411. Physical properties in distrofic Red Latosol under management systems in the succession soybean-maize in three years.; Propriedades fisicas de Latossolo Vermelho distroferrico tipico sob sistemas de manejo na sucessao soja-milho no periodo de tres anos.

• Authors:
  • Pereira, J.
  • Prior, M.
  • Uribe-Opazo, M.
  • Nobrega, L.
  • Lopes, R.
• Source: Acta Scientiarum Agronomy
• Volume: 29
• Issue: Suplemento Espec
• Year: 2007
• Summary: This study evaluated alterations in the physical properties water content, soil density and porosity in areas under no tillage and tillage systems in the cultures of soybean and maize in three agricultural years. The experiment was carried out at the Experimental Nucleus of Agricultural Engineering of Unioeste (Cascavel, state of Parana). Soybean culture occurred in the first two years and in the third year maize, as summer crop, black oats and forage turnip as winter cover crops. During these three years the study observed reduction of water content and soil density and increase of porosity. The variations as regards the physical properties of the soil showed direct proportional relation between water content and soil density and was in inverse proportion for soil porosity. The soil presented improvements on its physical conditions for the porosity increase and density reduction with the black oats and forage turnip crops and maize. The soybean/maize management in rotation with black oats and forage turnip showed more adequate in the improvement of the physical conditions of the soil as compared with the management systems, since neither of the systems had a major impact in the improvements of the physical properties evaluated throughout this whole period.

412. Effect of different vegetal coverings and soil tillage systems on soybean crop production.; Efeito de diferentes coberturas vegetais e sistemas de preparo do solo na producao da cultura da soja.

• Authors:
  • Lucca e Braccini, A.
  • Pinheiro Neto, R.
  • Lopes, R.
  • Souza, E.
• Source: Acta Scientiarum Agronomy
• Volume: 29
• Issue: 4
• Year: 2007
• Summary: This study evaluated the performance of the soybean under the influence of vegetal covering and soil management in Red Latosol dystrofic. Oats, turnip, hairy vetch, pea, millet and lupine were used. The study evaluated height and density of plants, height of insertion in string beans, number of string beans, productivity, a thousand grain mass, water contend, bulk density and soil resistance to penetration. The no-tillage system had greater height of insertion of string beans, amount of string beans, height of plants, water contend and soil bulk density. Greater values of soil resistance to penetration were verified in the tillage, though higher productivity was observed. The coverings and the soil tillage systems influenced the productivity of soybean plants. The vegetal coverings promoted improvement of the ground with reduction of the compactation in some layers of the soil. The oats/millet association is a viable option of soil covering predecessor of soybean. The no-tillage practice showed to be the adequate management technique for the type of soil studied.

413. Antecedent crops, doses and sources of nitrogen on yield compounds of corn.; Culturas antecessoras, doses e fontes de nitrogenio nos componentes de producao do milho.

• Authors:
  • Rodrigues, E.
  • Marchetti, M.
  • Goncalves, M.
  • Souza, L.
  • Ontocelli, R.
  • Lourente, E.
• Source: Acta Scientiarum Agronomy
• Volume: 29
• Issue: 1
• Year: 2007
• Summary: Some plants for mulching have the capacity to increase the availability of nutrients in the soil - nitrogen in particular - for crop succession, thus producing positive effects on the interaction between mineral fertilizer and green manure. As a result, there is a greater possibility to obtain higher incomes than by using each one separately. The objective of this study was to evaluate the effect of antecedent crops, levels and sources of nitrogen on yield compounds and foliar nitrogen content of maize by means of no-tillage system. These were constituted by crops preceding maize, i.e., black oat, wheat, pasture turnip, hairy vetch and one fallow treatment during winter. Subplots were established by four levels of nitrogen (0; 50; 100 and 200 kg ha -1 of N), which were applied as cover. Sub-subplots were represented by two sources of nitrogen (ammonium sulfate and urea). Results showed that antecedent crops had some influence upon yield, mass of 1000 grains and foliar nitrogen content of maize. The highest yield of maize was obtained after the winter rest, the pasture turnip and also in the absence of nitrogen fertilizer application as cover. Maximum yield of maize was also obtained when sowing was done after wheat and black oat, in nitrogen levels of 140 and 137 kg ha -1, respectively. The nitrogen sources utilized had some influence only upon the index of harvest, the number of grains per ear and the foliar nitrogen content.

414. The effect of ground cover or initial organic carbon on soil fungi, aggregation, moisture and organic carbon in one season with oat ( Avena sativa) plots.

