• Authors:
    • Granier, M.
  • Source: Options Mediterraneennes. Serie A, Seminaires Mediterraneens
  • Issue: 96
  • Year: 2011
  • Summary: Continuous use, mostly by mono cultivation of cereal, of agricultural lands leads to soil degradation by tillage erosion, rain and wind - especially in the Mediterranean region - with consequences for the loss of organic matter, the destruction of the field and finally the gradual disappearance of topsoil. The creation of a permanent cover by implantation of a legume pioneer and rational exploitation of this system of crops allows the recovery of the biosphere and the return to productivity of the treated lands. An environmental management of degraded land under a rainfall less than 400 mm sets a positive development in these soils following a cultural practices described and implemented in Tunisia from 2003 to 2009 in the Goubellat region by AAG/SAG.
  • Authors:
    • Dela Piccolla, C.
    • Mafra, A. L.
    • Pelissari, A.
    • de Moraes, A.
    • da Veiga, M.
    • Balbinot Junior, A. A.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 46
  • Issue: 10
  • Year: 2011
  • Summary: The objective of this work was to evaluate the effect of winter land use on the amount of residual straw, the physical soil properties and grain yields of maize, common bean and soybean summer crops cultivated in succession. The experiment was carried out in the North Plateau of Santa Catarina state, Brazil, from May 2006 to April 2010. Five strategies of land use in winter were evaluated: intercropping with black oat + ryegrass + vetch, without grazing and nitrogen (N) fertilization (intercropping cover); the same intercropping, with grazing and 100 kg ha(-1) of N per year topdressing (pasture with N); the same intercropping, with grazing and without nitrogen fertilization (pasture without N); oilseed radish, without grazing and nitrogen fertilization (oilseed radish); and natural vegetation, without grazing and nitrogen fertilization (fallow). Intercropping cover produces a greater amount of biomass in the system and, consequently, a greater accumulation of total and particulate organic carbon on the surface soil layer. However, land use in winter does not significantly affect soil physical properties related to soil compaction, nor the grain yield of maize, soybean and common bean cultivated in succession.
  • Authors:
    • Lal, R.
    • Ussiri, D. A. N.
    • Trumbore, S. E.
    • Mestelan, S.
    • Jagadamma, S.
  • Source: Biogeochemistry
  • Volume: 98
  • Issue: 1-3
  • Year: 2010
  • Summary: Accurate quantification of different soil organic carbon (SOC) fractions is needed to understand their relative importance in the global C cycle. Among the chemical methods of SOC fractionation, oxidative degradation is considered more promising because of its ability to mimic the natural microbial oxidative processes in soil. This study focuses on detailed understanding of changes in structural chemistry and isotopic signatures of SOC upon different oxidative treatments for assessing the ability of these chemicals to selectively isolate a refractory fraction of SOC. Replicated sampling (to ~1 m depth) of pedons classified as Typic Fragiudalf was conducted under four land uses (woodlot, grassland, no-till and conventional-till continuous corn [ Zea mays L.]) at Wooster, OH. Soil samples (<2 mm) were treated with three oxidizing agents (hydrogen peroxide (H 2O 2), disodium peroxodisulfate (Na 2S 2O 8) and sodium hypochlorite (NaOCl)). Oxidation resistant residues and the bulk soil from A1/Ap1 horizons of each land use were further analyzed by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and accelerator mass spectrometry to determine structural chemistry and 14C activity, respectively. Results indicated that, oxidation with NaOCl removed significantly less SOC compared to Na 2S 2O 8 and H 2O 2. The NMR spectra revealed that NaOCl oxidation preferentially removed lignin-derived compounds at 56 ppm and at 110-160 ppm. On the other hand, the SOC resistant to Na 2S 2O 8 and H 2O 2 oxidation were enriched with alkyl C groups, which dominate in recalcitrant macromolecules. This finding was corroborated by the 14C activity of residual material, which ranged from -542 to -259 per mil for Na 2S 2O 8 resistant SOC and -475 to -182 per mil for H 2O 2 resistant SOC as compared to relatively greater 14C activity of NaOCl resistant residues (-47 to 61 per mil). Additionally, H 2O 2 treatment on soils after light fraction removal was more effective in isolating the oldest ( 14C activity of -725 to -469 per mil) SOC fraction. The Delta 14C signature of SOC removed by different oxidizing agents, calculated by mass balance, was more or less similar irrespective of the difference in labile SOC removal efficiency. This suggests that SOC isolated by many fractionation methods is still a mixture of much younger and older material and therefore it is very important that the labile SOC should be completely removed before measuring the turnover time of stable and refractory pools of SOC.
