• Authors:
    • Flaten, D. N.
    • Entz, M. H.
    • Vaisman, I.
    • Gulden, R. H.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 3
  • Year: 2011
  • Summary: The blade roller offers new opportunities to reduce tillage, especially in organic farming. The objective of the study was to reduce tillage in the green manure phase of a green manure-wheat ( Triticum aestivum L.) rotation by substituting tillage with blade rolling. A pea ( Pisum sativum L.) and oat ( Avena sativa L.) green manure was used for two site-years at Carman, MB, while a pea monocrop was used for one site-year at Oxbow, SK. At pea flowering, the green manure was terminated by rolling, tilling, or a combination of the two. Ammonia emissions were greater in the no-till compared with the tilled green manure system, though total ammonia losses were low (<13 kg ha -1). Replacing tillage with rolling reduced soil nitrate N in autumn after green manure by 56 to 88 kg ha -1 in the 0- to 60-cm soil depth. Reduced green manure tillage did not affect wheat establishment but delayed plant development in some instances. Fewer weeds were often observed in wheat in the no-till compared with tilled plots. Total N supply in the green manure-wheat system was reduced in the no-till system compared to the tilled only system at two out of three site-years by an average of 44%. While reduced N supply in the reduced tillage system coincided with reduced wheat yield and protein, it was concluded that factors other than N also were involved. Using the blade roller instead of tillage in the green manure year provides soil conservation benefits and facilitates wheat production the following year.
  • Authors:
    • Drury, C. F.
    • Carter, M. R.
    • Angers, D. A.
    • Janzen, H. H.
    • Ellert, B. H.
    • McConkey, B. G.
    • Bremer, E.
    • VandenBygaart, A. J.
    • Lafond, G. P.
    • McKenzie, R. H.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 1
  • Year: 2011
  • Summary: The depth of sampling has recently been highlighted as critical to making accurate measurements of changes in SOC stocks. This paper aimed to determine the effects of land management changes (LMC) on soil organic carbon (SOC) by re-sampling long-term agoecosystem experiments (LTAEs) across Canada using identical sampling and laboratory protocols. The impact of sampling depth on the monitoring of LMC-induced differences in SOC stock in LTAEs in Canada, and the implications on statistical power and sampling design, were assessed. In most cases, four cores would be suitable for detecting a significant difference in SOC stock of 5 Mg ha -1 at 95% confidence for LMCs in western Canada. The impact of eliminating fallow on SOC stocks was typically restricted to the surface 15 cm. The impact of perennial forages on the average cumulative SOC was sufficiently large to be detectable at all sampling depths (to 60 cm). In three of the six LTAEs sampled in western Canada comparing conventional tillage to no-till, there was a significantly greater SOC storage in the 0- to 30-depth than the 0- to 15-cm depth, suggesting that sampling below 15 cm could be necessary. The same comparisons in eastern Canada suggested that sampling often must exceed the 30-cm depth to account for any changes in SOC due to moldboard plow tillage. Nonetheless, there was little evidence to suggest that increasing sampling intensity or sampling deeper would improve the ability to detect a difference in SOC stocks for this LMC.
  • Authors:
    • Torres, M. O.
    • Varennes, A. de
  • Source: Soil Use and Management
  • Volume: 27
  • Issue: 1
  • Year: 2011
  • Summary: Soil changes induced by crop rotations and soil management need to be quantified to clarify their impact on yield and soil quality. The objective of this study was to investigate the effect of continuous oat ( Avena sativa L.) and a lupin ( Lupinus albus L.)-oat rotation with and without tillage on soil enzymes, crop biomass and other soil properties In year 1, oat and lupin were grown in undisturbed plots or in plots subjected to disc tillage. Crop residues were incorporated before oat was sown in year 2 in the disc-tilled plots or remained on the soil surface of untilled plots. Soil samples were collected regularly and analysed for pH, organic C, Kjeldahl-N, mineral N, extractable P, and the enzyme activities of beta-glucosidase, cellulases, acid phosphatase, proteases, urease, and culturable bacteria and fungi. The main crop and tillage effects on soil parameters were: beta-glucosidase activity was greater after lupin than after oat, and the opposite was true for the number of culturable fungi. Organic carbon, phosphatase, cellulase and protease were greater in tilled soil than in the absence of tillage. Associations between variables that were stable over the 2 yr were those for mineral N and urease activity, cellulase activity and pH, and that of phosphatase activity and organic C. Our results contrast with most of the previous information on the effect of tillage on soil enzymes, where the activities were reported to be unchanged or decreased following tillage. This difference may be related to the small organic C content of the soil and to the fact that it was under fallow prior to the start of the experiment. In consequence, incorporation of residues would provide new sources of labile organic C for soil microbes, and result in increased enzymatic activity. The results obtained suggest that in coarse-textured soils poor in organic matter, tillage with residue conservation after a period of fallow rapidly improves several soil characteristics and should be carried out even if it were to be followed by a no-till system in the following years. This should be taken into consideration by land managers and technical advisers.
