• Authors:
    • Konopatzki, M. R. S.
    • Lima, G. P. de
    • Nobrega, L. H. P.
    • Pickler, E. P.
    • Pacheco, F. P.
  • Source: Engenharia na Agricultura
  • Volume: 20
  • Issue: 1
  • Year: 2012
  • Summary: The increased mechanization, without adequate management, contributes to changes in soil structure, which facilitate erosive processes and soil degradation. The cover crops help protect soil surface, enhance physical, chemical, biological and productive potential of a soil and minimize degradation. This trial was done to analyze the influence of winter cover crop on the soil density, water content, macro and microporosity of soil cultivated to soybean and corn under no-tillage system. The experiment was conducted in a field with 24 plots, having six treatments of cover crops (forage turnip, pearl millet, oilseed rape, black oat, wheat and fallow) with four replications. After cover crop management, twelve plots were planted with corn and the other twelve with soybeans. It was observed that the soil under corn had better macroporosity, porosity and density compared to the soil cultivated to soybean. The crop cover with forage turnip increased soil macroporosity. However, cover crops did not influence water content, density, microporosity and porosity.
  • Authors:
    • Michelsen, O.
    • Henriksen, T. M.
    • Korsaeth, A.
    • Roer, A. G.
    • Stromman, A. H.
  • Source: Agricultural Systems
  • Volume: 111
  • Year: 2012
  • Summary: This study assesses the environmental impacts from production of 1 kg barley, oat and spring wheat, in central southeast Norway by means of life cycle assessment. The results were given for twelve impact categories, selected based on relevance to the system. These categories are climate change, fossil depletion, freshwater ecotoxicity, freshwater eutrophication, human toxicity, marine ecotoxicity, marine eutrophication, ozone depletion, particulate matter formation, photochemical oxidant formation, terrestrial acidification and terrestrial ecotoxicity. The assessment covers processes from cradle to farm gate, including all farm activities related to grain cultivation, as well as the production and acquisition of machinery, equipments and buildings, diesel and oil, fertilizer, lime, seeds and pesticides. In order to reveal the importance of system boundaries, factors that are included in this study and often excluded in other studies, such as machinery manufacturing, buildings, pesticide production and use, humus mineralization and NO X loss from use of mineral fertilizer were systematically individually omitted. The sensitivity of the LCA results to several selected parameters governing greenhouse gas emissions and climate change (CC) was evaluated by varying the parameters50% of the default value. The assessment gave a CC impact of 0.79, 0.77 and 0.74 kg CO 2-eq for production of 1 kg barley, oat and spring wheat, respectively. The choice of system boundaries were found to have great impact on the results, and CC impact was reduced by more than 40% when factors that are not commonly reported in literature were excluded. This clearly demonstrates the need of comprehensive documentation of system boundaries in order to perform meaningful comparisons of environmental impact caused by grain production under different conditions. The sensitivity analysis revealed that most of the impact categories were not particularly sensitive to the parameters selected. A 50% change in the emission factor for N 2O emissions from N inputs had highest effect on CC with 11-13%. The highest overall impacts were found for the fraction of mineral fertilizer volatilized as NH 3 and NO X , with 32-53% change in photochemical oxidant and particular matter formation, and terrestrial acidification impact categories.
  • Authors:
    • Fontoura, S. M. V.
    • Bayer, C.
    • Rojas, C. A. L.
    • Weber, M. A.
