• Authors:
    • Pringle, H. C.,III
    • Martin, S. W.
  • Source: Journal of Cotton Science
  • Volume: 7
  • Issue: 4
  • Year: 2003
  • Summary: Deep tillage at a 45 angle has been a recommended practice since the mid-1970s on most Mississippi Delta cotton soils. This practice disrupts hard pans and allows deeper wetting of the soil profile with winter rainfall. The newest deep tillage "subsoiler" designs (Paratill, low-till parabolic) have the shank extending through the soil at an angle, thereby reducing soil surface disturbance and allowing the subsoiler to run under the row in the direction of the row, without the shank passing directly through the drill. Both centre pivot and furrow irrigation of cotton has expanded since the early 1980s. With intermittent rainfall, irrigation is supplemental and represents a type of insurance against yield uncertainty during extended periods of water deficit. Field experiments were conducted at Stoneville, Mississippi, USA, during 1994-2001, to determine the long-term effects of sprinkler irrigation and in-row subsoil tillage on cotton yield and economic return of cotton cultivars DES119 (1994-95), SG125 (1996-99) and SG747 (2000-01) on silt loam soil from 1994 to 2001. In-row subsoil tillage was performed with a low-till parabolic subsoiler and irrigation was applied with an overhead lateral-move sprinkler irrigation system. Production costs were calculated for direct costs and total specified costs excluding land rent, general farm overheads and returns to management. Average net returns were calculated as the difference between income at the cotton loan rate of $1.15 per kg of lint and total specified costs. Returns were maximized with either the irrigated, non-subsoiled or the non-irrigated, subsoiled environments. Lower returns occurred in the irrigated, subsoiled environment due to the higher costs and lack of yield increase.
  • Authors:
    • Tope, K. L.
    • Gaddis, S. E.
    • Petersen, B. E.
    • Sterner, R. T.
    • Poss, D. J.
  • Source: Crop Protection
  • Volume: 22
  • Issue: 4
  • Year: 2003
  • Summary: During 2000-2001, small mammals, birds, and potential corn/soybean damage were studied at a low-tillage, non-irrigated agricultural research site in the Colorado Piedmont. A small mammal survey involved four trapping sessions and 18, 12-live-trap grids each. Within years, two grids each were placed at random, fixed locations in experimental corn, fallow, millet, pea, soyabean, sunflower, and wheat plots at the site; two off-plot grids each were set at random, fixed locations
  • Authors:
    • Sadras, V. O.
    • Andrade, F. H.
    • Calvino, P. A.
  • Source: Agronomy Journal
  • Volume: 95
  • Issue: 2
  • Year: 2003
  • Summary: The aim of this study was to investigate the influence of rainfall, soil depth, and crop management practices on the yield of dryland maize ( Zea mays L.) crops of the Argentine Pampas. We were concerned with the relevance of known physiological mechanisms in commercial crops and with developing a framework to quantify the impact of improved management practices on crop yield. Our approach included three steps. First, baseline functions were developed to quantify the relationship between yield and water availability (W) during the critical period for kernel set. Second, baseline functions were tested using an independent data set. Third, using the baseline functions as benchmarks, the effects on yield of soil depth and crop management practices were evaluated. Yield varied between 4.2 and 10 t ha -1, and most of this variation (>84%) was accounted for by W during the period bracketing flowering. Shallow soils presented lower yield than deep soils at a given rainfall. Using yield vs. W functions to account for the effect of variation in W, we quantified the impact of crop management on productivity. Technology-related yield increases were (a) 2.3 t ha -1 from the late 1980s to the mid-1990s, mainly explained by P fertilization, better and earlier weed control, and improved hybrids; (b) 0.9 t ha -1 from the mid-1990s to 1996-1998, related to no-till and higher plant density; and (c) 0.8 t ha -1 from 1996-1998 to 1999-2000, mainly explained by enhanced rates of N fertilization.
  • Authors:
    • Featherstone, A. M.
    • Langemeier, M. R.
    • Abdulkadri, A. O.
  • Source: Applied Economics
  • Volume: 35
  • Issue: 7
  • Year: 2003
  • Summary: The risk attitudes of dryland wheat, irrigated maize, and dairy producers in Kansas, USA, are examined using the nonlinear mean-standard deviation approach. Observations on farm characteristics, obtained from 1993-97, and the statewide market year average prices for wheat and maize from 1950-97, are used. Results of analyses indicated that dryland wheat and dairy producers are characterized by increasing absolute and increasing relative risk aversion while irrigated maize producers are characterized by constant absolute and increasing relative risk aversion. Both crop enterprises exhibited constant returns to scale technology while the dairy enterprise exhibited decreasing returns to scale. Gross farm income was significant and positively related to relative risk aversion.
  • Authors:
    • Lyon, D. J.
    • Blumenthal, J. M.
    • Stroup, W. W.
