• Authors:
    • Raun, W. R.
    • Sander, D. H.
    • Olson, R.A.
  • Source: Soil Science Society of America Journal
  • Volume: 51
  • Issue: 4
  • Year: 1987
  • Authors:
    • Power, J. F.
    • Doran, J. W.
    • Wilhelm, W. W.
  • Source: Agronomy Journal
  • Volume: 78
  • Year: 1986
  • Summary: Crop residues (stover) have many potential uses by society: food, feed, shelter, fuel, and soil amendment. Use of residues for purposes other than as a soil amendment may have serious negative consequences on crop productivity. This study was conducted to investigate the yield response of continuous corn (Zea mays L.) and continuous soybean [Glycine max (L.) Merr.) to removal or addition of crop residues under no-tillage management. The study was conducted near Lincoln, NE, on a Crete-Butler silty clay loam (fine, montmorillonitic, mesic Pachic Arguistoll-Abruptic Argiaquoll) with 1 to 2% slope. Crop residue was collected and weighed immediately after harvest in autumn. Quantity of residue to be returned to each treatment (0, 50, 100, or 150% of that produced) was calculated and uniformly spread over the plot area (12.2 by 12.2 m) by hand. Corn and soybean were planted into the established residue levels with no tillage the following spring. Data were collected on soil water, soil temperature, and grain and residue yield. A positive linear response was found between grain and stover yield and amount of residue applied to the soil surface. Each Mg ha-1 of residue removed resulted in about a 0.10 Mg ha"1 reduction in grain yield and a 0.30 Mg ha-1 reduction in residue yield. Quantity of applied residue accounted for 81 and 84% of the variation in grain yield of corn and soybean, respectively, and 88 and 92% of the variation in residue yield. Amounts of stored soil water at planting were closely associated with quantity of residue applied the previous year. Differences in total available water (soil storage at planting plus rainfall) accounted for approximately 70% of the yield variation associated with the residue treatments. Soil temperature (50-mm depth) and total available water accounted for nearly the same amount of variation in yield (80 to 90%) as quantity of residue, emphasizing the importance of these factors in evaluating response of crops to residue-management practices. Residue removal reduced grain and residue yields by amounts equal to 10 and 30%, respectively, of the quantity of residue removed. Residue effects on crop yield were induced mainly through changes in soil water and soil temperature.
  • Authors:
    • Miranowski, J.
    • Shortle, J.
  • Source: Applied Agricultural Research
  • Volume: 1
  • Issue: 2
  • Year: 1986
  • Authors:
    • Miller, M.
    • O'Halloran, I.
    • Arnold, G.
  • Source: Canadian Journal of Soil Science
  • Volume: 66
  • Issue: 2
  • Year: 1986
  • Summary: In 1981, phosphorus absorption by young corn plants was greater from no-till than from plowed plots with similar NaHCO 3-extractable P (Ext P) concentrations. A series of growth room studies was conducted to explain this difference. Corn plants grown on cores from the no-till plots had a higher P concentration than plants grown on soil from the plowed plots, in spite of a lower root growth and a lower Ext P content. Disturbance of the no-till soil eliminated the effect. A parameter, accessible P (Acc-P), was calculated from root length and Ext P assuming P was absorbed from a cylinder of soil around each root. Shoot P content at a given Acc-P content was always higher with the undisturbed no-till soil than with either the disturbed no-till or the plowed soil. Irradiation (gamma-ray) of the no-till soil reduced P absorption by a similar degree to disturbance, indicating that a biological factor was involved. Disturbance of soil had no influence on P content of canola ( Brassica napus L.), a nonmycorrhizal crop. Soil disturbance reduced the intensity of mycorrhizal infection in corn roots. It is hypothesized that disturbance of the no-till soil reduced P absorption by reducing the effectiveness of the mycorrhizal symbiosis.
  • Authors:
    • Doran, J. W.
    • Linn, D. M.
  • Source: Soil Science Society of America Journal
  • Volume: 48
  • Issue: 4
  • Year: 1984
  • Summary: Surface soils from long-term tillage comparison experiments at six U.S. locations were characterized for aerobic and anaerobic microbial populations and denitrification potential using an in situ acetylene blockage technique. Measurements of soil water content, bulk density, and relative differences in pH, NO-3-N, water-soluble C, and total C and N contents between tillage treatments were also determined at the time of sampling. Numbers of aerobic and anaerobic microorganisms in surface (0-75 mm) no-till soils averaged 1.35 to 1.41 and 1.27 to 1.31 times greater, respectively, than in surface-plowed soils. Bulk density, volumetric water content, water-filled pore space, and water-soluble C and organic C and N values were similarly greater for surface no-till soils compared to conventionally tilled soils. Deeper in the soil (75-300 mm), however, aerobic microbial populations were significantly greater in conventionally tilled soils. In contrast, below 150 mm, the numbers of anaerobic microorganisms differed little between tillage treatments. In no-till soils, however, these organisms were found to comprise a greater proportion of the total bacterial population than in conventionally tilled soils. Measurements of the denitrification potential from soils at three locations generally followed the observed differences in anaerobic microbial populations. Denitrifying activity, after irrigation with 15 mm of water, was substantially greater in surface 0- to 75-mm no-till soils than in conventionally tilled soils at all locations. At the 75- to 150-mm soil depth, however, the denitrification potential in conventionally tilled soils was the same or higher than that of no-till soils. In surface no-till soils, increased numbers of anaerobic microorganisms and a substantially greater denitrification potential, following irrigation, indicate the presence of less-aerobic conditions in comparison to conventionally tilled soils. This condition appears to result from greater soil bulk densities and/or water contents of no-till soils, which act to increase water-filled porosity and the potential for water to act as a barrier to the diffusion of oxygen through the soil profile.
