• Authors:
    • Kutcher, H. R.
    • Johnston, A. M.
    • Bailey, K. L.
    • Malhi, S. S.
  • Source: Field Crops Research
  • Volume: 124
  • Issue: 2
  • Year: 2011
  • Summary: The impact of tillage system, rotation sequence and foliar fungicides on diseases and seed yield and quality of wheat, barley, pea, canola and flax was determined in the second cycle of three, 4-year rotations from 1998 to 2001 on a Black Chernozem (Udic Boroll) at Melfort, Saskatchewan, Canada. The objective of the study was to evaluate the impact of reduced-tillage production systems, broadleaf cropping intensity and fungicide use on cereal, oilseed and pulse crops in northeastern Saskatchewan, a sub-humid region of the northern Great Plains. A split-split plot design was used with three tillage systems (conventional, minimum and no-till) as main plots, three rotations of increasing broadleaf crop intensity (1. canola-wheat-barley-barley; 2. canola-barley-pea-wheat; and 3. canola-pea-flax-barley) as sub-plots, and fungicide treatments (treated or untreated) as sub-sub-plots. Fungicides appropriate for the diseases of concern were applied at recommended crop development stages and application rates, followed by assessment of diseases. Tillage system had little impact on diseases of any crop, although seed yield was usually greater under no-till for most crops under dry conditions. Rotation was not a major factor in disease severity of most of the crops, except barley in the rotation where it was grown for two consecutive years. Under dry conditions, barley yield was reduced when it followed flax compared with other crops, most likely due to less available soil moisture after flax. Fungicide application had the greatest impact on disease control and seed yield increase, although results varied among crops and years. In conclusion, the findings indicate that tillage system had little effect on disease severity, rotation contributed to greater disease severity only when a crop was grown intensively, such as on its own stubble, and fungicide application had variable effects on both disease control and seed yield.
  • Authors:
    • Walley, F.
    • May, W. E.
    • Holzapfel, C. B.
    • Lafond, G. P.
  • Source: Soil & Tillage Research
  • Volume: 117
  • Year: 2011
  • Summary: Meeting the needs of an increasing population requires protection of our arable land base and improvements in productivity. The study compared soil quality characteristics and crop yield to nitrogen (N) fertilizer in two adjacent fields; one field managed with no-till for 31 years while the other for 9 years. In 2003, the two fields along with native prairie were sampled for soil quality parameters across two landscape positions. A small plot study involving five rates of urea N (0, 30, 60 90 and 120 kg N ha -1) and two phosphorus fertilizer placement methods (seed-placed vs side-banded) was conducted on the two adjacent fields for the period 2002-2009. The rates of N were superimposed on the same plots each year whereas wheat and canola were normally grown in alternate years. An N balance was conducted after 8 years to account for inputs and outputs of N. Soil bulk density values were 0.98 g cm -3 for native prairie and 1.46 for LTNT and STNT in the 0-15 cm soil layer. The native prairie had 48.2 t ha -1of SOC vs 44.4 and 36.7 for LTNT and STNT, respectively, in the 0-15 cm soil layer and no detectable differences for the 15-30 cm soil layer in 2003. Potentially mineralizable N using the Hot KCl digestion in the 0-15 cm soil layer was 60 kg ha -1 of ammonium nitrogen for native prairie and 30 and 22 kg ha -1 for LTNT and STNT, respectively. For amino sugar-N, native prairie had 558 kg ha -1 vs 462 and 370 kg ha -1 for the LTNT and STNT, respectively. This indicates a positive relationship between SOC levels measured and potentially mineralizable N reflecting differences in land management. Phosphorus fertilizer placed in the side-band with N yielded 3.5% more than seed-placed phosphorus in spring wheat and no difference in canola. Grain yields were 14% and 16% more for LTNT than STNT in spring wheat and canola, respectively. Maximum grain N removal averaged in wheat was 87 kg ha -1 for LTNT and 74 kg ha -1 for STNT and 71 and 65.4 kg ha -1 in canola, respectively. A positive N balance was obtained provided that 60 kg ha -1 of N was applied every year and no accumulation of nitrate-N was noted even with rates that exceeded N removal in the grain. This supports the view that no-till combined with continuous cropping and proper fertility represents a path to sustaining the global soil resource.
  • Authors:
    • Lewis, D. B.
    • Kaye, J. P.
    • Jabbour, R.
