• Authors:
    • Lichtenberg, E.
    • Hanson, J. C.
    • Peters, S. E.
  • Source: American Journal of Alternative Agriculture
  • Volume: 12
  • Issue: 1
  • Year: 1997
  • Summary: Compares the profitability of the organic and conventional cash grain rotations since 1982. Dependence of sustainable farming on the generated income from farmers; Conduct of a Farming Systems Trial; Analysis of two FST systems; Advantage of the organic rotation; Tabulation of net returns for three different periods; Net returns and labor requirements.
  • Authors:
    • Kissel, D. E.
    • Havlin, J. L.
  • Source: Soil Organic Matter in Temperate Agroecosystems: Long-Term Experiments in North America
  • Volume: 1
  • Year: 1997
  • Authors:
    • Voroney, R.
    • Vyn, T.
    • Janovicek, K.
  • Source: Agronomy Journal
  • Volume: 89
  • Issue: 4
  • Year: 1997
  • Summary: Research in Ontario, Canada in 1989, 1990, and 1995 evaluated no-till maize yield response to various preceding crops and examined whether in-row residue removal affected no-till maize response to rotation crops. The soil was an imperfectly drained loam (medium, mixed, weakly to moderately calcareous Typic Hapludalf). The preceding crops were: maize harvested for grain or whole-plant silage; hard red spring wheat; barley; red clover ( Trifolium pratense) cover crops, following barley, that were killed by spraying either 3 weeks (early-kill) or 1 day (late-kill) prior to sowing maize; canola [rape]; and soyabeans. In-row residue was either retained while sowing or cleared using planter-mounted, notched-disc row cleaners. Clearing in-row cover crop residue increased early-season maize growth and was associated with yield increases of 0.61 t ha -1 (8%) following early-killed red clover and 0.43 t ha -1 (6%) ( P = 0.10) following late-killed red clover. In 2 of 3 years, maize yields following early-killed red clover were similar to following soyabeans and greater than following grain maize, provided that in-row residue was cleared. Following the other crops, grain yield response to clearing in-row residue was smaller and less consistent over years. Preceding cropping affected early-season maize growth, with the largest plants at 5 weeks after sowing following either soyabeans or silage maize and the smallest following either red clover or grain maize. In 2 of 3 years, when preceding crop effects on grain yield were statistically significant, yields following either soyabeans or spring wheat were more than 1.05 t ha -1 (16%) higher than after grain maize. That yield increase occurred regardless of in-row residue placement. Removing maize stover by harvesting as silage increased maize yield by 0.86 t ha -1 (12%) over yield following grain maize. During 1995, maize yield following silage maize was less than after soyabeans, canola, barley, or wheat; thus, no-till maize yield response to rotation is not exclusively due to the presence of surface-placed stover. In-row residue placement and preceding cropping practices affected in-row soil temperature, but this could not totally account for the treatment effects on early-season maize growth and yields.
  • Authors:
    • Maddux, L. D.
    • Gordon, W. B.
    • Rice, C. W.
    • Omay, A. B.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL Pages:
  • Volume: 61
  • Issue: 6
  • Year: 1997
  • Summary: With renewed interest in maintaining our soil resources, it is important to establish criteria that can describe and quantify the effect of different crop management practices on soil organic matter (SOM). We conducted this study to assess changes in SOM and other soil properties after long-term (>10 yr) continuous corn (Zea mays L.; CC) and corn-soybean rotation [Glycine max (L.) Merr,; C/SB] with and without fertilizer, Soil samples were collected from two furrow-irrigated CC and C/SB rotations on a Crete silt loam (ene, montmorillonitic, mesic Pachic Argiustoll) and a Eudora loam (coarse-silty, mixed, mesic Fluventic Hapludoll). Long term (350-d) laboratory incubation at optimum moisture and temperature conditions measured potentially mineralizable C (PMC) and N (PMN) as a measure of the active fraction of soil organic C and N, Microbial biomass C (MBC) and N (MBN), organic C and N, pH, and texture also were determined, Crop rotations that included high-residue-producing crops such as corn and addition of fertilizer increased soil organic C and N, Crop rotation did not affect PMC in the Crete soil, but addition of fertilizer significantly increased PMC by 32%. The PMN in both soils was not affected by crop rotation or fertilizer addition, Inclusion of soybean in the rotation decreased the stable and active fractions of organic C and N, Changes in soil organic C and N in response to crop rotation and fertilizer addition were related to the estimated amount of crop residues returned to the soil and to soil texture.
