• Authors:
    • Munkholm, L. J.
    • Abdollahi, L.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 1
  • Year: 2014
  • Summary: Optimal use of management systems including tillage and winter cover crops is recommended to improve soil quality and sustain agricultural production. The effects on soil properties of three tillage systems (as main plot) including direct drilling (D), harrowing to a depth of 8 to 10 cm (H), and moldboard plowing (MP) with and without a cover crop were evaluated in a long-term experiment on a sandy loam soil in Denmark. Chemical, physical, and biological soil properties were measured in the spring of 2012. The field measurements included mean weight diameter (MWD) after the drop-shatter test, penetration resistance, and visual evaluation of soil structure (VESS). In the laboratory, aggregate strength, water-stable aggregates (WSA), and clay dispersibility were measured. The analyzed chemical and biological properties included soil organic C (SOC), total N, microbial biomass C, labile P and K, and pH. Reduced tillage (D and H) resulted in a stratification of the chemical properties within the 0- to 20-cm topsoil layer but a uniform distribution for MP. There was an accumulation of SOC, total N, and labile P and K and reduced pH in the 0- to 10-cm layer. Reduced tillage increased soil strength in terms of greater MWD, VESS, WSA, aggregate tensile strength, and rupture energy. Five years of using a cover crop alleviated plow pan compaction at the 20- to 40-cm depth by reducing penetration resistance. A significant interaction between tillage and cover crop treatments indicated the potential benefit of using a combination of cover crops and direct drilling to produce a better soil friability. The usefulness of the VESS method for soil structural evaluation was supported by the high positive correlation of MWD with VESS scores. © Soil Science Society of America.
  • Authors:
    • Munkholm, L. J.
    • Abdollahi, L.
    • Garbout, A.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 1
  • Year: 2014
  • Summary: Information about the quantitative effect of conservation tillage combined with a cover crop on soil structure is still limited. This study examined the effect of these management practices on soil pore characteristics of a sandy loam soil in a long-term field trial. The tillage treatments (main plots) included direct drilling (D), harrowing to a depth of 8 to 10 cm (H), and moldboard plowing (MP). The cover crop treatments were subplot with cover crop (+CC) and without cover crop (-CC). Minimally disturbed soil cores were taken from the 4- to 8-, 12- to 16-, and 18- to 27-cm depth intervals in the spring of 2012 before cultivation. Soil water retention and air permeability were measured for matric potentials ranging from -1 to -30 kPa. Gas diffusivity was measured at -10 kPa. Computed tomography (CT) scanning was also used to characterize soil pore characteristics. At the 4- to 8- and 18- to 27-cm depths, pore characteristics did not differ significantly among tillage treatments. At the 12- to 16-cm depth, negative effects of reduced tillage (D and H) were recorded for total porosity and air-filled porosity at -10 kPa (that is, >30-μm pores). Generally, the use of a cover crop increased air-filled porosity at -10 kPa, air permeability, and pore organization and reduced the value of blocked air porosity at all depths for all tillage treatments. Our results show that the cover crop created continuous macropores and in this way improved the conditions for water and gas transport and root growth. The cover crop thus alleviated the effect of tillage pan compaction in all tillage treatments. © Soil Science Society of America.
  • Authors:
    • Elmholt, S.
    • Schjønning, P.
    • Abdollahi, L.
    • Munkholm, L. J.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 136
  • Year: 2014
  • Summary: Management strategies like organic matter (OM) amendment and mechanical energy inputs are known to influence the soil system. A long-term (13-14-year) field experiment was used to evaluate the effects of these management strategies on soil structural formation, structural stabilization and soil tilth of a sandy loam soil in Denmark. OM was applied as manure and by retention of plant residues (ORG) to be compared with plots dressed only with mineral fertilizer (MIN). The soils were rotovated (ROT), compacted (PAC) or left undisturbed (REF) as split-plot treatments in the main plots with OM management over two years prior to sampling. In two consecutive years, undisturbed soil samples were collected from the 6 to 13. cm soil layer in the field grown with winter wheat to assess soil organic carbon (C) fractions (total organic C, polysaccharide C and microbial biomass C), total organic C and polysaccharide C of 1-2. mm macro-aggregates, bulk density, hyphal length, aggregate stability, clay dispersibility, aggregate tensile strength, direct tensile strength and shear strength. The ease of fragmentation and the torsional shear strength of soil were measured in the field as well. OM application increased all soil organic C fractions. Response patterns of organic C fractions in aggregates were the same patterns as for whole-soil. Polysaccharide C appeared to be an important agent in the aggregation process. The effect of microbial C and fungal hyphae on the aggregation process was not clear. Extensive tillage and traffic produced unfavourable tilth conditions in terms of a greater degree of clay dispersion, lower aggregate stability, higher soil tensile strength and poorer soil fragmentation. OM affected soil reaction to compressive and tensile stresses applied at differing initial bulk densities. The results also indicated the profitability of supplementing the classical laboratory analysis with in situ measurements to better evaluate management effects on soil structure. © 2013 Elsevier B.V.
