• Authors:
    • Mishra, U.
    • Lal, R.
    • Christopher, S. F.
  • Source: Soil Science Society of America Journal
  • Volume: 73
  • Issue: 1
  • Year: 2009
  • Summary: No-till (NT) agriculture has been promoted as one of the optimal management practices that preserves soil and water, and increases soil organic C (SOC) compared with conventional tillage (CT) practices. Information on SOC sequestration in NT systems, however, has been based on measurements from the surface soil (<30 cm) and little is known about the extent of SOC sequestration in NT across the entire 0- to 60-cm soil profile. We conducted a regional study of NT farming to assess the extent of SOC sequestration in the whole soil profile across 12 contrasting but representative soils in the Midwestern United States, each within a Major Land Resource Area (MLRA: 98, 111C, 114B, 122 in Indiana; 111A, 111B, 111D, 124, and 126 in Ohio; and 127 and 147 in Pennsylvania). Soils on gentle terrain were sampled in paired NT and CT fields as well as in an adjacent woodlot in each MLRA. The SOC and N concentrations were greater in the surface 0- to 5-cm soil in NT than CT in MLRA 124. The SOC concentration in CT soil was greater than in NT soil at 10 to 30 cm in MLRAs 98 and 126. The total SOC pool for the whole soil profile did not differ between NT and CT in eight of the 12 MLRAs and the total profile SOC was actually greater under CT in MLRAs 98, 127, and 126, resulting in negative C sequestration rates on conversion from CT to NT in these three MLRAs. This regional study suggests that the entire soil profile must be examined and ecosystem C budget assessed when elucidating SOC sequestration in NT vs. CT fields.
  • Authors:
    • Del Grosso, S. J.
    • Halvorson, A. D.
    • Alluvione, F.
  • Source: Journal of Environmental Quality
  • Volume: 38
  • Issue: 5
  • Year: 2009
  • Summary: Long-term effects of tillage intensity, N fertilization, and crop rotation on carbon dioxide (CO2) and methane (CH4) flux. from semiarid irrigated soils are poorly understood. We evaluated effects of. (i) tillage intensity [no-till (NT) and conventional moldboard plow tillage (CT)] in a Continuous corn rotation; (ii) N fertilization levels [0-246 kg N ha(-1) for corn (Zea mays L.); 0 and 56 kg N ha(-1) for dry bean (Phaseolus vulgaris W; 0 and 112 kg N ha(-1) for barley (Hordeum distichon L.)]; and (iii) crop rotation Under NT soil management [corn-barley (NTCB); continuous corn (NT-CC); corn-dry bean (NI-CDb)] on CO2 and CH4 flux from a clay loam soil. Carbon dioxide and CH4 fluxes were monitored one to three times per week using vented nonsready state closed chambers. No-till reduced (14%) growing season (154 d) cumulative CO2 emissions relative to CT (NT 2.08 Mg CO2-C ha(-1); CT 2.41 Mg CO2-C ha(-1)), while N fertilization had no effect. Significantly lower (18%) growing season CO2 fluxes were found in NT-CDb than NT-CC and NT-CB (11.4, 13.2 and 13.9 kg CO2-C ha(-1)d(-1) respectively). Growing season CH4 emissions were higher in NT (20.2 g CH4 ha(-1)) than in CT (1.2 g CH4 ha(-1)). Nitrogen fertilization and cropping rotation did not affect CH4 flux. Implementation of NT for 7 yr with no N fertilization was not adequate for restoring the CH4 oxidation capacity Of this clay learn soil relative to CT plowed and fertilized soil.
  • Authors:
    • Smith, D. L.
    • Ma, B.-L.
    • Rochette, P.
    • Madramootoo,C.
    • Zhou, X.
    • Mabood, F.
    • Almaraz, J. J.
