• Authors:
    • Sequeira, C. H.
    • Alley, M. M.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 5
  • Year: 2011
  • Summary: Soil organic matter (SOM) is commonly used as an indicator of soil quality, with different fractions being used as indices to measure changes in SOM caused by management. The objective of this study was to compare whether selected SOM fractions exhibited sensitivity to short-term changes in management. The experiment was conducted for similar to 3 yr as a split-split-plot design with crop rotation as the whole-plot treatment factor, tillage as the subplot treatment factor, and cover crop management as the sub-subplot treatment factor. Soil samples were collected at the 0- to 15-cm depth. Soil organic C (SOC) and N, particulate organic matter (POM), free light fraction (FLF), Illinois soil N test (ISNT), and easily oxidizable C (EOC) were tested as possible sensitive indices to changes in management. The stable fraction SOC was only affected by cover crop management, while C and N contents and C/N ratio of the labile POM and FLF fractions were affected by additional management practices. Between POM and FLF, the latter was the most sensitive, with cover crop management having the greatest effect. Because FLF is chemically and structurally closer to plant residues than POM, the sensitivity rank position of these fractions would probably be at least more similar if only tillage management was considered. In addition, the lack of sensitivity of ISNT and EOC to any tested management practice is added to previous studies that have raised questions of the representation of the labile SOM pool through these fractions.
  • Authors:
    • Shipitalo, M. J.
    • Owens, L. B.
  • Source: Journal of Environmental Quality
  • Volume: 40
  • Issue: 4
  • Year: 2011
  • Summary: Residual herbicides regularly used in conjunction with conservation tillage to produce corn ( Zea mays L.) and soybean [ Glycine max (L.) Merr] are often detected in surface water at concentrations that exceed their U.S. maximum contaminant levels (MCL) and ecological standards. These risks might be reduced by planting glyphosate-tolerant varieties of these crops and totally or partially replacing the residual herbicides alachlor, atrazine, linuron, and metribuzin with glyphosate, a contact herbicide that has a short half-life and is strongly sorbed to soil. Therefore, we applied both herbicide types at typical rates and times to two chisel-plowed and two no-till watersheds in a 2-yr corn/soybean rotation and at half rates to three disked watersheds in a 3-yr corn/soybean/wheat-red clover ( Triticum aestivum L.- Trifolium pratense L.) rotation and monitored herbicide losses in surface runoff for three crop years. Average dissolved glyphosate loss for all tillage practices, as a percentage of the amount applied, was significantly less ( P≤0.05) than the losses of atrazine (21.4*), alachlor (3.5*), and linuron (8.7*) in corn-crop years. Annual, flow-weighted, concentration of atrazine was as high as 41.3 g L -1, much greater than its 3 g L -1 MCL. Likewise, annual, flow-weighted alachlor concentration (MCL=2 g L -1) was as high as 11.2 and 4.9 g L -1 in corn- and soybean-crop years, respectively. In only one runoff event during the 18 watershed-years it was applied did glyphosate concentration exceed its 700 g L -1 MCL and the highest, annual, flow-weighted concentration was 3.9 g L -1. Planting glyphosate-tolerant corn and soybean and using glyphosate in lieu of some residual herbicides should reduce the impact of the production of these crops on surface water quality.
  • Authors:
    • Silveira, F. de M.
    • Silva, E. D. B. da
    • Pauletti, V.
    • Favaretto, N.
    • Vezzani, F. M.
    • Dieckow, J.