  • Authors:
    • Schroeder, K. L.
    • Paulitz, T. C.
    • Schillinger, W. F.
  • Source: Plant Disease
  • Volume: 94
  • Issue: 1
  • Year: 2010
  • Summary: An irrigated cropping systems experiment was conducted for 6 years in east-central Washington State to examine agronomic and economic alternatives to continuous annual winter wheat ( Triticum aestivum) with burning and plowing, and to determine how root diseases of cereals are influenced by management practices. The continuous winter wheat treatment with burning and plowing was compared with a 3-year no-till rotation of winter wheat-spring barley ( Hordeum vulgare)-winter canola ( Brassica napus) and three straw management treatments: burning, straw removal, and leaving the straw stubble standing after harvest. Take-all disease and inoculum increased from years 1 to 4 in the continuous winter wheat treatment with burning and plowing, reducing plant growth compared to the no-till treatments with crop rotations. Inoculum of Rhizoctonia solani AG-8 was significantly lower in the tilled treatment compared to the no-till treatments. Inoculum concentration of Fusarium pseudograminearum was higher than that of F. culmorum, and in one of three years, the former was higher in treatments with standing stubble and mechanical straw removal compared to burned treatments. Residue management method had no effect on Rhizoctonia inoculum, but spring barley had more crown roots and tillers and greater height with stubble burning. This 6-year study showed that irrigated winter wheat can be produced in a no-till rotation without major disease losses and demonstrated how cropping practices influence the dynamics of soilborne cereal diseases and inoculum over time.
  • Authors:
    • Sainju, U. M.
    • Jabro, J. D.
    • Caesar-TonThat, T.
  • Source: Journal of Environmental Quality
  • Volume: 39
  • Issue: 3
  • Year: 2010
  • Summary: Management practices are needed to reduce dryland sod CO(2) emissions and to increase C sequestration We evaluated the effects of tillage and cropping sequence combinations and N fertilization on dryland crop biomass (stems + leaves) and sod surface CO(2) flux and C content (0- to 120-cm depth) in a Williams loam from May to October, 2006 to 2008, in eastern Montana. Treatments were no-tilled continuous malt barley (Hordeum vulgaris L) (NTCB), no-tilled malt bailey pea (Pivot; sativum L) (NTB-P), no-tilled malt barley fallow (NTB-F), and conventional-tilled malt barley fallow (CTB-F), each with 0 and 80 kg N ha(-1) Measurements were made both in Phase I (malt barley in NTCB, pea in NTB-P, and fallow in NTB-F and CTB-F) and Phase II (malt barley in all sequences) of each cropping sequence in every year Crop biomass varied among years. was greater in the barley than in the pea phase of the NTB-P treatment, and greater in NTCB and NTB-P than in NTB-F and CTB-F in 2 out of 3 yr Similarly biomass was greater with 80 than with 0 kg N ha(-1) in 1 out of 3 yr. Soil CO(2) flux increased from 8 mg C m(-2) h(-1) in early May to 239 mg C m(-2) h(-1) in mid-June as temperature increased and then declined to 3 mg C m(-2) h(-1) in September. October Fluxes peaked immediately following substantial precipitation (>10 mm). especially in NTCB and NTB-P Cumulative CO(2) flux from May to October was greater in 2006 and 2007 than in 2008, greater in cropping than in fallow phases, and greater in NTCB than in NTB-F. Tillage did not influence crop biomass and CO(2) flux but N fertilization had a variable effect on the flux in 2008. Similarly, soil total C content was not influenced by treatments Annual cropping increased CO(2) flux compared with crop fallow probably by increasing crop residue returns to sods and root and rhizosphere respiration Inclusion of peas in the rotation wills malt barley in the no-till system, which have been known to reduce N fertilization rates and sustain malt barley yields, resulted in a CO(2) flux similar to that in the CTB-F sequence
  • Authors:
    • Kennedy, A. C.
    • Schillinger, W. F.
    • Young, D. L.
    • Paulitz, T. C.
