• Authors:
    • Al-Kaisi, M.
    • Yin, X.
  • Source: Journal of Environmental Quality
  • Volume: 34
  • Issue: 437
  • Year: 2005
  • Summary: Soil C change and CO2 emission due to different tillage systems need to be evaluated to encourage the adoption of conservation practices to sustain soil productivity and protect the environment. We hypothesize that soil C storage and CO2 emission respond to conservation tillage differently from conventional tillage because of their differential effects on soil properties. This study was conducted from 1998 through 2001 to evaluate tillage effects on soil C storage and CO2 emission in Clarion-Nicollet-Webster soil association in a corn [Zea mays L.]-soybean [Glycine max (L.) Merr.] rotation in Iowa. Treatments included no-tillage with and without residue, strip-tillage, deep rip, chisel plow, and moldboard plow. No-tillage with residue and strip-tillage significantly increased total soil organic C (TC) and mineral fraction C (MFC) at the 0 to 5 and 5 to 10cm soil depths compared with chisel plow after 3 yr of tillage practices. Soil CO2 emission was lower for less intensive tillage treatments compared with moldboard plow, with the greatest differences occurring immediately after tillage operations. Cumulative soil CO2 emission was 19 to 41% lower for less intensive tillage treatments than moldboard plow, and it was 24% less for no-tillage with residue than without residue during the 480-h measurement period. Estimated soil mineralizable C pool was reduced by 22 to 66% with less intensive tillage treatments compared with moldboard plow. Adopting less intensive tillage systems such as no-tillage, strip-tillage, deep rip, and chisel plow and better crop residue cover are effective in reducing CO2 emission and thus improving soil C sequestration in a corn-soybean rotation.
  • Authors:
    • Arkebauer, Timothy J.
    • Amos, Brigid
    • Cardon, G.
    • Qian, Y.
    • Dillon, M.
    • Sparks, R.
    • Doran, John W.
    • Barbarick, K.
    • Delgado, J. A.
    • Al-Sheikh, A.
  • Source: Soil Science Society of America Journal
  • Volume: 69
  • Issue: 2
  • Year: 2005
  • Summary: An understanding of the effect of fertility management on soil surface fluxes of CO2, N2O, and CH4 is essential in evaluating C sequestration measures that attempt to increase the amount of crop residue returned to the soil through increased fertilizer inputs. In this study, soil surface CO2 flux was measured over a 27-mo sampling period in continuous maize (Zea mays L.) plots managed under either an intensive fertility regime (M2) or recommended best management (M1). Flux was significantly higher in the M2 treatment on only 2 d during the first growing season. Annual estimates of soil surface CO2 flux, based on a modified exponential equation that incorporates leaf area index (LAI) to predict temporal changes in soil respiration, averaged 11 550 kg C ha-1 yr-1 for both treatments (approximately 31.64 kg C ha-1 d-1 on average). Within row soil surface CO2 flux was, on average, 64% higher than between row flux. Plant population did not significantly affect measured soil surface CO2 flux. While fertility management had no significant effect on CH4 flux, N2O flux as measured on 3 d during the 2000 growing season was significantly higher in the M2 treatment. In 2001, no significant differences in N2O flux were observed, possibly due to changes in N management and irrigation method. Electrical conductivity measured during the 2000 and 2001 growing seasons was significantly higher in the M2 treatment while pH measured during the 2001 season was significantly lower for M2.
  • Authors:
    • Sweeney, D.
    • Kelley, K.