• Authors:
  • Emery, R.
  • Maxwell, C.
  • Manns, H.
• Source: Soil & Tillage Research
• Volume: 96
• Issue: 1/2
• Year: 2007
• Summary: The unique capacity of fungi to efficiently sequester carbon in aerobic conditions, presents a way to maximize OC gain in agricultural systems. Oat ( Avena sativa) was planted in the temperate climate of southern Ontario, Canada to study factors affecting soil organic carbon (OC). The plots varied with initial OC from 25 to 68 g kg -1 or with ground cover of differing decomposability (alfalfa ( Medicago sativa) growing from seed, dried oat straw, dried hay and compost) on high OC soil (60-70 g kg -1). The soil was analysed for correlation of changes in soil aggregation, moisture, OC, fungal hyphal number and length and distribution of organic matter by mass and OC in density fractions within the growing season. At harvest, soil OC and moisture were increased only in plots with ground cover. Total hyphal length was not significantly different with ground cover treatment at harvest, and did not correlate with soil aggregation and soil OC. However, the number of hyphae with >5 m diameter (primarily mycorrhizal fungi) correlated with % OC in ground cover plots while the number of hyphae

415. Lucerne establishment sequences to maximise weed control in ex- Pinus radiata L. plantations.

• Authors:
  • Marshall, A.
  • Mills, A.
  • Moot, D.
  • Edwards, G.
• Source: Proceedings of the New Zealand Grassland Association
• Volume: 69
• Year: 2007
• Summary: Lucerne sown immediately or after different forage crop sequences was investigated as a pasture option for post forestry conversion. In this experiment superphosphate and lime were applied in March 2005 before final seedbed preparation and establishment of seven cropping sequences; (1) lucerne sown in April 2005; (2-5) greenfeed cereals (oats or triticale) sown in April 2005 followed by lucerne in October 2005 with or without a rape cover crop; (6-7) winter fallow followed by glyphosate presowing in October 2005 or March 2006. After all crop sequences, lucerne was successfully established and provided 100% control of woody and annual weeds. Average lucerne dry matter (DM) yield was ~7.1 t DM/ha/yr for crops after a cereal. The last crop established also contained no woody weeds but produced 10.0 t DM/ha less over the 2 years due to the long (12 month) fallow. Lucerne sown in April 2005 had to be reestablished the following October. Thus, provided soil temperatures were adequate, lucerne was successfully spring and autumn sown after plantation forests. Lucerne offers flexibility for grazing or conserving in commercial conversions where internal fences and stock water supply are often, initially, inadequate for intensive pasture management.

416. Ion mobility in acid soils with surface application of lime, organic acid and crop residues.; Mobilidade de ions em solo acido com aplicacao de calcario, acido organico e material vegetal em superficie.

• Authors:
  • Coscione, A.
  • Quaggio, J.
  • Cantarella, H.
  • Moraes, M.
• Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
• Volume: 31
• Issue: 4
• Year: 2007
• Summary: The efficiency of subsurface acidity alleviation by surface liming in the presence of crop residues is controversial and needs more information. The study aimed to quantify the contribution of cover crop residues, regarding their contents of low molar mass organic acids and soluble nutrients to the mobilization of reaction products of surface-applied lime in the soil profile. Two experiments were conducted under laboratory conditions using 30 cm high PVC cylinders filled with acid and clayey red latosol. Treatments consisted of sole application of lime to 80% soil base saturation (6.1 t ha -1) or lime in combination with radish ( Raphanus sativus) or black oat ( Avena strigosa) [ Avena nuda] crop residues (20 t ha -1), as well as the equivalent amounts of organic acids and inorganic salts present in the plant materials. The application of lime alone or in combination with plant material reduced soil acidity in the 0-8 cm surface layer only. The low recovery of organic acids added to the soils (≤7.2%) indicates that the acids were rapidly metabolized or adsorbed to the soil colloidal fraction, which explains the small effect on cation mobilization. A substantial part of the ion mobilization in the soil and leached solution after application of crop residues was probably due to the plant-own inorganic ion content due to the high water solubility: 65 to 71% for cations and 84% for anions. The greatest amount of aluminium displaced from the soil was due to the application of inorganic salt solutions. The presence of plant residues had little effect on the mobilization of the reaction products of surface-applied lime.

417. Using pre-existing channel substrate to determine the effectiveness of best management practices, Sandusky River, Ohio.

• Authors:
  • Gomezdelcampo, E.
  • Murphy, R. P.
  • Evans, J. E.
• Source: JOURNAL OF GREAT LAKES RESEARCH
• Volume: 33
• Issue: SI2
• Year: 2007
• Summary: The Sandusky River basin, located in northwest Ohio, has been influenced by agriculture since the late-1800s. In 2003, the Ohio Environmental Protection Agency identified various tributaries of the Sandusky River as failing to meet biological water quality standards mainly due to siltation. To assess the effectiveness of best management practices (BMPs), a cutoff channel of the Sandusky River in Crawford County, Ohio was used as a unique archive of channel bed material that existed in the previous channel. Historical aerial photographs and USGS peak discharge data suggest the channel was likely abandoned between 1957 and 1964. Twelve sediment cores between 2 and 3 meters in depth were collected with a vibracore, and grain-size analyses of the cutoff channel substrate were compared to similar data collected from the modern channel. Results showed an historical fining-upward trend in the mean grain size of the coarse fraction, from gravel in the cutoff channel to sand in the modern channel, but no change in the mean grain size of the fine fraction. A series of alternative explanations were examined to elucidate this fining, including sediment storage, trends in population and crop cultivation, existence of BMPs, and sediment transport during floods. Evidence from this study strongly suggests that a shift from the cultivation of low-cover crops (hay and oats) to high-cover crops (corn and soybeans) has changed the proportion of coarse-grained to fine-grained sediment loading in this section of the Sandusky River. The results have implications both for the effectiveness of BMPs in Crawford County and possibly for Lake Erie sediment budgets.

