• Authors:
    • Thompson, C.
  • Source: Journal of Soil and Water Conservation
  • Volume: 56
  • Issue: 1
  • Year: 2001
  • Summary: A 24 year study of five cropping systems was conducted to determine how 1.) cropping systems, 2.) depth of soil water at planting, and 3.) tillage systems affected yields and economic returns. The study involved two crops, winter wheat (Triticum aestivum L.) and grain sorghum (Sorghum biocolor L Moench), in systems of continuous wheat (WWW), continuous sorghum (SSS), wheat/sorghum/fallow (WSF), wheat/fallow (WF), and sorghum/fallow (SF). These systems were farmed under reduced-till (RT) and no-till (NT) on a nearly level, high fertility, Crete silty clay loam soil (fine, smectitic, mesic Pachic Argiustolls) at the Kansas State University Agricultural Research Center-Hays. Depth of soil water at planting had significant effects on yields of all cropping/tillage systems. Tillage systems had limited effects on wheat yield, but significant effects on sorghum yields. Considering all factors, SSS with RT had the highest economic return on this upland fertile soil in the central Great Plains.
  • Authors:
    • Wuest, S. B.
  • Source: Applied Soil Ecology
  • Volume: 18
  • Issue: 2
  • Year: 2001
  • Summary: Dryland fanning in the Mediterranean climate of the Pacific Northwest, USA supports extremely low earthworm populations under conventional tillage. Increases in earthworm populations are being observed in fields under no-till cropping systems. A 30+ year experiment with four tillage levels in a pea (Pisum sativum L.)-winter wheat (Triticum aestivum L.) rotation was evaluated for earthworm populations and ponded infiltration rates. Where tillage has been limited to 2.5 cm depth, Apporectodea trapezoides (Duges) mean population was 25 m(-2). Plots subject to tillage by plow (25 cm depth) or chisel (35 cm depth) averaged less than 4 earthworms m-2. The shallow tillage treatment also had the highest average infiltration rate of 70 mm h(-1) compared to 36 for chisel, 27 for spring plow, and 19 mm h(-1) for fall plow treatments. The highly variable nature of earthworm counts and infiltration measurements prevented conclusive correlation between the two, but increases in both can be attributed to minimum tillage.
  • Authors:
    • Cochran,V. L.
    • Thorn,R. G.
    • Shelver,W. L.
    • Caesar-Tonthat,T. C.
  • Source: Applied Soil Ecology
  • Volume: 18
  • Issue: 2
  • Year: 2001
  • Summary: Polyclonal antisera were raised against cell walls of a soil aggregating basidiomycete isolated in eastern Montana (isolate BB1) which has been identified as a member of the russuloid clade using molecular genetic techniques. In cross-reactivity tests using quantitative enzyme-linked immunosorbent assay (ELISA), polyclonal antisera to BB I cross-reacted significantly with fungal species representative of the russuloid clade and little or no reactivity was observed with fungal species of the polyporoid, euagaric, hymenochaetoid, bolete and gomphoid-phalloid clades of the Homobasidiomycetes. These results suggested that the cell walls of fungal species from the russuloid clade share common antigenic binding sites that are recognizable by the polyclonal antibodies and that these sites were not found or were present in small amounts in fungal species from the other clades. Experiments on the water stability of artificial aggregates amended with fungal species representative of these six homobasidiomycete clades indicated that many species of the russuloid clade were very efficient soil stabilizers. Fungal species from the other clades vary in their ability to aggregate soil particles but cross-react weakly with the antibodies. ELISA was used on water stable aggregates (WSA) from soil samples of three dryland locations under conventional tillage, no tillage and fallow management practices and on WSA from soil samples from grass barrier strips that were undisturbed for 30 years. Greater antigenic response was observed from WSA of undisturbed soils compared to cultivated soils and from WSA of soils under no till compared to till or fallow management practices. These results suggested that specific soil aggregating russuloids in WSA are sensitive to soil disturbance such as tillage. To our knowledge, this study is the first report of the detection and quantification of a taxonomic group of specific soil aggregating Homobasidiomycetes in dryland soils under diverse agricultural systems.
  • Authors:
    • Halvorson, A. D.
    • Wienhold, B. J.
    • Black, A. L.