  • Authors:
    • Kucukalbay, M.
    • Akbolat, D.
  • Source: POLISH JOURNAL OF ENVIRONMENTAL STUDIES
  • Volume: 23
  • Issue: 4
  • Year: 2014
  • Summary: This study determined carbon dioxide (CO2) emissions from the cultivation of chickpeas cultivated in Usak using conventional wheat-chickpea crop rotation methods as a function of conventional tillage (CT), reduced tillage (RT), and direct seeding (DS). Measurements of carbon dioxide (CO2) emissions from the soil were started after planting using a portable CO2 measurement system (PP System) for a period of 55 days. Our results indicated CO2 emissions at rates of 4.1, 4.5, and 5.3 g.m(-2).h(-1) in response to the CT, RT, and DS treatments, respectively. A significant difference was found between CT and RT, and CO2 emissions under the DS treatment were higher than those of the other two treatments (p<0.05). Soil evaporation rates were estimated at 11.6, 10.9, and 13.1 g.m(-2).h(-1) under the CT, RT, and DS treatments, respectively. Mean soil temperafure was 17.5, 18.1, and 18.3 degrees C for the CT, RT, and DS treatments, respectively (p<0.05). Mean values of soil moisture content (wet base) after tillage were 19.7%, 19.1%, and 18.8% for CT, RT, and DS, respectively. Soil temperature and seedbed preparation methods appeared to influence soil CO2 emissions.
  • Authors:
    • Basanta, M.
    • Costantini, A.
    • Alvarez, C. R.
    • Alvarez, C.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 142
  • Year: 2014
  • Summary: Soil management affects distribution and the stocks of soil organic carbon and total nitrogen. The aim of this study was to evaluate the effect of different crop sequences and tillage systems on the vertical distribution and stocks of soil carbon and nitrogen. We hypothesized that no-tillage promotes surface organic carbon and total nitrogen accumulation, but does not affect the C and N stocks, when compared with reduced tillage. In addition, the incorporation of maize in the crop sequence increases total organic carbon and total nitrogen stocks. Observations were carried out in 2010 in an experiment located in the semiarid Argentine Pampa, on an Entic Haplustoll. A combination of three tillage systems (no tillage, no tillage with cover crop in winter and reduced tillage) and two crop sequences (soybean-maize and soybean monoculture) were assessed. After 15 years of management treatments, soil samples to a depth of 100. cm at seven intervals, were taken and analyzed for bulk density, organic carbon and total nitrogen. Total organic carbon stock up to a depth of 100. cm showed significant differences between soils under different tillage systems (reduced tillage. <. no tillage = no tillage with cover crop), the last ones having 8% more than the reduced tillage treatment. Soybean-maize had 3% more organic C up to 100. cm depth than the soybean monoculture. Total nitrogen stock was higher under no-till treatments than under reduced tillage, both at 0-50 and 0-100. cm depths. Total organic carbon stratification ratios (0-5. cm/5-10. cm) were around 1.6 under no-till and lower under reduced tillage. The stratification ratio explains less than 40% of soil carbon stock. Tillage system had a greater impact on soil carbon stock than crop sequence. © 2014 Elsevier B.V.
  • Authors:
    • Saxton, A. M.
    • Wight, J. P.
    • Allen, F. L.
    • Ashworth, A. J.
    • Tyler, D. D.
