• Authors:
    • Santos, V. P.
    • Antedomenico, S. R.
    • Borges, D. C.
    • Inomoto, M. M.
  • Source: Tropical Plant Pathology
  • Volume: 34
  • Issue: 1
  • Year: 2009
  • Summary: The black oat ( Avena strigosa), the white oat ( A. sativa) and the Algerian oat ( A. byzantina) have been widely used as cover crops under succession with soybean, cotton, bean, potato and carrot, which are crops highly damaged by Meloidogyne incognita. The management of M. incognita may have as a component the use of oat genotypes that reduce the nematode population density. Three greenhouse experiments were carried out in order to evaluate the host suitability of five genotypes of black oat ('CPAO 0010', 'Common', 'Embrapa 29', 'Embrapa 140' and 'IPFA 99006'), one of white oat ('UFRGS 17') and one of Algerian oat ('Sao Carlos') to three isolates of M. incognita race 4 (BA, SP and MT). The black oats increased the population density of the nematode. The oats 'UFRGS 17' and 'Sao Carlos' reduced or caused a small increase in the population of M. incognita race 4, and neither differentiated from Crotalaria spectabilis. Therefore, the white oat 'UFRGS 17' and the Algerian oat 'Sao Carlos' should be used in preference to black oats as cover crops in areas infested with M. incognita race 4.
  • Authors:
    • Sattler, A.
    • Faganello, A.
    • Fontaneli, R. S.
    • Vargas, L.
  • Source: Ciencia Rural
  • Volume: 39
  • Issue: 7
  • Year: 2009
  • Summary: Black oat ( Avena strigosa [ Avena nuda]), an important winter cover crop in south Brazil, is a weed problem in cool season grain crops as well as ryegrass. Two trials in a randomized complete block design were conducted in Passo Fundo, Rio Grande do Sul, Brazil, to study different oat management methods applied on black oat at anthesis and milk stages to avoid it from becoming a weed plant in wheat cropped after soyabean. The plot area was 60 m 2. Nine treatments were tested in both trials: spray herbicide; roll plus herbicide; hay harvest; silage harvest; mowing; grinding, silage; rolling; disking; and grain harvesting. The average total biomass at anthesis was 5016 kg DM/ha and at milk stage was 6050 kg DM/ha. Soyabean cropped in the summer season yield 2080 kg/ha and it was not affected by black oat treatments. During the second year, the wheat plots sprayed herbicide before planting yielded 2472 kg/ha and spike density of 355/m 2, however, plots without herbicide yielded 836 kg/ha and had 225 spikes/m 2. On black oat milk stage managements, the yield average was 1733 kg/ha and 334 spikes/m 2, on sprayed herbicide plots before planting. In opposite, the plots without herbicide, wheat plants were completely dominated by resurgent black oat plants, due to managements applied during the previous winter. Mechanical management methods applied only in black oat development stages allowed seed germination during winter crops cycle. This problem is avoided by spraying herbicide before oat anthesis, because after that any management method tested was unsuccessful to control oat after the following winter crops, so it is necessary to spray herbicide before seeding winter cash crops.
  • Authors:
    • Albuquerque, J. A.
    • Reichert, J. M.
    • Reinert, D. J.
    • Genro Junior, S. A.
  • Source: CIENCIA RURAL
  • Volume: 39
  • Issue: 1
  • Year: 2009
  • Summary: A study was conducted to evaluate the effects of crop succession and rotation on the crop yields and physical properties of an oxisol (clayey Haplortox) under no-tillage system, in Rio Grande do Sul State, Brazil. The treatments included four cropping sequences, used from 1998 to 2001: (1) succession wheat/soyabean; (2) rotation corn/oat/corn + Cajanus cajan/wheat/soyabean/wheat; (3) rotation Cajanus cajan/wheat/soyabean/wheat/soybean/oat; and (4) rotation Crotalaria juncea/wheat/soyabean/oat/corn/wheat. In October 2000 and 2001, soil samples were collected to determine the physical properties, and in all years, crop yields were measured. The oxisol under no-tillage had a high degree of compaction with the greater soil bulk density and lower macroporosity than the critical limit for clay texture. The largest limitations were observed below the layer of 0-0.03 m, because in the uppermost layer, soil mobilization by successive operations of fertilizer application and sowing increased soil porosity and reduced soil density. Thus, greater volume of pores was observed between soil saturation and field capacity, responsible for soil aeration, and between field capacity and wilting point, responsible for storage of plant available water. The use of cover crops once every three years was not efficient to reduce soil compaction. The yield of the subsequent crops was positively influenced in the rotation with Crotalaria juncea, while the other cropping systems did not differ from crop succession.
