• Authors:
    • He, J.
    • Wang, Q.
    • Rasaily, R. G.
    • Li, H.
    • Lu, C.
  • Source: African Journal of Biotechnology
  • Volume: 11
  • Issue: 4
  • Year: 2012
  • Summary: An experiment was conducted to determine the effects of tillage on soil properties in the field of maize ( Zea mays L.) and winter wheat ( Triticum aestivum L.) annual double cropping region in North China Plain. Measurements were made following six years (2005 to 2010) of three tillage treatments; no till with controlled traffic (NTCT), no till random trafficking (NTRT) and conventional tillage (CT) on a silt loam according to the USDA texture classification system soil in Daxing district, which lies in the suburb of Beijing. Long term no till with controlled traffic significantly (P<0.05) increased macro-aggregates, infiltration rate, soil moisture, together with reductions in soil bulk density, soil compaction in different layers compared with the no till random traffic and traditional mould board tillage treatment currently used in this region. Consequently, mean winter wheat and summer maize yields for the NTCT treatment were improved by 2.8 and 7.1% when compared with the soils under no till random traffic, while huge improvement was found when it was compared with conventional ploughing management (4.2 and 12.08% for wheat and maize, respectively). The long-term experiment demonstrated that no-tillage controlled traffic with residues retained, offers a potentially significant improvement over the current farming systems in annual double cropping areas of North China Plain.
  • Authors:
    • Rodionov, A.
    • Nii-Annang, S.
    • Bens, O.
    • Trimborn, M.
    • Schillem, S.
    • Schneider, B. U.
    • Huttl, R. F.
    • Raab, T.
  • Source: Pedosphere
  • Volume: 22
  • Issue: 3
  • Year: 2012
  • Summary: Opencast lignite mining in the Lusatia region of Germany has resulted in large scale landscape disturbances, which require suitable recultivation techniques in order to promote plant growth and establishment in the remaining nutrient-poor substrates with low water-holding capacity. Thus, the effects of two commercial soil additives (CSA), a hydrophilic polymer mixed with volcanic rock flour and bentonite (a-CSA), and digester solids from biogas plants enriched with humic acids and bentonite (b-CSA), on soil organic carbon (SOC) storage, plant yields and root biomass were assessed after cultivating perennial crops ( Dactylis glomerata L.) in monoculture and Helianthus annuus L.- Brassica napus L. in crop rotation systems. The CSA were incorporated into the top 20 cm soil depth using a rotary spader. The results indicated that a-CSA led to a significant increase in plant yield during the first year, and improved root biomass in the following year. As a result, SOC stocks increased, especially in the 0-10 cm soil layer. No significant sequestration of additional SOC was observed on b-CSA-amended plots at the end of both years. Bulk density values decreased in all treatments under the monoculture system. It can be concluded that application of a-CSA enhanced soil water availability for plant uptake and consequently promoted plant growth and organic carbon sequestration. The relative enrichment of organic matter without effects on water-holding capacities of b-CSA treatments suggested that it was not suitable for rapid land reclamation.
  • Authors:
    • Shirtliffe, S. J.
    • Johnson, E. N.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 1
  • Year: 2012
  • Summary: Organic farmers in western Canada rely on tillage to control weeds and incorporate crop residues that could plug mechanical weed-control implements. However, tillage significantly increases the risk of soil erosion. For farmers seeking to reduce or eliminate tillage, potential alternatives include mowing or using a roller crimper for terminating green manure crops (cover crops) or using a minimum tillage (min-till) rotary hoe for mechanically controlling weeds. Although many researchers have studied organic crop production in western Canada, few have studied no-till organic production practices. Two studies were recently conducted in Saskatchewan to determine the efficacy of the following alternatives to tillage: mowing and roller crimping for weed control, and min-till rotary hoeing weed control in field pea ( Pisum sativum L.). The first study compared mowing and roller crimping with tillage when terminating faba bean ( Vicia faba L.) and field pea green manure crops. Early termination of annual green manure crops with roller crimping or mowing resulted in less weed regrowth compared with tillage. When compared with faba bean, field pea produced greater crop biomass, suppressed weeds better and had less regrowth. Wheat yields following pea were not affected by the method of termination. Thus, this first study indicated that roller crimping and mowing are viable alternatives to tillage to terminate field pea green manure crops. The second study evaluated the tolerance and efficacy of a min-till rotary harrow in no-till field pea production. The min-till rotary hoe was able to operate in no-till cereal residues and multiple passes did not affect the level of residue cover. Field pea exhibited excellent tolerance to the min-till rotary hoe. Good weed control occurred with multiple rotary hoe passes, and pea seed yield was 87% of the yield obtained in the herbicide-treated check. Therefore, this second study demonstrated that min-till rotary hoeing effectively controls many small seeded annual weeds in the presence of crop residue and thus can reduce the need for tillage in organic-cropping systems.
