• Authors:
    • Bellinder, R. R.
    • Brainard, D. C.
    • Hahn, R. R.
    • Shah, D. A.
  • Source: WEED SCIENCE
  • Volume: 56
  • Issue: 3
  • Year: 2008
  • Summary: Three major hypotheses were examined in this study: (1) the density of summer annual weeds is reduced in crop rotation systems that include winter wheat compared to those with strictly summer annual crops, (2) the integration of a red clover in cropping systems reduces weed seedbank densities, and (3) changes in weed seedbanks due to crop rotation system have greater impact on future crops that are managed with cultivation alone, compared to those managed with herbicides. To test these hypotheses, five 3-year rotation sequences were examined in central New York state, USA: continuous field maize (FC); field maize with red clover (FC+CL); field maize-oats-wheat (FC/O/W); sweetcorn-peas-wheat (SC/P/W), and SC/P/W with red clover (SC/P/W+CL). In the fourth year, sweetcorn, snap beans, and cabbage were planted in subplots with three levels of weed management as sub-subplots: cultivation alone, reduced-rate herbicides (1/2*), and full-rate herbicides (1*). The trial was carried out in two separate cycles, from 1997 to 2000 (cycle 1) and from 1998 to 2001 (cycle 2). Crop rotations with strictly summer annual crops (FC) did not result in consistently higher weed seedbank densities of summer annual weeds compared to rotations involving winter wheat (FC/O/W; SC/P/W; SC/P/W+CL). Integration of red clover in continuous field maize resulted in higher weed seedbanks (cycle 1) or emergence (cycle 2) of several summer annual weeds compared to field maize alone. In contrast, integration of red clover in the SC/P/W rotation led to a 96% reduction in seedbank density of winter annuals in cycle 1, although this effect was not detected in cycle 2. Observed changes in weed seedbank density and emergence due to crop rotation resulted in increased weed biomass in the final year in only one case (sweetcorn, cycle 2), and did not result in detectable differences in crop yields. In contrast, final year weed management had a strong effect on weed biomass and yield; cultivation alone resulted in yield losses for sweetcorn (32 to 34%) and cabbage (0 to 7%), but not snap beans compared to either 1/2* or 1* herbicides.
  • Authors:
    • Barth, G.
    • Garbuio, F.
    • Caires, E.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 39
  • Issue: 13/14
  • Year: 2008
  • Summary: Crop residues that are left on the soil surface to serve as mulch can diminish the soybean response to surface application of lime under no-till management by ameliorating soil chemical and physical attributes and the plant nutrition. A field experiment was performed in the period from 2000 through 2003 in Parana State, Brazil, on a clayey-sandy Rhodic Hapludox. Soil chemical attributes and soybean [ Glycine max (L.) Merrill] nutrition, grain yield, and quality were evaluated after surface application of lime and covering with crop residues of black oat ( Avena strigosa Schreb) and corn ( Zea mays L.) under a no-till system. Dolomitic lime was surface applied at the rates of 0, 2.5, 5.0, and 7.5 t ha -1 on the main plots, and three treatments with vegetable covering were applied on the subplots: (i) without covering, (ii) with covering of corn straw, and (iii) with covering of corn straw and black oat residue (oat-corn-oat). After 30 months, surface-applied lime increased soil pH and the exchangeable calcium (Ca 2+) and magnesium (Mg 2+) levels down to a 10-cm depth, independent of the vegetable covering treatments. The black oat and corn residues on the soil surface increased the soil exchangeable K + level at the 5- to 10-cm depth. Liming increased leaf potassium (K) content and phosphorus (P) content in the soybean grain and reduced leaf zinc (Zn) content and manganese (Mn) content in the soybean leaf and grain. There was no effect of liming on soybean grain, oil, or protein yields, independent of the vegetable residues kept on the soil surface. The treatment with black oat covering and corn straw increased leaf N content, P content in the leaf and grain, and the contents of K, Mg, copper (Cu), and Zn in the soybean grain. It also increased soybean grain and protein yields. The corn straw left at the surface after harvesting was very important to the performance of the no-till soybean.
  • Authors:
    • Zardo Filho, R.
    • Pereira Filho, P.
    • Caires, E.
    • Feldhaus, I.