    • Sams, C. E.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 5
  • Year: 2014
  • Summary: Climate change may be mitigated through soil organic C (SOC) storage under no-tillage; however, crop management influences on SOC are not well defined in all systems. Our objective was to compare long-term C fluxes under two no-tillage sites at Research and Education Centers in Milan (RECM) on Oxyaquic Fragiudalfs and at Middle Tennessee (MTREC) on a Typic Paleudalf in a split-block design with four replications. The whole-block was cropping sequences of corn (Zea mays L.), soybeans [Glycine max (L.) Merr.], and cotton (Gossypium hirsutum L.) with split-block bio-cover treatments of winter wheat (Triticum aestivum L.), hairy vetch [Vicia villosa Roth subsp. villosa], poultry litter, and a fallow control. The same sequences were performed at MTREC without cotton. Soil C flux was calculated at surfaces (0-5 cm) and subsurfaces (5-15 cm) during Year 0, 2, 4, and 8. During the first 2 yr, C losses occurred in all treatments and locations (1.40 and 1.20 Mg ha-1at RECM and MTREC, respectively), with stabilization initiating by Year 4. By Year 8, sequences with high frequencies of soybean and greater temporal complexity gained more surface SOC. Poultry litter bio-covers gained more surface SOC compared to wheat, vetch, and fallow bio-covers (P < 0.05). After 8 yr, surface SOC surpassed initial levels (9.20 and 8.79 Mg ha-1), with mean gains of 1.33 and 1.16 Mg C ha-1at RECM and MTREC, respectively. Losses occurred in subsoils at MTREC and RECM, but by Year 8 several treatments had recovered to near baseline levels. Results suggest surface C storage may be enhanced by crop sequence diversity combined with poultry litter bio-covers in no-till systems, whereas subsurface levels may require more time.
  • Authors:
    • Hernandez-Ramirez, G.
    • Scott, C. L.
    • Beare, M. H.
    • Curtin, D.
    • Meenken, E. D.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 3
  • Year: 2014
  • Summary: Uncertainty persists regarding the influence of physical disturbance on mineralization of soil organic matter. This study examined how disturbance affects mineralization in soils with different management histories and textures. Results from a 100-d incubation (20°C, -10 kPa) using cores (0-15 cm deep; 5-cm diameter) from a field trial at Lincoln, New Zealand with different agronomic treatments in the previous 5 yr (pasture, arable cropping, and chemical fallow) confirmed that mineralization is strongly influenced by management history (C mineralized ranged from 390 mg kg-1 in fallow soil to 1570 mg kg-1 under pasture). However, there was no difference in C or N mineralization between disturbed (sieved <4 mm) and intact cores. In another experiment, comparisons of mineralization in intact and disturbed (<4 mm) cores from 14 arable and pasture fields with either silt loam or clay loam texture also showed no effect of disturbance. In a final experiment, large, air-dry aggregates (19-40 mm) from two soil types (silt loam and clay loam) were fragmented using a compressive force and the resulting subaggregates separated into size classes (<0.25, 0.25-1, 1-2, 2-4, 4-9.5, and 9.5-13.2 mm) by dry sieving. Mineralization increased only when aggregate size was below a certain threshold value (∼3 mm diameter); mineralization was ∼25-50% greater in fine (≤1 mm) vs. large (4-40 mm) aggregates, likely due to exposure of previously-occluded organic matter. Unless a substantial quantity of fine aggregates is generated, the influence of physical disturbance may be small.
  • Authors:
    • Hartman, D. C.
    • Briedis, C.
    • Lal, R.
    • Tivet, F.
    • De Moraes Sá, J. C.
    • dos Santos, J. Z.
    • dos Santos, J. B.
  • Source: Soil & Tillage Research
  • Volume: 136
  • Year: 2014
  • Summary: No-till (NT) cropping systems have been widely promoted in many regions as an important tool to enhance soil quality and improve agronomic productivity. However, knowledge of their long-term effects on soil organic carbon (SOC) stocks and functional SOC fractions linking soil resilience capacity and crop yield is still limited. The aims of this study were to: (i) assess the long-term (16 years) effects of tillage systems (i.e., conventional - CT, minimum - MT, no-till with chisel - NTch, and continuous no-till cropping systems - CNT) on SOC in bulk soil and functional C fractions isolated by chemical (hot water extractable organic C - HWEOC, permanganate oxidizable C - POXC) and physical methods (light organic C - LOC, particulate organic C - POC, mineral-associated organic C - MAOC) of a subtropical Oxisol to 40cm depth; (ii) evaluate the soil resilience restoration effectiveness of tillage systems, and (iii) assess the relationship between the SOC stock enhancement and crop yield. The crop rotation comprised a 3-year cropping sequence involving two crops per year with soybean (Glycine max, L. Merril) and maize (Zea mays L.) in the summer alternating with winter crops. In 2005, the soil under CNT contained 25.8, 20.9, and 5.3Mgha-1 more SOC (P<0.006) than those under CT, MT, and NTch in 0-40cm layer, representing recovery rates of 1.61, 1.31, and 0.33Mg Cha-1yr-1, respectively. The relative C conversion ratio of 0.398 at CNT was more efficient in converting biomass-C input into sequestered soil C than NTch (0.349), MT (0.136), and CT (0.069). The soil under CNT in 0-10cm depth contained ~1.9 times more HWEOC and POXC than those under CT (P<0.05), and concentrations of LOC and POC physical fractions of SOC were significantly higher throughout the year under CNT. Considering CT as the disturbance baseline, the resilience index (RI) increased in the order of MT (0.10)<NTch (0.43)<CNT (0.54). Grain yield was positively affected by increase in SOC stock, and an increase of 1Mg Cha-1 in 0-20cm depth resulted in an increase in yield equal to ~11 and 26kg grainha-1 of soybean (R2=0.97, P=0.03) and wheat (R2=0.96, P=0.03), respectively. The data presented emphasizes the role of labile fractions in the overall SOC accumulation processes in soils managed under CNT and their positive impacts on the soil resilience restoration and on agronomic productivity. © 2013 Elsevier B.V.
