• Authors:
    • Norman, J. M.
    • Morgan, C. L. S.
    • Lowery, B.
  • Source: Soil Science Society of America Journal
  • Volume: 67
  • Issue: 2
  • Year: 2003
  • Summary: The variability of crop yield in dryland production is primarily affected by the spatial distribution of plant-available water even for seemingly uniform fields. The most productive midwestern soils, which are loess caps over glacial till or outwash, can have a wide range of water-holding capacities in individual fields because of landscape processes and management. An inverse yield model was created as a robust method to quantify the spatial and temporal role of plant-available water on large agricultural fields to improve management options in precision agriculture. Plant-available water maps for a field were estimated from yield maps using inverse water-budget modeling based on measurements of solar radiation, temperature, precipitation, and vapor pressure deficit. The model presented in this paper was applied to 5 yr of corn ( Zea mays L.) yield-monitor data from a field in Waunakee, WI, having three soil mapping units, Plano silt loam (fine-silty, mixed, mesic Typic Argiudoll), St. Charles silt loam (fine-silty, mixed, mesic Typic Hapludalf), and Griswold loam (Fine-loamy, mixed, mesic Typic Argiudoll). The comparison of measured and inverse-modeled plant-available water suggests that the simple inverse yield model produces reasonable results in drier years with uncertainties of about 28 mm of plant-available water. The model helped to quantify the role of plant-available water in determining crop yield. Because of limited input requirements, the model shows promise as a practical tool for using precision farming to improve management decisions, and as a tool to obtain input for landscape-based models.
  • Authors:
    • Mir, Z.
    • Acharya, S. N.
    • Moyer, J. R.
    • Doram, R. C.
  • Source: Canadian Journal of Plant Science
  • Volume: 83
  • Issue: 1
  • Year: 2003
  • Summary: Fenugreek (Trigonella foenum-graecom L.) is an annual legume that has potential as a forage crop on the Canadian Prairies. Experiments were established to determine the tolerance of fenugreek to several herbicides and their efficacy on various weeds. Potentially, fenugreek could be grown in conservation tillage systems in rotation with other annual crops. Therefore, additional multi-factor experiments were conducted to determine the effect of herbicides, seeding method, and 11 previous crops on fenugreek yield. Without herbicide application, weeds contributed 37 to 86% to total dry matter production. When imazamox/imazethapyr, or-combinations of imazamoz/imazethapyr or imazethapyr with ethalfluralin was applied, weed contents were about 5% of the total dry matter and the herbicides did not reduce fenugreek yield compared to the hand-weeded check. Total forage samples with a low weed content had lower fibre content and higher protein and digestible dry matter content than forages with a high weed content. When imazamox/imazethapyr was used for weed control, fenugreek yields and weed biomass were similar after direct seeding and after cultivation plus seeding. In addition, the effect of previous crop and the previous crop by seeding method interaction was not significant for fenugreek yield and weed biomass. Therefore, irrigated fenugreek can be successfully grown in conservation tillage systems in rotation with several crops provided an effective herbicide is used for weed control.
  • Authors:
    • Counce, P. C.
    • Gordon, E. C.
    • Keisling, T. C.
    • Oliver, L. R.
    • Manning, P. M.
    • Popp, M. P.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 34
  • Issue: 19/20
  • Year: 2003
  • Summary: Clay soils are difficult to manage to obtain a soyabean [ Glycine max (L.) Merr.] stand, especially when dry. A novel production system, recently observed on several farms in Arkansas, consists of bedding the dry clayey soil with disk-bedders, broadcasting the soyabean seed over the surface, re-bedding the seedbed to cover the seed, rolling the beds to flatten the tops and finally furrow irrigating immediately thereafter. Typically this planting system provides a stand of soyabean within 4 to 6 days after irrigation and is designated as "hipped" after the common reference of a disk-bedder as a hipper. Studies were conducted on Sharkey soil at Keiser, AR from 1998 to 2000 for comparing this "hipped" system to more widely used planting methods. On dry clayey soils, a randomized complete block design with three replications was used to compare full-season soyabean under a conventional 96-cm row system, drilled-planting into a stale seedbed, and the "hipped" system. A similar study for double-cropped wheat-soybean involved straw management (burn or leave) coupled with no-till drill, tilled drill, and "hipped" systems. Other small studies on the "hipped" system were conducted to investigate the sensitivity to planting depth, soyabean plant population, and suitability for obtaining a stand on other crops such as cotton [ Gossypium hirsutum (L.)] and grain sorghum [ Sorghum bicolor (L.) Moench]. The "hipped" system worked well for obtaining stands of soyabean, cotton, and grain sorghum. In essence the "hipped" system (1) provides insurance against poor planting conditions; (2) allows for a reduction in the uncertainty of planting and stand establishment time required; (3) can be used to achieve high plant populations; (4) requires a relatively higher seeding rate in double-crop than full-season systems; (5) shows promise for situations when wheat stubble burning becomes curtailed especially if planting can occur early to lead to improved canopy coverage and (6) leads to yield reductions in fields where depth of seed placement cannot be controlled easily.