  • Source: Agronomy Journal
  • Volume: 97
  • Issue: 3
  • Year: 2005
  • Summary: In the eastern Great Plains, winter wheat ( Triticum aestivum L.) is often rotated with other crops to diversify cropping systems. In these multicropping systems, wheat typically is planted with conservation tillage methods, but previous crop residues influence fertilizer N management. This field study was conducted from 1992 through 2001 in southeastern Kansas on a Parsons silt loam soil (fine, mixed, thermic, Mollic Albaqualf). The objectives were to determine effects and interactions of previous crop {grain sorghum [ Sorghum bicolor (L.) Moench] and soybean [ Glycine max (L.) Merr.]}, tillage system [reduced tillage (RT) and no-tillage (NT)], N rate (67 and 134 kg ha -1), and preplant placement (surface-broadcast and subsurface-knife) of urea ammonium nitrate solution (UAN, 280 g kg -1) on wheat grain yield, yield components, and plant N uptake in a 2-yr cropping rotation. Wheat yields averaged 3.39 Mg ha -1 following soybean compared with 2.90 Mg ha -1 following grain sorghum. Tillage effects on grain yield were smaller than other treatment factors, averaging 3.23 Mg ha -1 for RT and 3.06 Mg ha -1 for NT. Grain yields were greatest in all cropping systems for the high-N-rate subsurface-knife treatment. Plant N uptake responses indicated that grain yield differences were primarily related to greater immobilization of both fertilizer and soil N following grain sorghum, compared with soybean, and to better utilization of subsurface-knifed N than surface-broadcast N. Results indicate that wheat yield potential is more strongly influenced by previous crop, fertilizer N rate, and N placement method than tillage system.
  • Authors:
    • Xia, K.
    • Fernando, W.
    • Rice, C.
  • Source: Soil Science Society of America Journal
  • Volume: 69
  • Issue: 4
  • Year: 2005
  • Summary: Understanding the sorption and desorption behavior of NH4+ in soils associated with animal waste is important because of the potential for the formation of NO3- and subsequent leaching that affects ground water quality. Batch equilibration experiments were conducted to evaluate the sorption and desorption of NH4+ in two soils exposed to a complex matrix (liquid swine waste) and a simple matrix [aqueous solution of 0.01 M CaCl2 containing (NH4)(2)SO4]. Kennebec silt loam (fine-silty, mixed, mesic Cumulic Hapludolls) and Haynie very fine sandy loam (coarse-silty, mixed, calcareous, mesic Mollic Udifluvents) were used. This study revealed that the sorption and desorption behavior of NH4+ in soils exposed to (NH4)(2)SO4 Solutions with a 0.01 M CaCl2 matrix is significantly different from that in soils exposed to liquid swine waste. Faster sorption rate, lower sorption capacity, and higher desorption capability were observed for NH4+ in soils exposed to the (NH4)(2)SO4 Solution compared with soils exposed to the liquid swine waste. Sequential extraction could not extract nonexchangeable NH4+ in both soils exposed to liquid swine waste, while a significant amount of nonexchangeable NH4+ was extracted from the two soils that were initially exposed to the (NH4)(2)SO4 solutions. The high dissolved organic C (DOC) content coupled with the high pH in swine waste appears to stimulate the sorption and retard desorption of NH4+ in the two soils. This study revealed that batch equilibrium studies using solutions with simple matrixes may underestimate the sorption or overestimate desorption of NH4+ in soils associated with swine waste.
  • Authors:
    • Dille, J. A.
    • Stahlman, P. W.
    • Bensch, C. N.
    • Al-Khatib, K.
    • Liphadzi, K. B.
    • Todd, T.
    • Rice, C. W.
    • Horak, M. J.
    • Head, G.
  • Source: Weed Science
  • Volume: 53
  • Issue: 4
  • Year: 2005
  • Summary: Field experiments were conducted at Ashland Bottoms in northeastern Kansas and at Hays in western Kansas in 2001, 2002, and 2003 to determine the response of soil microbial and nematode communities to different herbicides and tillage practices under a glyphosate-resistant cropping system. Conventional herbicide treatments were a tank mixture of cloransulam plus S metolachlor plus sulfentrazone for soybean and a commercially available mixture of acetochlor and atrazine for corn. Glyphosate was applied at 1.12 kg ai ha(-1) when weeds were 10 or 20 cm tall in both corn and soybean. Soil samples were collected monthly at Ashland Bottoms during the growing period for soil microbial biomass (SMB) carbon determination. In addition, substrate-induced respiration (SIR) and BIOLOG substrate utilization were determined at the end of the growing season each year at Ashland Bottoms, and nematode populations were determined at the beginning and the end of the growing season at both sites. Direct effects of glyphosate rates on soil microbial and nematode communities were also studied in a controlled environment. Values for SMB carbon, SIR, and BIOLOG substrate utilization were not altered by glyphosate. Nematode community response to the glyphosate treatment was similar under both conventional tillage and no-till environments. Total nematode densities were similar with the glyphosate and conventional herbicide treatments. SMB carbon and BIOLOG substrate utilization did not differ between tillage treatments. Nematode densities were greater under conventional tillage than in the no-till system. This study showed that soil health when glyphosate was applied in a glyphosate-resistant cropping system was similar to that of cropping systems that used conventional herbicides.