  • Source: Soil Science Society of America Journal
  • Volume: 73
  • Issue: 1
  • Year: 2009
  • Summary: Agriculture has an important potential role in mitigating greenhouse gas emissions (GHG). However, practices that reduce CO2 emissions from soils and increase the soil organic C level may stimulate N2O emissions. This is particularly critical in Quebec where heavy soils and a humid climate may limit the adoption of agricultural practices designed to mitigate GHG. The objective of this work was to study the effects of two tillage and N fertilization regimes on CO2 and N2O fluxes and the seasonal variability in emissions of these gases, associated with corn (Zea mays L.) grown in southwestern Quebec. Different seasonal emission patterns of CO2 and N2O were observed. Higher N2O fluxes occurred during the spring and were associated with precipitation events, while higher CO2 fluxes occurred in mid-season and were related to temperature. Conventional tillage (CT) had greater peaks of CO2 emissions than no-till (NT) only after disking in the spring. Once corn was established, differences between tillage systems were small. Peaks of N2O emission occurred in both systems (NT and CT) following N application. Plots receiving 180 kg N ha-1 in both tillage systems had large peak of N2O emission rates during the wettest parts of the season. The CT and NT systems generally had similar cumulative CO2 emissions but NT had higher cumulative N2O emissions than CT. Our findings suggests that changing from CT to NT under the heavy soil conditions of Quebec may increase GHG, mainly as result of the increase in N2O emission. This negative effect of NT could be reduced by avoiding fertilizing when precipitation is more intense.
  • Authors:
    • Nelson, K. A.
    • Udawatta, R. P.
    • Motavalli, P. P.
    • Bailey, N. J.
  • Source: Agroforestry Systems
  • Volume: 77
  • Issue: 2
  • Year: 2009
  • Summary: The potential for agricultural soils to act as a sink and sequester carbon (C) or a source and emit carbon dioxide (CO2) is largely dependent upon the agricultural management system. The establishment of permanent vegetation, such as trees and grass contour buffer strips, may cause accumulation of above- and below-ground C over time, thereby acting as a sink for tropospheric CO2. However, the effects of contour grass strips and grass-tree strips (agroforestry) on soil CO2 emissions have not been extensively studied in row-crop watersheds in the temperate regions. The objective of this study was to determine the effects of agroforestry and grass contour buffer strips and landscape position on soil surface efflux rate of CO2 in three adjacent agricultural watersheds with claypan soils in northeast Missouri. The three watersheds were in a corn-soybean rotation, and contained (1) cropped only (CR), (2) cropped with grass contour strips (GR), or (3) cropped with tree-grass contour strips (AF) management systems. Soil surface CO2 efflux was measured throughout the 2004 growing season at the upper (UBS), middle (MBS), and lower (LBS) backslope landscape positions within the three watersheds. The cumulative soil CO2 production was lowest in the CR (0.9 kg CO2-C m-2) compared to the AF (1.5 kg CO2-C m-2) and GR watersheds (1.5 kg CO2-C m-2). The lower backslope position (1.6 kg CO2-C m-2) across all three watersheds produced 32 and 40% greater cumulative soil CO2 than the upper and middle backslope positions, respectively. A 72-day incubation study determined the effects of 40, 60, 80, and 100% soil water-filled pore space (WFPS) and N rate (0 and 1.39 g KNO3 kg soil-1) on soil CO2 efflux from bulk soil collected under each management system. The cumulative CO2 production was highest in the grass soil (1,279 mg CO2-C kg soil-1) compared to the agroforestry (661 mg CO2-C kg soil-1) and cropped (483 mg CO2-C kg soil-1) soils regardless of WFPS and N rate. The highest cumulative CO2 production for the grass soil (1,279 mg CO2-C kg soil-1) occurred at 80% WFPS, and was approximately 2 to 2.6 times greater than the agroforestry and cropped soils at 80% WFPS. The results of this study indicate that conservation management practices, such as grass and grass-tree contour buffer strips, and landscape position affect soil surface CO2 production and accumulation of soil organic C that may influence soil C sequestration.
  • Authors:
    • Venterea, Rodney T.
    • Baker, John M.
    • Griffis, T. J.
    • Bavin, T. K.