    • Vieiro, F.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 36
  • Issue: 1
  • Year: 2012
  • Summary: Nitrogen losses from urea by ammonia volatilization are higher from no-tillage than from conventional tillage. The objective of this study was to evaluate the magnitude of this process under cool and wet spring conditions in the South-Central region of the State of Parana and to evaluate the influence of two winter cover crops (black oat and common vetch) on ammonia volatilization in no-tillage. The tillage systems were compared in a long-term tillage experiment (28 years) and the cover crops tested separately in a long-term (>15 yr) no-tillage area. Maize was grown in both experiments. Urea was applied at rates of 0, 80 and 160 kg ha -1 N in a single application in the tillage experiment and at rates of 0, 100 and 200 kg ha -1 N, split in two applications, in the cover crop experiment. Volatilization of NH 3 was measured for 20 days after urea application in a semi-open static system. Urease activity was evaluated in both experiments. The NH 3 loss rates were highest 5 days after urea application. Cumulative ammonia losses reached 18% of the applied N in no-tillage and 3% in conventional tillage. The higher losses from no-tillage may be partially related to the greatest urease activity in the soil surface layer. Ammonia volatilization was not affected by cover crops. As an isolated practice, split surface N fertilization does not ensure a decrease of NH 3 losses, which are primarily related to rain events immediately after urea application.
  • Authors:
    • Calegari, A.
    • Santos, D.
    • Tiecher, T.
  • Source: Soil & Tillage Research
  • Volume: 124
  • Year: 2012
  • Summary: Organic phosphorus (P) is an important source of phosphate for plants both in natural environments and in cultivated soils. Growing plants with high P recycling capacity may increase the importance of organic forms in phosphate availability mainly in undisturbed soils. The aim of this study was to evaluate the effect of long period of cultivation of different winter species under different soil management systems in the distribution of soil organic P forms, in the P content stored into the soil microbial biomass (SMB) and in the acid phosphatase enzyme activity. The experiment was established in 1986 with six winter treatments (blue lupine, hairy vetch, oat, radish, wheat and fallow) implanted in a Rhodic Hapludox in southern Brazil, under no-tillage system (NT) and conventional tillage system (CT). The crops were cultivated with rational use of chemical phosphate fertilizer, according to plant needs and soil type maintaining high levels of soil organic carbon leading to P organic form accumulation. Growing crops during the winter period in highly weathered subtropical soil increases the importance of microbial interactions in the P cycle, especially in the NT, where a large amount of crop residues is annually added to the soil surface, increasing soil organic P level, P content stored into the SMB and acid phosphatase enzyme activity.
  • Authors:
    • Baade, E.
    • Tramontin, A.
    • Sturmer, S.
    • Grossklaus, F.
    • Valicheski, R.
  • Source: REVISTA BRASILEIRA DE ENGENHARIA AGRICOLA E AMBIENTAL
  • Volume: 16
  • Issue: 9
  • Year: 2012
  • Summary: With the intense use of technologies geared toward the mechanization of agricultural operations, soil compaction is a factor limiting productivity. To mitigate this problem, the use of ground cover crops is frequently recommended. With the objective to determine the effect of compaction on the soil physical properties, an experiment was carried out using randomized block design in a 2*5 factorial scheme. Two cover crop species (black oat - Avena strigosa and forage radish - Raphanus sativus), five levels of compaction (0, 2, 4, 6 and 8 tractor passes with 5.0 Mg on the soil surface), with four repetitions were studied. Traffic intensities greater than 2 tractor passes change soil density, total porosity, and mechanical penetration resistance at a depth of 0-0,10 m, as well as linearly reduce the height and dry matter production of the above-ground parts of the cover crops. The cultivation of black oat or forage radish preceding the soybeans, associated with the use of a furrower during soybean sowing minimizes the effects of soil compaction, permitting to obtain productivity greater than 3,5 t ha -1.
  • 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:
    • Sadowski, J.
    • Wrobel, S.