  • Authors:
    • Strickland, G. L.
    • Epplin, F. M.
    • Varner, B. T.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 5
  • Year: 2011
  • Summary: The majority of cropland in the Southwest Oklahoma Agricultural Statistics District is tilled and seeded to continuous monoculture winter wheat (Triticum aestivum L.). This study was conducted to determine the expected yield and expected net returns of wheat, cotton (Gossypium hirsutum L.), and grain sorghum [Sorghum bicolor (L.) Moench], under two production systems, no-till (NT) and tilled (TL), and to determine the most risk-efficient system. The effect of tillage was investigated over 6 yr at Altus, OK, on a Hollister silty clay loam (fine, smectitic, thermic Typic Haplusterts) soil. Wheat and cotton yields were not different between tillage systems. Sorghum NT yielded significantly more than TL sorghum (P <= 0.05). Wheat NT produced the greatest expected net return to land, labor, overhead, and management ($217 ha(-1) yr(-1)). Tilled grain sorghum was the least profitable system (-$42 ha(-1) yr(-1)). Wheat NT required additional expenditures for herbicides ($15 ha(-1)), less for machinery fuel, lube, and repairs ($22 ha(-1)), and less ($23 ha(-1)) for machinery fixed costs. Net returns were slightly greater ($18 ha(-1)) for NT wheat than for TL wheat. However, since NT wheat yields were more variable, TL wheat may be preferred by risk-averse producers. Estimated machinery labor savings from switching from TL to NT wheat were 0.588 h ha(-1) or 609 h yr(-1) for a 1036 ha farm. The decision to switch from TL to NT wheat depends on risk preferences, and on the potential to use saved labor productively elsewhere, or to farm more land.
  • Authors:
    • Wilhelm, W. W.
    • Varvel, G. E.
  • Source: Soil & Tillage Research
  • Volume: 114
  • Issue: 1
  • Year: 2011
  • Summary: Emphasis and interest in carbon (C) and nitrogen (N) storage (sequestration) in soils has greatly increased in the last few years, especially C with its' potential to help alleviate or offset some of the negative effects of the increase in greenhouse gases in the atmosphere. Several questions still exist with regard to what management practices optimize C storage in the soil profile. A long-term rainfed study conducted in eastern Nebraska provided the opportunity to determine both the effects of different tillage treatments and cropping systems on soil N and soil organic C (SOC) levels throughout the soil profile. The study included six primary tillage systems (chisel, disk, plow, no-till, ridge-till, and subtill) with three cropping systems [continuous corn (CC), continuous soybean (CSB), and soybean-corn (SB-C)]. Soil samples were collected to a depth of 150-cm in depth increments of 0-15-, 15-30-, 15-30-, 30-60-, 60-90-, 90-120-, and 120-150-cm increments and composited by depth in the fall of 1999 after harvest and analyzed for total N and SOC. Significant differences in total N and SOC levels were obtained between tillage treatments and cropping systems in both surface depths of 0-15-, 15-30-cm, but also in the 30-60-cm depth. Total N and SOC accumulations throughout the profile (both calculated by depth and for equivalent masses of soil) were significantly affected by both tillage treatment and cropping system, with those in no-till the greatest among tillage treatments and those in CC the greatest among cropping systems. Soil N and SOC levels were increased at deeper depths in the profile, especially in those tillage systems with the least amount of soil disturbance. Most significant was the fact that soil N and SOC was sequestered deeper in the profile, which would strongly suggest that N and C at these depths would be less likely to be lost if the soil was tilled.
  • Authors:
    • Hoogmoed, W. B.
    • Cai, D.
    • Zhao, Q.
    • Wang, Y.
    • Zhang, X.
    • Zhang, D.