    • Batjes, Niels
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 134
  • Issue: 3
  • Year: 2009
  • Summary: Agricultural ecosystems have been viewed with the potential to sequester atmospheric carbon dioxide (CO2) by increasing soil organic carbon (SOC) through reduced tillage and cover cropping practices. There remains considerable uncertainty, however, regarding the carbon (C) sink/source potential of these systems and few studies have examined C dynamics in conjunction with other important greenhouse gases. The objective of this study was to evaluate the impact of an alternative management scenario (reduced tillage and cover cropping) on ecosystem respiration (RE) and nitrous oxide (N2O) and methane (CH4) fluxes in a maize (Zea mays L.)/soybean (Glycine max L) rotation ecosystem in east-central Minnesota, United States. The control treatment was managed using fall tillage with a chisel plow in combination with a tandem disk, and the experimental treatment was managed using strip tillage and a winter rye (Secal cereale) cover crop. Over the two-year study period (2004-2005), cumulative RE was 222.7 g C m(-2) higher in the alternatively managed treatment as a result of increased decomposition of the cover crop residue. N2O fluxes were similar in both treatments during the 2004 growing season and were 100.1 mg N m(-2) higher in the conventional treatment during the 2005 growing season after nitrogen (N) fertilization. N fertilization and fertilizer type were the dominant factors controlling N2O fluxes in both treatments. CH4 fluxes were negligible in both treatments and often below the detection limit. Cumulative growing season N2O losses in the control and experimental treatments, which totalled 38.9 +/- 3.1 and 26.1 +/- 1.7 g C m(-2) when converted to CO2 equivalents, were comparable to the annual estimates of net ecosystem CO2 exchange in both treatments. This study further supports that N2O losses are an important component of the total greenhouse gas budget of agroecosystems. It also suggests that spring cover cropping, without residue removal, has limited C sequestration potential. The results from this study, however, may not necessarily represent equilibrium conditions in the experimental treatment. Rather, they are a measure of the transient response of the system after tillage conversion and cover crop addition. It is expected that the soil microbes will continue to adjust to the reduction in tillage and increased C inputs. Therefore, continued, long-term monitoring is needed to confirm whether the results are representative of equilibrium conditions. (C) 2009 Elsevier B.V. All rights reserved.
  • Authors:
    • Benbrook, C.
  • Source: Critical Issue Report: The First Thirteen Years
  • Year: 2009
  • Summary: Th is report explores the impact of the adoption of genetically engineered (GE) corn, soybean, and cotton on pesticide use in the United States, drawing principally on data from the United States Department of Agriculture. Th e most striking finding is that GE crops have been responsible for an increase of 383 million pounds of herbicide use in the U.S. over the first 13 years of commercial use of GE crops (1996-2008).
  • Authors:
    • Lal, R.
    • Blanco-Canqui, H.
  • Source: Soil Science Society of America Journal
  • Volume: 73
  • Issue: 2
  • Year: 2009
  • Summary: Franzluebbers (2009) is right about the need for a more intensive soil sampling, "repeated sampling with time,"and "stratified sampling" as well as for the use of multiple fields and collection of larger number of pseudoreplicates to overcome the high field variability in soil organic carbon (SOC) pools within each Major Land Resource Area (MLRA). The selected fields were representative of each MLRA in terms of soil type, slope, and management, but it is correct that a single soil would not capture all the variability in soil and management for the whole MLRA. This study was not intended to relate the data from the single soil to the whole MLRA but rather to emphasize the differences in SOC sequestration rates among the three management systems within each soil.
  • Authors:
    • Pepo, P.
  • Source: Cereal Research Communications
  • Volume: 37
  • Issue: Suppl. 1
  • Year: 2009
  • Summary: The effects of different water supply cropyears (2007 year=dry, with water stress; 2008 year=optimum water supply) on the yields and agronomic traits of wheat in different crop models (crop rotation, fertilization, irrigation) were studied. In non-irrigated treatment the maximum yields of winter wheat were 5590 kg ha -1 in biculture (maize-wheat) and 7279 kg ha -1 in triculture (peas-wheat-maize) in 2007 year characterized by water-deficit stress. In 2008 (optimum rain amount and distribution) the maximum yields were 7065 kg ha -1 (biculture) and 8112 kg ha -1 (triculture) in non irrigated conditions. In water-deficit stress cropyear (2007 year) the yield-surpluses of wheat were 2245 kg ha -1 (biculture) and 1213 kg ha -1 (triculture), respectively. The nutrient utilization of wheat was modified by abiotic (water) and biotic (leaf- and stem-diseases) stress. The fertilization surpluses of wheat were 2853-3698 kg ha -1 (non-irrigated) and 3164-5505 kg ha -1 (irrigated) in a dry cropyear (2007) and 884-4050 kg ha -1 (non-irrigated) and 524-3990 kg ha -1 (irrigated) in an optimum cropyear (2008). The optimum fertilizer doses varied N 150-200+PK in biculture and N 50-150+PK in triculture depending on cropyear and irrigation. The abiotic stress (water deficit) influenced the agronomic traits (diseases, lodging) of winter wheat. The optimalization of agrotechnical elements provides 7,8-8,5 t ha -1 yields in dry cropyear and 7,1-8,1 t ha -1 yields of wheat in good cropyear, respectively.