  • Source: Agronomy Journal
  • Volume: 93
  • Issue: 5
  • Year: 2001
  • Summary: Spring wheat (Triticum aestivum L.) is generally produced in the northern Great Plains using tillage and a crop-fallow system. This study evaluated the influence of tillage system [conventional-till (CT), minimum-till (MT), and no-till (NT)] and N fertilizer rate (0, 22, and 45 kg N ha(-1)) on grain N, grain N removal from cropping system, and changes in residual postharvest soil NO3-N during six rotation cycles of a dryland spring wheat-fallow (SW-F) cropping system. Grain N concentration increased vith increasing N rate and was higher with CT (33-3 g kg(-1)) than with NT (32.3 g kg-1) at 45 kg ha(-1) N rate. Grain N removal per crop was greater with CT (70 kg N ha (1)) and MT (68 kg N ha(-1)) than with NT (66 kg N ha (1)) and tended to increase with increasing N rate, but varied with rotation cycle. Total grain N removal in six rotation cycles was in the order: CT > MT > NT. Total grain N removal by six SW crops was increased by N fertilization, with only 21 and 17% of the applied N removed in the grain for the 22 and 45 kg ha(-1) N rates, respectively. Postharvest soil NO3-N levels in the 150-cm profile varied with N rate and rotation cycle, with residual NO3-N increasing during consecutive dry crop cycles. In contrast, some leaching of NO3-N below the SW root zone may have occurred during wetter crop cycles. Soil profile NO3-N levels tended to be greater with CT and MT than with NT. Variation in precipitation during rotation cycles and N fertilization impacted grain N removal and residual soil NO3-N levels more than tillage system within this SW-F cropping system.
  • Authors:
    • Kling, C. L.
    • Babcock, B. A.
    • Kurkalova, L. A.
    • Pautsch, G. R.
  • Source: Contemporary Economic Policy
  • Volume: 19
  • Issue: 2
  • Year: 2001
  • Summary: Agricultural tillage practices are important human-induced activities that can alter carbon emissions from agricultural soils and have the potential to contribute significantly to reductions in greenhouse gas emission (Lal et al., The Potential of U.S. Cropland, 1998). This research investigates the expected costs of sequestering carbon in agricultural soils under different subsidy and market-based policies. Using detailed National Resources Inventory data, we estimate the probability that farmers adopt conservation tillage practices based on a variety of exogenous characteristics and profit from conventional practices. These estimates are used with physical models of carbon sequestration to estimate the subsidy costs of achieving increased carbon sequestration with alternative subsidy schemes.
  • Authors:
    • Ball, A.
    • Pretty, J.
  • Year: 2001
  • Authors:
    • Drinkwater, L. E.
    • Puget, P.
  • Source: Soil Science Society of America Journal
  • Volume: 65
  • Issue: 3
  • Year: 2001
  • Summary: Although roots are an important source of soil organic matter (SOM) and are thought to be the major constituent of the particulate organic matter (POM) fraction, few studies have documented the fate of belowground C inputs in situ. The main purpose of this experiment was to determine the fate of root-derived C vs. shoot-derived C and to identify factors contributing to any differences in the retention of aboveground vs. belowground C inputs. We labeled hairy vetch (Vicia villosa Roth subsp. villosa) in situ with 13CO2 and followed both root- and shoot-derived C in total soil organic C (SOC) and labile C pools for the first growing season following hairy vetch incorporation. At the end of the growing season, nearly one-half of the root-derived C was still present in the soil, whereas only 13% of shoot-derived C remained. A greater proportion of root-derived C was found as occluded POM and associated with the clay and silt fraction. Greater root-derived C also was retained as chloroform-extractable microbial biomass. We suggest that three different mechanisms contributed to the increased retention of root-derived C: (i) the greater biochemical recalcitrance of root litter, (ii) increased physical protection of root-derived POM within aggregates, and (iii) the continuous nature of root C inputs from exudates and fine root turnover. We conclude that shoot residues are broken down rapidly and serve as the source of N for the following cash crop, whereas the root litter is probably largely responsible for the short-term soil structural improvements associated with the use of green manures. Furthermore, on the basis of these findings, we hypothesize that the greater retention of root-derived C in the first 6 mo of decomposition will increase the persistence of this C in SOM in the long term.
  • Authors:
    • Owensby, C. E.
    • Rice, C. W.
  • Source: The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect
  • Year: 2001
  • Authors:
    • Stuedemann, J. A.
    • Franzluebbers,A. J.
    • Sanderson, M. A.
    • Stout, W. L.
    • Schnabel, R. R.
  • Source: The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect
  • Year: 2001
  • Authors:
    • Skaggs, R. K.
  • Source: Agricultural Water Management
  • Volume: 51
  • Issue: 2
  • Year: 2001
  • Summary: The possibility that drip irrigation technology could increase yields, reduce the incidence of crop diseases, and improve fruit quality has been identified as a critical research issue for the New Mexico chile pepper industry. Numerous hypotheses have been expressed regarding the low incidence of drip irrigation usage among New Mexico farmers. A survey of farmers was conducted in 1999 to assess commercial chile pepper producers' attitudes toward and knowledge of drip irrigation technology. The survey data were used in logistic regression models that predict current high-tech irrigation system usage, drip irrigation usage, and plans for future drip irrigation adoption by chile pepper producers. The results of this research provide information useful to extension personnel, other researchers, and chile industry members. Results also raise questions about the impact of widespread drip irrigation adoption on multi-user irrigation systems, such as those found in New Mexico.