• Authors:
    • O'Donovan, J.
    • Harker, K.
    • Clayton, G.
    • Dosdall, L.
    • Hummel, J.
  • Source: Environmental Entomology
  • Volume: 41
  • Issue: 1
  • Year: 2012
  • Summary: Diversity and abundance of ground beetles (Coleoptera: Carabidae) can be enhanced in vegetable and field intercropping systems, but the complexity of polycultures precludes the application of generalized assumptions of effects for novel intercropping combinations. In a field experiment conducted at Lacombe and Ellerslie, Alberta, Canada, in 2005 and 2006, we investigated the effects of intercropping canola ( Brassica napus L.) with wheat ( Triticum aestivum L.) on the diversity and community structure of carabid beetles, and on the activity density responses of individual carabid species. Shannon-Wiener diversity index scores and species evenness increased significantly as the proportion of wheat comprising total crop plant populations increased in one site-year of the study, indicating a positive response to enhanced crop plant species evenness in the intercrops, and in that same site-year, ground beetle communities in intercrops shifted to more closely approximate those in wheat monocultures as the percentage of wheat in the intercrops increased. Individual carabid species activity densities showed differing responses to intercropping, although activity densities of some potential root maggot ( Delia spp.) (Diptera: Anthomyiidae) predators were greater in intercrops with high proportions of wheat than in canola monocultures. The activity density of Pterostichus melanarius (Illiger), the most abundant species collected, tended to be greater in canola monocultures than high-wheat intercrops or wheat monocultures. We conclude that intercrops of canola and wheat have the potential to enhance populations of some carabid species, therefore possibly exerting increased pressure on some canola insect pests.
  • Authors:
    • Liu, We.
    • Meng, P.
    • Zhang, J.
    • Lu, S.
  • Source: Journal of Food Agriculture & Environment
  • Volume: 10
  • Issue: 2 part 3
  • Year: 2012
  • Summary: Agroforestry systems have unique advantages over conventional agricultural land in the carbon (C) balance. In this study, soil respiration under a tree intercropping system, an orchard and an agricultural land in north China were quantified during the growing season of March-November 2010. In the tree intercropping system, eight-year-old walnut ( Juglans regia L.) was intercropped with an annual wheat ( Triticum aestivum L.) - mung bean ( Vigna radiata L.) rotation. In the orchard and cropland, the eight-year-old walnut and wheat-mung bean rotation were grown as a mono practice, respectively. During the study period, the overall soil respiration rate was 1.89, 1.63 and 2.05 mol m 2 s 1 for the walnut intercropping, walnut orchard and cropland systems, respectively. Thus, there was a reduction in soil respiration when the cropland was converted to walnut intercropping and walnut orchard in north China. The higher soil CO 2 emission in the cropland result from the higher soil organic carbon and soil temperature. The van't Hoff model described the soil respiration as a function of soil temperature in the walnut intercropping system with R 2>0.78. Moreover, the temperature sensitivity of soil respiration (Q 10) was determined in the walnut intercropping system. The Q 10 values were similar in the walnut intercropping system and walnut orchard at 2.33 and 2.28, respectively, and significantly greater than for cropland (1.59). The result suggests that the walnut intercropping system had a higher sensitivity of soil respiration to temperature change than agricultural land. Compared with cropland, the slightly lower soil organic carbon in the walnut intercropping system may due to the short-term agroforestry practice, while in general the soil organic matter requires long term of turnover interactions. There was no significant difference in the walnut basal diameter and tree height between orchard and intercropping systems, showing that walnut growth was not affected by the introduction of the crop. Our results suggest that walnut intercropping could be practiced above conventional agriculture and produced less soil CO 2 emissions.
  • Authors:
    • Quideau, S.
    • Pswarayi, A.
    • Nelson, A. G.
    • Frick, B.
    • Spaner, D.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 3
  • Year: 2012
  • Summary: To investigate intercropping as a management strategy to increase crop productivity and weed suppression in organic systems, spring wheat ( Triticum aestivum L.), barley ( Hordeum vulgare L.), canola ( Brassica napus L.) and field pea ( Pisum sativum L.) monocultures were compared with two-, three-, and four-crop intercrops containing wheat at two organic and one conventional site in 2006 and 2007, central Alberta, Canada. We measured crop and weed biomass, grain yield, and crop competitiveness against weeds from a replacement design in a completely randomized block experiment. Pea and canola monocrops on organic sites yielded the least of all crop treatments. Conventional crop treatments generally yielded higher than organic treatments. Few land equivalent ratios (LERs) on organic sites were significantly >1.0. Some wheat intercrops without barley showed overyielding (LER >1.0) potential. Most of the significant LERs were from three- and four-crop intercrops. More than 50% of the intercrops on organic sites significantly suppressed weeds (based on relative weed biomass) and most of these intercrops had barley in the mixture. Barley as a sole crop and in intercrops suppressed weeds better than all other intercrops and sole crops. The wheat-canola intercrop exhibited the best weed suppression of the two-crop intercrops on organic and conventional sites. The crop densities used in this study may have contributed to the extremely low pea and canola monocrop yields as well as low LERs. Due to this, our findings should be regarded as showing trends and potential from intercrops only. We therefore recommend further studies to establish ideal densities for the intercrops used.
