19802015
  • Authors:
    • Liu, R.
    • Phillips, D. L.
    • Lee, J. J.
  • Source: Water, Air, & Soil Pollution
  • Volume: 70
  • Issue: 1
  • Year: 1993
  • Summary: The EPIC model was used to simulate soil erosion and soil C content at 100 randomly selected sites in the US corn belt. Four management scenarios were run for 100 years: (1) current mix of tillage practices maintained; (2) current trend of conversion to mulch-till and no-till maintained; (3) trend to increased no-till; (4) trend to increased no-till with addition of winter wheat cover crop. As expected, the three alternative scenarios resulted in substantial decreases in soil erosion compared to the current mix of tillage practices. C content of the top 15 cm of soil increased for the alternative scenarios, while remaining approximately constant for the current tillage mix. However, total soil C to a depth of 1 m from the original surface decreased for all scenarios except for the no-till plus winter wheat cover crop scenario. Extrapolated to the entire US corn belt, the model results suggest that, under the current mix of tillage practices, soils used for corn and/or soybean production will lose 3.2 x 10^6 tons of C per year for the next 100 years. About 21% of this loss will be C transported off-site by soil erosion; an unknown fraction of this C will be released to the atmosphere. For the base trend and increased no-till trend, these soils are projected to lose 2.2 x 10^6 t-C yr-1 and 1.0 x 10^6 t-C yr-1, respectively. Under the increased no-till plus cover crop scenario, these soils become a small sink of 0.1 x 10^6 t-C yr-1. Thus, a shift from current tillage practices to widespread use of no-till plus winter cover could conserve and sequester a total of 3.3 x 10^6 t-C yr-1 in the soil for the next 100 years.
  • Authors:
    • Luna, J. M.
    • Laub, C. A.
    • Pimentel, D.
  • Source: Environmental Entomology
  • Volume: 21
  • Issue: 1
  • Year: 1992
  • Summary: Rye, Secale cereale L., used as a winter cover crop was killed by the herbicide paraquat or by mowing with a rotary mower. In subsequent no-ill corn, Glyptapanteles militaris (Walsh) (Hymenoptera: Braconidae) and Periscepsia laevigata (Wulp) (Diptera: Tachinidae) were the most abundant of twelve species of parasitoids that emerged from field-collected larvae of the armyworm, Pseudaletia unipuncta (Haworth). No effects of cover crop suppression practices were detected for parasitism rates for any individual species or for total armyworm parasitism. Seasonal parasitism rates ranged from 32 to 45%. HIgher numbers of Pterostichus spp. and Scarites spp. (Coleoptera: Carabidae), and wolf spiders (Araneae: Lycosidae) occurred early in the corn season in the mowed cover crop treatment compared with the herbicide killed cover crop treatment. Subsequent reduction oflarval densities of armyworm in mowed plots following higher predator densities suggests the role of these generalist predators in biological control of armyworm.
  • Authors:
    • Anderson, G. W.
    • Shaw, J. E.
    • Swanton, C. J.
    • Eadie, A. G.
  • Source: Weed Technology
  • Volume: 6
  • Issue: 3
  • Year: 1992
  • Summary: The acceptance of no-till crop production systems has been limited due to expected problems with weed management. Field experiments were established at two locations in Ontario in 1988 and one location in 1989. Band or broadcast applications of preemergence (PRE) combinations of high or low label rates of atrazine with or without metolachlor or inter-row cultivation, were evaluated for their effectiveness in controlling annual weeds in no-till corn. At each location, different herbicide and cultivation combinations were required to achieve adequate weed control. Corn grain yield was equivalent regardless of whether herbicides were applied as a band or broadcast treatment at all three sites. At two of the three sites, one cultivation combined with herbicides applied as a band was adequate to maintain weed control and corn grain yields. Selective application of herbicides in bands represented an approximate 60% reduction in total herbicide applied into the environment. The integration of a shallow post-plant inter-row cultivation combined with the soil conservation attributes of no-till, would enhance the sustainability of a modified no-till corn production system.
  • Authors:
    • Cole, C.
    • Westfall, D.
    • Peterson, G.
    • Wood, C.
    • Willis, W.
