• Authors:
    • Guzman, J.
    • Al-Kaisi, M.
  • Source: Integrated Crop Management
  • Volume: IC-498
  • Issue: 7
  • Year: 2007
  • Authors:
    • Mielniczuk, J.
    • Vieira, F.
    • Dieckow, J.
    • Bayer, C.
    • Zanatta, J.
  • Source: Soil & Tillage Research
  • Volume: 94
  • Issue: 2
  • Year: 2007
  • Summary: Conservation management systems can improve soil organic matter stocks and contribute to atmospheric C mitigation. This study was carried out in a 18-year long-term experiment conducted on a subtropical Acrisol in Southern Brazil to assess the potential of tillage systems [conventional tillage (CT) and no-till (NT)], cropping systems [oat/maize (O/M), vetch/maize (V/M) and oat+vetch/maize+cowpea (OV/MC)] and N fertilization [0 kg N ha -1 year -1 (0 N) and 180 kg N ha -1 year -1 (180 N)] for mitigating atmospheric C. For that, the soil organic carbon (SOC) accumulation and the C equivalent (CE) costs of the investigated management systems were taken into account in comparison to the CT O/M 0 N used as reference system. No-till is known to produce a less oxidative environment than CT and resulted in SOC accumulation, mainly in the 0-5 cm soil layer, at rates related to the addition of crop residues, which were increased by legume cover crops and N fertilization. Considering the reference treatment, the SOC accumulation rates in the 0-20 cm layer varied from 0.09 to 0.34 Mg ha -1 year -1 in CT and from 0.19 to 0.65 Mg ha -1 year-1 in NT. However, the SOC accumulation rates peaked during the first years (5th to 9th) after the adoption of the management practices and decreased exponentially over time, indicating that conservation soil management was a short-term strategy for atmospheric C mitigation. On the other hand, when the CE costs of tillage operations were taken into account, the benefits of NT to C mitigation compared to CT were enhanced. When CE costs related to N-based fertilizers were taken into account, the increases in SOC accumulation due to N did not necessarily improve atmospheric C mitigation, although this does not diminish the agricultural and economic importance of inorganic N fertilization.
  • Authors:
    • Myers, L.
    • Sherwood, J.
    • Edelson, J.
    • Damicone, J.
    • Motes, J.
  • Source: Plant Disease
  • Volume: 91
  • Issue: 5
  • Year: 2007
  • Summary: In five field trials over 3 years, control of aphid-transmitted, nonpersistent virus diseases on pumpkin, caused mostly by the potyviruses Watermelon mosaic virus (WMV) and Papaya ringspot virus type-W (PRSV-W), was achieved by intercropping with grain sorghum, as opposed to clean tillage. Reductions in disease incidence ranged from 43 to 96% ( P≤0.05). Surrounding pumpkin plots with borders of peanut, soybean, or corn was not effective. Borders of grain sorghum were effective, but disease control was generally less than for the intercrop treatment. Intercropping soybean and peanut with pumpkin reduced disease incidence by 27 to 60% ( P≤0.05), but disease control generally was less than for grain sorghum. Peak periods of alate aphid immigration generally preceded virus disease outbreaks by 7 to 14 days. However, alate landing rates, as measured in green tile traps, did not differ among treatments. Marketable yield was not increased by the intercrop treatments, and yield was reduced by up to 50% for the intercrop treatment with grain sorghum in two trials. The use of grass-selective herbicide applied along pumpkin rows, reduced seeding rates of the intercrops, or mowing did not alleviate the adverse effects of competition between pumpkin and the grain sorghum intercrop on yield.
  • Authors:
    • Silva, A. C.
    • Duarte, A. P.
    • Deuber, R.
  • Source: PLANTA DANINHA
  • Volume: 25
  • Issue: 2
  • Year: 2007
  • Summary: A weed infestation survey was performed in 20 second maize crop areas in 1997 and in 40 areas in 1998 and 1999 after soyabean planting in the Medio Paranapanema Region, Sao Paulo, Brazil. The survey was conducted in the counties of Assis, Campos Novos, Candido Mota, Cruzalia, Florinea, Maracai, Palmital, Pedrinhas Paulista and Platina. When the maize reached the grain filling stage, the crop weeds were evaluated by zigzag walking through the areas starting from different points to represent the whole area. The crops were classified in three types, according to the system applied: no-tillage, conventional system with disc plowing, and second maize crop in the soyabean straw only. Infestation level and occurring weed species were evaluated in each crop. The weed control systems adopted were also considered, according to the herbicides applied. The most important weed species occurring in the areas were: Cenchrus echinatus, Bidens pilosa, Euphorbia heterophylla, Raphanus sativus, Digitaria horizontalis, Commelina benghalensis, Amaranthus sp., Achyrocline satureioides, Sinapis arvensis, Sida sp., Glycine max, Avena strigosa [ Avena nuda], Eleusine indica and Sorghum halepense. The results showed a strong infestation increase of C. echinatus, which turned out to be the most important weed species in the area evaluated. R. sativus was also important and showed an expressive increase from 1997 to 1999. Weed infestations were higher in the conventional system areas, showing that this system is inferior to the others, concerning weed control. The chemical weed control most used was the mixture of (atrazine+oil) plus 2,4-D, followed by (atrazine+oil) and atrazine alone. No weed control was used in 22% of the crops, which were the most infested. The infestation level varied from year to year for the different weed control systems, depending on climate conditions.