  • Authors:
    • Walters, D. T.
    • Kessavalou, A.
  • Source: Agronomy Journal
  • Volume: 89
  • Issue: 1
  • Year: 1997
  • Summary: Rotation of corn (Zea mays L.) with soybean [Glycine max (L.) Merr.] provides certain economic and environmental advantages over monoculture corn. Low soybean residue production and persistence, however, promote potentially excessive soil erosion following soybean harvest. An irrigated field experiment was conducted in eastern Nebraska for 4 yr (1990-1993) under various tillage treatments and N rates to evaluate the effects of a winter rye (Secale cereale L.) cover crop following soybean on (i) rye dry matter yield, (ii) surface residue cover for erosion protection, and (iii) corn establishment and production. The soil was a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls). Treatments were (i) no-tillage and disk tillage; (ii) corn following soybean with a winter rye cover crop (CBR), corn following soybean without rye (CB) and corn following corn (CC); and (iii) 0, 50, 100, 150, and 300 kg N ha(-1) (applied to corn). Rye aboveground dry matter yield, surface residue cover, and corn yield parameters were estimated. Rye dry matter yield ranged from 0.25 to 2.9 Mg ha(-1) and was influenced by tillage, N rate, and weather conditions in different years. During the years of high rye dry matter yield, presence of rye in the corn-soybean system gave approximately 16% additional surface residue cover prior to planting through cultivation, compared with soybean residue alone. Surface cover by rye and soybean residues in CBR was equivalent to corn residue in CC under both disk and no-till management. In 1 of the 3 yr, corn plant population and grain yield were reduced following rye (CBR) compared with the no rye system (CB), possibly due to apparent allelopathic effects related to the age of rye. No significant difference in N response was observed between CBR and CB corn yields. In general, rotation of corn with soybean (with and without rye) resulted in an increase of approximately 27% in corn grain yield and N uptake over continuous corn. During the years of high rye dry matter production, rye accumulated approximately 45 kg N ha(-1) through aboveground dry matter. Overall, including a winter rye cover crop in the corn-soybean rotation system was beneficial.
  • Authors:
    • Harriss, R. C.
    • Narayanan, V.
    • Li, C.
  • Source: Global Biogeochemical Cycles
  • Volume: 10
  • Issue: 2
  • Year: 1996
  • Summary: The Denitrification-Decomposition (DNDC) model was used to elucidate the role of climate, soil properties, and farming practices in determining spatial and temporal variations in the production and emission of nitrous oxide (N[2]O) from agriculture in the United States. Sensitivity studies documented possible causes of annual variability in N[2]O flux for a simulated Iowa corn-growing soil. The 37 scenarios tested indicated that soil tillage and nitrate pollution in rainfall may be especially significant anthropogenic factors which have increased N[2]O emissions from soils in the United States. Feedbacks to climate change and biogeochemical manipulation of agricultural soil reflect complex interactions between the nitrogen and carbon cycles. A 20% increase in annual average temperature in °C produced a 33% increase in N[2]O emissions. Manure applications to Iowa corn crops enhanced carbon storage in soils, but also increased N[2]O emissions. A DNDC simulation of annual N[2]O emissions from all crop and pasture lands in the United States indicated that the value lies in the range 0.9 - 1.2 TgN. Soil tillage and fertilizer use were the most important farming practices contributing to enhanced N[2]O emissions at the national scale. Soil organic matter and climate variables were the primary determinants of spatial variability in N[2]O emissions. Our results suggest that the United States Government, and possibly the Intergovernmental Panel on Climatic Change (IPCC), have underestimated the importance of agriculture as a national and global source of atmospheric N[2]O. The coupled nature of the nitrogen and carbon cycles in soils results in complex feedbacks which complicate the formulation of strategies to reduce the global warming potential of greenhouse gas emissions from agriculture.
