• 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:
    • Valadyani, A.
    • Ajali, J.
    • Taghavi, D.
    • Fatahi, I.
  • Source: Journal of New Agricultural Science
  • Volume: 3
  • Issue: 7
  • Year: 2007
  • Summary: The main goal of management of agricultural ecosystems is to maximize the energy flow and human's artificial inputs. This investigation was conducted to evaluate the economic efficiency and crop energy of dry farming of barley ( Hordeum vulgare) in Azarbayejan-e-Sharqi province, Iran. Information and data were obtained from barley farmers and Jihad-e-Agriculture organization of the province. In this study, routine scientific methods were used to change input and output data to their equal quantities and then energy efficiency (ratio of produced energy to consumed energy) was calculated. The rate of inputs applied in these fields was 5923.79 kcal/ha and the rate of produced energy was computed 7644.16 kcal/ha. The rate of energy efficiency (the ratio of output/input) was 1.22 for the crop. Results revealed that most used energy in barley cultivation belonged to fertilizers and machinery energy, so consumption of the energy can be reduced and the energy efficiency can be increased for correct management.
  • 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.
  • Authors:
    • Anderson, R. L.
  • Source: Weed Technology
  • Volume: 21
  • Issue: 2
  • Year: 2007
  • Summary: Weed management is evolving to include cultural tactics that reduce weed populations. This study near Brookings, SD, evaluated the effect of crop sequence and tillage on seedling emergence of common sunflower across years. In the third and fourth years of the study, seedling density was sevenfold greater after 2 yr of soyabean with tillage compared with a 2-yr sequence of canola and winter wheat with no-till. Apparently, canola and winter wheat enhanced the natural decline of common sunflower seed density in soil, leading to fewer seedlings in following years. In the first year of the study, tillage increased seedling emergence of common sunflower compared with no-till; seedlings rarely emerged in canola or winter wheat. Most seedlings of common sunflower emerged in May, with more than 90% of seedlings emerging between May 7 and June 4. Cool-season crops grown with no-till may affect weed seed survival in soil in the western Corn Belt.
  • Authors:
    • Anderson, R. L.
    • Beck, D. L.
  • Source: Weed Technology
  • Volume: 21
  • Issue: 1
  • Year: 2007
  • Summary: Producers in the Great Plains are exploring alternative crop rotations with the goal of reducing the use of fallow. In 1990, a study was established with no-till practices to compare 8 rotations comprising various combinations of winter wheat (W), spring wheat (SW), maize (C), chickpea (CP), dry pea (Pea), soyabean (SB), or fallow (F). After 12 years, we characterized weed communities by recording seedling emergence in each rotation. Downy brome ( Bromus tectorum), cheat ( Bromus secalinus), redroot pigweed ( Amaranthus retroflexus), and green foxtail ( Setaria viridis) were the most common weeds observed. Weed community density was highest for W-CP, being 13-fold greater than with Pea-W-C-SB. Downy brome and cheat were rarely observed in rotations where winter wheat was grown only once every 3 or 4 years; in contrast, density of the brome species was 75-fold greater in W-CP. Warm-season weeds were also affected by rotation design; density of redroot pigweed and green foxtail was 6-fold greater in W-C-CP compared with Pea-W-C-SB or W-F. One rotation design that was especially favourable for low weed density was arranging crops in a cycle of 4, with 2 cool-season crops followed by 2 warm-season crops.
  • Authors:
    • Paulitz, T. C.
  • Source: European Journal of Plant Pathology
  • Volume: 115
  • Issue: 3
  • Year: 2006
  • Summary: Direct-seeding or no-till is defined as planting directly into residue of the previous crop without tillage that mixes or stirs soil prior to planting. No-till reduces soil erosion, improves soil structure and organic matter, and reduces fuel inputs. No-till is widely used in cereal production in Australia, Canada, Argentina, and Brazil, but has not been widely adopted in Europe and the Pacific Northwest of the U.S. One of the limitations is that root diseases may increase with a reduction in tillage. This paper discusses the importance and management of take-all, Fusarium dryland foot rot, Rhizoctonia bare patch and root rot, and Pythium root rot in dryland cereal production systems, and how they are influenced by changes in tillage practices. To address this challenge, specifically with Rhizoctonia and Pythium, our research group has (1) developed classical and molecular techniques to detect and quantify Rhizoctonia and Pythium spp. from the soil to assess disease risk; (2) studied the disease dynamics of root disease during the transition from conventional to no-till; (3) developed greenhouse methods to screen germplasm for tolerance or resistance to Pythium and Rhizoctonia, and (4) using GPS and geostatistics, has examined the spatial distribution of R. solani and R. oryzae at a field scale up to 36 ha, across a number of crop rotations and years. By a combination of ecological, epidemiological, field, and laboratory studies, we hope to provide growers with a set of disease management tools to permit the economical and sustainable production of dryland cereals without degradation of the soil resource.
  • Authors:
    • Wang, X.
  • Source: Conservation tillage and nutrient management in dryland farming in China
  • Year: 2006
  • Summary: This thesis contains 8 chapters focusing on the relations between rainfall and crop yields, and on the effects of various tillage and nutrient management practices on erosion, crop yields and water and nutrient use efficiencies. The bases of the study were: desk studies on conservation tillage and on dust storm erosion in China; long-term field experiments conducted in the dry semi-humid region of northern China (Shanxi and Henan); and simulation modelling. The first two chapters provide a brief introduction and background information on the trends in soil conservation and conservation tillage practices on global, national and regional scales, with emphasis on dryland farming of northern China. Chapter 3 analyses the effects of variation in rainfall on crop yields. The next chapter covers tillage and residue effects on rainfed wheat and maize production. Chapters 5 and 6 discuss nutrient dynamics in dryland maize cropping systems with emphasis on grain yield, and water and nutrient use efficiencies and on nutrient balances and soil fertility indices. Chapter 7 presents a scenario analysis of tillage, crop residue, cattle manure and fertilizer application management effects on soil organic carbon dynamics, using the Century model with input from the long-term field studies. The final chapter provides a general discussion and synthesis of the research findings. The consequences for future research and application of conservation tillage are also discussed.