  • Authors:
    • Peterson, G. A.
    • Westfall, D. G.
    • Ortega, R. A.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 36
  • Issue: 19/20
  • Year: 2005
  • Summary: In the West Central Great Plains of the United States, no-till management has allowed for increased cropping intensity under dryland conditions. This, in turn, has affected the carbon (C) and nitrogen (N) mineralization dynamics of these systems. In this region, moisture stress increases from north to south due to an increase in evapotranspiration (ET), resulting in a climatic gradient that affects cropping system management. The objectives of this study were to determine the interaction of cropping system intensification and climatic gradient (ET) on C and N mineralization and to determine if the presence or absence of crop residue on the soil surface affects C and net N mineralization. Two cropping systems, winter wheat-fallow (WF) ( Triticum aestivium L.) and winter wheat-corn (sorghum)-millet-fallow (WCMF) [ Zea mays (L.), Sorghum bicolor (L.) Moench, Panicum milaceum (L.)] were studied at three locations across this aforementioned ET gradient. The treatments had been in place for 8 yrs prior to sampling in the study. These results showed that the more intense cropping system (WCMF) had a higher laboratory C mineralization rate at two of the three locations, which the study concluded resulted from larger residue biomass additions and larger quantities of surface residue and soil residue at these locations (Soil residue is defined as recognizable crop residue in the soil that is retained on a 0.6 mm screen). However, no differences in N mineralization occurred. This is most likely due to more N immobilization under WCMF as compared to WF. Presence or absence of crop residue on the surface of undisturbed soil cores during incubation affected potential C and net N mineralization more than either cropping system or location. Soil cores with the surface residue intact mineralized as much as 270% more C than the same soils where the surface crop residue had been removed. In laboratory studies evaluating the relative differences in cropping systems effects on C and N mineralization, the retention of crop residue on the soil surface may more accurately access the cropping system effects.
  • Authors:
    • Abou-Alaiw, W.
    • Al-Abed, D.
    • Zhang, S. L.
    • Parani, M.
    • Chennareddy, S.
    • Sairam, R.
    • Goldman, S.
  • Source: In Vitro Cellular & Developmental Biology - Plant
  • Volume: 41
  • Issue: 4
  • Year: 2005
  • Summary: The development of robust plant regeneration technology in cereals, dicots and ornamentals that is in turn coupled to a high-frequency DNA transfer technology is reported. Transgenic cereals that include maize, Tripsacum, sorghum, Festuca and Lolium, in addition to dicots that include soybean, cotton and various ornamentals such as petunia, begonia, and geranium have been produced following either somatic embryogenesis or direct organogenesis independent of genotype. Coupled with these regeneration protocols, we have also identified several interesting genes and promoters for incorporation into various crops and ornamentals. In addition, the phenomenon of direct in vitro flowering from cotyledonary nodes in soybean is described. In in vitro flowering, the formation of a plant body is suppressed and the cells of the cotyledonary node produce complete flowers from which fertile seed is recovered. This in vitro flowering technology serves as a complementary tool to chloroplast transformation for developing a new transgenic pollen containment strategy for crop species. Recently, the center has undertaken to screen the expression response of the 24 000 Arabidopsis genes to nitric oxide. This signaling molecule upregulated 342 genes and downregulated 80 genes. The object here was to identify a population of promoters that can be manipulated by using a signaling molecule. In addition, in keeping with the mission of enhancing greenhouse profitability for North West Ohio growers, we cloned a number of genes responsive for disease resistance from ornamentals that play an important role in disease management and abiotic stress. We have constructed a plant transformation vector with CBF3 gene under the rd29A promoter for engineering cold and freezing tolerance in petunia. Leaf discs of Petunia * hybrida v26 were used for Agrobacterium-mediated transformation, and 44 hygromycin-resistant T0 plants were obtained. The presence of CBF3 gene was confirmed in all the transgenic plants by PCR and Southern analyses.
  • Authors:
    • Williams, S.
    • Weil, R.
