• Authors:
    • Morrison, M. J.
    • Biswas, D. K.
    • Liang, B. C.
    • Ma, B. L.
    • McLaughlin, N. B.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 94
  • Issue: 1
  • Year: 2012
  • Summary: Studies on the sustainability of crop production systems should consider both the carbon (C) footprint and the crop yield. Knowledge is urgently needed to estimate the C cost of maize (Zea mays L.) production in a continuous monoculture or in rotation with a leguminous crop, the popular rotation system in North America. In this study, we used a 19-year field experiment with maize under different levels of synthetic N treatments in a continuous culture or rotation with forage legume (Alfalfa or red clover; Medicago sativa L./Trifolium pratense L.) or soybean (Glycine max L. Merr) to assess the sustainability of maize production systems by estimating total greenhouse gas (GHG) emissions (kg CO2 eq ha(-1)) and the equivalent C cost of yield or C footprint (kg CO2 eq kg(-1) grain). High N application increased both total GHG emissions and the C footprint across all the rotation systems. Compared to continuous maize monoculture (MM), maize following forage (alfalfa or red clover; FM) or grain (soybean; SM) legumes was estimated to generate greater total GHG emissions, however both FM and SM had a lower C footprint across all N levels due to increased productivity. When compared to MM treated with 100 kg N ha(-1), maize treated with 100 kg N ha(-1), following a forage legume resulted in a 5 % increase in total GHG emissions while reducing the C footprint by 17 %. Similarly, in 18 out of the 19-year period, maize treated with 100 kg N ha(-1), following soybean (SM) had a minimal effect on total GHG emissions (1 %), but reduced the C footprint by 8 %. Compared to the conventional MM with the 200 kg N ha(-1) treatment, FM with the 100 kg N ha(-1) treatment had 40 % lower total GHG emissions and 46 % lower C footprint. Maize with 100 kg N ha(-1) following soybean had a 42 % lower total GHG emissions and 41 % lower C footprint than MM treated with 200 kg N ha(-1). Clearly, there was a trade-off among total GHG emissions, C footprint and yield, and yield and GHG emissions or C footprint not linearly related. Our data indicate that maize production with 100 kg N ha(-1) in rotation with forage or grain legumes can maintain high productivity while reducing GHG emissions and the C footprint when compared to a continuous maize cropping system with 200 kg N ha(-1).
  • Authors:
    • Ostonen, I.
    • Aavola, R.
    • Soosaar, K.
    • Maddison, M.
    • Jaerveoja, J.
    • Mander, U.
    • Salm, J.
  • Source: GCB Bioenergy
  • Volume: 4
  • Issue: 4
  • Year: 2012
  • Summary: We studied the impact of reed canary grass (RCG) cultivation on greenhouse gas emission in the following sites of an abandoned peat extraction area in Estonia: a bare soil (BS) site, a nonfertilized Phalaris (nfP) plot, a fertilized Phalaris (fP) plot, and a natural bog (NB) and a fen meadow (FM) as reference areas. The C balance and global warming potential (GWP) were estimated by measuring CO2, CH4, and N2O emissions and aboveground and belowground biomass variations. The high CO2 flux from the nfP and fP sites and the low CO2 emission from the BS are due to the enhancement of mineralization by plant growth on planted sites and inhibited mineralization by the recalcitrant C of BS. The NB site emitted 24 kg CH4 ha(-1) yr(-1), whereas the almost zero CH4 emission from the Phalaris plots and the BS site was due to the high S concentration in peat, which probably inhibited methanogenesis. The N2O flux varied from <0.1 kg on the Phalaris plots and the NB to 2.64 kg N2O ha(-1) yr(-1) on the FM. The highest yield of RCG was obtained in autumn (13.9 t and 8.0 t dw ha(-1) on the fP and nfP, respectively). By spring, the biomass yield on the fP and nfP plot was 12.7 and 7.9 t dw ha(-1), respectively. The C balance of nfP and fP plots was negative in comparison to the BS (-3322, -5983, and 2504 kg CO2 ha(-1) yr(-1), respectively). This indicates that the cultivation of RCG transformed them from a net source of C into a net sink of C. The GWP for the fP and nfP sites was -5981 and -3885 kg CO2 eq ha(-1) yr(-1), respectively. The BS site had a total GWP of 2544 kg CO2 eq ha(-1) yr(-1).
