• Authors:
    • Dı́az-Zorita, M.
  • Source: Soil & Tillage Research
  • Volume: 54
  • Issue: 1-2
  • Year: 2000
  • Summary: Subsoiling a compacted soil should loosen it, improve the physical conditions, and increase nutrient availability and crop yields. The aim of this work is to compare the effects of different tillage and fertility treatments in a loamy Typic Hapludoll soil, and to determine the interactions of N fertilization with several soil properties and dryland corn (Zea mays L.) productivity, The experiment, conducted in 1995 and in 1997, had a split-plot design consisting of three tillage systems (MB=moldboard plowing, CH=chisel plowing or NT=no-tillage) in a corn-soybean (Glycine max (L.) Merrill) rotation since 1991 as main treatments. Four subtreatments: (i) subsoil (paratill subsoiler to 40 cm depth in fallow 1995)+N fertilization (100 kg ha(-1) N as ammonium nitrate, at the V6 development stags of corn), (ii) subsoil+no N fertilization, (iii) no subsoiling+N fertilization, and (iv) no subsoiling+no N fertilization. Chemical and physical properties in the top layer of the soils were determined at seeding in 1995. Penetration resistance was measured at seeding, flowering and at harvest in 1995 and at seeding in 1997. Corn shoot dry matter during vegetative stages and grain yield components were also determined. The preparation of seedbed using either moldboard or chisel plowing with or without deep-tillage, increased the vegetative biomass by 27% and the grain yield of the corn crops by 9% over the no-tillage system. Subsoiling no-till plots improved the vegetative growth of the crops, but the effect of the deep-tillage did not modify the corn grain yields. Grain yields were strongly related to the N fertilization treatments. Although bulk density values (BD) ranged between 1.05 and 1.33 Mg m(-3) differences in crop yields were attributed to differences in the ED and the N fertilization. In the western Pampas Region of Argentina, the production of high yielding corn crops, under no water stress conditions, is independent of the tillage systems but negatively related with the soil BD values, and positively dependent on N fertilization.
  • Authors:
    • Tanaka, D. L.
    • Halvorson, A. D.
    • Black, A. L.
    • Krupinsky, J. M.
    • Merrill, S. D.
    • Wienhold, B. J.
  • Source: Agronomy Journal
  • Volume: 92
  • Issue: 2
  • Year: 2000
  • Summary: Spring wheat (Triticum aestivum L.) production in the northern Great Plains generally utilizes conventional tillage systems. A 12-yr study evaluated the effects of tillage system [conventional-till (CT), minimum-till (MT), and no-till (NT)], N fertilizer rate (0, 22, and 45 kg N ha(-1)), and cultivar (Butte86 and Stoa) on spring wheat grain yields in a dryland spring wheat-fallow rotation (SW-F). Butte86 yields with CT exceeded NT yields in five out of 12 years with 0 and 22 kg N ha(-1) applied, and four years with 45 kg N ha(-1) applied. Stoa yields with CT exceeded NT yields in three out of 12 years with no N applied, four years with 22 kg N ha(-1) applied, and only one year with 45 kg N ha(-1) applied. Yields with NT exceeded those with CT in one year. Most years, yields with MT equaled those with CT. Responses to N tended to be greatest in years when spring soil NO3-N was lowest. Positive yield responses to N fertilization with CT occurred in three years with Butte86 and two years with Stoa; with MT, four years with Butte86 and two years with Stoa; and with NT, five years with Butte86 and three years with Stoa. Cultivars were not consistent in their response to tillage and N fertilization. These results indicate that farmers in the northern Great Plains can successfully produce spring wheat in a SW-F system using MT and NT systems, but yields may be slightly reduced when compared with CT systems some years.
  • Authors:
    • Schneider, U. A.
  • Volume: Ph.D.
  • Year: 2000
  • Authors:
    • Sherrod, L.
    • Ahuja, L. R.
    • Peterson, G. A.
    • Shaffer, M. J.
    • Rojas, K. W.
    • Ma, L. W.