  • Authors:
    • Wang, X.
    • Yang, Y.
    • Wu, F.
    • Li, Q.
  • Source: Acta Agriculturae Scandinavica Section B-Soil and Plant Science
  • Volume: 59
  • Issue: 5
  • Year: 2009
  • Summary: We studied the effects of rotation and interplanting on soil bacterial communities and crop yields using cucumber as the main vegetable. Onion and garlic were used as interplanting species, and wheat, soybean, villose (more commonly, villous) vetch, clover, and alfalfa were used as rotation plants. T-RFLP techniques were used to show the effects of rotation and interplanting systems on diversity index and richness index of cucumber rhizosphere soil bacterial communities. The results showed that both rotation and interplanting systems increased the richness index and diversity index of soil bacterial community structures, except where alfalfa was used as the rotation plant. The diversity index of the cucumber rhizosphere bacterial community structure was highest in the wheat rotation cropping system, and the richness index of soil bacteria was highest in wheat and clover rotations and in the onion interplanting system. Our results show that rotation and interplanting systems beneficially altered community structures of dominant soil bacteria, and increased cucumber yield and soil bacterial diversity. The best cultivation system to increase cucumber yield utilized onion as an interplanting species and wheat as a rotation plant.
  • Authors:
    • Rosenthal, M. D.
    • Pinho, C. F.
    • Machado, A.
    • Noldin, J. A.
    • Pinto, J. J. O.
    • Donida, A.
    • Galon, L.
    • Durigan ,M.
  • Source: PLANTA DANINHA
  • Volume: 27
  • Issue: Especial
  • Year: 2009
  • Summary: The objective of this study was to evaluate the residual soil activity of herbicide (imazethapyr+imazapic), labeled for the Clearfield (CL) system and using corn, cv. Biomatrix 2202, as a bioindicator. The study was carried out in a greenhouse, at the Universidade Federal de Pelotas, in southern Brazil. Rice, cv. IRGA 422 CL, was planted in boxes (60*40*20 cm). At the 3-4 leaf stage, the herbicide Only (imazethapyr+imazapic) was sprayed at 0; 25+75; 37.5+112.5 and 50+150 g ha -1. After harvesting the rice, boxes were kept without flooding for 45 days. Black oat (Avena strigosa) was planted to keep the soil covered during the winter. In the spring, oat was harvested and 360 or 540 days after herbicide application (DAA), the soil from the boxes was transferred to two sets of pots labeled as experiment 1 (main corn crop) and experiment 2 (minor corn crop), respectively. The soil for experiment 2 was kept drained during the time period between seeding the two studies (360 to 540 DAA). Corn was planted in both studies and harvested at the 4-5 leaf stages. The variables evaluated were shoot and root biomass, plant height and leaf area index (for experiment 2). The data from both studies were analyzed using ANOVA (
  • Authors:
    • Cao, E.
    • Andrigueti, M.
    • Carvalho, P.
    • Anghinoni, I.
    • Costa, S.
    • Souza, E.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 33
  • Issue: 6
  • Year: 2009
  • Summary: The potential for adopting crop-livestock systems in southern Brazil is high, especially in untilled soybean areas with cover crops in the winter season. The long-term use of this system at different grazing intensities will result in different carbon and nitrogen stocks in the soil due to the different plant and animal residues. This research was conducted to evaluate alterations in total carbon and nitrogen pools and in organic matter fractions in a soil under different grazing intensities under no-tillage. The experiment on a Rhodic Hapludult (Oxisol) was initiated in 2001, after soybean harvest. The treatments were different cattle grazing (black oat+ryegrass) pressures (10, 20 and 40 cm sward height) and an ungrazed treatment in the winter and soybean in the summer, in a randomized block design. Soil samples were taken at the beginning of the experiment (May, 2001), after three years (May, 2004) and after six years (May, 2007) to evaluate the content and stocks of organic carbon and nitrogen. Moderate grazing intensities (20 and 40 cm plant height) resulted in an increase of total carbon and nitrogen and in the organic matter particulate fraction, similarly to the ungrazed area. However, at the most intensive grazing pressure (10 cm plant height) there were losses in the stocks of these elements and reduction in soil organic matter quality.
  • Authors:
    • Sanginga, N.
    • Olufajo, O.
    • Iwuafor, E.
