• Authors:
    • Klakegg, O.
    • Janzen, H. H.
    • Skjelvag, A. O.
    • Bonesmo, H.
    • Tveito, O. E.
  • Source: Agricultural Systems
  • Volume: 110
  • Issue: July
  • Year: 2012
  • Summary: To increase food production while mitigating climate change, cropping systems in the future will need to reduce greenhouse gas emission per unit of production. We conducted an analysis of 95 arable farms in Norway to calculate farm scale emissions of greenhouse gases, expressed both as CO2 eq per unit area, and CO2 eq per kg DM produced and to describe relationships between the farms' GHG intensities and heir economic efficiencies (gross margin). The study included: (1) design of a farm scale model for net GHG emission from crop production systems; (2) establishing a consistent farm scale data set for the farms with required soil, weather, and farm operation data; (3) a stochastic simulation of the variation in the sources of GHG emission intensities, and sensitivity analysis of selected parameters and equations on GHG emission intensities; and (4) describing relationships between GHG emission intensities and gross margins on farms. Among small seed and grain crops the variation in GHG emissions per kg DM was highest in oilseed (emission intensity at the 75th percentile level was 1.9 times higher than at the 25th percentile). For barley, oats, spring wheat, and winter wheat, emissions per kg DM at the 75th percentile levels were between 1.4 and 1.6 times higher than those at the 25th percentiles. Similar trends were observed for emissions per unit land area. Invariably soil N2O emission was the largest source of GHG emissions, accounting for almost half of the emissions. The second largest source was the off farm manufacturing of inputs (similar to 25%). Except for the oilseed crop, in which soil carbon (C) change contributed least, the on farm emissions due to fuel use contributed least to the total GHG intensities (similar to 10%). The soil C change contributed most to the variability in GHG emission intensities among farms in all crops, and among the sensitivity elasticities the highest one was related to environmental impacts on soil C change. The high variation in GHG intensities evident in our study implies the potential for significant mitigation of GHG emissions. The GHG emissions per kg DM (intensity) decreased with increasing gross margin in grain and oilseed crops, suggesting that crop producers have economic incentives to reduce GHG emissions. (c) 2012 Elsevier Ltd. All rights reserved,
  • 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:
    • Riley, H.
    • Mangerud, K.
    • Bakken, A.
    • Brandsater, L.
    • Eltun, R.
    • Fykse, H.
  • Source: European Journal of Agronomy
  • Volume: 34
  • Issue: 4
  • Year: 2011
  • Summary: To ensure optimum conditions for organic cereal growing, it is important to minimize both compaction and soil inversion depth. The relative effects of using light versus heavier tractors, shallow versus deeper ploughing and on-land versus in-furrow wheel placement during ploughing were investigated in three-year organic rotations dominated by cereals with naturally infested stands of perennial weeds. The second part of the experiments was carried out in continuous barley with transplanted root fragments of Cirsium arvense (L.) Scop. and rhizome pieces of Elymus repens (L.) Gould. Ploughing was performed in spring under favourable weather conditions. Neither tractor weight nor wheel placement influenced decisively the numbers and above-ground biomass of perennial weeds. Depth of ploughing, on the other hand, affected both perennial weed infestation and yield levels consistently. Weed numbers and the total above-ground weed biomass were mostly 50% lower with deep ploughing (25 cm) than with shallow ploughing (15 cm). The greatest advantage of deep ploughing appeared in the control of C. arvense, which in some cases was reduced by more than 90% compared to shallow ploughing. In organic rotations dominated by cereals, therefore, combating of perennial weeds by deep ploughing may be more important than factors such as tractor weight and wheel placement.
  • Authors:
    • Kvarno, S.