  • Source: Agronomy Journal
  • Volume: 83
  • Issue: 3
  • Year: 1991
  • Summary: Soil-crop management affects the soil-N balance and, thus, has a direct bearing on soil productivity. This study determined the effects of cropping intensity (crops/time) under no-till and grassland establishment on aboveground biomass production and the system-N balance after 4 yr (1985-1989). The effects were examined across toposequences in the West Central Great Plains that had been tilled and frequently fallowed for > 50 yr. Production systems included wheat (Triticum aestivum L.)-fallow (WF), wheat-corn (Zea mays L.) or sorghum (Sorghum vulgare L.)-millet (Panicum miliaceum L.)-fallow (WCMF), and perennial grass (CG). Intense agronomic systems (WCMF) had greater aboveground production, greater N uptake, and greater percent plant residue retention than WF. Continuous grass systems had less aboveground production and N uptake but greater percent plant residue retention than agronomic systems. Soil-profile NO3-N was lower under WCMF systems than WF systems, but organic N showed the opposite trend implying that more intense systems are at less risk for NO3-N leaching, and have greater potential for replenishment of soil-organic N via enhanced immobilization. Aboveground biomass production and plant residue production increased downslope, but slope position had little effect on plant-N uptake, plant residue retention, or soil-N dynamics. Imposing no-till and perennial grassland systems created a N-balance disequilibrium, but more time will be required to ascertain the trajectory of N loss or gain due to establishment of no-till or grassland management on these soils.
  • Authors:
    • Kitchen, N. R.
  • Source: Dissertation Abstracts International. B, Sciences and Engineering
  • Volume: 51
  • Issue: 8
  • Year: 1990
  • Summary: A long-term study was conducted at 2 sites in E. Colorado to study the influence of N fertilizer rate and source/placement/timing (NSP), and crop rotation wheat/fallow (WF), and wheat, maize or sorghum/fallow (MSF) on no-tillage dryland cropping systems. Grain yield and vegetative biomass increased linearly with fertilizer N rate up to 84 kg/ha for wheat and 101 kg/ha for maize indicating that current N recommendations at Colorado State University may be insufficient for meeting N needs of no-tillage crops. N fertilizer recovery efficiency (NFRE) decreased with N fertilizer rate. Production increased more with N fertilizer additions in the MSF than in the WF rotation system. If differences occurred with NSP treatments, banding gave greater production and NFRE than broadcast application. In 1989 at one location, wheat production from the MSF rotation was greater than from the WF rotation. The av. annual grain and vegetative production from MSF was approx. double that produced in the WF cropping system. Water conservation with no-tillage systems allowed more intense cropping than a WF rotation. N loss from the MSF rotation was significant, increased with N rate and was attributed to N loss in both inorganic- and organic-N pools. Nitrate leaching in the no-tillage MSF rotation was unlikely since NO 3 decreased with soil depth.
  • Authors:
    • Evanylo, G. K.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 21
  • Issue: 1-2
  • Year: 1990
  • Summary: Crop response to fertilizer nitrogen (N) is dependent upon tillage management. This study was conducted to determine how tillage rotation influences non‐irrigated crop growth, N uptake and yield. The effects of tillage rotation, N rate and N timing schedule on early season dry matter production and N uptake, ear leaf N concentration at silking, and yield of corn [Zea mays (L.) Pioneer 3378] were investigated at Painter, VA, on an Altavista loam (fine‐loamy, mixed, thermic Aquic Hapludult). In 1986, maximum yields achieved in the 6‐year continuous no till (NT) [5.82 Mg/ha] and first year no till (AT) [5.64 Mg/ha] were significantly greater than that of the 6‐year continuous conventional till (CT) [3.67 Mg/ha], but no yield differences were obtained in the drier 1987 season. A higher rate of N fertilizer was required to obtain maximum yield in the first year no till (168 kg N/ha) than in the NT (112 kg N/ha) during 1986. Early 1986 N uptake and growth response with and without N at planting increased in the order CT < AT = NT and AT < CT < NT, respectively, indicating greatest immobilization of soil N occurred in the newly established no till soil. Lack of differences in critical ear leaf N values developed for NT and CT in each year imply that plant norms developed for one tillage system may accurately assess N status of corn grown under different tillage practices.
  • Authors:
    • Raun, W. R.
    • Sander, D. H.
    • Olson, R. A.
  • Source: Agronomy Journal
  • Volume: 81
  • Issue: 2
  • Year: 1989
  • Authors:
    • Deibert, E. J.