  • Source: Agronomy Journal
  • Volume: 91
  • Issue: 3
  • Year: 1999
  • Summary: Decomposition of surface crop residues is important for agricultural management, especially under conservation tillage. The objective of this study was to test several models for describing crop residue decomposition under three eastern Colorado dryland agroecosystems at Sterling, Stratton, and Walsh with a yearly mean air temperature of 9.7, 10.4, and 12.0 degrees C, respectively. At each site, a soil toposequence common to its geographic region was chosen to include a summit, a sideslope, and a toeslope position, and several crop rotations were practiced under no-till conditions. Grab samples were taken at planting and before harvesting for surface residue measurement since 1985, Simulation results showed that the Douglas-Rickman model described surface crop residue decomposition better than the Gregory model during a 13-year period, based on a normalized objective function (NOF). Our fitted decomposition rate coefficients using the Douglas-Rickman model matched those originally published. The Douglas-Rickman model, which uses a first-order decay with respect to degree-days, was further evaluated against two other first-order decay models: one using a first-order decay equation with respect to decomposition-days and the other assuming a first order decay with respect to time (d), Although the three approaches performed equally well in terms of NOF values (P = 0.354), fitted decomposition rate coefficients were significantly different (P < 0.012) among the three experiment sites when models based on decomposition-days or on time (in days) were used. Therefore, the Douglas-Rickman model may be more applicable for describing long-term crop residue decomposition because of its consistency in model parameters among experimental sites and simplicity in modeling approach.
  • Authors:
    • Norwood, C. A.
  • Source: Agronomy Journal
  • Volume: 91
  • Issue: 1
  • Year: 1999
  • Summary: The dryland winter wheat (Triticum aestivum L,)-grain sorghum [Sorghum bicolor (L.) Moench]-fallow rotation is suitable for large areas of the U,S. Great Plains. High temperatures and potential evapotranspiration limit the number of other crops that can be grown, Sunflower (Helianthus annnus L.) is drought tolerant, but crops such as corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] are perceived to lark sufficient heat and drought tolerance for semiarid areas. A study was conducted near Garden City, KS, from 1991 through 1995 to compare yield and water uses of conventional tillage (CT) and no tillage (NT) corn, grain sorghum, sunflower, and soybean to determine if crops other than grain sorghum are suitable for dryland production. Conventional tillage (CT) and no tillage (NT) were included in a wheat-row crop-fallow rotation. Corn and soybean were similar in their depletion of soil water, as were sorghum and sunflower. Below a depth of 1.2 m, sorghum and sunflower removed the most water. Sunflower removed the most water nom the last 0.3 m of the profile and probably removed deeper water. Sorghum and sunflower removed an average of 19 mm more water from the 1.8-m soil profile than did corn and soybean. No-till increased yields of corn in 3 yr, of sorghum and sunflower in 2 yr, and of soybean in 1 yr, Corn had the greatest yield response to NT, averaging 31%. Average yields of corn were 25% higher than sorghum yields, whereas average yields of sunflower were 83% higher than soybean yields. Other crops can be successfully grown in the wheat-row crop-fallow rotation, but sorghum should occupy the most acres until the other crops have been tested under different climatic conditions.
  • Authors:
    • Schomberg, H. H.
    • Jones, O. R.
  • Source: Soil Science Society of America Journal
  • Volume: 63
  • Issue: 5
  • Year: 1999
  • Summary: Soil C and N greatly influence Long-term sustainability of agricultural systems, We hypothesized that cropping and tillage differentially influence dryland soil C and N characteristics in the Southern High Plains. A Pullman clay loam (fine, mixed, thermic Torrertic Paleustol) cropped to vc heat (Triticum aestivum L.)-sorghum [Sorghum bicolor (L) Moench]-fallow (WSF), continuous wheat (CW) and continuous sorghum (CS) under no-tillage (NT), and stubble mulch (SM) was sampled at three depths to determine soil C and N characteristics. For CW, CS, and WSF phases (F-WSF, S-WSF, W-WSF), soil organic C (SOC) averaged 10.6 to 13.1 kg m(-3) and was greatest for CW, Carbon mineralization (C-MIN) at 0 to 20 mm was 30 to 40% greater for CW and F-WSF than for CS, S-WSF, or W-WSF. Cropping system by depth influenced soil organic N (SON),vith greatest SON at 0 to 20 mm in CW (1.5 kg m(-3)). At 0 to 20 mm for SM and NT, SOC was 9.9 and 12.5 kg m(-3), soil microbial biomass C (SMBC) was 0.80 and 1.1 kg m(-3), and soil microbial biomass N (SMBN) was 0.14 and 0.11 kg m(-3). Also at 0 to 20 mm, NT had 60% greater C-MIN, 11% more SMBC as a portion SOC, and 25% more SON compared to SM. Summed for 0 to 80 mm, NT had more SOC (0.98 vs 0.85 kg m(-2)) and SON (0.10 vs 0.9 kg m(-2)) than SM, and CW had greater or equal C and N activity as other systems. Negative correlations between yield and SOC, SMBC, C-MIN, SON, and SMBN indicate N removal in grain negatively affects active and labile C and N pools. Under dryland conditions, C and N conservation is greater with NT and with winter wheat because of less soil disturbance and shorter fallow.