  • Source: Variability and uncertainty in soil physical properties: effects of data source on functional criteria
  • Year: 2011
  • Summary: This thesis aims to quantify variability in soil physical properties on arable land, uncertainties related to data sources, and effects of variability and uncertainty on selected functional criteria. The study was conducted in the Skuterud catchment in South-east Norway, representative of agricultural areas with cereal production on marine deposits. Data collected in other parts of Norway were used. Two soils for aggregate stability measurements were collected from a small catchment located in the municipality of Nes, Akershus county, to represent soils with assumed lower aggregate stability than found for the clay soils in the Skuterud catchment: an artificially leveled soil with clay loam texture, and a Gleyic Cambisol with silt texture. For pedotransfer function (PTF) performance evaluation, data from many parts in Norway were collected to form a database. Marine deposits, brackish flood sediment, fluvial deposits and glacial till are represented, all common parent material for arable soils in Norway. Textural compositions of the samples varied from sandy to heavy clay. Two point PTFs developed for soils in Norway, and six parameter PTFs developed for soils in Europe and USA, were evaluated using multiple statistical indicators. The point PTFs showed overall good performance. The parameter PTFs showed variable performance. The class PTFs showed poorer performance than the continuous PTFs, especially if organic matter was not an input to the PTF. Implications of variability, uncertainty and data source were investigated for selected functional criteria in the Skuterud catchment. This study also showed that differences related to choice of data source could be larger than differences as a result of different risk of runoff and erosion (crop covered situation versus "worst case" situation with reduced soil stability and without crop cover). The major conclusion of this work is that inadequate choice of input data sources can significantly underestimate or overestimate optimum workability (W opt), number of days until W opt is obtained, surface discharge and soil loss, and consequently the effect of e.g. climate change and measures.
  • Authors:
    • Trond M. Henriksen, T. M.
    • Anne-Kristin Løes, A.-K.
    • Sjursen, H.
    • Ragnar Eltun, R.
  • Source: Acta Agriculturae Scandinavica, Section B - Soil & Plant Science
  • Volume: 61
  • Issue: 2
  • Year: 2011
  • Summary: By restricted access to manure, nitrogen (N) supply in organic agriculture relies on biological N-fixation. This study compares grain yields after one full-season green manure (FSGM) to yields with repeated use of a green-manure catch crop. At two sites in south-eastern Norway, in a simple 4-year rotation (oats/wheat/oats/wheat), the repeated use of ryegrass, clover, or a mixture of ryegrass and clover as catch crops was compared with an FSGM established as a catch crop in year 1. The FSGM treatments had no subsequent catch crops. In year 5, the final residual effects were measured in barley. The yield levels were about equal for grains with no catch crop and a ryegrass catch crop. On average, the green-manure catch crops increased subsequent cereal yields close to 30%. The FSGM increased subsequent cereal yields significantly in two years, but across the rotation the yields were comparable to those of the treatments without green-manure catch crop. To achieve acceptable yields under Norwegian conditions, more than 25% of the land should be used for full-season green manure, or this method combined with green-manure catch crops. The accumulated amount of N in aboveground biomass in late autumn did not compensate for the N removed by cereal yields. To account for the deficiency, the roots of the green-manure catch crops would have to contain about 60% of the total N (tot-N) required to balance the cereal yields. Such high average values for root N are likely not realistic to achieve. However, measurement of biomass in late autumn may not reflect all N made available to concurrent or subsequent main crops.
  • Authors:
    • Andrasko, K.
    • Bosquet, B.
  • Year: 2010
  • Authors:
    • Krogstad, T.
    • Bechmann, M.
    • Aronsson, H.
    • Ulen, B.
    • Øygarden, L.
    • Stenberg, M.
  • Source: Soil Use and Management
  • Volume: 26
  • Issue: 2
  • Year: 2010
  • Summary: In Scandinavia high losses of soil and particulate-bound phosphorus (PP) have been shown to occur from tine-cultivated and mouldboard-ploughed soils in clay soil areas, especially in relatively warm, wet winters. The omission in the autumn of primary tillage (not ploughing) and the maintenance of a continuous crop cover are generally used to control soil erosion. In Norway, ploughing and shallow cultivation of sloping fields in spring instead of ploughing in autumn have been shown to reduce particle transport by up to 89% on highly erodible soils. Particle erosion from clay soils can be reduced by 79% by direct drilling in spring compared with autumn ploughing. Field experiments in Scandinavia with ploughless tillage of clay loams and clay soils compared to conventional autumn ploughing usually show reductions in total P losses of 10-80% by both surface and subsurface runoff (lateral movements to drains). However, the effects of not ploughing during the autumn on losses of dissolved reactive P (DRP) are frequently negative, since the DRP losses without ploughing compared to conventional ploughing have increased up to fourfold in field experiments. In addition, a comprehensive Norwegian field experiment at a site with high erosion risk has shown that the proportion of DRP compared to total P was twice as high in runoff water after direct drilling compared to ploughing. Therefore, erosion control measures should be further evaluated for fields with an erosion risk since reduction in PP losses may be low and DRP losses still high. Ploughless tillage systems have potential side-effects, including an increased need for pesticides to control weeds [e.g. Elytrigia repens (L.) Desv. ex Nevski] and plant diseases (e.g. Fusarium spp.) harboured by crop residues on the soil surface. Overall, soil tillage systems should be appraised for their positive and negative environmental effects before they are widely used for all types of soil, management practice, climate and landscape.