  • Source: Agronomy Journal
  • Volume: 81
  • Issue: 4
  • Year: 1989
  • Summary: Information on response of soybean [Glycine max (L.) Merr.] cultivars to reduced tillage systems in northern dryland areas is limited. A 4-yr field study (1984 to 1987) was conducted to evaluate the effect of tillage system, weed control method, and cultivar maturity on soybean seed yield variables. An early and a late-maturing soybean cultivar were grown on a Fargo clay (fine, montmorillonitic frigid Vertic Haplaquoll) on established tillage plots. Tillage systems included conventional (moldboard plow) and three reduced tillage systems (sweep, intertill, and no-till) with herbicides or herbicides plus cultivation for weed control. Climatic conditions resulted in differences among years in seed yield, seed weight, seed moisture, seed oil concentration, and seed oil yield. These seed variables were not significantly influenced by tillage system, weed control method, or cultivar maturity when grown in rotation with barley (Hordeum vulgare L.), but showed significant interactions. Cultivation for weed control depressed seed yield and weight of only the early cultivar. Early plant water stress (June and July) lowered yield of the early cultivar more than the late cultivar. Early cultivar no-till yields (1240 kg ha−1) were greater than tilled system yields (average 1070 kg ha−1). while late cultivar yields were similar among systems (average 1420 kg ha−1). An early maturing cultivar performed similarly to a late-maturing cultivar irrespective of tillage system unless early plant water stress was encountered. Fall application of granular herbicide provided good weed control, but cultivation for weed control was not beneficial for the yields parameters measured.
  • Authors:
    • Dalal, R. C.
  • Source: Soil Science Society of America Journal
  • Volume: 53
  • Issue: 5
  • Year: 1989
  • Summary: There is a paucity of information on the long-term effects of crop residue management under no-tillage culture on properties of clay soils in tropical and subtropical regions. The objective of this study was to compare the effects of 13 yr of conventional tillage vs. no tillage, crop residue retained vs. burned, and no fertilizer N vs. application of 23 and 69 kg N ha-1 yr-1 on organic C content, total N, mineralizable N, pH, electrical conductivity, chloride, exchangeable sodium percentage (ESP), and aggregation index (undispersed fraction <20 fim silt + clay) in a fine-textured Vertisol (650 g clay kg-1 soil). Highest concentrations of organic C and total N were found in the surface soil (0-0.1 m) with a combination of no-tillage, crop residue retained, and fertilizer N. Mineralizable N followed similar trends. Soil pH to 0.3-m depth and electrical conductivity to 1.2-m depth were significantly lower under no-tillage than under conventional tillage. Aggregation index of the surface soil (0-0.1 m), was higher under no-tillage. The ESP was lowest in the surface soil (0- 0.04 m) under no-tillage with crop residues retained; the soil profile (0-1.2 m) under this treatment also contained far less NaCl-equivalent salts (0.8 Mg ha-1) than under conventional tillage with crop residue burned (7.3 Mg ha-1). Available water and nitrate were lower in the surface soil but greater at depths (0.6-1.2 m) under no-tillage than in tilled soil. Thus tillage and crop residue management can substantially affect soil organic matter and microbial activity in the surface layers, and water relations and salt movement to at least 1.2-m depth, even in a fine-textured Vertisol.
  • Authors:
    • Harman, W.
    • Jones, O.
    • Smith, S.
  • Source: Optimum erosion control at least cost. Proceedings of the National Symposium on Conservation Systems, December 14-15, 1987, Chicago, IL, USA
  • Year: 1987
  • Summary: Graded-terraced field-size watersheds have been cropped in a dryland wheat - fallow - sorghum - fallow (2 crops in 3 years) sequence with no-till and conventional (stubble-mulch) tillage systems at Bushland, Texas since 1982. No-till had little effect on wheat yields but increased sorghum yields 14% due to reduced evaporation, as a result of surface residue. No-till reduced erosion by 66%; however, soil loss with conventional tillage was also low due to terracing and contouring. NPK loss was very low. Economically, no-till performed very well, due mainly to reduced equipment inventories and lower operating costs. No-till gave increased storm runoff due to soil crusting, and there were problems with grass weeds. A system consisting of successive no-tillage and stubble-mulch tillage is proposed.