  • Authors:
    • Black, A. L.
    • Krupinsky, J. M.
    • Merrill, S. D.
    • Halvorson, A. D.
  • Source: Agronomy Journal
  • Volume: 91
  • Issue: 4
  • Year: 1999
  • Summary: Winter wheat (Triticum aestivum L.) can add diversity to dryland crop rotations in the northern Great plains, but it is susceptible to winterkill in low surface residue environments. A 12-year study was conducted to determine the response of two winter wheat cultivars, Roughrider and Norstar; to tillage system (conventional-till, CT; minimum-till, MT: and no-till, NT) and N fertilizer rate (34, 67, and 101 kg N ha(-1)) in a dryland spring wheat-winter wheat-sunflower (Helianthus annuus L,) rotation. Grain yields were greater with MT (1968 kg ha(-1)) and NT (2022 kg ha(-1)) than with CT (1801 kg ha(-1)), but tillage system effects on grain yield varied among years, Increasing N rate from 34 kg N ha(-1) to 67 kg N ha(-1) increased grain production from 1844 to 1953 kg ha(-1), but yield response to N rate varied among years., The greatest overall grain yield (2111 kg ha(-1)) if as obtained with NT and application of 101 kg N ha(-1). Grain yields were lowest during gears when plant-available Hater (PAW) was 400 an PAW, leaf spot disease incidence was greatest, particularly at the lowest N rate with NT. Application of adequate N reduced the disease incidence in all tillage treatments. Cultivar differences Here significant 3 out of 12 years, but not consistent. Winterkill was a factor for both cultivars in only 1 year in the CT and MT plots. Winter wheat performed Hell as a rotational crop in this cropping system when using,tfT and NT systems and adequate N fertility, Our long-term results indicate that producers in the northern Great Plains ran use winter wheat successfully in annual cropping systems that do not include a fallow period, particularly if NT is used with adequate N fertilization.
  • Authors:
    • Merrill, S. D.
    • Tanaka, D. L.
    • Black, A. L.
    • Halvorson, A. D.
    • Krupinsky, J. M.
  • Source: Agronomy Journal
  • Volume: 91
  • Issue: 4
  • Year: 1999
  • Summary: Sunflower (Helianthus annuus L.) is a warm-season, intermediate water-use crop that can add diversity to dryland crop rotations, Reduced tillage systems may Enhance sunflower yield in intensive cropping systems. A 12-year study was conducted to determine how sunflower cultivars of early and medium maturity respond to tillage system (conventional-till, CT; minimum-till, MT; no-till, NT) and N fertilization (34, 67, and 101 kg N ha(-1)) within a dryland spring wheat (Triticum aestivum L.)-winter wheat-sunflower rotation. Averaged across N rates, cultivars, and years, sunflower seed yields were greater with MT (1550 kg ha(-1)) than with NT (1460 kg ha(-1)) and CT (1450 kg ha(-1)). Increasing N rate above 34 kg N ha-L generally increased gain yield, but varied from year to year. The tillage X N interaction showed that the highest seed yields were obtained with NT (1638 kg ha(-1)) and MT (1614 kg ha(-1)) at 101 kg N ha(-1). Total plant-available water (TPAW) of 500 mm did not result in increased sunflower yields over those with 350 to 500 mm TPAW. Yield differences between cultivar maturity classes varied from year to gear and with tillage and N level. At the lowest N rate, weeds were more problematic in NT than in CT and MT plots. More N fertilizer may be needed with NT to optimize sunflower yields than with CT and MT, because of less residual soil NO3-N with NT. Results indicate that producers in the northern Great Plains can use sunflower successfully in annual a cropping systems, particularly if MT and NT are used with adequate N fertilization.
