• Authors:
    • Bertholdsson, N. O.
  • Source: Sveriges Utsädesförenings Tidskrift
  • Volume: 110
  • Issue: 4
  • Year: 2000
  • Summary: The use of hydroponic techniques to measure the response to stress by cereals is discussed with reference to studies on drought, low N inputs and crop weed competition with barley, wheat, oats, triticale and rape.
  • 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:
    • Bonfil, D. J.
    • Mufradi, I.
    • Klitman, S.
    • Asido, S.
  • Source: Agronomy Journal
  • Volume: 91
  • Issue: 3
  • Year: 1999
  • Summary: Yields of dryland crops in semiarid and arid zones are limited by precipitation, and so water content and placement are very important at each stage of development. Spring wheat (Triticum aestivum L.) grown in a wheat-fallow (WF) rotation system (1 crop in 2 years) generally occupies the greatest area in the Israeli dryland region, more than the continuous wheat (CW) rotation system. To identify the optimal crop management for dryland farming where annual precipitation is <250 mm, we compared the effects of no-tillage (NT) and conventional tillage (CT) on wheat growth and water use efficiency (WUE) in both the WF and the CW rotation systems, and on water storage in fallow (F) plots. During the 4-year period from 1994 to 1997, experiments Here conducted at Gilat Experimental Station, located in the south of Israel (average annual precipitation, 237 mm; soil type, sandy loam loess-Calcic Xerosol). In the fallow year, F-NT increased water infiltration and soil water content in comparison with F-CT. However, most of the water evaporated during the summer, especially from the upper soil layer (0-120 cm). During growth, uncultivated soil with straw mulch increased water content in the upper soil layer and also encouraged the development of a longer root system capable of utilizing deeper water. During 1995, similar grain yields were obtained with both NT and CT treatments, an average of 3.45 t ha(-1) for WF and 2.9 t ha(-1) for CW. In the last 2 drought gears (1996 and 1997), NT management increased yields by 62 to 67% for WF and by 18 to 75% for CW, relative to CT management. During the 2 years when water deficiency occurred during the grain-filling stage (1994 and 1997), NT management increased grain weight by 20% and test weight by 5 to 7%, in addition to the 70 to 200% increase in the total grain yield, relative to CT management. Crop yield and WUE can be increased in arid zones with annual precipitation of < 200 mm, through use of a wheat-fallow rotation system that is managed by NT.
  • 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:
    • Peters, M.
    • House, R.
    • Lewandrowski, J.
    • McDowell, H.
  • Source: Agricultural Outlook
  • Year: 1999
  • Authors:
    • Peinemann, N.
    • Buschiazzo, D. E.
    • Dí­az-Zorita, M.
  • Source: Agronomy Journal
  • Volume: 91
  • Issue: 2
  • Year: 1999
  • Summary: Crop productivity under dryland conditions is largely limited by soil water availability. Soil organic matter (SOM) contents have been found to be a reliable index of crop productivity in semiarid regions because it positively affects soil water-holding capacity. Our objectives were to explain differences in wheat (Triticum aestivum L.) yields in response to SOM levels and related properties and to quantify the contribution of a unit increment of SOM content to soil productivity during 1991,1992, and 1994 on a total of 134 production fields in the semiarid Argentine Pampas. Wheat yields were related to both soil water retention and total organic C (TOC) contents in the top layers (0-20 cm) in years with low moisture availability (1992 [r = 0.51, P < 0.01] and 1994 [r = 0.59, P < 0.01]), and were related to both total N and available P contents in a year without water deficit stress (1991 [r = 0.58, P < 0.01]). Wheat yields over all years were linearly related to TOC (r = 0.68, P < 0.01) when these contents were <17.5 g kg-. Dependence of wheat yields on soil water retention and on TOC contents under water deficit was related to the positive effect of these soil components on plant-available water. In the absence of water deficit (1991), nutrient availability was the limiting factor. Losses of 1 Mg SOM ha- were associated with a decrease in wheat yield of approximately 40 kg ha-. These results demonstrate the importance of using cultural practices that minimize losses of soil organic C in the semiarid Argentine Pampas.
  • Authors:
    • Gerard, C. J.
    • Choudhary, M.
    • Bordovsky, D. G.
  • Source: Soil Science
  • Volume: 164
  • Issue: 5
  • Year: 1999
  • Summary: In the Texas Rolling Plains, low rainfall results in low crop residue production and low soil organic matter. Low soil organic matter, coupled with low levels of silt and clay, give soils poor structure. An 11-year (1979-1989) field experiment was conducted to determine the effects of tillage (reduced vs. conventional), cropping, and residue management (with residue vs. without residue) on soil properties under dryland and irrigated systems. Cropping included a grain sorghum (Sorghum bicolor (L.) Moench.) and wheat (Triticum aestivum L.) monoculture and doublecropped, reduced tillage wheat-grain sorghum under irrigation only. Surface soil organic matter in plots with irrigated grain sorghum and wheat increased with time. Reduced-tillage irrigated grain sorghum and wheat, and especially reduced-tillage, double-cropped grain sorghum and wheat plots, had significantly higher organic matter content than conventional-tillage grain sorghum and wheat plots. Bulk density under the reduced tillage system was higher than with the conventional tillage system. However, saturated hydraulic conductivity (Ks) of the surface soil was increased by reduced tillage practices compared with conventional tillage. This may have been attributable to higher amounts of microaggregates and larger macropores under the reduced tillage system. Residue removal decreased the Ks of surface soil, especially in reduced-tillage grain sorghum and wheat plots. Microaggregation values were higher with residue retained than with residue removed (27.1 vs. 23.5 g kg-1 in dryland and 32.3 vs. 27.1 g kg-1 in irrigation). Results indicate that residue removal from Rolling Plains soils should be discouraged. Because of higher bulk density, use of a reduced tillage system may result in the need for occasional deep chiseling to reduce the effects of compaction.