    • Barbercheck, M. E.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 26
  • Issue: 4
  • Year: 2011
  • Summary: Weed management is one of the primary challenges for producers transitioning from conventional to organic agriculture. Tillage and the use of cover crops are two weed control tactics available to farmers transitioning to organic management, but little is known about their interactive effects on soil quality during the transition period. We investigated the response of soils to tillage and initial cover crop during the 3-year transition to organic in a cover crop-soybean ( Glycine max)-maize ( Zea mays) rotation in the Mid-Atlantic region of the USA. The tillage treatment contrasted full, inversion tillage with moldboard plowing (FT) versus reduced tillage with chisel plowing (RT). The cover crop treatment contrasted annual versus mostly perennial species during the first year of the rotation. The experiment was initiated twice (Start 1 and Start 2), in consecutive years in adjacent fields. By the end of the experiment, labile carbon, electrical conductivity, pH and soil moisture were all greater under RT than under FT in both starts. Soil organic matter and several other soil attributes were greater under RT than under FT in Start 1, but not in Start 2, perhaps owing to differences between starts in initial field conditions and realized weather. Soil attributes did not differ between the two cover crop treatments. Combining our soils results with agronomic and economic analyses on these plots suggests that using RT during the organic transition can increase soil quality without compromising yield and profitability.
  • Authors:
    • Liesch, A. M.
    • Krueger, E. S.
    • Ochsner, T. E.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 4
  • Year: 2011
  • Summary: Soils under continuous corn (Zea mays L.) silage production are oft en subjected to heavy traffic and tillage, which can degrade soil structure and physical properties. Cover crops have been shown to benefit soil structure, but the effects of double-cropping on soil structure and physical properties are unknown. Our objective was to compare the soil structure and physical properties under rye (Secale cereale L.) and corn silage double-cropping with those under continuous corn silage in Minnesota during the 2007-2008 cropping year. A conventional tillage corn silage system served as the control. Double-crop treatments were conventional tillage winter rye harvested in May or June followed by no-till corn silage. Relative to the control, the double-cropping systems exhibited superior soil structure with up to 57% better visual soil structure scores and up to 16% smaller mean weight aggregate diameter. Visual soil structure scores exhibited seasonal dynamics with significant treatment effects in November and June but not in May when the structural assessment was conducted shortly after preplant tillage in the control. The double-cropping system increased the resilience of the soil to traffic. The saturated hydraulic conductivity in wheel-tracked interrows was 375% higher in the double-cropping system relative to the control in July. Both the rye and the absence of tillage before corn planting may have contributed to this improved resilience. Heavy traffic and tillage in continuous corn silage production systems can degrade soil structure and physical properties; however, the rye-corn silage double-cropping system provided a measure of protection.
  • Authors:
    • Malhi, S. S.
    • Nyborg, M.
    • Solberg, E.
    • Wang, Z.-H.
    • Henriquez, B.
  • Source: Journal of Plant Nutrition
  • Volume: 34
  • Issue: 10
  • Year: 2011
  • Summary: Most soils in the Prairie Provinces of Canada are deficient in plant-available nitrogen (N), and many soils in the Parkland region also contain insufficient amounts of plant-available sulfur (S) for high crop production. A field experiment with perennial grass stand was conducted to determine the effects of long-term annual N (112 kg N ha -1), S (11 kg S ha -1) and potassium (K) (40 kg K ha -1) fertilization, and one-time lime application on forage dry matter yield (DMY) and soil properties [pH, total organic carbon (TOC) and N (TON), and light fraction organic C (LFOC) and N (LFON)] on a Dark Gray Chernozem (Boralfic Boroll) loam at Canwood in north-central Saskatchewan, Canada. The experiment had surface-broadcast annual treatments of no fertilizer (Nil), N, S, NS, and NSK fertilizers from 1980 to 2002, and one-time lime application in 1992 to bring soil pH to about 7. Application of N or S alone had only a little effect on DMY compared to unfertilized Nil treatment, while application of both NS together substantially increased DMY, and forage yield was further increased when K was also applied (NSK). The DMY following one-time liming was greater in limed plots than in unlimed plots for at least 10 years. Decline of soil pH by fertilization mainly happened in the 0-10 cm depth with N only, and in the 0-5 cm layer with NS treatment, whereas these treatments tended to increase soil pH in layers below 10 cm. One-time surface application of granular lime increased soil pH, mainly in the 0-5 cm layer, and the effect was maintained for at least 9 years. Mass of TOC, TON, LFOC, and LFON in different soil layers increased with combined applications of N and S fertilizers (NS), but the effect was much more pronounced in the 0-7.5 cm soil layer, and also varied with organic fraction. Light organic fractions were more responsive to applied NS than total organic fractions. The findings suggest that application of N and S together was effective in sustaining high forage yield and increasing C and N sequestration in a soil deficient in both N and S.
  • Authors:
    • Ziadi, N.
    • Angers, D. A.
    • Morel, C.
    • Parent, L. E.
    • Messiga, A. J.