  • Source: Field Crops Research
  • Volume: 115
  • Issue: 1
  • Year: 2010
  • Summary: Field burning of residue is a traditional management tool for irrigated wheat ( Triticum aestivum L.) production in the Inland Pacific Northwest of the United States (PNW) that can result in reduced air quality. A 6-year no-till field experiment to evaluate two complete cycles of a 3-year irrigated crop rotation of winter wheat-spring barley ( Hordeum vulgare L.)-winter canola ( Brassica napus L.) was sown (i) directly into standing residue of the previous crop, (ii) after mechanical removal of residue and, (iii) after burning of residue. The traditional practice of continuous annual winter wheat sown after burning residue and inverting the topsoil with a moldboard plow was included as a check treatment. Over-winter precipitation storage efficiency (PSE) was markedly improved when residue was not burned or burned and plowed after grain harvest. Grain yield of winter wheat trended higher in all no-till residue management treatments compared to the check treatment. Average grain yields of spring barley and canola were not significantly different among the no-till residue management treatments. Winter canola failed in 5 of 6 years due to a combination of a newly identified Rhizoctonia damping-off disease caused by Rhizoctonia solani AG-2-1 and cold temperatures that necessitated replanting to spring canola. Six-year average net returns over total costs were statistically equal over all four systems. All systems lost from $358 to $396 ha -1. Soil organic carbon (SOC) increased linearly each year with no-till at the 0-5 cm depth and accumulated at a slower rate at the 5-10 cm depth. Take-all of wheat caused by Gaeumannomyces graminis var. tritici was most severe in continuous annual winter wheat. The incidence and severity of Rhizoctonia on roots of wheat and inoculum of R. solani AG-8, was highest in the no-till treatments, but there was no grain yield loss due to this disease in any treatment. Residue management method had no consistent effect on Rhizoctonia root rot on barley. The annual winter grass downy brome ( Bromus tectorum L.) was problematic for winter wheat in the standing and mechanically removed residue treatments, but was controlled in the no-till residue burned and the burn and plow check. Another winter annual grass weed, rattail fescue ( Vulpia myuros L.), infested all no-till treatments. This was the first comprehensive and multidisciplinary no-till irrigated crop rotation study conducted in the Pacific Northwest.
  • Authors:
    • Zekaite, V.
  • Source: Vagos
  • Issue: 88
  • Year: 2010
  • Summary: Field experiments, designed to study weed incidence in Poaceae and Fabaceae monocrops and their mixtures as influenced by an organic cropping system, were carried out during 2007-2009 at the Experimental station of the Lithuanian Research Centre for Agriculture and Forest in Perloja on a Hapli-Albic Luvisol. Short-lived weeds prevailed in the crops. They accounted for 93-95% of the total weeds. The highest counts of weeds were recorded at the beginning of the growing season when the conditions for their emergence were the most conducive ones. In 2007 and 2009 the weather conditions during cereal tillering stage were wet and warm, which created optimal conditions for weed emergence and the weed count per m -2 was 257-264. In the third ten-day period of April 2008, re-current night frosts inhibited cereal and weed emergence, which resulted in 43.6-51.7% lower emergence. With increasing crop competitive power (milk maturity stage), weed emergence tended to decline and was by 17.9-9.8% lower compared with the weed count at tillering stage. Weed air dry weight decreased proportionally, however, only at crop hard maturity stage, with the reduction in crop competitive power, weed air dry weight increased by 31.6%. Due to the weather conditions, weed air dry weight in the wet year 2007 was by 35-55% higher than that in 2008 and 2009. Lupines, oats and wheat and its mixture with peas performed best in suppressing weeds. A strong linear correlation was established between weed number and precipitation and weigh (r=0.901, r=0.758); between plant density and precipitation amount (r=0.745).
  • Authors:
    • Robertson, G. P.
    • Grace, P. R.
    • Bohm, S.
    • McSwiney, C. P.