  • Source: Agronomy Journal
  • Volume: 95
  • Issue: 4
  • Year: 2003
  • Summary: Dryland corn ( Zea mays L.) production increased more than 10-fold from 1995 through 2000 in semiarid western Nebraska. Corn population and N fertilizer management recommendations are needed for this area. The objectives of this study were to determine the influence of plant population and N fertility on corn yields in semiarid western Nebraska. In 1999 and 2000, experiments were conducted each year at four sites. Factorial experimental treatments were five plant populations (17 300, 27 200, 37 100, 46 900, and 56 800 plants ha -1) and five N fertilizer rates (0, 34, 67, 101, and 134 kg N ha -1) arranged in a randomized complete block with five blocks. Corn yields ranged from less than 100 kg ha -1 to more than 5550 kg ha -1. Overall, grain yield increased 353 kg ha -1 with increasing population from 17 300 to 27 200 plants ha -1. Population increases above 27 200 plants ha -1 resulted in inconsistent yield results. Nitrogen fertilization and plant population effects did not interact. Yields were maximized by 202 kg N ha -1 in the form of soil NO 3-N and fertilizer N available before crop emergence. Growers are advised to use a plant population of 27 200 plants ha -1. Economic optimal fertilizer rate can be estimated using the equation: Nfert.=(10.6 * Pcorn- Pfert.)/(0.0526 * Pcorn)- Nsoil, where Pcorn and Pfert. are corn and fertilizer price ($ kg -1), respectively, Nsoil is soil test NO 3-N (kg ha -1) as determined by preplant soil test in a 0- to 120-cm soil sample, and Nfert. is economic optimal fertilizer rate (kg ha -1).
  • Authors:
    • Westfall, D. G.
    • Peterson, G. A.
    • Ortega, R. A.
  • Source: Agronomy Journal
  • Volume: 94
  • Issue: 4
  • Year: 2002
  • Summary: Crop residue is a valuable resource in Great Plains dryland agroecosystems because it aids in water conservation and soil erosion control. The objectives of our research were to (i) determine the effect of cropping intensity, climate gradient, and soil depth on levels and changes in soil C, soil N, and residue parameters after 8 yr of no-till management in dryland cropping systems and (ii) relate soil and residue parameters to soil C and N levels. Surface soil properties and residue parameters were compared in two cropping systems, wheat (Triticum aestivum L.)-fallow (WF) and wheat-corn (Zea mays L.) or sorghum [Sorghum bicolor (L.) Moench]-proso millet (Panicum miliaceum L.)-fallow (WCMF). The effects were examined on the summit position of a catenary sequence of soils across three environments representing an evapotranspiration (ET) gradient. Soils at the low- and medium-ET sites are classified as Argiustols, and the soil at the high-ET site is an Ustochrept. There was 3.0 Mg ha-1 of residue in the surface 10 cm of soil compared with 2.7 Mg ha-1 of residue on the soil surface averaged over ET gradient and cropping systems. About 90% of the residue in the soil was found within the 2.5-cm soil depth. The highest soil organic C (SOC) and soil organic N (SON) were observed in the surface 0- to 2.5-cm depth. There was a trend (P [<=] 0.16) for the more intense WCMF cropping system to have higher SOC and SON contents than the traditional WF system (C = 6.6 g kg-1 for WF compared with 7.5 g kg-1 for WCMF and N = 0.70 g kg-1 for WF compared with 0.74 g kg-1 for WCMF). From 1985 to 1993, gains in SOC (967 kg ha-1) and SON (74 kg ha-1) occurred in the surface 0- to 2.5- and 2.5- to 5-cm depths while losses were observed in the 5- to 10-cm depth (SOC = -694 kg ha-1; SON = -44 kg ha-1). Climate strongly modified these effects but did not reflect a clear ET gradient effect. The results suggest that higher levels of surface SOC and SON can be attained by increasing cropping intensity under no-till management.
  • Authors:
    • Schimel, D. S.
    • Peterson, G. A.
    • Mosier, A.
    • Parton, W.
    • Ojima, D.
    • Del Grosso, S.
  • Source: Environmental Pollution
  • Volume: 116
  • Issue: Supplement 1
  • Year: 2002
  • Summary: We present evidence to show that DAYCENT can reliably simulate soil C levels, crop yields, and annual trace gas fluxes for various soils. DAYCENT was applied to compare the net greenhouse gas fluxes for soils under different land uses. To calculate net greenhouse gas flux we accounted for changes in soil organic C, the C equivalents of N2O emissions and CH4 uptake, and the CO2 costs of N fertilizer production. Model results and data show that dryland soils that are depleted of C due to conventional till winter wheat/fallow cropping can store C upon conversion to no till, by reducing the fallow period, or by reversion to native vegetation. However, model results suggest that dryland agricultural soils will still be net sources of greenhouse gases although the magnitude of the source can be significantly reduced and yields can be increased upon conversion to no till annual cropping. (C) 2001 Elsevier Science Ltd. All rights reserved.