  • 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:
    • Soon, Y. K.
    • O'Donovan, J. T.
    • Drabble, J. C.
    • Darwent, A. L.
    • Milis, P. F.
    • Clayton, G. W.
    • Rice, W. A.
  • Source: Canadian Journal of Plant Science
  • Volume: 83
  • Issue: 1
  • Year: 2003
  • Summary: A study was conducted on the Agriculture and Agri-Food Canada Research Farm, Beaverlodge, Alberta, to compare nine cropping systems in relation to productivity and wild oat (Avena fatua L.) control. The nine cropping systems consisted of three crop rotations and three levels of banded N fertilizer. Each cropping system had its own regime of tillage and weed control. One of the rotations consisted of mechanical fallow, along with canola (Brassica rapa L.), barley (Hordeum vulgare L.) and wheat (Trificum aestivum L.), while the other two rotations consisted of the same annual crops, but with either flax (Linum usitatissimum L.) or red clover (Trifolium pratense L.) plowdown with partial fallow substituted for mechanical fallow. The three rates of banded N fertilizer were 0, 75 and 150% of recommended, based on soil tests and provincial recommendations. From 1991 to 1994, cropping systems with mechanical fallow and fall tillage after annual crops produced 24% higher total seed yields than cropping systems with no fall tillage after annual crops and either continuous annual crops or red clover plowdown. Increasing the rate of banded N fertilizer from 0 to 75% of recommended increased total crop seed yields but a further increase from 75 to 150% had no significant effect. Although cropping systems with mechanical fallow had an advantage over other cropping systems, the effect of crop sequencing and yearly weather conditions on total crop seed yields was greater than the effect of cropping systems. Wild oat populations varied greatly with year, but the ease of management was greater in cropping systems with the mechanical fallow than in other cropping systems. Wild oat density increased when diclofop or difenzoquat performed inadequately or when poor red clover establishment allowed populations to increase. Reductions in wild oat populations appeared to be largely due to the consistent effectiveness of sethoxydim.
  • Authors:
    • Bacon, R. K.
    • Gibbons, J.
    • Moldenhauer, K. A. K.
    • Windham, T. E.
    • Anders, M. M.
    • McNew, R. W.
    • Grantham, J.
    • Holzhauer, J.
  • Source: Research Series - Arkansas Agricultural Experiment Station
  • Issue: 504
  • Year: 2003
  • Summary: Rotation, tillage, and variety main effects on grain yield were all significant in 2002. Rice grain yield, over all treatment combinations, averaged 159 bu/acre, which was 22 bu/acre more than in 2001. Grain yields for the two 3-phase rotations were 180 bu/acre for the rice-corn-soybeans rotation and 177 bu/acre for the rice-corn (wheat)-soybean rotation. These yields were slightly better than the 174 bu/acre yield from the rice-soybean rotation and 165 bu/acre from the rice-corn rotation. Grain yield declined 13 bu/acre in the continuous rice treatments when compared to 2001 yields and 27 bu/acre from the 2000 yields. Plant growth was poor in all the continuous rice plots with leaf nitrogen (N) levels lower than in other rotations. Conventional tillage treatment combinations yielded 17 bu/acre more than the no-till combinations, but this difference varied between rotations. For the continuous rice rotation, the conventional-till yielded 37 bu/acre more than the no-till whereas the same difference was 14 bu/acre in the rice-soybean rotation. There was a non-significant 7 bu/acre increase in rice yield over all treatment combinations with the 'enhanced' fertility treatments when compared to the 'standard' fertility treatments. Wells yielded a non-significant 7 bu/acre better than LaGrue across all treatments. Rice grain yield from the two rotations where rice was planted after wheat averaged 144 bu/acre-significantly higher than any previous year. There was an overall yield loss of 12 bu/acre from no-till when compared to conventional tillage, a 4 bu/acre gain from increased fertility, and a 16 bu/acre gain from the variety XL-7 when compared to RU1093. Of all the treatment combinations in this comparison the no-till rice (wheat)-soybean (wheat) rotation using enhanced fertility and the variety XL-7 was the most productive with a rice yield of 181 bu/acre and a wheat yield of 77 bu/acre. Overall, irrigation-water use declined from the previous year with an average of 26 inches needed for the conventional till treatments and 24 inches for the no-till treatments. Continuous rice needed only 17 inches of irrigation while all other rotations required between 28 and 32 inches.