  • Authors:
    • Wise, J. C.
    • van Timmeren, S.
    • Isaacs, R.
  • Source: Pest Management Science
  • Volume: 68
  • Issue: 4
  • Year: 2012
  • Summary: BACKGROUND: Soil application of systemic neonicotinoid insecticides can provide opportunities for long-term control of insect pests in vineyards, with minimal risk of pesticide drift or worker exposure. This study compared the effectiveness of neonicotinoid insecticides applied via irrigation injection on key early-season and mid-season insect pests of vineyards in the eastern United States. RESULTS: On vines trained to grow on drip irrigation, early-season application of imidacloprid, clothianidin, thiamethoxam and dinotefuran provided high levels of control against the potato leafhopper, Empoasca fabae. Protection of vines against Japanese beetle, Popillia japonica, and grape berry moth, Paralobesia viteana, was also observed after mid-season applications. Efficacy was poor in commercial vineyards when treatments were applied to the soil before irrigation or rain, indicating that vines must be grown with an irrigation system for efficient uptake of the insecticide. CONCLUSIONS: In drip-irrigated vineyards, soil-applied neonicotinoids can be used to provide long residual control of either early-season or mid- to late-season foliage pests of vineyards. This approach can reduce the dependence on foliar-applied insecticides, with associated benefits for non-target exposure to workers and natural enemies.
  • Authors:
    • Rosen, C. J.
    • Bierman, P. M.
    • Venterea, R. T.
    • Lamb, J. A.
  • Source: Agricultural Systems
  • Volume: 109
  • Year: 2012
  • Summary: A survey was conducted in the spring of 2010 to characterize the use of nitrogen (N) fertilizer on corn ( Zea mays L.) by Minnesota farmers in the 2009 growing season. Detailed information on synthetic N fertilizer management practices was collected from interviews with 1496 farmers distributed across all of the corn growing regions in the state. The total amount of corn they grew represented 6.8% of the ha of corn harvested in Minnesota in 2009. This report summarizes data on: (1) N fertilizer rates, (2) major N sources (excluding manures), (3) application timing of the major N source, (4) use of nitrification inhibitors, additives, and specialty N fertilizer formulations, (5) fertilizer placement and incorporation practices, (6) use of starter fertilizer, split and sidedress applications, and other N sources such as ammonium phosphates, (7) N fertilization of irrigated corn, and (8) use of soil testing as a fertility management tool. Many of the survey results are reported as statewide averages, but where regional differences occurred the data are broken down and presented separately for different parts of the state. This survey provides the most comprehensive set of data on N fertilizer use on corn that has been collected in Minnesota. The information can be used to target research and education programs to improve N management for both production and environmental goals. The statewide average N fertilizer rate was 157 kg N ha -1. Variable rate application was used to apply N by 23% of farmers. About 59% of surveyed farmers applied the majority of their N fertilizer in the spring before planting, 32.5% made their main N application in the fall, and 9% sidedressed the majority of their N after corn emergence. Most farmers used anhydrous ammonia (46%) or urea (45%) as their major source of N fertilizer, while 6.5% used a liquid N formulation as their primary N source. Soil testing was used as a fertility management tool on 84% of the surveyed fields in the last 5 years. Overall results indicate that N fertilizer use by Minnesota corn farmers is generally consistent with University of Minnesota Extension N management guidelines. Fertilizer N use could probably be improved by taking adequate N credit for previous soybean crops. In the South Central region of the state, fertilizer N recovery could potentially be improved by increased use of nitrification inhibitors with fall-applied anhydrous ammonia or by delaying anhydrous ammonia application until spring.
  • Authors:
    • Breland, T. A.
    • Bleken, M. A.