  • Authors:
    • Drijber, R.
    • Mamo, M.
    • Wortmann, C.
    • Garcia, J.
    • Tarkalson, D.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 4
  • Year: 2007
  • Summary: Stratification of nutrient availability, especially of P, that develops with continuous no-till (NT) can affect runoff nutrient concentration and possibly nutrient uptake. The effects of composted manure application and one-time tillage of NT on the distribution of soil chemical properties, root colonization by arbuscular mycorrhizae (AM), and plant P uptake were determined. Research was conducted on Typic Argiudoll and Mollic Hapludalf soils under rainfed corn ( Zea mays L.) or sorghum [ Sorghum bicolor (L.) Moench.] rotated with soybean [ Glycine max (L.) Merr.] in eastern Nebraska. Tillage treatments included NT, disk, chisel, moldboard plow (MP), and mini-moldboard plow (MMP). Subplots had either 0 or 87.4 kg P ha -1 applied in compost before tillage. Bray-P1 was five to 21 times as high for the 0- to 5-cm as compared with the 10- to 20-cm soil depth. Greater redistribution of nutrients and incorporation of compost P resulted from MP tillage than from other tillage treatments. One-time chisel or disk tillage did not effectively redistribute nutrients while MMP tillage had an intermediate effect. Compost application reduced AM colonization of roots at R6 for all crops. Tillage reduced AM colonization with reductions at R6 due to MP tillage of 58 to 87%. The tillage effect on colonization persisted through the second year with no indication of AM recovery. Root P concentration was increased by MP and was negatively correlated to colonization. Decreased colonization did not result in decreased plant P uptake. Infrequent MP tillage can reduce surface soil P and the potential for P loss in runoff, but may reduce AM colonization of the roots, possibly reducing P uptake with some low P soils. The results do not indicate any advantage to one-time tillage of NT if runoff P loss is not a concern.
  • Authors:
    • Sweeney, D.W.
    • Kelley, K.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 4
  • Year: 2007
  • Summary: Because of improved equipment technology, many producers in the eastern Great Plains are planting winter wheat ( Triticum aestivum L.) no-till (NT) into previous crop residues, but management of fertilizer N and P remains critical. This field study was conducted from 1998 through 2003 in southeastern Kansas on a Parsons silt loam soil (fine, mixed, thermic, Mollic Albaqualf). The objectives were to determine effects and interactions of previous crop [corn, Zea mays L.; grain sorghum, Sorghum bicolor (L.); and soybean, Glycine max (L.) Merr.], preplant placement method of liquid N-P fertilizer [subsurface-knife (KN), surface-band (SB), and surface-broadcast (BC)], and fertilizer N rate (22, 45, 90, and 134 kg N ha -1) on NT winter wheat yield, yield components, and nutrient uptake in a 2-yr cropping rotation. Wheat yields averaged 3.73, 3.56, and 2.97 Mg ha -1 following soybean, corn, and grain sorghum, respectively. However, as fertilizer N rate increased, yield differences between previous crops decreased. Grain yields also were influenced by placement of N-P fertilizer, averaging 3.68 Mg ha -1 for KN, 3.40 Mg ha -1 for SB, and 3.19 Mg ha -1 for BC. Plant and grain N responses indicated that grain yield differences were primarily related to greater immobilization of both fertilizer and soil N following grain sorghum, compared with soybean and corn, and to better utilization of KN N-P than surface-applied. Fertilizing with greater N rates applied as a subsurface band, especially if following grain sorghum, may be necessary to maximize NT wheat yield potential in the eastern Great Plains.
  • Authors:
    • Franti, T.
    • Mamo, M.
    • Wortmann, C.
    • Quincke, J.
    • Drijber, R.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 4
  • Year: 2007
  • Summary: Soil organic carbon (SOC) accumulation occurs mostly in the top 5 cm of soil with continuous no-till (NT) while SOC losses often occur at deeper depths. We hypothesize that one-time tillage conducted once in >10 yr to mix the high SOC surface layer with deeper soil will not result in large SOC losses following tillage with a net positive gain in SOC eventually. Two experiments in long-term NT fields were installed under rainfed corn ( Zea mays L.) or sorghum [ Sorghum bicolor (L.) Moench.] rotated with soybean [ Glycine max (L.) Merr.] in eastern Nebraska. Tillage treatments were applied in the spring or fall and included: NT, disk, chisel with 10-cm wide twisted shanks, moldboard plow (MP), and mini-moldboard plow (miniMP). A portable infrared gas analyzer was used to monitor CO 2 flux immediately following tillage. Effect of tillage on profile distribution of total and labile (particulate and oxidizable) SOC was determined. At 24 to 32 mo following tillage, SOC mass was determined for depths of 0 to 5, 5 to 20, and 20 to 30 cm. Some tillage operations effectively redistributed total and labile SOC with little increase in CO 2 flux compared with NT. Total and labile SOC concentrations were reduced by 24 to 88% in the 0- to 2.5-cm depth and increased by 13 to 381% for the 5- to 10-cm depth for the various tillage operations. Moldboard plowing caused the greatest redistribution of SOC. On an equivalent soil mass basis, tillage did not cause significant losses of total or labile SOC between tillage and planting of the next crop or by 24 to 32 mo after tillage. Stratification of SOC in long-term NT soil could be reduced most effectively by means of one-time MP tillage without increased loss of labile SOC.