    • Dai, K.
    • Wang, X.
    • Oenema, O.
  • Source: Field Crops Research
  • Volume: 120
  • Issue: 1
  • Year: 2011
  • Summary: Rainfed crop production in northern China is constrained by low and variable rainfall. This study explored the effects of tillage/crop residue and nutrient management practices on maize ( Zea mays L.) yield, water use efficiency (WUE), and N agronomic use efficiency (NAE) at Shouyang Dryland Farming Experimental Station in northern China during 2003-2008. The experiment was set-up using a split-plot design with 3 tillage/crop residue methods as main treatments: conventional, reduced (till with crop residue incorporated in fall but no-till in spring), and no-till (with crop residue mulching in fall). Sub-treatments were 3 NP fertilizer rates: 105-46, 179-78 and 210-92 kg N and P ha -1. Maize grain yields were greatly influenced by the growing season rainfall and soil water contents at sowing. Mean grain yields over the 6-year period in response to tillage/crop residue treatments were 5604, 5347 and 5185 kg ha -1, under reduced, no-till and conventional tillage, respectively. Grain yields under no-till, were generally higher (+19%) in dry years but lower (-7%) in wet years. Mean WUE was 13.7, 13.6 and 12.6 kg ha -1 mm -1 under reduced, no-till, and conventional tillage, respectively. The no-till treatment had 8-12% more water in the soil profiles than the conventional and reduced tillage treatments at sowing and harvest time. Grain yields, WUE and NAE were highest with the lowest NP fertilizer application rates (at 105 kg N and 46 kg P ha -1) under reduced tillage, while yields and WUE tended to be higher with additional NP fertilizer rates under conventional tillage, however, there was no significant yield increase above the optimum fertilizer rate. In conclusion, maize grain yields, WUE and NAE were highest under reduced tillage at modest NP fertilizer application rates of 105 kg N and 46 kg P ha -1. No-till increased soil water storage by 8-12% and improved WUE compared to conventional tillage, thus showing potentials for drought mitigation and economic use of fertilizers in drought-prone rainfed conditions in northern China.
  • Authors:
    • Wu, Z. J.
    • Zhu, A. N.
    • Chen, L. J.
    • Chen, Z. H.
    • Wang, J. B.
  • Source: Plant, Soil and Environment
  • Volume: 57
  • Issue: 6
  • Year: 2011
  • Summary: The effects of tillage and residue input amounts on soil phosphatase (alkaline phosphomonoesterase ALP, acid phosphomonoesterase ACP, phosphodiesterase PD, and inorganic pyrophosphatase IPP) activities and soil phosphorus (P) forms (total P, organic P, and available P) were evaluated using soils collected from a three-year experiment. The results showed that no-till increased soil total and organic P, but not available P as compared to conventional tillage treatments. Total P was increased as inputs of crop residue increased for no-till treatment. There were higher ALP and IPP activities in no-till treatments, while higher PD activity was found in tillage treatments and tillage had no significant effect on ACP activity. Overall phosphatase activities increased with an increase of crop residue amounts. Soil total P was correlated negatively with PD activity and positively with other phosphatase activities. Organic P had a positive correlation with ACP activity, but a negative correlation with PD activity. Available P had no significant correlation with phosphatase activities. Our data suggests that no-till and residue input could increase soil P contents and enhance the activities of phosphatase.
  • Authors:
    • Hubbell, D. S.,III
    • Anders, M. M.
    • Beck, P. A.
    • Hignight, J. A.
    • Watkins, K. B.
    • Gadberry, S.
  • Source: Journal of Soil and Water Conservation
  • Volume: 66
  • Issue: 1
  • Year: 2011
  • Summary: Grazing cattle on winter wheat is a common income-generating practice in the Southern Great Plains, but few Arkansas cattle producers utilize this practice. Many areas in the state with potential to benefit from this practice are highly erodible, and conservation tillage may be needed to best ensure the existing natural resource base is not degraded over time. This study evaluates the profitability and return variability of grazing stocker steers on conservation tillage winter wheat pasture using simulation and stochastic dominance analysis. Average daily gains are simulated for steers grazed on conventional tillage, reduced tillage, and no-till winter wheat pasture using seven years of steer weight gain data from a conservation tillage winter wheat forage study near Batesville, Arkansas. Steer prices and prices for key forage production inputs such as diesel, fertilizer, and glyphosate are also simulated to account for their stochastic impacts on return variability. Steer net return distributions are generated for each tillage system, and first and second degree stochastic dominance are used to rank each tillage system according to specified producer preferences. The results indicate both conservation tillage systems are more profitable and less risky than the conventional tillage system. The conventional tillage system is dominated by no-till based on first degree stochastic dominance and by reduced tillage based on second degree stochastic dominance. Thus both conservation tillage systems would be preferred by risk-averse cattle producers to the conventional tillage system based on this analysis.