  • Source: Journal of Natural Resources & Life Sciences Education
  • Volume: 39
  • Year: 2010
  • Summary: Opportunities for farmers to participate in greenhouse gas (GHG) credit markets require that growers, students, extension educators, offset aggregators, and other stakeholders understand the impact of agricultural practices on GHG emissions. The Farming Systems Greenhouse Gas Emissions Calculator, a web-based tool linked to the SOCRATES soil carbon process model, provides a simple introduction to the concepts and magnitudes of gas emissions associated with crop management. Users choose a county of interest on an introductory screen and are taken to the input/output window, where they choose crops, yields, tillage practices, or nitrogen fertilizer rates. Default values are provided based on convention and county averages. Outputs include major contributors of greenhouse gases in field crops: soil carbon change, nitrous oxide (N2O) emission, fuel use, and fertilizer. We contrast conventional tillage and no-till in a corn-soybean-wheat (Zea mays L. Glycine max (L.) Merr. Triticum aestivum L.) rotation and compare continuous corn fertilized at 101 and 134 kg N ha -1 yr -1. In corn years, N2O was the dominant GHG, due to high fertilizer requirements for corn. No-till management reduced greenhouse gas emissions by 50% due to net soil carbon storage. Continuous corn fertilized at 101 kg N ha-1 yr-1 emitted 1.25 Mg CO2 equivalents ha-1 yr-1 compared with 1.42 Mg CO2 equivalents ha-1 yr-1 at 134 kg N ha-1 yr-1, providing a 12% GHG savings. The calculator demonstrates how cropping systems and management choices affect greenhouse gas emissions in field crops.
  • Authors:
    • Stahlman,P. W.
    • Vigil,M. F.
    • Benjamin,J. G.
    • Schlegel,A. J.
    • Stone,L. R.
    • Blanco-Canqui,H.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 4
  • Year: 2010
  • Summary: Because of increased concerns over compaction in no-till (NT) soils, it is important to assess how continuous cropping systems influence risks of soil compaction across a range of soils and NT management systems. We quantified differences in maximum bulk density (BD max) and critical water content (CWC) by the Proctor test, field bulk density (rho b), and their relationships with soil organic carbon (SOC) concentration across three (>11 yr) cropping systems on a silty clay loam, silt loam, and loam in the central Great Plains. On the silty clay loam, BD max in sorghum [ Sorghum bicolor (L.) Moench]-fallow (SF) and winter wheat [ Triticum aestivum (L.)]-fallow (WF) was greater than in continuous wheat (WW) and continuous sorghum (SS) by 0.1 Mg m -3 in the 0- to 5-cm soil depth. On the loam, BD max in WF was greater than in W-corn ( Zea mays L.)-millet ( Panicum liliaceum L.) (WCM) by 0.24 Mg m -3 and perennial grass (GRASS) by 0.11 Mg m -3. On the silt loam, soil properties were unaffected by cropping systems. Elimination of fallowing increased the CWC by 10 to 25%. The rho b was greater in WF (1.52 Mg m -3) than in WW (1.16 Mg m -3) in the silty clay loam, while rho b under WF and WCF was greater than under WCM and GRASS in the loam for the 0- to 5-cm depth. The BD max and rho b decreased whereas CWC increased with an increase in SOC concentration in the 0- to 15-cm depth. Overall, continuous cropping systems in NT reduced near-surface maximum soil compaction primarily by increasing SOC concentration.
  • Authors:
    • Caesar-TonThat, T.
    • Wright, S. F.
    • Sainju, U. M.
    • Kolberg, R.
    • West, M.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a Changing World, Brisbane, Australia, 1-6 August 2010. Congress Symposium 2: Soil ecosystem services
  • Year: 2010
  • Summary: Lentil ( Lens culinaris Medikus CV. Indianhead) used to replace fallow in spring-wheat ( Triticum aestivum) rotation in the semi-arid Eastern Montana USA, may improve soil quality. We evaluate the 14 years influence of continuous wheat under no-tillage (WNT), fallow-wheat under conventional tillage (FCT) and no-tillage (FNT), lentil-wheat under tillage (LCT) and no-tillage (LNT) on soil formation and stability, and on the amount of immunoreactive easily-extractable glomalin (IREEG) and soil aggregating basidiomycete fungi in the 4.75-2.00, 2.00-1.00, 1.00-0.50, 0.50-0.25, and 0.25-0.00 mm aggregate-size classes, at 0-5 cm soil depth. The 4.75-2.00 mm aggregate proportion was higher in LNT than FNT and higher in LT than FT treatments and mean weight diameter (MWD) was higher when lentil was used to replace fallow under NT. No-till systems had higher glomalin and basidiomycete amount than CT in all aggregate-size classes and glomalin was higher in LNT than FNT in aggregate-size classes less than 0.50 mm. We conclude that residue input in NT systems triggers fungal populations which are involved in soil binding in aggregates, and that replacing fallow by lentil in spring wheat rotation in dryland seems to favor aggregate formation/stability under NT probably by increasing N fertility during the course of 14 years.