  • Authors:
    • Garcia, J.
    • Drijber, R.
    • Franti, T.
    • Mamo, M.
    • Wortmann, C.
    • Quincke, J.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 4
  • Year: 2007
  • Summary: Continuous no-till (NT) has numerous benefits, including improved soil aggregate stability in the surface soil and increased rate of water infiltration, but accumulation of soil P at the soil surface with NT can increase P concentration in runoff. We hypothesized that occasional one-time tillage of NT land, conducted once in 10 or more years, can reduce P runoff and improve crop yields without reducing soil aggregation or increasing runoff. Research was conducted in long-term NT fields under rainfed corn [ Zea mays (L.)] or sorghum [ Sorghum bicolor (L.) Moench.] rotated with soybeans [ Glycine max (L.) Merr.] at two locations in eastern Nebraska. Tillage treatments were applied in the spring or fall and included continuous NT, tandem disk (disk), chisel with 10-cm-wide twisted shanks, moldboard plow (MP), and mini-moldboard plow (miniMP). Subplots had either 0 or 87.4 kg P ha -1 applied as composted feedlot manure before tillage. Yield and yield components were measured for 2 and 3 yr after the spring and fall one-time tillage, respectively. In Year 2 or 3 after tillage, soil sorptivity, field-saturated infiltration rate, runoff volume, runoff P loss, and soil aggregate stability were determined. Yield was not affected by the tillage * compost interaction, but was increased by compost application at one location and sorghum yield was affected by tillage treatments at the second location. Grain yield was never significantly more or less with one-time tillage as compared with NT. Soil aggregate stability was not affected by tillage treatments. Sorptivity and infiltration were increased with MP tillage compared with NT at one location but reduced at the other. One-time MP tillage reduced dissolved P loss at both locations and total phosphorus (TP) loss at one location. The benefit of one-time MP tillage in terms of reduced dissolved reactive P loss in runoff was positive with no negative effect on soil aggregate stability but no gain in yield.
  • Authors:
    • Avila, A.
    • Spera, S.
    • Tomm, G.
    • Santos, H.
  • Source: Bragantia
  • Volume: 66
  • Issue: 2
  • Year: 2007
  • Summary: The effects of soil management systems and crop rotations were assessed from 1997 to 2003, in Passo Fundo, Rio Grande do Sul State, Brazil. Four soil management systems (no-tillage, minimum tillage, conventional tillage using disc plough, and conventional tillage using mouldboard plough) and three crop rotation systems (system I (wheat/soyabean), system II (wheat/soyabean and common vetch/maize or sorghum), and system III (wheat/soyabean, common vetch/maize or sorghum and white oats/soyabean)) were compared. The main plot consisted of soil management systems, while the split-plots consisted of crop rotation systems. Energy conversion (energy available/energy consumed) and balance (energy available-energy consumed) during the seven-year period is presented. No-tillage resulted in higher energy conversion and balance (72.44 and 190 766 MJ/ha) than minimum tillage (64.06 and 167 349 MJ/ha), conventional tillage using disc plough (54.35 and 134 982 MJ/ha), and conventional tillage using mouldboard (52.02 and 128 159 MJ/ha), respectively. Wheat in crop rotations presented higher energy efficiency than that in monoculture. Maize had the highest energy efficiency among the crops.
  • Authors:
    • Rice, C. W.
    • Boyles, S. B.
    • Williams, J. R.
    • Pendell, D. L.
    • Nelson, R. G.
  • Source: Review of Agricultural Economics
  • Volume: 29
  • Issue: 2
  • Year: 2007
  • Summary: This study examines the economic potential of using either no-tillage or conventional tillage with either commercial nitrogen or cattle manure to sequester soil in continuous corn production. This research uses stochastic efficiency with respect to a function to determine the preferred production systems under various risk preferences and utility-weighted certainty equivalent risk premiums to determine the carbon credit values needed to motivate adoption of systems, which sequester higher levels of carbon. The results indicate that no-tillage and cattle manure increase carbon sequestration. Carbon credits or government program incentives are not required to entice risk-averse managers to use no-tillage, but are required to encourage manure use as a means of sequestering additional carbon even at historically high nitrogen prices. New environmental rules for confined animal feeding operations may increase the demand for land to apply manure as a primary nutrient source and participation in the Environmental Quality Incentives Program, Conservation Security Program, and a carbon credit market to obtain payments to offset some or all of the costs of manure application.