    • Bakken, L. R.
    • Lunde, H. W.
    • Borgen, S. K.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 92
  • Issue: 3
  • Year: 2012
  • Summary: We applied a mechanistic ecosystem model to investigate the production and environmental performances of (1) current agricultural practice on two fields of a stockless organic cereal farm in southeast Norway and (2) alternative cereal-ley rotations and plowing time scenarios. Scenarios were simulated using historic weather data and a climate change scenario. Measured and simulated soil mineral N concentrations were generally low (1-4 g N m(-2)) and in good agreement. Simulated nitrate leaching was similar for the two fields, except when an extended period of black fallow weeding was practiced on one of them. Scenario simulations indicated that continuous cereal cropping undersown with a clover-grass winter cover crop performed best when evaluated by whole-rotation grain yield, the N yield/input-, and N loss/yield-ratios, and greenhouse gas emissions. However, the rotation had the largest soil organic matter losses. The N use and loss efficiency indicators were especially poor when ley years occurred consecutively and under fall plowing. Total greenhouse gas emissions were, however, smaller for the fall-plowed scenarios. In conclusion, our results indicated a modest potential for improving stockless systems by management changes in plowing time or crop rotation, which was hardly different in the climate change scenarios, although nitrate leaching increased substantially in the winter. Alternative strategies seem necessary to substantially improve the N-use efficiency in stockless organic grain production systems, e.g., biogas production from green manure and subsequent recycling of the digestate. Abandoning the stockless system and reintegrating livestock should also be considered.
  • Authors:
    • Jossi, W.
    • Zihlmann, U.
    • Heijden, M. van der
    • Anken, T.
    • Dorn, B.
  • Source: Agrarforschung Schwei
  • Volume: 18
  • Issue: 10
  • Year: 2011
  • Summary: Earthworm activity improves soil fertility. In arable crop rotations highest earthworm populations are usually found in leys. The impact of tillage system and tillage intensity on earthworm populations was studied in the two long term trials at Burgrain (Albertswil LU) and at Hausweid (Aadorf TG). At Burgrain having a crop rotation lasting six years and including a ley, no significant difference of earthworm biomass was found between ploughed plots and plots with in the sampling period 2004-2008 in the tillage system using minimum tillage (mulch drilling for oilseed rape and sowing with a rotary band cultivator rotary band seeding for silage maize) (IP extensive) compared to ploughing in both, the organic as well as the integrated production (IP intensive). In contrast, at Hausweid having a four years crop rotation at Hausweid without ley, earthworm populations differed significantly depending on tillage system and tillage intensity after 21 years of the trial. Earthworm biomass reached 330 g per m 2 in the permanent grassland adjacent to the trial whereas it was reduced by 50% in the no-till and even by 80% in the ploughed plots. Additionally, average earthworm species diversity in permanent grassland and no-till was 30% higher than in ploughed tillage system. These findings confirm the positive impact of no-till on the increase of earthworm populations and species diversity.
  • Authors:
    • Sanadze, E.
    • Weismiller, R.
    • Kirvalidze, D.
    • Kvrivishvil, T.
    • Korakhashvili, A.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 42
  • Issue: 7
  • Year: 2011
  • Summary: In 2006, the International Organization of Christian Charities (IOCC) began a program in the country of Georgia to establish an improved dairy enterprise in the villages of Minadze and Ghreli in the Akhaltsikhe district. To correctly determine the fertility requirements for the use of either mineral or organic fertilizer materials for improving soil fertility for legume grain crops (beans, peas, soybeans, etc.) and perennial pastures (a mixture of perennial cereal grasses and perennial legumes) and for the proper management of these soils, it was necessary to understand the geomorphic, chemical, and physical characteristics of the soils of this region. Soils of this region belong to a sub-type of Cinnamonic Calcareous soils. The characteristics of these soils as well as their fertility and soil management needs were ascertained. Appropriate amounts of mineral and organic fertilizers needed for the proper growth of legume crops and perennial pastures as well as timing of application are presented.
  • 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.