  • Authors:
    • Torbert, H. A.
    • Watts, D. B.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 5
  • Year: 2011
  • Summary: Reduced tillage, poultry litter applications, crop rotations, and winter cover cropping are management practices that could be used with conservation tillage systems to increase yields compared to conventional monoculture systems. This study evaluated cropping sequences of corn ( Zea mays L.), soybean [ Glycine max (L.) Merr.], and corn-soybean rotations with wheat ( Triticum aestivum L.) covers in conventional, strip, and no-tillage (no-till) systems, following poultry litter additions to wheat cover. The study was conducted from 1991 to 2001 on a Hartsells fine sandy loam (fine-loamy, siliceous, subactive, thermic Typic Hapludults). Poultry litter (112 kg N ha -1) was applied to wheat each year in fall. Wheat not receiving poultry litter received equivalent inorganic N. Corn was fertilized with inorganic fertilizer in spring with 56 kg N ha -1 at planting followed by 168 kg N ha -1 3 wk after emergence; soybean received no fertilizer. Corn yields were influenced by tillage in 1991, 1992, 1993, 1994, 1996, 1997, 1998, and 2001 with conventional tillage producing greater yields, except in 1993 (strip tillage) and 2001 (no-till). Poultry litter increased corn yield in 1991, 1997, and 1998. Crop rotations increased corn yield for all years, except 2001. Soybean yields were not impacted by differences in tillage. Crop rotations significantly impacted soybean yield in 1992, 1995, and 1998, with higher yields observed in 1992, and 1995, and lower yields in 1998. Poultry litter significantly increased soybean yield 8 of the 9 yr evaluated. This study suggests that poultry litter use for these crop rotations in conservation tillage systems could increase sustainable yield production.
  • Authors:
    • Hilker, T.
    • Lawrence, R. L.
    • Powell, S. L.
    • Watts, J. D.
  • Source: Remote Sensing of Environment
  • Volume: 115
  • Issue: 1
  • Year: 2011
  • Summary: Conservation tillage management has been advocated for carbon sequestration and soil quality preservation purposes. Past satellite image analyses have had difficulty in differentiating between no-till (NT) and minimal tillage (MT) conservation classes due to similarities in surface residues, and may have been restricted by the availability of cloud-free satellite imagery. This study hypothesized that the inclusion of high temporal data into the classification process would increase conservation tillage accuracy due to the added likelihood of capturing spectral changes in MT fields following a tillage disturbance. Classification accuracies were evaluated for Random Forest models based on 250-m and 500-m MODIS, 30-m Landsat, and 30-m synthetic reflectance values. Synthetic (30-m) data derived from the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) were evaluated because high frequency Landsat image sets are often unavailable within a cropping season due to cloud issues. Classification results from a five-date Landsat model were substantially better than those reported by previous classification tillage studies, with 94% total and >= 88% class producer's accuracies. Landsat-derived models based on individual image scenes (May through August) yielded poor MT classifications, but a monthly increase in accuracy illustrated the importance of temporal sampling for capturing regional tillage disturbance signatures. MODIS-based model accuracies (90% total; >= 82% class) were lower than in the five-date Landsat model, but were higher than previous image-based and survey-based tillage classification results. Almost all the STARFM prediction-based models had classification accuracies higher than, or comparable to, the MODIS-based results (>90% total; >= 84% class) but the resulting model accuracies were dependent on the MODIS/Landsat base pairs used to generate the STARFM predictions. Also evident within the STARFM prediction-based models was the ability for high frequency data series to compensate for degraded synthetic spectral values when classifying field-based tillage. The decision to use MODIS or STARFM-based data within conservation tillage analysis is likely situation dependent. A MODIS-based approach requires little data processing and could be more efficient for large-area mapping; however a STARFM-based analysis might be more appropriate in mixed-pixel situations that could potentially compromise classification accuracy.