  • Source: Revista Brasileira de Ciencia do Solo
  • Volume: 35
  • Issue: 5
  • Year: 2011
  • Summary: The use of manure in agricultural system is a possibility to dispose of the waste generated in animal production, but improper use can cause environmental problems. The general objective of this study was to evaluate carbon and nitrogen concentrations and losses in runoff in four doses of liquid dairy manure (0, 60, 120, 180 m 3 ha -1 yr -1) applied to a silt clay loam Oxisol with 13% slope, in no-till with soybean, oat, corn, and wheat in crop rotation. The runoff was collected for two years and seven months in 60 L containers after every rain with runoff from at least one plot. Soluble nutrients were analyzed in runoff samples filtered through a 0.45 m membrane and total nutrients in unfiltered samples. The application of liquid dairy manure reduced the losses of organic carbon and nitrogen, with positive consequences for water quality. However, higher rates tended to increase the concentrations of these elements and, consequently, reduce water quality. The weighted average concentrations of nitrate were below the limit allowed by Brazilian legislation, but ammonium exceeded the threshold values, indicating the need of control measures to prevent the runoff from reaching the water bodies, even in no-tillage systems. It should be pointed out that these data were obtained under low potential polluting conditions, i.e, on 13% slope, low rainfall and with a minimum interval of ten days between manure application and rainfall. Further studies should also evaluate nitrate leaching.
  • Authors:
    • Perello, A. E.
    • Moreno, V.
    • Chidichimo, H. O.
    • Terrile, I. I.
    • Simon, M. R.
    • Ayala, F. M.
    • Golik, S. I.
    • Cordo, C. A.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 5
  • Year: 2011
  • Summary: Zero tillage often leads to wheat ( Triticum aestivum L.) yield losses from diseases caused by necrotrophic foliar pathogens. The aim of this work was to evaluate the combined effect of tillage, N fertilization, fungicides, and resistant cultivars in reducing foliar disease severity to prevent significant yield losses. A 2-yr study including combinations of (i) conventional and zero tillage; (ii) N fertilization rates 0, 80, or 160 kg ha -1 N; (iii) two fungicide treatments (with and without a fungicide (1 L of metconazole, 9%)) at growth stages (GS) 32 and 39; and (iv) three wheat cultivars was conducted in the Rolling Pampas region in Argentina. The most common foliar disease in the trial was tan spot [ Pyrenophora tritici-repentis (Died.) Drechs.]. Conventional tillage reduced foliar disease severity at GS 23 by 46 and 56% and the area under disease progress curve (AUDPC) by 20 and 14% for each season, respectively compared with zero tillage. The cultivar Buck Bigua had significantly lower AUDPC values than the others. Fungicide and N application reduced disease severity at GS 23 by 35 and 34% respectively, on average over both years. Disease was less severe in zero tillage plots which received a fungicide compared to conventional tillage plots that were not treated with fungicide. In 2002 yields were greater in conventional tillage plots with 160 kg ha -1 N and fungicide application than in all other treatments. In 2003 yields were greatest in zero tillage plots with 160 kg ha -1 N and fungicide. The results of this study indicate that in spite of the increase of necrotrophic diseases, developing no-till systems in wheat monoculture is possible without significant yield losses if effective disease management practices are applied.
  • Authors:
    • Sousa, D.
    • Rein, T.
  • Source: Better Crops with Plant Food
  • Volume: 95
  • Issue: 3
  • Year: 2011
  • Summary: The authors review recommended practices for evaluating and managing liming and fertilizer use for high yielding annual crops growing under no-till (NT) cultivation within the Cerrado.
  • Authors:
    • Maul, J. E.
    • Meisinger, J. J.
    • Cavigelli, M. A.
    • Spargo, J. T.