  • Authors:
    • Frye, W. W.
  • Source: No Tillage Agriculture, Principles and Practices
  • Year: 1984
  • Authors:
    • Paul, E. A.
    • Rennie, D. A.
    • Aulakh, M. S.
  • Source: Journal of Environmental Quality
  • Volume: 13
  • Issue: 1
  • Year: 1984
  • Summary: The gaseous losses of N from conventional-till (CT) and zero-till (ZT) crop fields were 3 to 7 and 12 to 16 kg N ha-1 y-1, respectively. In contrast, losses from CT and ZT fallow were severalfold higher, namely, 12 to 14 and 34 kg N ha-1, respectively. The more dense surface soil and consistently higher moisture content (lower air-filled porosity) were identified as major factors affecting increased denitrification under ZT. The potential denitrification rates were markedly higher under ZT, and the population of denitrifiers was up to six times higher than in CT soil samples. The contribution of lower soil horizons towards gaseous N losses was found to be low on both CT and ZT fields, and this finding was confirmed from a survey carried out on three other widely differing soils. Volumetric soil moisture and air temperature were the only two of several factors that accounted for a significant portion of the variations in gaseous N fluxes under field conditions. The average mole fraction of N2O ranged from almost 100% to as low as 28% of the total gaseous products and showed a negative relationship with soil moisture.
  • Authors:
    • Elharis, M. K.
    • Cochran, V. L.
    • Elliott, L. F.
    • Bezdicek, D. F.
  • Source: Soil Science Society of America Journal
  • Volume: 47
  • Issue: 6
  • Year: 1983
  • Authors:
    • Fenster, C. R.
    • Mannering, J. V.
  • Source: Journal of Soil and Water Conservation
  • Volume: 38
  • Issue: 3
  • Year: 1983
  • Authors:
    • Doran, J. W.
  • Source: Soil Science Society of America Journal
  • Volume: 44
  • Issue: 4
  • Year: 1980
  • Summary: The physical, chemical, and biological soil environment for reduced or no-till farming differs greatly from that for conventional tillage. Evaluation of the soil microbial and biochemical environment greatly aids predictions of N availability to crop plants and in optimizing management practices for reduced and no-till soils. Surface soils from long-term no-till and conventional tillage plots at seven U.S. locations were characterized for microbial and biochemical components. The counts of aerobic micro-organisms, facultative anaerobes, and denitrifiers in the surface (0-7.5 cm) of no-till soils were 1.14 to 1.58, 1.57, and 7.31 times higher, respectively, than in the surface of plowed soil. Phosphatase and dehydrogenase enzyme activities and contents of water and organic C and N in the surface of no-till soil were also significantly higher than those for conventional tillage. However, at the 7.5- to 15-cm and 15- to 30-cm depths these trends were reversed and microbial populations, enzyme activities, and water and organic C and N contents were the same or higher for conventional tillage than for no-till. The trends in microbial populations with both tillage treatments were closely paralleled by soil enzyme activities and were also regulated by soil pH and levels of organic C and N. The surface 0- to 7.5-cm of no-till soil contained more potentially mineralizable N--20 to 101 kg/ha--than did that of plowed soils. This increased labile N reserve is apparently related to the higher microbial biomass present under no-till soils. Maximum aerobic microbial activity with conventional tillage extends to a greater depth than with no-till. Microbial populations under no-till decrease rapidly below the 7.5-cm depth. At the 7.5- to 15-cm depth counts of aerobic microor-ganisms and nitrifiers were 1.32 to 1.82 times higher on the conventionally tilled soils. However, counts for facultative anaerobes and denitrifiers were 1.23 to 1.77 times higher for no-till soil. Also, the proportion of the total aerobic population represented by facultative anaerobes and denitrifiers for no-till was twice that for conventional tillage. Consequently the potential rate of mineralization and nitrification is higher with conventional tillage while that for denitrification is higher with no-till. Microbial population counts and the relative abundance of various microbial types suggests that the bochemical environment of no-till soils is less oxidative than that under conventional tillage. Changes in tillage and fertilizer management practices required for no-till soils should reflect the increased potential for immobilization of surface applied N and the lower levels of plant available NO3- as compared with those under conventional tillage.