• 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:
    • Knicker, H.
    • Berns, A. E.
    • Panettieri, M.
    • Murillo, J. M.
    • Madejón, E.
  • Source: Soil and Tillage Research
  • Volume: 151
  • Year: 2015
  • Summary: An augment of soil organic matter (SOM) in agricultural lands is mandatory to improve soil quality and fertility and to limit greenhouse gases emissions. A better protection of SOM from degradation is seconded to its inclusion in aggregates and to the formation of organo-mineral interactions with the clay fraction within the soil matrix. Under Mediterranean conditions, conservation agriculture (CA) has been widely related with macro-aggregates formation, SOM protection, and to an improvement of soil fertility and crop yields.The objective of this work was to evaluate the biogeochemical properties of five aggregate-size fractions obtained by dry sieving of a Calcic Fluvisol of an experimental farm managed under three different tillages. Soil aggregates distribution, total organic carbon (TOC), labile carbon pools, and enzymatic activities were measured in 2 different periods of the same agricultural campaign. CPMAS 13C NMR analyses were also performed to elucidate the structure of preserved SOM.The results evidenced seasonal variability in aggregate distribution, labile carbon pools and dehydrogenase activity (DHA), whereas TOC, permanganate oxidizable carbon (POxC), and β-. glucosidase activity demonstrated to be reliable soil quality indices for soil fractions. The NMR analyses showed a better SOM preservation under conservation tillages, due to higher plant litter inputs and/or higher amount of necromass derived compounds if compared with traditional tillage. Particularly interesting are the results of the Ø 0.5-1. mm fraction, in which different trends were found for β-Glu and several organic compound classes if compared with the other fractions. Possibly, in this fraction are concentrated most of the products from cellulose depolymerization stabilized by organo-mineral interactions. © 2015 Elsevier B.V.
  • Authors:
    • Erskine, R. H.
    • Sherrod, L. A.
    • Green, T. R.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 79
  • Issue: 2
  • Year: 2015
  • Summary: Soil erosion and deposition impact the sustainability of agricultural lands within the semiarid Great Plains in the United States. Temporal differences between high-resolution digital elevation maps provide physical estimates of spatial erosion or deposition, and the depth to a calcic horizon is a chemical indicator. We hypothesized that soil surface layer CaCO3 concentration is inversely correlated with the change in surface elevation (Δz). We studied a 109-ha field in northeastern Colorado under winter wheat (Triticum aestivum L.)-fallow rotation in alternating strips perpendicular to the prevailing wind. Soil samples (top 30 cm) collected from 185 landscape positions in 2001 and 2012 were analyzed for CaCO3 using a modified pressure-calcimeter method. The change in CaCO3 (ΔC) was significantly correlated with large-scale erosional and depositional areas (west and east blocks, respectively) and with soil units, whereas Δz was correlated with management strips and blocks. The west block had an average ΔC of 3.2 g kg-1 with 2.0 cm of erosion, whereas the east block decreased by 4.4 g kg-1 with 4.2 cm of deposition. Summit positions had the highest CaCO3, and toeslope positions had the lowest. We found inverse relationships between Δz and ΔC in summit and toeslope positions at both erosional (Δz 5 cm) areas, but Δz was not correlated significantly with ΔC overall. High values of CaCO3 (>100 g kg-1) decreased with time. A high-resolution map of Δz showed complex spatial patterns across scales, which inferred water and wind erosion and deposition affected by terrain and management.
  • Authors:
    • Tenorio, J. L.
    • Lopez-Solanilla, E.
    • Navas, M.
    • Garcia-Marco, S.
    • Tellez-Rio, A.
    • Vallejo, A.
  • Source: SCIENCE OF THE TOTAL ENVIRONMENT
  • Volume: 508
  • Year: 2015
  • Summary: Conservation agriculture that includes no tillage (NT) or minimum tillage (MT) and crop rotation is an effective practice to increase soil organic matter in Mediterranean semiarid agrosystems. But the impact of these agricultural practices on greenhouse gases (GHGs), such as nitrous oxide (N2O) and methane (CH4), is variable depending mainly on soil structure and short/long-term tillage. The main objective of this study was to assess the long-term effect of three tillage systems (NT, MT and conventional tillage (CT)) and land-covers (fallow/wheat) on the emissions of N2O and CH4 in a low N input agricultural system during one year. This was achieved by measuring crop yields, soil mineral N and dissolved organic C contents, and fluxes of N2O and CH4. Total cumulative N2O emissions were not significantly different (P > 0.05) among the tillage systems or between fallow and wheat The only difference was produced in spring, when N2O emissions were significantly higher (P < 0.05) in fallow than in wheat subplots, and NT reduced N2O emissions (P < 0.05) compared with MT and CT. Taking into account the water filled pore space (WFPS), both nitrification and denitrification could have occurred during the experimental period. Denitrification capacity in March was similar in all tillage systems, in spite of the higher DOC content maintained in the topsoil of NT. This could be due to the similar denitrifier densities, targeted by nirk copy numbers at that time. Cumulative CH4 fluxes resulted in small net uptake for all treatments, and no significant differences were found among tillage systems or between fallow and wheat land-covers. These results suggest that under a coarse-textured soil in low N agricultural systems, the impact of tillage on GHG is very low and that the fallow cycle within a crop rotation is not a useful strategy to reduce GHG emissions.