  • Authors:
    • Black, A. L.
    • Wienhold, B. J.
    • Halvorson, A. D.
  • Source: Soil Science Society of America Journal
  • Volume: 66
  • Issue: 3
  • Year: 2002
  • Summary: Soil C sequestration can improve soil quality and reduce agriculture's contribution to CO2 emissions. The long-term (12 yr) effects of tillage system and N fertilization on crop residue production and soil organic C (SOC) sequestration in two dryland cropping systems in North Dakota on a loam soil were evaluated. An annual cropping (AC) rotation [spring wheat (SW) (Triticum aestivum L.)-winter wheat (WW)-sunflower (SF) (Helianthus annuus L.)] and a spring wheat-fallow (SW-F) rotation were studied. Tillage systems included conventional-till (CT), minimum-till (MT), and no-till (NT). Nitrogen rates were 34, 67, and 101 kg N ha-1 for the AC system and 0, 22, and 45 kg N ha-1 for the SW-F system. Total crop residue returned to the soil was greater with AC than with SW-F. As tillage intensity decreased, SOC sequestration increased (NT > MT > CT) in the AC system but not in the SW-F system. Fertilizer N increased crop residue quantity returned to the soil, but generally did not increase SOC sequestration in either cropping system. Soil bulk density decreased with increasing tillage intensity in both systems. The results suggest that continued use of a crop-fallow farming system, even with NT, may result in loss of SOC. With NT, an estimated 233 kg C ha-1 was sequestered each year in AC system, compared with 25 kg C ha-1 with MT and a loss of 141 kg C ha-1 with CT. Conversion from crop-fallow to more intensive cropping systems utilizing NT will be needed to have a positive impact on reducing CO2 loss from croplands in the northern Great Plains.
  • Authors:
    • Chanasyk, D. S.
    • Mathison, M. N.
    • Naeth, M. A.
  • Source: Canadian Journal of Soil Science
  • Volume: 82
  • Issue: 2
  • Year: 2002
  • Summary: The longevity of deep ripping effects on Solonetzic soils was investigated at 11 field sites in east-central Alberta after a period of 15 to 20 yr. Select soil properties and crop yield of deep-ripped and non-ripped control plots were analyzed. Dryland yield data of wheat, barley, oats and canola were assessed for 10 of the 11 sites over a 16-yr time period. Select soil properties were analyzed once in 1998 with penetration resistance (PR) evaluated again in 1999. A significant difference in penetration resistance was found between the deep ripped versus control treatments ( P≤0.05). There were no significant treatment differences for soil texture, bulk density (Db), pH, electrical conductivity (EC) or sodium adsorption ratio (SAR). A significant yield difference between the deep ripping and control treatments (for all crop species) was found for 6 of 10 sites ( P≤0.10), with all sites having an increase in mean yield for the majority of years evaluated. Generally, sites in the drier ecoregions had smaller yield increases than those in the wetter ones. Hence some beneficial effects from deep ripping remain for a long time period.
  • Authors:
    • Norsworthy, J. K.
    • Oliver, L. R.
  • Source: Weed Technology
  • Volume: 16
  • Issue: 1
  • Year: 2002
  • Summary: A field experiment was conducted in 1998 and 1999 at Keiser, AR, to evaluate glyphosate timing and soybean population in reducing hemp sesbania and pitted morningglory interference with dryland and irrigated glyphosate-resistant soybean under a narrow row, no-till production system. Soybean densities following emergence were 247,000, 475,000, and 729,000 plants/ha. Glyphosate was applied at 0.56 kg ai/ha at the V2; V4; V2 and V4; and V2, V4, and R2 stages of soybean. In dry portions of the growing season, glyphosate increased moisture availability for dryland soybean because of control of hemp sesbania and pitted morningglory. As soybean population increased from 247,000 to 729,000 plants/ha, pitted morningglory and hemp sesbania control increased from 60 to 91%, respectively, for the V2 glyphosate application. Control of both species at 14 wk after emergence was at least 90% following the V4 alone treatment and sequential applications, with no differences in control among soybean populations. Untreated, irrigated hemp sesbania produced up to 32 million seeds/ha in 1999. Irrigation did not influence pitted morningglory seed production either year, and untreated pitted morningglory produced a maximum of 1 million seeds/ha in 1998 at 247,000 soybean plants/ha. Three sequential applications of glyphosate reduced pitted morningglory seed production to 9,000 seeds/ha and eliminated hemp sesbania seed production. Soybean yielded 1,297 kg/ha greater under irrigated than dryland conditions, whereas increasing soybean density from 247,000 to 729,000 plants/ha resulted in 416 kg/ha improvement in seed yield. At the densities of pitted morningglory and hemp sesbania present in this study, seed yield of drill-seeded soybean can be maximized following a V4 alone treatment or sequential glyphosate applications.