT from 2005 to 2007. The NH4-N and NO3-N contents at 5 to 10 and 10 to 20 cm in 2005 and STN at 0 to 5 cm in 2007 were greater with ST than with CT, but SOC at 5 to 10 and 10 to 20 cm, POC and MBN at 5 to 10 cm, and PNM at 0 to 5 cm in 2007 were greater with CT than with ST. The MBC at 0 to 5 cm and MBN at 10 to 20 cm were greater in LEPA than in MESA. The PCM at 10 to 20 cm was greater with CT than with ST in LEPA . While ST increased surface soil residue and N storage, residue incorporation to a greater depth in CT increased soil C storage, microbial activity, and N mineralization. Slow rate of water application near the soil surface increased microbial biomass in LEPA.
  • Authors:
    • Shaver, T. M.
    • Mamo, M.
    • Drijber, R. A.
    • Wortmann, C. S.
    • Shapiro, C. A.
    • Blanco-Canqui, H.
    • Ferguson, R. B.
  • Source: Web Of Knowledge
  • Volume: 68
  • Issue: 5
  • Year: 2013
  • 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:
    • Blanco-Canqui, H.
  • Source: BioEnergy Research
  • Volume: 6
  • Issue: 1
  • Year: 2013
  • Summary: Crop residue removal for bioenergy can deplete soil organic carbon (SOC) pools. Management strategies to counteract the adverse effects of residue removal on SOC pools have not been, however, widely discussed. This paper reviews potential practices that can be used to offset the SOC lost with residue removal. Literature indicates that practices including no-till cover crops, manure and compost application, and return of biofuel co-products increase SOC pools and may thus be used to offset some SOC loss. No-till rotations that include semi-perennial grasses or legumes also offer a promise to promote soil-profile C sequestration and improve soil resilience after residue removal. No-till cover crops can sequester between 0.10 and 1 Mg ha(-1) per year of SOC relative to no-till without cover crops, depending on cover crop species, soil type, and precipitation input. Animal manure and compost contain about 15 % of C and thus their addition to soil can enhance SOC pools and boost soil biological activity. Similarly, application of biofuel co-products such as biochar, which contain between 45 % and 85 % of C depending on the feedstock source and processing method, can enhance long-term C sequestration. These mitigation strategies may maintain SOC pools under partial residue removal in no-till soils but are unlikely to replace all the SOC lost if residue is removed at excessive rates. More field research and modeling efforts are needed to assess the magnitude at which the different mitigation strategies can overcome SOC loss with crop residue removal.
  • Authors:
    • Jolejole, M. C.
    • McCarthy, N.
    • Lipper, L.
    • Branca, G.
  • Source: Agronomy for Sustainable Development
  • Volume: 33
  • Issue: 4
  • Year: 2013
  • Summary: Agriculture production in developing countries must be increased to meet food demand for a growing population. Earlier literature suggests that sustainable land management could increase food production without degrading soil and water resources. Improved agronomic practices include organic fertilization, minimum soil disturbance, and incorporation of residues, terraces, water harvesting and conservation, and agroforestry. These practices can also deliver co-benefits in the form of reduced greenhouse gas emissions and enhanced carbon storage in soils and biomass. Here, we review 160 studies reporting original field data on the yield effects of sustainable land management practices sequestering soil carbon. The major points are: (1) sustainable land management generally leads to increased yields, although the magnitude and variability of results varies by specific practice and agro-climatic conditions. For instance, yield effects are in some cases negative for improved fallows, terraces, minimum tillage, and live fences. Whereas, positive yield effects are observed consistently for cover crops, organic fertilizer, mulching, and water harvesting. Yields are also generally higher in areas of low and variable rainfall. (2) Isolating the yield effects of individual practices is complicated by the adoption of combinations or "packages" of sustainable land management options. (3) Sustainable land management generally increases soil carbon sequestration. Agroforestry increases aboveground C sequestration and organic fertilization reduces CO2 emissions. (4) Rainfall distribution is a key determinant of the mitigation effects of adopting specific sustainable land management practices. Mitigation effects of adopting sustainable land management are higher in higher rainfall areas, with the exception of water management.
  • Authors:
    • Sawyer, J. E.
    • Castellano, M. J.
    • Mitchell, D. C.
    • Pantoja, J.
  • Source: Soil Science Society of America Journal
  • Volume: 77
  • Issue: 5
  • Year: 2013
  • Summary: Nitrous oxide (N2O) emission from denitrification in agricultural soils often increases with N fertilizer and soil nitrate (NO3) concentrations. Overwintering cover crops in cereal rotations can decrease soil NO3 concentrations and may decrease N2O emissions. However, mineralizable C availability can be a more important control on N2O emission than NO3 concentration in fertilized soils, and cover crop residue provides mineralizable C input. We measured the effect of a winter rye (Secale cereale L.) cover crop on soil N2O emissions from a maize (Zea mays L.) cropping system treated with banded N fertilizer at three rates (0, 135, and 225 kg N ha(-1)) in Iowa. In addition, we conducted laboratory incubations to determine if potential N2O emissions were limited by mineralizable C or NO3 at these N rates. The rye cover crop decreased soil NO3 concentrations at all N rates. Although the cover crop decreased N2O emissions when no N fertilizer was applied, it increased N2O emissions at an N rate near the economic optimum. In laboratory incubations, N2O emissions from soils from fertilizer bands did not increase with added NO3, but did increase with added glucose. These results show that mineralizable C availability can control N2O emissions, indicating that C from cover crop residue increased N2O emissions from fertilizer band soils in the field. Mineralizable C availability should be considered in future evaluations of cover crop effects on N2O emissions, especially as cover crops are evaluated as a strategy to mitigate agricultural greenhouse gas emissions.