  • Authors:
    • Zhang, H. L.
    • Lal, R.
    • Chen, Z. D.
    • Dikgwatlhe ,S. B.
    • Chen, F.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 144
  • Year: 2014
  • Summary: The importance of soil organic carbon (SOC) and nitrogen (N) sequestration in agricultural soils as climate-change-mitigating strategy has received robust attention worldwide in relation to soil management. This study was conducted to determine the temporal effects of different tillage systems and residue management on distribution, storage and stratification of SOC and N under wheat (Triticum aestivum L.) - maize (Zea mays L.) cropping systems in the North China Plain (NCP). Four tillage systems for winter wheat established in 2001 were: moldboard plow tillage with maize residues removed (PT0), moldboard plow tillage with maize residues incorporated (PT), rotary tillage with maize residues incorporated (RT), and no-till with maize residues retained on the soil surface (NT). Compared with PT0 and PT, significantly higher SOC and N concentrations were observed in the surface layer (0-10cm depth) under NT and RT. In 2004, the SOC stocks were lower (PRT>PT>PT0 in both years. Compared with other treatments, SOC and N stocks were the lowest (P<0.05) under PT0. Therefore, crop residues play an important role in SOC and N management, and improvement of soil quality. The higher SOC stratification was observed under NT and RT than under PT and PT0, whereas the C:N ratio was higher (P<0.05) under PT and PT0 than under NT and RT systems. Therefore, the notion that NT leads to higher SOC stocks than plowed systems requires cautious scrutiny. Nonetheless, some benefits associated with NT present a greater potential for its adoption in view of the long-term environmental sustainability under wheat-maize double-cropping system in the NCP. © 2014 Elsevier B.V.
  • Authors:
    • Franzluebbers, A. J.
    • Stuedemann, J. A.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 4
  • Year: 2014
  • Summary: Soil organic C and N are important indicators of agricultural sustainability, yet numerous field studies have revealed a multitude of responses in the extent and rate of change imposed by conservation management and, therefore, a lack of clarity on responses. We conducted an evaluation of total and particulate organic C and N in the surface 30 cm on a Typic Kanhapludult in northern Georgia during 7 yr of tillage (conventional disk and no tillage) and cover crop utilization (ungrazed and grazed by cattle). Soil organic C and total soil N were greater under no tillage (NT) than under conventional tillage (CT) at depths of 0 to 3 and 3 to 6 cm but were lower under NT than CT at depths of 12 to 20 and 20 to 30 cm. Total soil N accumulated with time at a depth of 0 to 6 cm under both tillage systems and the rate tended to be greater under NT than under CT (0.039 vs. 0.021 Mg N ha-1 yr -1, p = 0.10). Soil organic C accumulated with time at a depth of 0 to 6 cm under all management systems, but there was a significant tillage × cover crop interaction (0.68 and 1.09 Mg C ha-1 yr -1 with ungrazed cover crop management under CT and NT, respectively, and 0.84 and 0.66 Mg C ha-1 yr-1 with grazed cover crop management under CT and NT, respectively). At a depth of 0 to 30 cm, there was only a tillage trend (1.00 and 1.59 Mg C ha-1 yr-1 under CT and NT, respectively; p = 0.09). Particulate organic C was more dramatically different than soil organic C between tillage regimes at a depth of 0 to 30 cm (-0.49 and 0.35 Mg C ha-1 yr-1 under CT and NT, respectively; p < 0.001). Grazing of cover crops had little negative impact on soil C and N fractions, suggesting that NT and grazing of cover crops could provide a broader-spectrum conservation cropping approach in the southeastern United States. © Soil Science Society of America, 5585 Guilford Rd.