  • Authors:
    • Follett,R. F.
    • Reule,C. A.
    • Halvorson,A. D.
  • Source: Soil Science Society of America Journal
  • Volume: 63
  • Issue: 4
  • Year: 1999
  • Summary: No-till (NT) increases the potential to crop more frequently in the Great Plains than with the conventional-till (CT) crop-fallow farming system. More frequent cropping requires N input to maintain economical yields. We evaluated the effects of N Fertilization on crop residue production and its subsequent effects on soil organic C (SOC) and total soil N (TSN) in a dryland NT annual cropping system. Six N rates (0, 22, 45, 67, 90, and 134 kg N ha(-1)) were applied to the same plots from 1984 through 1994, except 1988 when rates sere reduced 50%, on a Weld silt loam (fine, smectitic, mesic Aridic Argiustoll). Spring hal leg (Hordeum vulgare L.), corn (Zea mays L.),winter wheat (Triticum aestivum L.), and oat (Avena sativa L.)-pea (Lathyrus tingitanus L.) hay were grown in rotation. Crop residue production varied with crop and gear. Estimated average annual aboveground residue returned to the soil (excluding hay years) was 2925, 3845, 4354, 4365, 4371, and 4615 kg ha(-1), while estimated annual contributions to belowground (root) residue C were 1060, 1397, 1729, 1992, 1952, and 2031 kg C ha(-1) for the above N rates, respectively. The increased amount of crop residue returned to the soil with increasing N rate resulted in increased SOC and TSN levels in the 0- to 7.5-cm soil depth after 11 crops. The fraction of applied N fertilizer in the crop residue decreased with increasing N rate. Soil bulk density (D-b) in the 0- to 7.5-cm soil depth decreased as SOC increased, The increase in SOC with N fertilization contributes to improved soil quality and productivity, and increased efficiency of C sequestration into the soil. Carbon sequestration can be enhanced by increasing crop residue production through adequate N fertility.
  • Authors:
    • Anderson, R. L.
    • Nielsen, D. C.
    • Vigil, M. F.
    • Bowman, R. A.
  • Source: Soil Science Society of America Journal
  • Volume: 63
  • Issue: 1
  • Year: 1999
  • Summary: Continuous cropping or decreasing the frequency of summer fallow (F) in cereal-based dryland rotations may have benefits other than greater water utilization and erosion control. We hypothesized that rotations with no fallow or minimum fallow frequency can produce more biomass and cover than the traditional winter wheat (Triticum aestivum L.)-summer fallow systems (W-F), and ultimately, greater amounts of soil organic matter (SOM). To this end, we evaluated changes in various pools of SOM at the 0- to 5- and 0- to 15-cm depths on a Weld loam (fine, smectitic, mesic aridic Paleustolls) that were caused by (i) decreasing fallow or increasing cropping intensities, (ii) specific rotations of the same length but with different crop sequencing, and (iii) accumulated residue and roots from reduced- or notillage from 1993 to 1997. Total soil organic carbon (SOC) and N for the 0- to 5-cm depth increased by =20% with continuous cropping rotations compared with W-F rotations. Particulate organic matter-carbon (POM-C) doubled, while POM-N, and soluble organic C (OC) increased by one third for the same comparison. At the 0- to 15-cm depth, SOC, POM-C, and POM-N did not differ among systems with fallow, nor among systems with cropping intensities greater than W-F. Thus, significant differences always existed between W-F and continuous cropping. Generally, fallow had a negative influence on SOC accumulation, and continuous cropping a positive influence on surface SOM. Changes in SOC did not correlate with yields in the five-year comparison of this ongoing study.