  • Authors:
    • Li, C.
  • Source: Soil Management and Greenhouse Effect
  • Year: 1995
  • Authors:
    • Rowell, A. L.
    • Weinrich, K. B.
    • Barnwell, T. O.
    • Jackson, R. B.,IV
    • Patwardhan, A. S.
    • Donigian, A. S.
  • Source: Soil Management and Greenhouse Effect
  • Year: 1995
  • Authors:
    • Porter, P.
  • Source: Journal of Production Agriculture
  • Volume: 8
  • Issue: 2
  • Year: 1995
  • Summary: A study was conducted on an Orangeburg loamy sand (fine-loamy, siliceous, thermic Typic Paleudults) near Blackville, South Carolina in 1990-92 to determine the effect of deep tillage on both canola [rape] and wheat, the subsequent response of doublecropped soyabeans, and response of wheat grown following the soyabean crop when controlled traffic and minimum tillage practices were used. Canola yields averaged 37.8 bu/acre in 1991 and 43.2 bu/acre in 1992, whereas wheat yields were 58.0 and 72.5 bu/acre, respectively. In both years, deep tillage (chiselling to 11 in) had no effect on wheat yields when compared with discing. Deep tillage increased canola yields by 12.5% in the drier of the two growing seasons. Soyabean yields were not significantly affected by the tillage used for the previous crops. Subsoiled soyabeans yielded 33.7 vs. 31.9 bu/acre for no-till soyabeans in 1991, and 22.6 vs. 19.4 bu/acre in 1992. In 1992, soyabean tillage following wheat did not affect soyabean yield but following canola, in-row subsoiling resulted in greater soyabean yields than no-till. Wheat following soyabeans was not affected by the tillage practice used for the previous winter crops, and the 1992 wheat yields were unaffected by previous winter crop or soyabean tillage. In 1993, soyabean tillage did not affect subsequent wheat yield but following canola, in-row subsoiling resulted in greater wheat yields than no-till. It is suggested that canola has no adverse effect on either soyabeans or wheat when grown in sequence on a Coastal Plain soil.
  • Authors:
    • Coady, S. A.
    • Clark, R. T.
    • Schneekloth, J. P.
    • Klocke, N. L.
    • Hergert, G. W.
  • Source: Journal of Production Agriculture
  • Volume: 8
  • Issue: 3
  • Year: 1995
  • Summary: Declining groundwater levels in parts of the Great Plains could lead to reduced irrigation and a decline in the economies of those areas. Improved irrigation efficiency has helped slow the rate of decline in aquifer levels but adoption of limited irrigation and water conserving rotations could slow the decline even more. The objective was to estimate the riskiness and profitability of these alternatives with and without farm commodity programs. Three water levels-rainfed, limited irrigation (6 in./yr water allocation) and full irrigation (meet crop evapotranspiration demands) were established for continuous corn (Zea mays L.), winter wheat (Triticum aestivum L.)-corn-soybean [Glycine max (L.) Merr.], and corn-soybean rotations. The profitability of each rotation under each water level was estimated using results of field experiments conducted since 1981 in west central Nebraska and cost estimates based on a typical center pivot irrigation system covering 126 acres. Stochastic dominance techniques were then applied to the data by using combinations of prices for corn, wheat, and soybean to generate cumulative distribution functions. Profitability and riskiness were estimated with and without participation in the wheat and feed grain programs and with alternate acreage conservation reserve (ACR) levels. Results showed that the government program improved income levels and reduced income variation for each water level and all rotations. Program participation did encourage monoculture corn under full irrigation and under limited irrigation with low ACR requirements. Under rainfed conditions the relative ranking of the three rotations was not changed by program participation.