  • Authors:
    • Slepetiene, A.
    • Romanovskaja, D.
    • Tripolskaja, L.
    • Verbyliene, I.
  • Source: Zemes ukio Mokslai
  • Volume: 19
  • Issue: 1
  • Year: 2012
  • Summary: Possibilities to reduce the application of industrial mineral nitrogen fertilizers in crop rotations of the sustainable farming system by using the biological nitrogen accumulated by green manure crops were evaluated based on the data of stationary experiments performed during the 1997-2005 period in the Voke branch of LRCAF. Investigations were carried out in cereals (barley, barley, winter rye, oat) rotation on a sandy loam Luvisol ( Haplic Luvisols) of low acidity, with medium phosphorus content and high potassium level. It was determined that on the sandy loam the main green manure crops (clover aftermath of the 1st year of use, yellow lupine, uncultivated fallow vegetation) had formed more abundant biomass - 3.10-3.74 t ha -1 of dry matter on average, with which 50.0-83.6 kg ha -1 of nitrogen had been added to the soil. The productivity of green manure catch crops (clover under-sowing, oilseed radish) was lower and exhibited higher variation than that of the main crop plants. In autumn, the biomass of the dry matter reached an average of 1.29-2.14 t ha -1, which added 43.3-48.4 kg ha -1 of nitrogen to the soil. The application of green manure exclusively for winter rye and barley fertilization on the sandy loam soil was not successful - cereal harvest substantially decreased compared to fertilization with mineral nitrogen fertilizers N 80: for winter rye - by 15.6-27.6%, for barley - by 62.2%. A combination of the uncultivated fallow vegetation for green manure and nitrogen fertilizer (N 60) rates reduced by 25% was efficient. This variant of fertilization ensured the highest winter rye grain yield (3.30 t ha -1); grains were also significantly larger (+0.7 g).
  • Authors:
    • Jansone, Z.
    • Vicupe, Z.
  • Source: Zinatniski praktiskas konference, "Zinatne Latvijas Lauksaimniecibas Nakotnei: Partika, Lopbariba, Skiedra un Energija"
  • Year: 2012
  • Summary: The objectives of the present study were to compare oat genetic material according to its phenological traits under organic and conventional conditions. The field trials in two management systems (plot size 10 m 2, 3 replicates) were carried out in 2010 and 2011 at State Stende Cereal Breeding Institute. Twenty-one oat genotypes from the breeding program were chosen for this experiment. The phenological traits: field germination (growing stage/GS10), tillering (GS21), stem elongation (GS30), flag leaf emergence (GS 42-43), panicle stage (GS50-52) and maturity (GS92) were determined. The significant genotypic variation noted for most of the evaluated traits indicated the possibility of selection for these traits in oat. As the t-test indicated, the oat genotypes grown in organic conditions had significantly (p
  • Authors:
    • Wuthrich, R.
    • Hebeisen, T.
    • Ballmer, T.
    • Gut, F.
  • Source: AGRARFORSCHUNG SCHWEIZ
  • Volume: 19
  • Issue: 5
  • Year: 2012
  • Summary: From 2008 to 2010 Agroscope Reckenholz-Tanikon Research Station ART examined the effectiveness of drip irrigation with the potato varieties Agria and Charlotte. Irrigation hoses were laid out between the rows or in each ridge of the furrow with an identical water supply. Only in 2008 there was a tendency for the gross yields produced by the irrigated methods to be higher. In 2008 and 2009, the Agria variety produced 12 to 16 per cent higher marketable yields with the irrigated methods. The percentage yield of oversized tubers (>70 mm) was the lowest in all three years of the trial with ridge irrigation. With irrigation, Agria's yield share in ware size rose by 2 to 9 absolute per cent in all the years of the trial. With the Charlotte variety, no effects of irrigation were noted on the percentage of ware size tubers. In two of the three years, the irrigated tubers of both varieties displayed a higher starch content. Irrigated tubers showed a higher infestation rate with powdery scab, but a lower infestation rate with common scab in netted, deep pitted and raised form respectively than non-irrigated tubers. Drip irrigation is a water- and energy-saving method for future yield and quality assurance in potato production.
  • Authors:
    • Burke, I.
    • Snyder, A.
    • Pittmann, D.
    • Gallagher, R.
    • Koenig, R.
    • Borrelli, K.
    • Hoagland, L.
    • Fuerst, E.
  • Source: Journal of Sustainable Agriculture
  • Volume: 36
  • Issue: 4
  • Year: 2012
  • Summary: The nitrogen (N) dynamics of nine rotation systems designed to transition dryland cereal to organic production in eastern Washington State were examined. Systems combined cereal and legumes for grain, forage (FOR), and green manure (GRM). Few differences in N balances and soil inorganic N levels were found among transition systems when poor spring crop establishment resulted in competition from weeds. However, FOR and winter GRM crops produced adequate stands that were competitive with weeds and increased residual soil inorganic N in the final year of the transition. Winter legumes and continuous FOR systems demonstrated the greatest potential to provide a sustainable inorganic N source to subsequent organic cereal crops.