  • Source: Fresenius Environmental Bulletin
  • Volume: 21
  • Issue: 3
  • Year: 2012
  • Summary: A vegetative experiment was carried out to determine the consequences of phytotoxicity and results of the remediation of soil contaminated with excess copper and residue of the herbicide metazachlor. The remediation treatments consisted of the soil enrichment with organic matter in the form of peat or earthworm humus, separately or in combination with CaCO 3. The test plant was oat. When no remediation was conducted, copper contamination at the level of 360 mg Cu.kg -1 reduced oat yield by 95% versus the yield obtained on natural (unpolluted) soil. It has been found out that combined presence of the metal and herbicide in soil compounded the negative effect of these pollutants compared to their separate effect. When copper concentration in soil was elevated, the decomposition of metazachlor in soil was slowed down. The best remediation effect such as improved yields of oat and depressed Cu concentration in plants was obtained by introducing to soil a combination of 3% by weight of soil dry matter of the earthworm humus and CaCO 3 in a doze according to 1.5 hydrolytic acidity.
  • Authors:
    • Xu, Z.
    • Wu, H.
    • Rui, Y.
    • Lu, S.
    • Chen, C.
    • Zhou, X.
  • Source: Biology and Fertility of Soils
  • Volume: 48
  • Issue: 2
  • Year: 2012
  • Summary: Little information is available about the effects of cover crops on soil labile organic carbon (C), especially in Australia. In this study, two cover crop species, i.e., wheat and Saia oat, were broadcast-seeded in May 2009 and then crop biomass was crimp-rolled onto the soil surface at anthesis in October 2009 in southeastern Australia. Soil and crop residue samples were taken in December 2009 to investigate the short-term effects of cover crops on soil pH, moisture, NH 4+-N, NO 3--N, soluble organic C and nitrogen (N), total organic C and N, and C mineralization in comparison with a nil-crop control (CK). The soil is a Chromic Luvisol according to the FAO classification with 48.42.2% sand, 19.52.1% silt, and 32.12.1% clay. An exponential model fitting was employed to assess soil potentially labile organic C ( C0) and easily decomposable organic C for all treatments based on 46-day incubations. The results showed that crop residue biomass significantly decreased over the course of 2-month decomposition. The cover crop treatments had significantly higher soil pH, soluble organic C and N, cumulative CO 2-C, C0, and easily decomposable organic C, but significantly lower NO 3--N than the CK. However, no significant differences were found in soil moisture, NH 4+-N, and total organic C and N contents among the treatments. Our results indicated that the short-term cover crops increased soil labile organic C pools, which might have implications for local agricultural ecosystem managements in this region.
  • Authors:
    • Xu, Z.
    • Wu, H.
    • Chen, C.
    • Zhou, X.
  • Source: Journal of Soils and Sediments
  • Volume: 12
  • Issue: 6
  • Year: 2012
  • Summary: Purpose: Cover crop residue is generally applied to improve soil quality and crop productivity. Improved understanding of dynamics of soil extractable organic carbon (EOC) and nitrogen (EON) under cover crops is useful for developing effective agronomic management and nitrogen (N) fertilization strategies. Materials and methods: Dynamics of soil extractable inorganic and organic carbon (C) and N pools were investigated under six cover crop treatments, which included two legume crops (capello woolly pod vetch and field pea), three non-legume crops (wheat, Saia oat and Indian mustard), and a nil-crop control (CK) in southeastern Australia. Cover crops at anthesis were crimp-rolled onto the soil surface in October 2009. Soil and crop residue samples were taken over the periods October-December (2009) and March-May (2010), respectively, to examine remaining crop residue biomass, soil NH 4++N and NO 3--N as well as EOC and EON concentrations using extraction methods of 2 M KCl and hot water. Additionally, soil net N mineralization rates were measured for soil samples collected in May 2010. Results and discussion The CK treatment had the highest soil inorganic N (NH 4+-N+NO 3--N) at the sampling time in December 2009 but decreased greatly with sampling time. The cover crop treatments had greater soil EOC and EON concentrations than the CK treatment. However, no significant differences in soil NH 4+-N, NO 3--N, EOC, EON, and ratios of EOC to EON were found between the legume and non-legume cover crop treatments across the sampling times, which were supported by the similar results of soil net N mineralization rates among the treatments. Stepwise multiple regression analyses indicated that soil EOC in the hot water extracts was mainly affected by soil total C ( R2=0.654, P