  • Source: Geoderma
  • Volume: 164
  • Issue: 3-4
  • Year: 2011
  • Summary: Under long-term cultivation, greater accumulations of soil organic matter (SOM) and phosphorus (P) are found in the surface soil layer under no-till (NT) versus mouldboard ploughing (MP) practices. Our objective was to evaluate the effects of NT and MP practices on concomitant SOM and P distribution and sorption characteristics among water-stable aggregates and non-aggregated particles. The study was conducted in Quebec, Canada, as part of a long-term corn and soybean rotation experiment (established since 1992) on a clay loam soil of the St-Blaise series (Dark Grey Gleysol). Soil samples were collected in the fall of 2007 in the 0-5 cm layer from plots under NT and MP receiving 35 kg P ha -1 and 160 kg N ha -1. Samples were separated into three water-stable aggregate-sized classes (macro, 2000-250 m; meso, 250-180 m; micro, 180-53 m) and (silt+clay)-sized particles (<53 m) using wet-sieving. Macro aggregates made up 60.2 and 48.5% of total soil weight under NT and MP, respectively. In wet-sieved soils from NT plots, water-extractable P (Pw) concentration increased in the order (silt+clay)-sized particles < micro- < meso- < macro-aggregates; under MP, micro-, meso-, and macro-aggregate fractions had the same Pw concentration, while the (silt+clay)-sized particles showed the lowest Pw concentration. The hierarchy observed among aggregate-sized classes under NT in relation to Pw concentration was also observed for carbon content, indicating that Pw is influenced by soil aggregation as driven by SOM accumulation. The lower Pw concentration in (silt+clay)-sized particles could be explained by a greater retention of P by reactive oxides and highly disordered alumino-silicates present on (silt+clay)-sized particles, thereby reducing the soluble P released from these particles. One important aspect of this study is the contrasting P sorption characteristics of solid particles under NT and MP. The P sorption maxima (S max value) of the (silt+clay)-sized particles was twice that of the water-stable aggregates. Sorption characteristics reflect the hierarchy observed under NT for organic C and Pw, indicating a closer link between SOM and P dynamics within soil aggregates in contrast with MP.
  • Authors:
    • Dubois, D.
    • Gaillard, G.
    • Schaller, B.
    • Chervet, A.
    • Nemecek, T.
    • Huguenin-Elie, O.
  • Source: Agricultural Systems
  • Volume: 104
  • Issue: 3
  • Year: 2011
  • Summary: Extensive or low-input farming is considered a way of remedying many problems associated with intensive farming practices. But do extensive farming systems really result in a clear reduction in environmental impacts, especially if their lower productivity is taken into account? This question is studied for Swiss arable cropping and forage production systems in a comprehensive life cycle assessment (LCA) study. Three long-term experiments (DOC) experiment comparing bio-dynamic, bio-organic and conventional farming, the "Burgrain" experiment including integrated intensive, integrated extensive and organic systems and the "Oberacker" experiment with conventional ploughing and no-till soil cultivation, are considered in the LCA study. Furthermore, model systems for arable crops and forage production for feeding livestock are investigated by using the Swiss Agricultural Life Cycle Assessment method (SALCA). The analysis covers an overall extensification of cropping systems and forage production on the one hand and a partial extensification of fertiliser use, plant protection and soil cultivation on the other. The overall extensification of an intensively managed system reduced environmental impacts in general, both per area unit and per product unit. In arable cropping systems medium production intensity gave the best results for the environment, and the intensity should not fall below the environmental optimum in order to avoid a deterioration of eco-efficiency. In grassland systems, on the contrary, a combination of both intensively and extensively managed plots was preferable to medium intensity practices on the whole area. The differences in yield, production intensity and environmental impact were much more pronounced in grassland than in arable cropping systems. Partial extensification of a farming system should be conceived in the context of the whole system in order to be successful. For example, the extensification solely of fertiliser use and soil cultivation resulted in a general improvement in the environmental performance of the farming system, whereas a reduction in plant protection intensity by banning certain pesticide categories reduced negative impacts on ecotoxicity and biodiversity only, while increasing other burdens such as global warming, ozone formation, eutrophication and acidification per product unit. The replacement of mineral fertilisers by farmyard manure as a special form of extensification reduced resource use and improved soil quality, while slightly increasing nutrient losses. These results show that a considerable environmental improvement potential exists in Swiss farming systems and that a detailed eco-efficiency analysis could help to target a further reduction in their environmental impacts.
  • Authors:
    • Nord, E. A.
    • Curran, W. S.
    • Mortensen, D. A.
    • Mirsky, S. B.