  • Authors:
    • Rydberg, T.
    • Arvidssona, J.
    • Kellerab, T.
    • Håkanssona, I.
  • Source: Acta Agriculturae Scandinavica, Section B - Soil & Plant Science
  • Volume: 62
  • Issue: 4
  • Year: 2012
  • Summary: Rapid, uniform crop establishment is a precondition for efficient crop production. In order to develop guidelines for seedbed preparation and sowing, extensive experiments were carried out in plastic boxes placed in the field directly on the ground for studies of the effects of seedbed properties on crop emergence. This paper deals with the effects on emergence of cereals caused by surface-layer hardening, induced by simulated rainfall (irrigation) after sowing followed by dry weather. The experimental crop was spring barley (Hordeum vulgare L.). Soils for the experiments (Eutric Cambisols, silt loam or clay loam in most cases) were collected from the surface layer of farm fields in various parts of Sweden. On soils with high silt content, irrigation after sowing often caused slumping and subsequent hardening of the whole seedbed. On clay soils, usually only a shallow surface crust formed. The earliest irrigation had the most negative effects on crop emergence. On a silt loam soil with unstable structure, irrigation with only 5 mm reduced emergence to under 20%. Later or heavier irrigation was often less negative, as it allowed the plants to emerge before the surface layer dried and hardened. Deep sowing greatly increased the negative effects on emergence, whereas soil aggregate size usually had negligible effects. It was concluded that when sowing in practice, seedbed preparation and sowing depth should be chosen to promote the fastest possible emergence. Sowing immediately before rain should be avoided, as should shallow sowing that requires rain for the seed to germinate.
  • Authors:
    • O'Donovan, J. T.
    • Blackshaw, R. E.
    • Hao, X. Y.
    • Li. C. L.
    • Harker, K. N.
    • Clayton, G. W.
  • Source: Soil & Tillage Research
  • Volume: 118
  • Year: 2012
  • Summary: Environmentally Smart Nitrogen (ESN), a type of polymer-coated urea, synchronizes N release with crop demand to increase N use efficiency and potentially reduce N 2O emissions. This study investigated the effects of ESN and weed management on N 2O emissions from soil under a canola ( Brassica napus L.) no-till cropping system. The experiment was conducted from 2005 to 2008 at three sites: Lethbridge, Lacombe, and Beaverlodge, located in southern, central and northern Alberta, Canada. Treatments included a hybrid and an open-pollinated canola cultivar, with ESN and urea applied at 1 and 1.5 times (*) the recommended rate, and herbicide at 50 and 100% of registered in-crop application rates. Canola was grown in rotation with barley ( Hordeum vulgare L.) and both phases of crop rotation were present each year. The N 2O fluxes from soil were measured using vented static chambers at 2-week intervals during the growing season from 2006 to 2008. Except for a few occasions with higher fluxes from urea than ESN earlier in the growing season and higher fluxes from ESN than urea later on, N 2O fluxes were similar among all treatments for all three years and three sites. The N 2O fluxes also varied over the growing season, and peak flux occurred in response to rainfall events. Similarly, cumulative N 2O emissions, expressed as either per land area or per canola seed yield, over the three growing seasons were low (0.15-2.97 kg N ha -1 yr -1 or 0.05-1.19 g N kg -1 seed) for all treatments and sites, and unaffected by weed management or crop variety ( P>0.05). The N 2O emission across the three sites from ESN averaged 20% lower ( P=0.040) than from urea although the differences between fertilizer types or application rates were not significant ( P>0.05) at each site. Elevated N 2O emissions (72% higher; P=0.028) from 1.5 * ESN (0.83 kg N ha -1 yr -1 or 0.33 g N kg -1 seed) relative to 1 * ESN (0.26 kg N ha -1 yr -1 or 0.16 g N kg -1 seed) were only observed at Beaverlodge while emissions were similar ( P>0.05) at the other two sites. The higher N 2O emissions at 1.5 * ESN at Beaverlodge were due to excess N accumulation in soil caused by unfavourable weather conditions that reduced canola N uptake and yield. Our results suggest that ESN fertilizer could reduce N 2O emissions in Alberta, Canada, but reductions will depend on rainfall events and canola N utilization.
  • Authors:
    • Tomasiewicz, D. J.
    • Mohr, R. M.
  • Source: Canadian Journal of Plant Science
  • Volume: 92
  • Issue: 4
  • Year: 2012
  • Summary: Potassium is frequently applied to irrigated potato in Manitoba. Field experiments were conducted at two sites in each of 2006, 2007 and 2008 to assess effects of rate and timing of potassium chloride (KCl) application on the yield, quality, and nutrient status of irrigated potato ( Solanum tuberosum 'Russet Burbank') in southern Manitoba. Preplant application of KCl increased total and marketable yield at one site, and tended (0.05