  • Authors:
    • Lokaj, G. R. W.
    • Majek, B. A.
    • Belding, R. D.
    • Hammerstedt, J.
    • Ayeni, A. O.
  • Source: HortTechnology
  • Volume: 13
  • Issue: 2
  • Year: 2003
  • Summary: Peach ( Prunus persica cv. Candor) trees were established and grown from 1996 to 1999 at the Rutgers Agricultural Research and Extension Center, Bridgeton, New Jersey, USA, to compare their performance under four methods of orchard floor preparation: flat no-till, flat cultivated, mound unmulched, and mound mulched orchard floors. The experimental site was flat and the soil was a well-drained Aura gravelly sandy loam (61% sand, 31% silt and 8% clay) with a pH of 6.5, cation exchange capacity of 5.7, and organic matter content of 2.0%. Soil moisture holding capacity and gas exchange capacity determine the efficacy of mounding in peach orchards. Under these conditions, the method of orchard floor preparation had no effect on peach tree trunk cross-sectional area, fruit number per tree, fruit size and yield. Thus, without irrigation, there was no advantage to the early performance of peach trees associated with orchard floor mounding on Aura gravelly sandy loam when situated on a flat terrain.
  • Authors:
    • Marland, G.
    • West, T. O.
  • Source: Environmental Pollution
  • Volume: 116
  • Issue: 3
  • Year: 2002
  • Summary: Agricultural ecosystems have the potential to sequester carbon in soils by altering agricultural management practices (i.e. tillage practice, cover crops, and crop rotation) and using agricultural inputs (i.e. fertilizers and irrigation) more efficiently. Changes in agricultural practices can also cause changes in CO2 emissions associated with these practices. In order to account for changes in net CO2 emissions, and thereby estimate the overall impact of carbon sequestration initiatives on the atmospheric CO2 pool, we use a methodology for full carbon cycle analysis of agricultural ecosystems. The analysis accounts for changes in carbon sequestration and emission rates with time, and results in values representing a change in net carbon flux. Comparison among values of net carbon flux for two or more systems, using the initial system as a baseline value, results in a value for relative net carbon flux. Some results from using the full carbon cycle methodology, along with US national average values for agricultural inputs, indicate that the net carbon flux averaged over all crops following conversion from conventional tillage to no-till is -189 kg C ha(-1) year(-1) (a negative value indicates net transfer of carbon from the atmosphere). The relative net carbon flux, using conventional tillage as the baseline, is -371 kg C ha(-1) year(-1), which represents the total atmospheric CO2 reduction caused by changing tillage practices. The methodology used here illustrates the importance of (1) delineating system boundaries, (2) including CO2 emissions associated with sequestration initiatives in the accounting process, and (3) comparing the new management practices associated with sequestration initiatives with the original management practices to obtain the true impact of sequestration projects on the atmospheric CO2 pool.
  • Authors:
    • Post, W. M.
    • West, T. O.
  • Source: Soil Science Society of America Journal
  • Volume: 66
  • Issue: 6
  • Year: 2002
  • Summary: Changes agricultural management can potentially increase the accumulation rate of soil organic C (SOC), thereby sequestering CO2 from the atmosphere. This study was conducted to quantify potential soil C sequestration rates for different crops in response to decreasing tillage intensity or enhancing rotation complexity, and to estimate the duration of time over which sequestration may occur. Analyses of C sequestration rates were completed using a global database of 67 long-term agricultural experiments, consisting of 276 paired treatments. Results indicate, on average, that a change from conventional tillage (CT) to no-till (NT) can sequester 57 +/- 14 g C m(-2) yr(-1), excluding wheat (Triticum aestivum L.)-fallow systems which may not result in SOC accumulation with a change from CT to NT. Enhancing rotation complexity can sequester an average 20 +/- 12 g C m(-2) yr(-1), excluding a change from continuous corn (Zea mays L.) to corn-soybean (Glycine mar L.) which may not result in a significant accumulation of SOC. Carbon sequestration rates, with a change from CT to NT, can be expected to peak in 5 to 10 yr with SOC reaching a new equilibrium in 15 to 20 yr. Following initiation of an enhancement in rotation complexity, SOC may reach a new equilibrium in approximately 40 to 60 yr. Carbon sequestration rates, estimated for a number of individual crops and crop rotations in this study, can be used in spatial modeling analyses to more accurately predict regional, national, and global C sequestration potentials.