  • Authors:
    • Roger-Estrade, J.
    • Basch, G.
    • Moreno, F.
    • Soane, B. D.
    • Ball, B. C.
    • Arvidsson, J.
  • Source: Soil & Tillage Research
  • Volume: 118
  • Year: 2012
  • Summary: Recent literature on no-till is reviewed with particular emphasis on research on commercial uptake and environmental concerns in northern, western and south-western Europe. Increased interest in no-till, and minimum or reduced tillage, results from changes in the economic circumstances of crop production, the opportunity to increase the area of more profitable autumn-sown crops and increased concern about environmental damage associated with soil inversion by ploughing. Highly contrasting soil and climate types within and between these regions exert a strong influence on the success of no-till. While no-till may often result in crop yields which equal or exceed those obtained after ploughing, modest reductions in yield may be tolerated if production costs are lower than with ploughing. The relative costs of fuel and herbicides have changed appreciably in recent years making no-till more attractive commercially. While effective weed control is an essential aspect of no-till, current herbicide technology may not yet fully achieve this. In northern regions no-till usually allows earlier drilling of winter-sown crops but will give lower soil temperature and higher moisture content in spring, causing delayed drilling of spring-sown crops. No-till soils have greater bulk density and bearing capacity than ploughed soils with a pronounced vertical orientation of macroporosity allowing penetration of roots and water, especially in view of the increased population of deep-burrowing earthworms. Particular care must be taken with no-till to minimise soil damage at harvest and to ensure the even distribution of crop residues prior to drilling. Reduced erosion and runoff after adoption of no-till are widely observed and are of particular importance in southwestern Europe. No-till reduces losses of phosphorus in runoff and, in some cases, reduces the loss of nitrate through leaching. Emissions of greenhouse gases CO 2 and N 2O from no-till soils are highly variable and depend on complex interactions of soil properties. Emission of CO 2 from fuel during machinery usage is always appreciably reduced with no-till. Increased soil organic carbon in surface layers of no-till soils is widely found but may not be associated with increased carbon sequestration throughout the profile. The evaluation of the relative carbon balance for no-till and ploughing depends upon complex inter-relationships between soil and climate factors which are as yet poorly understood. Adoption of no-till could be encouraged by government financial assistance in recognition of environmental benefits, although future restrictions on the use of herbicides may be a deterrent. Opportunities for further research on no-till are outlined.
  • Authors:
    • Lee, Y.
    • Kwak, Y.
    • Lee, S.
    • Choi, K.
    • Seo, Y.
    • Kim, M.
    • Yang, S.
  • Source: World Journal of Microbiology and Biotechnology
  • Volume: 28
  • Issue: 4
  • Year: 2012
  • Summary: The present study evaluated the changes of soil microbial communities that were subjected to no-till and compared the results to those subject to tillage for organic farming in a controlled horticultural field by fatty acid methyl ester. Fungi ( P<0.001), gram-positive bacteria ( P<0.001), arbuscular mycorrhizal fungi ( P<0.01), and actinomycetes ( P<0.01) in the no-till soils were significantly larger than those in the tillage soils. The no-till in the subsoil had a significantly lower ratio of cy17:0 to 16:1omega7c compared to that of tillage, indicating that microbial stress decreased because the soils were not disturbed ( P<0.05). Fungi should be considered as a potential factor responsible for the obvious microbial community differentiation that was observed between the no-till and tillage areas in a controlled horticultural field.
  • Authors:
    • Bryant, R. B.
    • Schmidt, J. P.
    • Zhu, Q.