  • 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.
  • Authors:
    • Masilionyte, L.
    • Sasnauskiene, J.
    • Romaneckas, K.
    • Sarauskis, E.
    • Buragiene, S.
    • Kriauciuniene, Z.
  • Source: SCIENCE OF THE TOTAL ENVIRONMENT
  • Volume: 514
  • Year: 2015
  • Summary: Intensive agricultural production strongly influences the global processes that determine climate change. Thus, tillage can play a very important role in climate change. The intensity of soil carbon dioxide (CO 2) emissions, which contribute to the greenhouse effect, can vary depending on the following factors: the tillage system used, meteorological conditions (which vary in different regions of the world), soil properties, plant residue characteristics and other factors. The main purpose of this research was to analyse and assess the effects of autumn tillage systems with different intensities on CO 2 emissions from soils during different seasons and under the climatic conditions of Central Lithuania. The research was conducted at the Experimental Station of Aleksandras Stulginskis University from 2009 to2012; and in 2014. The soils at the experimental site were classified as Eutric Endogleyic Planosol (Drainic). The investigations were conducted using five tillage systems with different intensities, typical of the Baltic Region. Deep conventional ploughing was performed at a depth of 230-250 mm, shallow ploughing was conducted at a depth of 120-150 mm, deep loosening was conducted at depths of 250-270 mm, and shallow loosening was conducted at depths of 120-150 mm. The fifth system was a no-tillage system. Overall, autumn tillage resulted in greater CO 2 emissions from the soil over both short- and long-term periods under the climatic conditions of Central Lithuania, regardless of the tillage system applied. The highest soil CO 2 emissions were observed for the conventional deep ploughing tillage system, and the lowest emissions were observed for the no-tillage system. The meteorological conditions greatly influenced the CO 2 emissions from the soil during the spring. Soil CO 2 emissions were enhanced as precipitation and the air and soil temperatures increased. Long-term investigations regarding the dynamics of CO 2 emissions from soils during the maize vegetation period indicated that autumn tillage systems affect the total soil CO 2 emissions. The highest (2.17 mol m -2 s -1) soil CO 2 emissions during the vegetation period were observed in the deep ploughing tillage system, and the lowest values were observed (1.59 mol m -2 s -1) in the no-tillage system.
  • Authors:
    • Gan, Y. T.
    • Cui, H. Y.
    • Yin, W.
    • Yu, A. Z.
    • Chai, Q.
    • Hu, F. L.
  • Source: AGRONOMY FOR SUSTAINABLE DEVELOPMENT
  • Volume: 35
  • Issue: 2
  • Year: 2015
  • Summary: Intercropping is used to increase grain production in many areas of the world. However, this increasing crop yield costs large amounts of water used by intercropped plants. In addition, intercropping usually requires higher inputs that induce greenhouse gas emissions. Actually, it is unknown whether intercropping can be effective in water-limited arid areas. Here, we measured crop yield, water consumption, soil respiration, and carbon emissions of wheat-maize intercropping under different tillage and crop residue management options. A field experiment was conducted at Wuwei in northwest China in 2011 and 2012. Our results show that wheat-maize intercropping increased grain yield by 61 % in 2011 and 63 % in 2012 compared with the average yield of monoculture crops. The intercropping under reduced tillage with stubble mulching yielded 15.9 t ha(-1) in 2011 and 15.5 t ha(-1) in 2012, an increase of 7.8 % in 2011 and 8.1 % in 2012, compared to conventional tillage. Wheat-maize intercropping had carbon emission of 2,400 kg C ha(-1) during the growing season, about 7 % less than monoculture maize, of 2,580 kg C ha(-1). Reduced tillage decreased C emission over conventional tillage by 6.7 % for the intercropping, 5.9 % for monoculture maize, and 7.1 % for monoculture wheat. Compared to monoculture maize, wheat-maize intercropping used more water but emitted 3.4 kg C per hectare per millimeter of water used, which was 23 % lower than monoculture maize. Overall, our findings show that maize-wheat intercropping with reduced tillage coupled with stubble mulching can be used to increase grain production while effectively lower carbon emissions in arid areas.
  • Authors:
    • Armstrong, S.