  • Source: Soil Use and Management
  • Volume: 24
  • Issue: 3
  • Year: 2008
  • Summary: A 3-year field trial examined in a long-term no-till system the effects of surface-applied lime and cover black oat ( Avena strigosa Schreb) residues on soil chemical attributes, root growth and grain yield of corn ( Zea mays L.) and soybean ( Glycine max L. Merrill) on a loamy, kaolinitic, thermic Typic Hapludox in Parana State, Brazil. The treatments consisted of dolomitic lime broadcast on the soil surface at 0 or 12 t/ha, with and without cover of black oat residues. Corn and soybeans were grown without rainfall limitation. Applying lime on the surface improved soil acidity and decreased aluminium (Al) toxicity to a 10-cm depth 1 year after application. Surface liming increased pH and the content of exchangeable Ca 2+ to a 20-cm depth, and decreased Al toxicity to a 40- to 60-cm depth, 3 years after application, indicating that the surface-applied lime moved deeper. Cover black oat residues did not favour the mobility of surface-applied lime to alleviate subsoil acidity and an increase in the Al 3+ saturation level at the soil surface was found in unlimed plots with black oat residues. Root growth and grain yields of corn and soybean were not influenced by surface liming with or without cover black oat residue. Despite the soil acidity level, root length of corn and soybean ranged from 55 to 60% at 0- to 10-cm depth. The results suggest that Al toxicity is low in no-till systems during cropping seasons with adequate and well-distributed rainfall, but this effect is not related to the presence of cover oat residues.
  • Authors:
    • Zanatta, J. A.
    • Bayer, C.
    • Costa, F. de S.
    • Mielniczuk, J.
  • Source: Revista Brasileira de Ciencia do Solo
  • Volume: 32
  • Issue: 1
  • Year: 2008
  • Summary: Carbon (C) addition through crop residues (residue-C), C dioxide emission (CO 2-C) and the soil C stock (soil-C) are components of the C cycle in the soil-plant-atmosphere system. This 18-year study was conducted to identify agricultural practices that could potentially increase C retention in the soil and lessen global warming trends. The three C pools (residue-C, CO 2-C and soil-C) under different tillage systems (CT-conventional tillage and NT-no tillage) and cropping systems (O/M-oat ( Avena strigosa [ Avena nuda])/maize ( Zea mays) and V/M-vetch ( Vicia sativa)/maize) were evaluated and the CO 2-C/[residue-C+soil-C] quotient was proposed as C retention index (CRI), where low values indicate a high capacity of the management system to keep C in the soil. The CO 2-C emissions were measured for 17 months (between November 2002 and March 2004), sampling of aboveground residues of cover crops and harvest indexes of maize were used to quantify C addition by cropping systems, and soil-C stocks (0-0.2 m) were evaluated in 2003. The soil temperature (0.05 m) and gravimetric water content (0-0.05, 0.05-0.1 and 0.1-0.2 m) were also monitored from May 2003 onwards. In comparison to 1985, the C balance was negative in the soil under CT (-0.31 t ha -1 year -1 for O/M and -0.10 t ha -1 year -1 for V/M). On the other hand, the C balance was positive in NT soil, but only under V/M (+0.15 t ha -1 year -1) due to the greater C addition by crop residues. The CO 2-C emission was related to the soil temperature (r>0.85). The total CO 2-C emission varied from 3.6 to 4.0 t ha -1 and was not affected by the soil management systems. However, the CRI allowed a clear discrimination of the soil management systems to keep C in the soil. The C retention potential increased in the following order: CT O/M
  • Authors:
    • Aita, C.
    • Reichert, J. M.
    • Albuquerque, J. A.
    • Reinert, D. J.
    • Andrada, M. M. C.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 32
  • Issue: 5
  • Year: 2008
  • Summary: The physical quality of a Typic Hapludalf in a no-tillage system was evaluated after the use of cover crops, and the critical limit of bulk density was measured. In autumn/winter of 1999/00 and 2000/01, the site was cultivated with black oats ( Avena strigosa) [ Avena nuda] with vetch ( Vicia sativa) and in 2001/02, with forage turnip ( Raphanus sativus). Corn ( Zea mays) was sown in summer and at the end of the cycle, four summer cover crops ( Crotalaria juncea, Cajanus cajan, Stilozobium cinereum and Canavalia ensiformis) were sown compared to fallow soil. Soil bulk density and penetration resistance were measured. The rooting system was evaluated by a root profile method during the cycle of forage turnip, corn and summer cover crops. The soil bulk density was increased by no-tillage to levels considered critical for plant growth. The root growth of all crops used in the rotations suffered some degree of restriction. There was no difference among the species in their root growth potential in the compacted soil. The root growth of the cover crop was normal up to a bulk density of 1.75 Mg/m 3, while values between 1.75 and 1.85 Mg/m 3 were restrictive, with visible deformation of the root morphology. These deformations were more pronounced when bulk density was greater than 1.85 Mg/m 3, with increased root thickening, deviations in the vertical root growth direction and concentration of roots in the topmost soil layer. The evaluated species can be used in compacted soils, but at soil bulk density >1.85 Mg/m 3, soil mobilization through mechanical methods may be necessary to alleviate the effects on root and plant growth.
  • Authors:
    • Tyrankiewicz-Czaplewska, M.