    • Abaidoo, R.
    • Yusuf, A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 129
  • Issue: 1/3
  • Year: 2009
  • Summary: Understanding changes in soil chemical and biological properties is important in explaining the mechanism involved in the yield increases of cereals following legumes in rotation. Field trials were conducted between 2003 and 2005 to compare the effect of six 2-year rotations involving two genotypes each of cowpea (IT 96D-724 and SAMPEA-7) and soybean (TGx 1448-2E and SAMSOY-2), a natural bush fallow and maize on soil microbial and chemical properties and yield of subsequent maize. Changes in soil pH, total nitrogen (N tot), organic carbon (C org), water soluble carbon (WSC), microbial biomass carbon (C mic) and nitrogen (N mic) were measured under different cropping systems. Cropping sequence has no significant ( P>0.05) effect on soil pH and C org, while WSC increased significantly when maize followed IT 96D-724 (100%), SAMPEA-7 (95%), TGx 1448-2E (79%) and SAMSOY-2 (106%) compared with continuous maize. On average, legume rotation caused 23% increase in N tot relative to continuous maize. The C mic and N mic values were significantly affected by cropping sequence. The highest values were found in legume-maize rotation and the lowest values were found in fallow-maize and continuous maize. On average, C mic made up to 4.8% of C org and N mic accounted for 4.4% of N tot under different cropping systems. Maize grain yield increased significantly following legumes and had strong positive correlation with C mic and N mic suggesting that they are associated with yield increases due to other rotation effects. Negative correlation of grain yield with C mic:N mic and C org:N tot indicate that high C:N ratios contribute to nitrogen immobilization in the soil and are detrimental to crop productivity. The results showed that integration of grain legumes will reverse this process and ensure maintenance of soil quality and maize crop yield, which on average, increased by 68% and 49% following soybean and cowpea, respectively compared to continuous maize.
  • Authors:
    • Brown, S.
    • Westhoff, P.
  • Issue: 05-09
  • Year: 2009
  • Summary: This report incorporates higher energy prices estimated by CRA International under H.R. 2454 (The American Clean Energy and Security Act of 2009) on Missouri crop production costs. This analysis uses current 2009 Missouri crop production cost estimates as the base and examines the level of these production costs in 2020, 2030, 2040 and 2050 assuming these production costs change only as a result of the higher energy costs estimated by CRA International under H.R. 2454. Using the 11, 34 and 45 percent increases found by CRA International in motor fuel, natural gas and electricity prices, respectively, by 2050 as a result of H.R. 2454, estimated Missouri crop operating costs increase by 8.1, 8.8, 4.4 and 10.4 percent for dryland maize, irrigated maize, soyabeans and wheat, respectively.
  • Authors:
    • NASS
    • USDA
  • Year: 2009
  • Authors:
    • Fortin, J.
    • Tremblay, G.
    • Ziadi, N.
    • Chantigny, M. H.
    • Rochette, P.
    • Angers, D. A.
    • Poirier, V.
  • Source: Soil Science Society of America Journal
  • Volume: 73
  • Issue: 1
  • Year: 2009
  • Summary: Both tillage and fertilizer management influence soil organic C (SOC) storage, but their interactive effects remain to be determined for various soil and climatic conditions. We evaluated the long-term effects of tillage (no-till, NT, and moldboard plowing, MP), and N and P fertilization on SOC stocks and concentrations in profiles of a clay loam soil (clayey, mixed, mesic Typic Humaquept). Corn (Zea mays L.) and soybean [Glycine max (L) Merr.] were grown in a yearly rotation for 14 yr. Our results showed that NT enhanced the SOC content in the soil surface layer, but MP resulted in greater SOC content near the bottom of the plow layer. When the entire soil profile (0-60 cm) was considered, both effects compensated each other, which resulted in statistically equivalent SOC stocks for both tillage practices. Nitrogen and P fertilization with MP increased the estimated crop C inputs to the soil but did not significantly influence SOC stocks in the whole soil profile. At the 0- to 20-cm depth, however, lower C stocks were measured in the plowed soil with the highest N fertilizer level than in any other treatment, which was probably caused by a greater decomposition of crop residues and soil organic matter. Conversely, the highest SOC stocks of the 0- to 20-cm soil layer were observed in the NT treatment with the highest N rates, reflecting a greater residue accumulation at the soil Surface. When accounting for the whole soil profile, the variations in surface SOC due to tillage and fertilizer interactions were masked by tillage-induced differences in the 20- to 30-cm soil layer.