• Authors:
    • Mamo, M.
    • Drijber, R.
    • Quincke, J.
    • Wortmann, C.
    • Franti, T.
  • Source: Agronomy Journal
  • Volume: 100
  • Issue: 6
  • Year: 2008
  • Summary: Continuous no-till (NT) results in soil improvements, primarily in the surface 5 cm of soil. One-time tillage may improve NT systems by inverting surface soil with less improved deeper soil. Research was conducted to determine the change in abundance of soil microbial groups after a one-time tillage of NT and their recovery dynamics. Experiments were conducted under rainfed corn ( Zea mays L.) or sorghum [ Sorghum bicolor (L.) Moench] rotated with soybean [ Glycine max (L.) Merr.] in eastern Nebraska with one-time moldboard plow (MP) and mini-moldboard plow (mini-MP) tillage compared with continuous NT. Fatty acid methyl ester (FAME) profiles were used as biomarkers of soil microbial groups. The biomass of microbial groups within the soil profile was affected by tillage treatment, soil depth, and time after one-time tillage. Soil microbial biomass under NT was greatest at the 0- to 5-cm depth with 50% less in the 5- to 20-cm depth, and least in the 20- to 30-cm depth. Microbial group biomass was decreased by one-time MP tillage, and generally by mini-MP tillage, compared with NT. On an equivalent soil mass basis, the quantity of the arbuscular mycorrhizal (AM) biomarker C16:1(c11) in the second year after tillage was 22% less for tilled treatments compared with NT. In contrast, the fungal biomarker C18:2(c9,12) was 6% more in the second year after tillage for tilled compared with NT. Tillage affected biomass and recovery of microbial groups differently, with all except AM returning to the NT microbial biomass levels within 1 to 3 yr.
  • Authors:
    • Krupinsky, J. M.
    • Tanaka, D. L.
    • Merrill, S. D.
    • van Donk, S. J.
  • Source: Transactions of the ASABE
  • Volume: 51
  • Issue: 5
  • Year: 2008
  • Summary: Residue cover is very important for controlling soil erosion by water and wind. Thus, the wind erosion prediction system (WEPS) includes a model for the decomposition of crop residue. It simulates the fall rate of standing residue and the decomposition of standing and flat residue as a function of temperature and moisture. It also calculates residue cover from flat residue mass. Most of the data used to develop and parameterize this model have been collected in the southern USA. We compared WEPS-simulated residue cover with that measured in south-central North Dakota for 50 two-year cropping sequences from nine crops species that were grown using no-till management. Measured data included residue mass at the time of harvest and residue cover just after seeding the next spring.
  • Authors:
    • Wei, C. F.
    • Tang, X. H.
    • Wang, Z. F.
    • Luo, Y. J.
    • Gao, M.
  • Source: Pedosphere
  • Volume: 18
  • Issue: 5
  • Year: 2008
  • Summary: The effect of different tillage systems on the size distribution of aggregates and organic carbon distribution and storage in different size aggregates in a Hydragric Anthrosol were studied in a long-term experiment in Chongqing, China. The experiment included three tillage treatments: conventional tillage with rotation of rice and winter fallow (CT-r) system, no-till and ridge culture with rotation of rice and rape (RT-rr) system, and conventional tillage with rotation of rice and rape (CT-rr) system. The results showed that the aggregates 0.02-0.25 mm in diameter accounted for the largest portion in each soil layer under all treatments. Compared with the CT-r system, in the 0-10 cm layer, the amount of aggregates >0.02 mm was larger under the RT-rr system, but smaller under the CT-rr system. In the 0-20 cm layer, the organic carbon content of all fractions of aggregates was the highest under the RT-rr system and lowest under the CT-rr system. The total organic carbon content showed a positive linear relationship with the amount of aggregates with diameter ranging from 0.25 to 2 mm. The storage of organic carbon in all fractions of aggregates under the RT-rr system was higher than that under the CT-r system in the 0-20 cm layer, but in the 0-60 cm soil layer, there was no distinct difference. Under the CT-rr system, the storage of organic carbon in all fractions of aggregates was lower than that under the CT-r system; most of the newly lost organic carbon was from the aggregates 0.002-0.02 and 0.02-0.25 mm in diameter.
  • Authors:
    • Jones, C. A.
    • Buschena, D. E.
    • Miller, P. R.
    • Holmes, J. A.