    • Mirsky, S. B.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 90
  • Issue: 2
  • Year: 2011
  • Summary: Sustainable soil fertility management depends on long-term integrated strategies that build and maintain soil organic matter and mineralizable soil N levels. These strategies increase the portion of crop N needs met by soil N and reduce dependence on external N inputs required for crop production. To better understand the impact of management on soil N dynamics, we conducted field and laboratory research on five diverse management systems at a long-term study in Maryland, the USDA- Agricultural Research Service Beltsville Farming Systems Project (FSP). The FSP is comprised of a conventional no-till corn ( Zea mays L.)-soybean ( Glycine max L.)-wheat ( Triticum aestivum L.)/double-crop soybean rotation (NT), a conventional chisel-till corn-soybean-wheat/soybean rotation (CT), a 2 year organic corn-soybean rotation (Org2), a 3 year organic corn-soybean-wheat rotation (Org3), and a 6 year organic corn-soybean-wheat-alfalfa ( Medicago sativa L.) (3 years) rotation (Org6). We found that total potentially mineralizable N in organic systems (average 315 kg N ha -1) was significantly greater than the conventional systems (average 235 kg N ha -1). Particulate organic matter (POM)-C and -N also tended to be greater in organic than conventional cropping systems. Average corn yield and N uptake from unamended (minus N) field microplots were 40 and 48%, respectively, greater in organic than conventional grain cropping systems. Among the three organic systems, all measures of N availability tended to increase with increasing frequency of manure application and crop rotation length (Org2 < Org3 ≤ Org6) while most measures were similar between NT and CT. Our results demonstrate that organic soil fertility management increases soil N availability by increasing labile soil organic matter. Relatively high levels of mineralizable soil N must be considered when developing soil fertility management plans for organic systems.
  • Authors:
    • Kravchenko, A. N.
    • Mokma, D. L.
    • Corbin, A. T.
    • Syswerda, S. P.
    • Robertson, G. P.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 1
  • Year: 2011
  • Summary: Soil C sequestration research has historically focused on the top 0 to 30 cm of the soil profile, ignoring deeper portions that might also respond to management. In this study we sampled soils along a 10-treatment management intensity gradient to a 1-m depth to test the hypothesis that C gains in surface soils are offset by losses lower in the profile. Treatments included four annual cropping systems in a corn ( Zea mays)-soybean ( Glycine max)-wheat ( Triticum aestivum) rotation, perennial alfalfa ( Medicago sativa) and poplar ( Populus * euramericana), and four unmanaged successional systems. The annual grain systems included conventionally tilled, no-tillage, reduced-input, and organic systems. Unmanaged treatments included a 12-yr-old early successional community, two 50-yr-old mid-successional communities, and a mature forest never cleared for agriculture. All treatments were replicated three to six times and all cropping systems were 12 yr post-establishment when sampled. Surface soil C concentrations and total C pools were significantly greater under no-till, organic, early successional, never-tilled mid-successional, and deciduous forest systems than in the conventionally managed cropping system ( p≤0.05, n=3-6 replicate sites). We found no consistent differences in soil C at depth, despite intensive sampling (30-60 deep soil cores per treatment). Carbon concentrations in the B/Bt and Bt2/C horizons were lower and two and three times more variable, respectively, than in surface soils. We found no evidence for C gains in the surface soils of no-till and other treatments to be either offset or magnified by carbon change at depth.
  • Authors:
    • Das, T. K.
    • Tuti, M. D.
  • Source: Indian Journal of Agronomy
  • Volume: 56
  • Issue: 2
  • Year: 2011
  • Summary: Effective weed control in no-till systems is mainly dependent on herbicides. Appropriate weed management strategies, however, can reduce the amount of herbicides. In this study possible weed management was attempted in wheat ( Triticum aestivum L. emend. Fiori & Paol.) under zero-tillage (without residue) and conventional tillage between 2006-07 and 2007-08 following residual effects of 13 weed control treatments with metribuzin applied during previous rainy ( kharif) seasons, 2006 and 2007 in soybean [ Glycine max (L) Mirrill]. The experiment was laid out in a split plot design with three replications. Total density of weeds did not differ significantly between weed control measures adopted during previous rainy season. But, conventional tillage (CT) caused a significant reduction in the populations of grass, broad-leaved (e.g., Chenopodium album L. and Melilotus indica L.) and total weeds when compared with zero-tillage (ZT) without crop residues. Similarly, higher nutrient removal by weeds was under zero-tillage than under conventional tillage. In general, residual effect of all the previous season metribuzin treatments was more pronounced on the grasses ( Phalaris minor Retz. and Avena sterilis ssp. ludoviciana Dur.) when compared with Chenopodium album and Melilotus indica. Wheat yield was similar in all previous season metribuzin treatments except in weed-free check in both years. However, metribuzin at 0.5 kg/ha pre-emergence, on yield, was more effective, indicating its considerable residual effect on weeds in wheat. This treatment also gave the highest net benefit:cost ratio.