  • Authors:
    • Pepo, P.
  • Source: Analele Universităţii din Oradea, Fascicula: Protecţia Mediului
  • Volume: 14
  • Year: 2009
  • Summary: In non-irrigated treatment the maximum yields of winter wheat were 5590 kg ha -1 in biculture (maize-wheat) and 7279 kg ha -1 in triculture (peas-wheat-maize) in 2007 year characterized by water-deficit stress. In 2008 (optimum rain amount and distribution) the maximum yields were 7065 kg ha -1 (biculture) and 8112 kg ha -1 (triculture) in non irrigated conditions. The fertilization surpluses of wheat were 2853-3698 kg ha -1 (non-irrigated) and 3164-5505 kg ha -1 (irrigated) in a dry cropyear (2007) and 884-4050 kg ha -1 (non-irrigated) and 524-3990 kg ha -1 (irrigated) in an optimum cropyear (2008). The optimum fertilizer doses varied N 150-200+PK in biculture and N 50-150+PK in triculture depending on cropyear and irrigation. The optimalization of agrotechnical elements provides 7,8-8,5 t ha -1 yields in dry cropyear and 7,1-8,1 t ha -1 yields of wheat in good cropyear, respectively. Our scientific results proved that in water stress cropyear (2007) the maximum yields of maize were 4316 kg ha -1 (monoculture), 7706 kg ha -1 (biculture), 7998 kg ha -1 (triculture) in non irrigated circumstances and 8586 kg ha -1, 10 970 kg ha -1, 10 679 kg ha -1 in irrigated treatment, respectively. In dry cropyear (2007) the yield-surpluses of irrigation were 4270 kg ha -1 (mono), 3264 kg ha -1 (bi), 2681 kg ha -1 (tri), respectively. In optimum water supply cropyear (2008) the maximum yields of maize were 13 729-13 787 (mono), 14 137-14 152 kg ha -1 (bi), 13 987-14 180 kg ha -1 (tri) so there was no crop-rotation effect. We obtained 8,6-11,0 t ha -1 maximum yields of maize in water stress cropyear and 13,7-14,2 t ha -1 in optimum cropyear on chernozem soil with using appropriate agrotechnical elements.
  • Authors:
    • Al-Dalain, S.
  • Source: Agricultural Journal
  • Volume: 4
  • Issue: 3
  • Year: 2009
  • Summary: This research was carried out during two growing seasons of 2006/2007-2007/2008 in order to determine the effect of intercropping of zea maize ( Miert cultivar) with potato ( Marfona cultivar) on potato growth and on the productivity and Land Equivalent Ratio (LER) of potato and maize. The results of this research showed that intercropping of maize with potato in the case of equal plant densities (4.76 plant m -2) of both crops caused an increase in the mean length of potato stems, which reached 27.45 cm. Moreover, intercropping of maize of 2.38 plant m -2 led into the increase of the mean weight of potato shoots (fresh and dry) to 227 and 21.28 g plant -1 for fresh and dry weight, respectively, besides the increase of the mean weight of potato tubers, which reached 101 g tuber -1. Results also, showed that the number of potato stems and formed tubers were not affected by intercropping of maize with potato. As for productivity, results indicated that the total productivity of each unit area using intercropping system was higher than the productivity of the sole crop, with superiority of treatments with 2.38 plant m -2 of maize and 4.76 plant m -2 of potato where mean yield of 44 ton ha -1, while, the productivity in the other treatments were 36 and 37.8 ton ha -1. LER showed positive influence using the intercropping system compared to the sole cropping, as it shown in the LER values, which were higher (1.43-1.55) in intercropping compared to (1) in the sole cropping.