    • Jones, B. P.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 5
  • Year: 2011
  • Summary: Rolled cover crop mulches can suppress weeds in subsequent cash crops, reduce the need for herbicides, and allow organic no-till cash crop establishment. This study investigated the weed suppressiveness of a cereal rye ( Secale cereale L.) cover crop mulch across varying weed seedbank density. Cereal rye was seeded at two dates in the fall and terminated at five dates in the spring to create biomass ranging from 100 to 1600 g m -2. The first three termination dates included both herbicide (glyphosate) and rolling of the rye, while later three dates were only rolled. Soybean [ Glycine max (L.) Merr.] was no-till planted after rye termination, and weed biomass and soybean yield were assessed. Spring termination date more strongly affected cereal rye biomass than fall planting date; a termination delay of 5 to 15 d compensated for a planting delay of 30 d. Weed biomass generally declined with increasing cereal rye biomass, and this relationship was stronger at higher weed seedbank densities. Supplemental weed control reduced weed biomass compared to no supplemental control and postherbicide was more effective than cultivation. While increasing cereal rye biomass was associated with a decline in soybean yield in 2009, it did not consistently impact soybean stand. Instead soybean stand establishment appeared to be impacted by high cover crop biomass and changing edaphic conditions at planting. Future research should focus on improved technology for direct seeding in high residue environments and developing longer term cropping systems less reliant on tillage and herbicides.
  • Authors:
    • Smith, D. R.
    • Gal, A.
    • Vyn, T. J.
    • Omonode, R. A.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 1
  • Year: 2011
  • Summary: Few experiments have directly compared the long-term effects of moldboard, chisel, and no-till tillage practices on N 2O emissions from the predominant crop rotation systems in the midwestern United States. This study was conducted from 2004 to 2006 on a tillage and rotation experiment initiated in 1975 on a Chalmers silty clay loam (a Typic Endoaquoll) in west-central Indiana. Our objectives were to assess (i) long-term tillage (chisel [CP], moldboard plow [MP], and no-till [NT]), rotation (continuous corn [ Zea mays L.] and corn-soybean [ Glycine max (L.) Merr.]), and rotation * tillage interaction effects on soil N 2O emission, and (ii) how soil N 2O emission is related to environmental factors during corn production under identical N fertilizer management. Seasonal N 2O emissions were measured at intervals ranging from a few days to biweekly for up to 14 sampling dates in each growing season for corn. Nitrous oxide emissions during the growing season were significantly affected by tillage and rotation but not their interaction; however, 50% of total emissions occurred shortly after N application regardless of tillage or rotation practices. Seasonal cumulative emissions were significantly lower under NT but not statistically different for CP and MP. Overall, emissions under NT were about 40% lower relative to MP and 57% lower relative to CP. Rotation corn lowered N 2O emissions by 20% relative to continuous corn. Higher N 2O emission under MP and CP appeared to be driven by soil organic C decomposition associated with higher levels of soil-residue mixing and higher soil temperatures.
  • Authors:
    • Petersen, S. O.
    • Mutegi, J. K.
    • Hansen, E. M.
    • Munkholm, L. J.
  • Source: Soil Biology and Biochemistry
  • Volume: 43
  • Issue: 7
  • Year: 2011
  • Summary: Conservation tillage practices are widely used to protect against soil erosion and soil C losses, whereas winter cover crops are used mainly to protect against N losses during autumn and winter. For the greenhouse gas balance of a cropping system the effect of reduced tillage and cover crops on N2O emissions may be more important than the effect on soil C. This study monitored emissions of N2O between September 2008 and May 2009 in three tillage treatments, i.e., conventional tillage (CT), reduced tillage (RI) and direct drilling (DD), all with (+CC) or without (-CC) fodder radish as a winter cover crop. Cover crop growth, soil mineral N dynamics, and other soil characteristics were recorded. Furthermore, soil concentrations of N2O were determined eight times during the monitoring period using permanently installed needles. There was little evidence for effects of the cover crop on soil mineral N. Following spring tillage and slurry application soil mineral N was dominated by the input from slurry. Nitrous oxide emissions during autumn, winter and early spring remained low, although higher emissions from +CC treatments were indicated after freezing events. Following spring tillage and slurry application by direct injection N2O emissions were stimulated in all tillage treatments, reaching 250-400 mu g N m(-2) h(-1) except in the CT + CC treatment, where emissions peaked at 900 mu g N M-2 h(-1). Accumulated emissions ranged from 1.6 to 3.9 kg N2O ha(-1). A strong positive interaction between cover crop and tillage was observed. Soil concentration profiles of N2O showed a significant accumulation of N2O in CT relative to RI and DD treatments after spring tillage and slurry application, and a positive interaction between slurry and cover crop residues. A comparison in early May of N2O emissions with flux estimates based on soil concentration profiles indicated that much of the N2O emitted was produced near the soil surface.