    • Lacey, C.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY
  • Volume: 44
  • Issue: 2
  • Year: 2015
  • Summary: There is a dearth of knowledge on the ability of cover crops to increase the effectiveness of fall-applied nitrogen (N). The objective of this study was to investigate the efficacy of two cover crop species to stabilize inorganic soil N after a fall application of N. Fall N was applied at a rate of 200 kg N ha -1 into living stands of cereal rye, tillage radish, and a control (no cover crop) at the Illinois State University Research and Teaching Farm in Lexington, Illinois. Cover crops were sampled to determine N uptake, and soil samples were collected in the spring at four depths to 80 cm to determine the distribution of inorganic N within the soil profile. Tillage radish (131.9-226.8 kg ha -1) and cereal rye (188.1-249.9 kg ha -1 N) demonstrated the capacity to absorb a minimum of 60 to 80% of the equivalent rate of fall-applied N, respectively. Fall applying N without cover crops resulted in a greater percentage of soil NO 3-N (40%) in the 50- to 80-cm depth, compared with only 31 and 27% when tillage radish and cereal rye were present at N application. At planting, tillage radish stabilized an average of 91% of the equivalent rate of fall-applied N within the 0- to 20-cm, depth compared with 66 and 57% for the cereal rye and control treatments, respectively. This study has demonstrated that fall applying N into a living cover crop stand has the potential to reduce the vulnerability of soil nitrate and to stabilize a greater concentration of inorganic N within the agronomic depths of soil.
  • Authors:
    • Francaviglia, R.
    • Ledda, L.
    • Doro, L.
    • Munoz-Rojas, M.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 202
  • Year: 2015
  • Summary: CarboSOIL model and climate outputs from two GCMs (GISS and HadCM3), three time horizons (2020, 2050, 2080), and two emission scenarios (A2 and B2) according to IPCC were used to study the effects of climate change on soil organic carbon (SOC) stocks in a Mediterranean region (Northeast Sardinia, Italy). CarboSOIL is an empirical model based on regression techniques and developed to predict SOC contents at standard soil depths of 0-25, 25-50 and 50-75 cm. The area is characterized by extensive agro-silvo-pastoral systems, and six land uses with different levels of cropping intensification were compared: tilled vineyards (TV), no-tilled grassed vineyards (GV), hay crop (HC), pasture (PA), cork oak forest (CO), and semi-natural systems (SN). The main objectives were: (i) to validate the model predictions with the measured SOC stocks, and (ii) to predict SOC stocks in future climate projections for the different land use types. The model proved its ability to predict SOC stocks at different soil depths, and can be used as a tool for predicting SOC stocks under different climate change scenarios. The results suggest that future climatic scenarios can have a negative effect on SOC stocks in the upper sections of the soil profile, mainly due to a very low increase in the 0-25 cm section and a sharp decrease in the 25-50 cm soil section, in particular in a long term perspective (2080) and under the emission scenario A2. Important decreases of SOC stocks were found in the upper soil sections of the vineyards.
  • Authors:
    • Lambert, D. M.
    • Thierfelder, C.
    • Hicks, B. B.
    • Sauer, T. J.
    • O'Dell, D.
    • Logan, J.
    • Eash, N. S.
  • Source: Journal of Agricultural Science (Toronto)
  • Volume: 7
  • Issue: 3
  • Year: 2015
  • Summary: Two of the biggest problems facing humankind are feeding an exponentially growing human population and preventing the accumulation of atmospheric greenhouse gases and its climate change consequences. Refined agricultural practices could address both of these problems. The research addressed here is an exploration of the efficacy of alternative agricultural practices in sequestering carbon (C). The study was conducted in Zimbabwe with the intent to (a) demonstrate the utility of micrometeorological methods for measuring carbon dioxide (CO 2) exchange between the surface and the atmosphere in the short-term, and (b) to quantify differences in such exchange rates for a variety of agricultural practices. Four Bowen ratio energy balance (BREB) systems were established on the following agricultural management practices: (1) no-till (NT) followed by planting of winter wheat ( Triticum aestivum), (2) NT followed by planting of blue lupin ( Lupinus angustifolios L.), (3) maize crop residue ( Zea mays L.) left on the surface, and (4) maize crop residue incorporated with tillage. Over a period of 139 days (from 15 June to 31 October 2013) the winter wheat cover crop produced a net accumulation of 257 g CO 2-C m -2, while the tilled plot with no cover crop produced a net emission of 197 g CO 2-C m -2 and the untilled plot with no cover emitted 235 g CO 2-C m -2. The blue lupin cover crop emitted 58 g CO 2-C m -2, indicating that winter cover crops can sequester carbon and reduce emissions over land left fallow through the non-growing season. The micrometeorological methods described in this work can detect significant differences between treatments over a period of a few months, an outcome important to determine which smallholder soil management practices can contribute towards mitigating climate change.