  • Authors:
    • Holan, S. H.
    • Goyne, K. W.
    • Veum, K. S.
    • Motavalli, P. P.
  • Source: Geoderma
  • Volume: 167-168
  • Year: 2011
  • Summary: Conservation management practices including upland vegetative filter strips (VFS) and no-till cultivation have the potential to enhance soil carbon sequestration and other ecosystem services in agroecosystems. A modified two-factor analysis of variance (ANOVA) with subsamples was used to compare SOC and TN on a concentration, soil volume and soil mass basis in claypan soils planted to different conservation management practices and as a function of landscape position. The three conservation management practices (no-till cultivation, grass VFS and agroforestry VFS) and four landscape positions (summit, shoulder, backslope and footslope) investigated were compared 10 years after VFS establishment in a no-till system planted to maize ( Zea mays. L.)-soybean ( Glycine max (L.) Merr.) rotation. Two soil depth increments (0-5 cm and 5-13 cm) were modeled separately to test for treatment effects. In the surface layer, mean SOC concentration was significantly greater in the VFS soils compared to no-till. On a soil volume or mass basis, no significant differences in SOC stocks were found among treatment means. Concentration and mass based TN values were significantly greater in the grass VFS relative to no-till in the surface layer. A rapid slaking stability test, developed to separate particulate, adsorbed and occluded organic carbon (PAO-C) and nitrogen (PAO-N), showed that VFS soils had significantly greater mean PAO-C and PAO-N concentrations, soil volume and soil mass based stocks than no-till. In addition, comparison of SOC:TN and PAO-C:PAO-N ratios suggest reduced decomposition and mineralization of SOC in the PAO fraction. No significant treatment effects were detected in total or PAO soil fractions in the subsurface layer or among landscape position in either depth increment. Study results emphasize the need to compare soil carbon and nitrogen stocks on a soil volume and/or soil mass basis using bulk density measurements. Additionally, the rapid PAO separation technique was found to be a good indicator of early changes in SOC and TN in the systems studied. Overall, this research indicates that grass VFS may sequester TN more rapidly than agroforestry VFS and that a greater proportion of SOC and TN may be stabilized in VFS soils compared to no-till.
  • Authors:
    • Torbert, H. A.
    • Watts, D. B.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 5
  • Year: 2011
  • Summary: Reduced tillage, poultry litter applications, crop rotations, and winter cover cropping are management practices that could be used with conservation tillage systems to increase yields compared to conventional monoculture systems. This study evaluated cropping sequences of corn ( Zea mays L.), soybean [ Glycine max (L.) Merr.], and corn-soybean rotations with wheat ( Triticum aestivum L.) covers in conventional, strip, and no-tillage (no-till) systems, following poultry litter additions to wheat cover. The study was conducted from 1991 to 2001 on a Hartsells fine sandy loam (fine-loamy, siliceous, subactive, thermic Typic Hapludults). Poultry litter (112 kg N ha -1) was applied to wheat each year in fall. Wheat not receiving poultry litter received equivalent inorganic N. Corn was fertilized with inorganic fertilizer in spring with 56 kg N ha -1 at planting followed by 168 kg N ha -1 3 wk after emergence; soybean received no fertilizer. Corn yields were influenced by tillage in 1991, 1992, 1993, 1994, 1996, 1997, 1998, and 2001 with conventional tillage producing greater yields, except in 1993 (strip tillage) and 2001 (no-till). Poultry litter increased corn yield in 1991, 1997, and 1998. Crop rotations increased corn yield for all years, except 2001. Soybean yields were not impacted by differences in tillage. Crop rotations significantly impacted soybean yield in 1992, 1995, and 1998, with higher yields observed in 1992, and 1995, and lower yields in 1998. Poultry litter significantly increased soybean yield 8 of the 9 yr evaluated. This study suggests that poultry litter use for these crop rotations in conservation tillage systems could increase sustainable yield production.