  • Source: Agronomy Journal
  • Volume: 100
  • Issue: 3
  • Year: 2008
  • Summary: Transition to no-till (NT) and organic (ORG) farming systems may enhance sustainability. Our objectives were to compare transitional crop productivity and soil nutrient status among diversified NT and ORG cropping systems in Montana. Three NT systems were designed as 4-yr rotations, including a pulse (lentil [ Lens culinaris Medik.] or pea [ Pisum sativum L.]), an oilseed (canola [ Brassica napus L.] or sunflower [ Helianthus annuus L.]) and two cereal crops (corn [ Zea mays L.], proso millet [ Panicum miliaceum L.], or wheat [ Triticum aestivum L.]). No-till continuous wheat was also included. The ORG system included a green manure (pea), wheat, lentil, and barley ( Hordeum vulgare L.) and received no inputs. Winter wheat in the ORG system yielded equal or greater than in the NT systems, and had superior grain quality, even though 117 kg N ha -1 was applied to the NT winter wheat. After 4 yr, soil nitrate-N and Olsen-P were 41 and 14% lower in the ORG system, whereas potentially mineralizable N was 23% higher in the ORG system. After 4 yr, total economic net returns were equal between NT and ORG systems on a per-ha basis. Studying simultaneous transition to diversified NT and ORG cropping systems was instructive for increased sustainability.
  • Authors:
    • Kay, B. D.
    • Wander, M. M.
    • Drury, C. F.
    • Yang, X. M.
  • Source: Pedosphere
  • Volume: 18
  • Issue: 4
  • Year: 2008
  • Summary: Three long-term field trials in humid regions of Canada and the USA were used to evaluate the influence of soil depth and sample numbers on soil organic carbon (SOC) sequestration in no-tillage (NT) and moldboard plow (MP) corn (Zea mays L.) and soybean (Glycine max L.) production systems. The first trial was conducted on a Maryhill silt loam (Typic Hapludalf) at Elora, Ontario, Canada, the second on a Brookston clay loam (Typic Argiaquoll) at Woodslee, Ontario, Canada, and the third on a Thorp silt loam (Argiaquic Argialboll) at Urbana, Illinois, USA. No-tillage led to significantly higher SOC concentrations in the top 5 cm compared to MP at all 3 sites. However, NT resulted in significantly lower SOC in sub-surface soils as compared to MP at Woodslee (10-20 cm, P = 0.01) and Urbana (20-30 cm, P < 0.10). No-tillage had significantly more SOC storage than MP at the Elora site (3.3 Mg C ha(-1)) and at the Woodslee site (6.2 Mg C ha(-1)) on an equivalent mass basis (1350 Mg ha(-1) soil equivalent mass). Similarly, NT had greater SOC storage than NIP at the Urbana site (2.7 Mg C ha(-1)) on an equivalent mass basis of 675 Mg ha-1 soil. However, these differences disappeared when the entire plow layer was evaluated for both the Woodslee and Urbana sites as a result of the higher SOC concentrations in NIP than in NT at depth. Using the minimum detectable difference technique, we observed that up to 1500 soil sample per tillage treatment comparison will have to be collected and analyzed for the Elora and Woodslee sites and over 40 soil samples per tillage treatment comparison for the Urbana to statistically separate significant differences in the SOC contents of sub-plow depth soils. Therefore, it is impracticable, and at the least prohibitively expensive, to detect tillage-induced differences in soil C beyond the plow layer in various soils.
  • Authors:
    • Archer, D. W.
    • Halvorson, A. D.
    • Reule, C. A.
  • Source: Agronomy Journal
  • Volume: 100
  • Issue: 4
  • Year: 2008
  • Summary: Conversion of irrigated cropland from conventional tillage (CT) to no-till (NT) could have several environmental benefits including reduced erosion potential, reduction of greenhouse gas emissions, and conservation of water. However NT must be economically viable if it is to be adopted. Costs of production and economic returns were evaluated for an irrigated, continuous corn ( Zea mays L.) system under CT and NT over 6 yr on a clay loam soil in northern Colorado. Yield responses to N fertilization were included to determine economic optimum fertilization rates under each tillage system. Corn grain yields at economic optimum N fertilizer rates were 1.1 to 1.4 Mg ha -1 lower for NT than for CT. However, net returns were $46 to 74 ha -1 higher for NT than for CT due to reductions in operating costs of $57 to 114 ha -1 and reductions in machinery ownership costs of $87 to 90 ha -1. Operating cost savings were realized largely due to fuel and labor reductions of 75% and 71 to 72%, respectively, and in spite of higher N fertilizer requirements of 16 to 55 kg ha -1 for NT compared to CT. No-till, irrigated, continuous corn appears to be an economically viable option for replacing CT production systems in the central Great Plains, especially when combined with the environmental benefits of the NT system.
  • Authors:
    • Eckard, R.
    • Barker-Reid, F.
    • Chen, D.
    • Li, Y.
  • Source: Plant and Soil
  • Volume: 309
  • Issue: 1-2
  • Year: 2008
  • Authors:
    • Lopez, M. V.
    • Cantero-Martinez, C.
    • Arrue, J. L.
    • Alvaro-Fuentes, J.