  • Authors:
    • Brandsater, L. O.
    • Løes, A. K.
    • Riley, H.
  • Source: European weed research society. Proceedings of the 6th EWRS workshop on physical and cultural weed control, Lillehammer, Norway, 8-10 March, 2004
  • Year: 2004
  • Summary: Due to official regulations, Norwegian agriculture is divided into cereal cropping areas with very little animal husbandry, and areas with high livestock density in the coastal and mountain regions. Stockless organic farming requires a good management of green manure crops. This paper presents crop rotations designed for organic farming with low livestock density, combining weed control and nutrient supply. Rotation 1 consists of green manure, followed by barley with subcropped legume, oats and peas, green manure or winter rye, rye, ryegrass-clover, and late planted rapeseed. Rotation 1 is designed for a full-time farmer with good access to cultivated land, where 66% of the land is used for cereals and rapeseed, and 34% for green manure. Rotation 2 consists of cereal or lettuce, followed by 4-5 rotations of ley, then potatoes, green manure, cabbage with early mulch, and carrots with late mulch. Rotation 2 is designed for a part-time farmer with less farmland who wants to keep the land in shape and produce some cash crops, but cannot manage to cultivate all the farmland intensively. Forty-four percent of the land is then used for vegetables and herbs, and 56% to produce mulch or green manure crops. Green manure and mulch leys must be cut regularly to control perennial weeds.
  • Authors:
    • Riley, H.
    • Løes, A. K.
    • Brandsæter, L. O.
  • Source: European weed research society. Proceedings of the 6th EWRS workshop on physical and cultural weed control, Lillehammer, Norway, 8-10 March, 2004
  • Year: 2004
  • Summary: Due to official regulations, Norwegian agriculture is divided into cereal cropping areas with very little animal husbandry, and areas with high livestock density in the coastal and mountain regions. Stockless organic farming requires a good management of green manure crops. This paper presents crop rotations designed for organic farming with low livestock density, combining weed control and nutrient supply. Rotation 1 consists of green manure, followed by barley with subcropped legume, oats and peas, green manure or winter rye, rye, ryegrass-clover, and late planted rapeseed. Rotation 1 is designed for a full-time farmer with good access to cultivated land, where 66% of the land is used for cereals and rapeseed, and 34% for green manure. Rotation 2 consists of cereal or lettuce, followed by 4-5 rotations of ley, then potatoes, green manure, cabbage with early mulch, and carrots with late mulch. Rotation 2 is designed for a part-time farmer with less farmland who wants to keep the land in shape and produce some cash crops, but cannot manage to cultivate all the farmland intensively. Forty-four percent of the land is then used for vegetables and herbs, and 56% to produce mulch or green manure crops. Green manure and mulch leys must be cut regularly to control perennial weeds.
  • Authors:
    • Post, W. M.
    • West, T. O.
  • Source: Soil Science Society of America Journal
  • Volume: 66
  • Issue: 6
  • Year: 2002
  • Summary: Changes agricultural management can potentially increase the accumulation rate of soil organic C (SOC), thereby sequestering CO2 from the atmosphere. This study was conducted to quantify potential soil C sequestration rates for different crops in response to decreasing tillage intensity or enhancing rotation complexity, and to estimate the duration of time over which sequestration may occur. Analyses of C sequestration rates were completed using a global database of 67 long-term agricultural experiments, consisting of 276 paired treatments. Results indicate, on average, that a change from conventional tillage (CT) to no-till (NT) can sequester 57 +/- 14 g C m(-2) yr(-1), excluding wheat (Triticum aestivum L.)-fallow systems which may not result in SOC accumulation with a change from CT to NT. Enhancing rotation complexity can sequester an average 20 +/- 12 g C m(-2) yr(-1), excluding a change from continuous corn (Zea mays L.) to corn-soybean (Glycine mar L.) which may not result in a significant accumulation of SOC. Carbon sequestration rates, with a change from CT to NT, can be expected to peak in 5 to 10 yr with SOC reaching a new equilibrium in 15 to 20 yr. Following initiation of an enhancement in rotation complexity, SOC may reach a new equilibrium in approximately 40 to 60 yr. Carbon sequestration rates, estimated for a number of individual crops and crop rotations in this study, can be used in spatial modeling analyses to more accurately predict regional, national, and global C sequestration potentials.