  • Source: Soil Science Society of America Journal
  • Volume: 68
  • Issue: 4
  • Year: 2004
  • Summary: Deep-rooted cover crops may help alleviate effects of soil compaction, especially in no-till systems. We evaluated the compaction-alleviating ability of 4 cover crops (rape, oilseed radish, forage radish and cereal rye). The experiments were conducted at the University of Maryland Wye Research Station and Education Centre on a Mattapex silt loam (Aquic Hapludults) and at the USDA Beltsville Agricultural Research Centre on an Elkton silt loam (Typic Endoaquults). Using a minirhizotron camera, we observed soyabean ( Glycine max) roots growing through compacted plough pan soil using channels made by decomposing cover crop roots. Soyabean yield response to the preceding cover crops was most pronounced at the site with most severe drought and soil compaction. At this location, with or without deep tillage, soyabean yields were significantly greater following a forage radish cv. Diachon+rye combination cover crop. Rye left a thick mulch, resulting in conservation of soil water early in the season. Root channels left by forage radish may have provided soyabean roots with low resistance paths to subsoil water. Due to lower than normal winter precipitation, this study was a conservative test of the cover crops' ability to alleviate the effects of soil compaction.
  • Authors:
    • Wolt, J. D.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 69
  • Issue: 1
  • Year: 2004
  • Summary: The effectiveness of nitrification inhibitors for abatement of N loss from the agroecosystem is difficult to measure at typical agronomic scales, since performance varies at the research field scale due to complex interactions among crop management, soil properties, length of the trial, and environmental factors. The environmental impact of the nitrification inhibitor nitrapyrin on N losses from agronomic ecosystems was considered with emphasis on the Midwestern USA. A meta-evaluation approach considered the integrated responses to nitrification inhibition found across research trials conducted in diverse environments over many years as measured in side- by-side comparisons of fertilizer N or manure applied with and without nitrapyrin. The resulting distributions of response indices were evaluated with respect to the magnitude and variance of the agronomic and environmental effects that may be achieved when nitrification inhibitors are used regionally over time. The indices considered (1) crop yield, (2) annual or season-long maintenance of inorganic N within the crop root zone, (3) NO3-N leached past the crop root zone, and (4) greenhouse gas emission from soil. Results showed that on average, the crop yield increased (relative to N fertilization without nitrapyrin) 7% and soil N retention increased by 28%, while N leaching decreased by 16% and greenhouse gas emissions decreased by 51%. In more than 75% of individual comparisons, use of a nitrification inhibitor increased soil N retention and crop yield, and decreased N leaching and volatilization. The potential of nitrification inhibitors for reducing N loss needs to be considered at the scale of a sensitive region, such as a watershed, over a prolonged period of use as well as within the context of overall goals for abatement of N losses from the agroecosystem to the environment.
  • Authors:
    • Paustian, K.
    • Mosier, A. R.
    • Conant, R. T.
    • Breidt, F. J.
    • Ogle, S. M.
    • Six, J.
  • Source: Global Change Biology
  • Volume: 10
  • Issue: 2
  • Year: 2004
  • Summary: No-tillage (NT) management has been promoted as a practice capable of offsetting greenhouse gas (GHG) emissions because of its ability to sequester carbon in soils. However, true mitigation is only possible if the overall impact of NT adoption reduces the net global warming potential (GWP) determined by fluxes of the three major biogenic GHGs (i.e. CO2, N2O, and CH4). We compiled all available data of soil-derived GHG emission comparisons between conventional tilled (CT) and NT systems for humid and dry temperate climates. Newly converted NT systems increase GWP relative to CT practices, in both humid and dry climate regimes, and longer-term adoption (>10 years) only significantly reduces GWP in humid climates. Mean cumulative GWP over a 20-year period is also reduced under continuous NT in dry areas, but with a high degree of uncertainty. Emissions of N2O drive much of the trend in net GWP, suggesting improved nitrogen management is essential to realize the full benefit from carbon storage in the soil for purposes of global warming mitigation. Our results indicate a strong time dependency in the GHG mitigation potential of NT agriculture, demonstrating that GHG mitigation by adoption of NT is much more variable and complex than previously considered, and policy plans to reduce global warming through this land management practice need further scrutiny to ensure success.