418. Evaluation of five plant species as cover crops in the high valleys of Mexico.; Evaluacion de cinco especies vegetales como cultivos de cobertura en valles altos de Mexico.

• Authors:
  • Castillo Gonzalez, F.
  • Perez Olvera, M. A.
  • Navarro Garza, H.
• Source: Revista Fitotecnia Mexicana
• Volume: 30
• Issue: 2
• Year: 2007
• Summary: In this study we compared the plant coverage ability and main agronomic characteristics of five plant species in Nonoalco (2250 masl) and Ixayoc (2500 masl) in north eastern State of Mexico. The populations were: Scarlet runner bean ( Phaseolus coccineus), two faba bean varieties ( Vicia faba, var 'Purepecha' and 'V-35'), common vetch ( Vicia sativa), and oat ( Avena sativa var 'Saia'), in an experimental design in random blocks with three replications, in 6*4 m experimental plots. The scarlet runner and faba beans were planted in rows, while the vetch and oat were thrown sowed. The main variables evaluated were: percentage of area coverage and plant height, on four dates; biomass production at 70 d and at harvest, and grain yield. The results showed differences among populations in ground coverage and agronomic characteristics. Oat and vetch had the best ground cover in both sites. Oat showed the highest growth in both sites, and vetch had the second best behavior. The 'Purepecha' faba bean showed the lowest growth in both sites. The highest production of biomass for all populations in both periods, were obtained in Nonoalco because of its physical-chemical soil characteristics.

419. Review of Landsforsgene (the country's experiments) 2007. Experiments in the [plant] management sector.; Oversigt over Landsforsgene 2007. Forsg og undersgelser i de landkonomiske foreninger.

• Authors:
  • Pedersen, J. B.
• Source: Oversigt over Landsfors<o>gene 2007. Fors<o>g og unders<o>gelser i de land<o>konomiske foreninger
• Year: 2007
• Summary: Work conducted by Landsforsgene, a collaborative body that undertakes field trials and experiments on crop plants in Denmark, is reported. A general introduction gives details of conditions in the 2007 growing season (warmer in spring and wetter than usual in summer), and their effects on factors such as the efficacy of fertilizer application and the harvest. The aim is to give growers a basis for future planning, taking account of environmental conditions and profitable plant production. Most of the report is devoted to separate sections covering individual crops: winter barley, winter rye, triticale, winter wheat, spring barley, oats, spring wheat, field peas, grass seeds, rape, hemp, spinach, strawberries, potatoes, sugar beet, pasture plants (grasses and clovers), and maize. Within these sections details of varieties, fertilizers, weeds, and diseases are provided in the text and in numerous tables and photographs. Other small sections deal with topics including organic production, fertilizers, plant breeding, statistical methods, policies, and names and addresses of suppliers. The report concludes with a list of the 23 authors of sections, and a comprehensive index.

420. Challenges for sustainable cereal rust control in South Africa.

• Authors:
  • Marais, G. F.
  • Pakendorf, K. W.
  • Pretorius, Z. A.
  • Prins, R.
  • Komen, J. S.
• Source: Australian Journal of Agricultural Research
• Volume: 58
• Issue: 6
• Year: 2007
• Summary: The cultivation of small grain cereals was introduced to South Africa by Dutch settlers in the 17th Century. According to historical records the first documented epidemic of wheat stem rust occurred in the south-western parts of the current Western Cape in 1726. Recurring stem and leaf rust epidemics were associated with expanding wheat production and became particularly severe in the winter-rainfall regions of the Western and Eastern Cape, as well as in the summer-rainfall regions of the Free State. The wheat stripe rust pathogen was first detected in South Africa in 1996. Due to susceptibility of cultivars at the time of this exotic introduction, stripe rust has caused significant losses in commercial wheat production over the past 10 years. Pathotype surveys of Puccinia graminis and P. triticina were initiated in the 1920s, but were discontinued until research on wheat stem rust was resumed in the 1960s. Recent evidence has shown that P. graminis f. sp. tritici continues to evolve. In addition, the annual number of wheat stem rust collections is increasing, emphasising the sustained threat of this damaging pathogen. A stem rust pathotype first detected in 2000, with newly acquired virulence for Sr8b and Sr38, currently constitutes more than 80% of all collections. Leaf and stem rust diseases also occur on barley, oat, triticale, and rye and are important production constraints in several regions. Some studies have described variability in these pathogens but long-term records of pathogenicity changes in barley and oat rust are not available. Cereal rust diseases have clearly played an important role in South African agriculture and many production regions remain favourable for rust development. Current expertise in cereal rusts covers most technologies necessary to study the respective host-pathogen systems. However, a general lack of capacity and fragmentation of research groups prevent a unified approach and remain a challenge for sustainable cereal rust control in South Africa. A national strategy for cereal rust control, with particular emphasis on pathogen and host resources, and breeding for resistance, is urgently needed.