  • Authors:
    • McVay, K.
    • Langemeier, M.
    • Regehr, D.
    • Devlin, D.
    • Mankin, K.
    • Pierzynski, G.
    • Sweeney, D.
    • Janssen, K.
    • Zeimen, M.
  • Source: Journal of Soil and Water Conservation
  • Volume: 61
  • Issue: 5
  • Year: 2006
  • Summary: Best management practices have been recommended for controlling nutrient, herbicide, or sediment losses with surface runoff. This study was designed to determine the best overall combination of tillage and application practices to reduce surface losses from cropland. Runoff was collected from two Kansas sites in sorghum-soybean rotation during the 2001 to 2004 crop years and analysed for bioavailable phosphorus (P), soluble P, total P, ammonium, nitrate, total nitrogen (N), sediment, atrazine, and metolachlor concentrations. No-till treatments consistently experienced higher runoff water volumes than the chisel/disk tillage system used to warm and dry these clay soils in the spring. For this reason the no-till treatments also had higher nutrient and herbicide losses than chisel/disk tillage regardless of use of high or low application management techniques. The high included fertilizer and herbicide application practices intended to reduce losses with runoff while the standard application broadcast applied fertilizer and herbicide at planting. Few consistent differences were seen for pollutant loss between the high and standard application management. When average losses for all eight location-years were compared to chisel/disk low, soluble P losses were 3.0 and 2.1 times higher for no-till low and no-till high, respectively; metolachlor losses were 2.4 and 2.7 times higher for no-till low and no-till high, respectively; and atrazine losses were 4.8 and 6.1 times higher for no-till low and no-till high, respectively. The chisel/disk low did experience two times higher sediment losses compared with the no-till low or no-till high, when averaging over all eight location-years. However, tolerable soil loss was not exceeded, chisel/disk low generally had small losses for all tested pollutants and may be the best management combination to simultaneously reduce nutrient, herbicide, and sediment losses with cropland runoff for sites like those used in this study.
  • Authors:
    • Pitts, T.
    • Atwood, J. D.
    • Williams, J. R.
    • Potter, S. R.
    • Wang, X.
  • Source: Transactions of the ASABE
  • Volume: 49
  • Issue: 3
  • Year: 2006
  • Summary: Sensitivity analysis for mathematical simulation models is helpful in identifying influential parameters for model outputs. Representative sets of APEX (Agricultural Policy/Environmental eXtender) model data from across the U.S. were used for sensitivity analysis to identify influential parameters for APEX outputs of crop grain yields, runoff/water yield, water and wind erosion, nutrient loss, and soil carbon change for a national assessment project: the Conservation Effects Assessment Project (CEAP). The analysis was based on global sensitivity analysis techniques. A test case, randomly selected from the representative sets of APEX model data, was first analyzed using both the variance-based sensitivity analysis technique and the enhanced Morris method. The analysis confirmed the reliability of the enhanced Morris measure in screening subsets of influential and non-influential parameters. Therefore, the enhanced Morris method was used for the national assessment, where the cost of applying variance-based techniques would be excessive. Although sensitivities are dynamic in both temporal and spatial dimensions, the very influential parameters (ranking 1st and 2nd) appear very influential in most cases. Statistical analyses identified that the NRCS curve number index coefficient is very influential for runoff and water-related output variables, such as soil loss by water, N and P losses in runoff. The Hargreaves PET equation exponent, moisture fraction required for seed germination, RUSLE C factor coefficient, and the potential heat units are influential for more than two APEX outputs studied.
  • Authors:
    • Grace, P. R.
    • Colunga-Garcia, M.
    • Gage, S.
    • Safir, G.
    • Robertson, G. P.
  • Source: Ecosystems
  • Volume: 9
  • Issue: 5
  • Year: 2006
  • Summary: Soil organic carbon (SOC) represents a significant pool of carbon within the biosphere. Climatic shifts in temperature and precipitation have a major influence on the decomposition and amount of SOC stored within an ecosystem. We have linked net primary production algorithms, which include the impact of enhanced atmospheric CO2 on plant growth, to the Soil Organic Carbon Resources And Transformations in EcoSystems (SOCRATES) model to develop a SOC map for the North Central Region of the United States between the years 1850 and 2100 in response to agricultural activity and climate conditions generated by the CSIRO Mk2 Global Circulation Model (GCM) and based on the Intergovernmental Panel for Climate Change (IPCC) IS92a emission scenario. We estimate that the current day (1990) stocks of SOC in the top 10 cm of the North Central Region to be 4692 Mt, and 8090 Mt in the top 20 cm of soil. This is 19% lower than the pre-settlement steady state value predicted by the SOCRATES model. By the year 2100, with temperature and precipitation increasing across the North Central Region by an average of 3.9 C and 8.1 cm, respectively, SOCRATES predicts SOC stores of the North Central Region to decline by 11.5 and 2% (in relation to 1990 values) for conventional and conservation tillage scenarios, respectively.