  • Source: Soil Science Society of America Journal
  • Volume: 72
  • Issue: 2
  • Year: 2008
  • Summary: Under semiarid conditions, soil quality and productivity can be improved by enhancing soil organic matter content by means of alternative management practices. In this study, we evaluated the feasibility of no-till (NT) and cropping intensification as alternative soil practices to increase soil organic C (SOC). At the same time, we studied the influence of these management practices on two SOC fractions (particulate organic matter C, POM-C, and the mineral-associated C, Min-C), in semiarid agroecosystems of the Ebro River valley. Soil samples were collected from five soil layers (0–5-, 5–10-, 10–20-, 20–30-, 30–40-cm depth) during July 2005 at three long-term tillage experiments located at different sites in the Ebro River valley (northeast Spain). Soil bulk density, SOC concentration and content, SOC stratification ratio, POM-C, and Min-C were measured. Higher soil bulk density was observed under NT than under reduced tillage (RT), subsoil tillage (ST), or conventional tillage (CT). At the soil surface (0–5-cm depth), the highest total SOC concentration, POM-C, and Min-C were measured under NT, followed by RT, ST, and CT, respectively. In the whole soil profile (0–40 cm), similarly, slightly greater SOC content was measured under NT than under CT with the exception of the Selvanera site, where deep subsoil tillage combined with moldboard plowing accumulated more SOC than NT. In semiarid Mediterranean agroecosystems where CT consists in moldboard plowing, NT is a viable management practice to increase SOC.
  • Authors:
    • Bridges, M.
    • Henry, W. B.
    • Shaner, D. L.
    • Khosla, R.
    • Westra, P.
    • Reich, R.
  • Source: Journal of Environmental Quality
  • Volume: 37
  • Issue: 6
  • Year: 2008
  • Summary: An area of interest in precision farming is variable-rate application of herbicides to optimize herbicide use efficiency and minimize negative off-site and non-target effects. Site-specific weed management based on field scale management zones derived from soil characteristics known to affect soil-applied herbicide efficacy could alleviate challenges posed by post-emergence precision weed management. Two commonly used soil-applied herbicides in dryland corn ( Zea mays L.) production are atrazine and metolachlor. Accelerated dissipation of atrazine has been discovered recently in irrigated corn fields in eastern Colorado. The objectives of this study were (i) to compare the rates of dissipation of atrazine and metolachlor across different soil zones from three dryland no-tillage fields under laboratory incubation conditions and (ii) to determine if rapid dissipation of atrazine and/or metolachlor occurred in dryland soils. Herbicide dissipation was evaluated at time points between 0 and 35 d after soil treatment using a toluene extraction procedure with GC/MS analysis. Differential rates of atrazine and metolachlor dissipation occurred between two soil zones on two of three fields evaluated. Accelerated atrazine dissipation occurred in soil from all fields of this study, with half-lives ranging from 1.8 to 3.2 d in the laboratory. The rapid atrazine dissipation rates were likely attributed to the history of atrazine use on all fields investigated in this study. Metolachlor dissipation was not considered accelerated and exhibited half-lives ranging from 9.0 to 10.7 d in the laboratory.
  • Authors:
    • Diaz Franco, A.
    • Salinas Garcia, J. R.
    • Garza Cano, I.
    • Mayek Perez, N.
  • Source: Revista Fitotecnia Mexicana
  • Volume: 31
  • Issue: 3
  • Year: 2008
  • Summary: Conservation tillage promotes agricultural soil sustainability and the inoculation of arbuscular mycorrhiza fungi (AMF) enhances crop growth and yields. In this study, single and combined effects of tillage systems and inoculation of AMF on charcoal rot ( Macrophomina phaseolina) incidence and severity, and grain yield in maize ( Zea mays L.) were determined. The study was conducted in semi-arid dryland conditions. Three factors with different levels were tested in maize hybrid 'Pioneer 3025W': four tillage systems (moldboard or conventional tillage, subsoil-bedding, shred-bedding and no-tillage); two fertilization levels (inoculated seeds with AMF Glomus intraradices, and fertilization rate of 60N-40P-00K); and three years of evaluation (2003 to 2005). Chlorophyll leaf index (CI), incidence (IM) and severity (SM) of M. phaseolina, arbuscular mycorrhizal colonization (AMC), and grain yield (GY) were determined. No tillage showed the lowest charcoal rot (IM and SM), but also the lowest GY. Tillage systems did not affect AMC of maize. Inoculation was similar to chemical fertilization in CI, IM, SM and GY, although with increase of AMC on mycorrhization treatment. The highest values CI, lesser IM and SM, and highest GY were found in 2004 due to the highest rain fall (460 mm) compared to 2003 (230 mm) and 2005 (125 mm). Results indicate that conservation tillage is a strategy to reduce charcoal in maize crop, although associated with grain yield losses, respect to conventional tillage.