  • Source: Journal of Hydrology
  • Volume: 414-415
  • Year: 2012
  • Summary: Non-point nitrogen (N) and phosphorus (P) pollution from agriculture has increasingly received more public attention. In this study. NO3-N, dissolved P (DP) and particulate P (PP) concentrations and loads were investigated for four sub-basins (labeled 1-4 going up the watershed) within a mixed land use watershed (39.5 ha) in the Appalachian Valley and Ridge Physiographic Province. The hot moments of NO3-N concentration and load occurred in base flow and during the non-growing season. Great and temporally variable DP and PP concentrations were observed in storm flow. The hot moments of DP concentration and load were in storm flow from May to December and from September to Nov, respectively, while the hot moments of PP concentration and load were in storm flow from January to June. The NO3-N, DP, and PP loads were compared for all four sub-basins on a loss per length of stream reach basis to determine the hot spots and their corresponding losses. The hot spots and hot moments of NO3-N loads were in Sub-basins 1 and 4 during the non-growing season base flow period and Sub-basin 2 during the post-growing season base flow period (>110 g m(-1) mo(-1)). The hot spots of DP loads were also in Subbasins 1 and 4, but during the growing and post-growing season storm flow period (>1.4 g m(-1) mo(-1)). In contrast, the hot spots and hot moments of PP load were in Sub-basin 3 during the pre-growing and growing season storm flow, as much as 13.4 and 14.1 g m(-1) mo(-1), respectively. Controlling factors of nutrient export were discussed in this study, including season, hydrology (base flow, storm flow, surface and subsurface runoff), and land use. Although different hot moments and hot spots within the watershed were identified for NO3-N, DP, and PP losses, the implementation of a couple of management practices (cover crops and no-till) might be sufficient to effectively reduce nutrient losses from this and similar Valley and Ridge watersheds.
  • Authors:
    • Liu, W. Z.
    • Li, Y.
    • Zhu, H. H.
    • Coleman, K.
    • Wu, J. S.
    • Guo, S. L.
  • Source: Plant and Soil
  • Volume: 353
  • Issue: 1/2
  • Year: 2012
  • Summary: Aims: Concerns over food security and global climate change require an improved understanding of how to achieve optimal crop yields whilst minimizing net greenhouse gas emissions from agriculture. In the semi-arid Loess Plateau region of China, as elsewhere, fertilizer nitrogen (N) inputs are necessary to increase yields and improve local food security. Methods: In a dryland annual cropping system, we evaluated the effects of N fertilizers on crop yield, its long-term impact on soil organic carbon (SOC) concentrations and stock sizes, and the distribution of carbon (C) within various aggregate-size fractions. A current version (RothC) of the Rothamsted model for the turnover of organic C in soil was used to simulate changes in SOC. Five N application rates [0 (N0), 45 (N45), 90 (N90), 135 (N135), and 180 (N180) kg N ha -1] were applied to plots for 25 years (1984-2009) on a loam soil (Cumulic Haplustoll) at the Changwu State Key Agro-Ecological Experimental Station, Shaanxi, China. Results: Crop yield varied with year, but increased over time in the fertilized plots. Average annual grain yields were 1.15, 2.46, 3.11, 3.49, and 3.55 Mg ha -1 with the increasing N application rates, respectively. Long-term N fertilizer application increased significantly ( P=0.041) SOC concentrations and stocks in the 0-20 cm horizon. Each kilogram of fertilizer N applied increased SOC by 0.51 kg in the top soil from 1984 to 2009. Using RothC, the calculated annual inputs of plant C (in roots, stubble, root exudates, etc.) to the soil were 0.61, 0.74, 0.78, 0.86, and 0.97 Mg Cha -1 year -1 in N0, N45, N90, N135 and N180 treatments, respectively. The modeled turnover time of SOC (excluding inert organic C) in the continuous wheat cropping system was 26 years. The SOC accumulation rate was calculated to be 40.0, 48.0, 68.0, and 100.0 kg C ha -1 year -1 for the N45, N90, N135 and N180 treatments over 25 years, respectively. As aboveground biomass was removed, the increases in SOC stocks with higher N application are attributed to increased inputs of root biomass and root exudates. Increasing N application rates significantly improved C concentrations in the macroaggregate fractions (>1 mm). Conclusions: Applying N fertilizer is a sustainable practice, especially in carbon sequestration and crop productivity, for the semiarid Loess Plateau region.
  • 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