    • Jaskulski, D.
    • Rudnicki, F.
  • Source: Fragmenta Agronomica
  • Volume: 25
  • Issue: 3
  • Year: 2008
  • Summary: The effect of some natural and economic and organizational factors on the share of fodder crops in the crop structure on the Kujawy and Pomorze Province, Poland. The research covered 127 municipalities and communes for which the analysis of spatial distribution of 4 species of fodder cereals (oat, triticale, cereal mixtures and maize grown for grain) and groups of fodder crops was made. It was observed that the share of fodder crops in the cropland structure in the communes of the Kujawy and Pomorze Province varied significantly. The greatest spatial variation was observed for the cultivation of maize and oat and lowest for triticale and fodder crops. The greatest share of oat in the cropland structure was recorded in the regions of low soil quality and, at the same time, low livestock density and relatively high farm acreage. Triticale and cereal mixtures in the cropland structure occurred especially on soils of lower agricultural quality, located in the regions of better-developed animal farming, mostly pigs. Fodder crops occur on arable land more abundantly wherever cattle farming was more developed and where, at the same time, the farms were relatively large. The soil quality, however, does not define the regions for this group of crops, similarly as the cultivation of maize for grain.
  • Authors:
    • Scudamore, K.
  • Source: World Mycotoxin Journal
  • Volume: 1
  • Issue: 3
  • Year: 2008
  • Summary: The cereal food chain covers events from the sowing of the seed until the point of ingestion of a food by the consumer. Mycotoxins may develop prior to harvest or through inadequate storage. Most mycotoxins are inherently stable natural chemicals but cleaning, milling and different methods of processing can change their concentrations. Legislation is necessary to protect the consumer so it is important to consider, among other things, the relationship between concentrations of mycotoxins in the raw grains and those in the product purchased by the consumer, especially where different limits are specified at successive stages in manufacture. Recent studies of the fate of fusarium mycotoxins in the cereal food chain carried out alongside industry in the UK have examined changes in the concentrations of deoxynivalenol, nivalenol, T-2 toxin, HT-2 toxin and zearalenone in wheat, maize and oats and the fumonisin mycotoxins in maize at key stages in the cereal chain. For example, fumonisin concentrations in maize grits after milling were reduced by about 75% compared with the raw maize, but remained similar to the maize in the flour and were increased (*3 to *5) in the bran and meal. Maize flour and grits were then processed into a range of food products such as breakfast cereals, cornflakes, extruded snack products and tortillas and the changes in concentrations were established. Simple extrusion of flour or grits reduced fumonisins by a further 30-70% depending on the process. Deoxynivalenol and zearalenone were found to be more stable than fumonisins during most processes.
  • Authors:
    • Gallandt, E.
    • Reberg-Horton, S.
    • Shearin, A.
  • Source: Weed Science
  • Volume: 56
  • Issue: 3
  • Year: 2008
  • Summary: Cover crop systems were investigated in 2004 and 2005 for their effects on the activity-density (a function of movement and density) of a promising group of weed biological control organisms, the ground beetles collectively known as carabids, with particular emphasis on a beneficial carabid species Harpalus rufipes. Marked H. rufipes released into pea/oat-rye/vetch cover crop plots were more than twice as likely to be recaptured within the same plots as beetles released in nonvegetated fallow plots (18 and 8%, respectively). Marked beetles released into fallow plots were more than twice as likely to leave their plots and be recaptured in pea/oat-rye/vetch plots as vice versa (13 vs. 5%), indicating a clear preference for habitat with vegetative cover. Overall recapture rates were not different between treatments. Unmarked H. rufipes activity-density was also higher in pea/oat-rye/vetch compared to fallow plots. Additionally, five cover crop systems, including the fallow and pea/oat-rye/vetch treatments, and two residue management methods (conventional and zone tillage) were investigated from June to August in 2005 for their effects on H. rufipes activity-density. Maize was planted in 2005 into residues of the five cover crop systems grown in 2004. H. rufipes activity-density was higher in zone and conventionally tilled maize planted in pea/oat-rye/vetch residues and conventionally tilled maize planted in red clover/oat residues than in any other cover crop and residue management combination. Pea/oat-rye/vetch cover crop systems are apparently beneficial for H. rufipes during the cover crop year as well as in subsequent crops planted into this cover crop's residues. This system was not the least disturbed system but, based on the number of tillage events, represented a medium level of disturbance among the various systems. Thus, some level of disturbance might be beneficial for H. rufipes, but how and when that soil disturbance occurs requires further research to determine the best means of conserving this species.
  • Authors:
    • Jandrey, D.
    • Strieder, M.
    • Minetto, T.
    • Silva, P.
    • Silva, A.
    • Endrigo, P.
  • Source: Ciencia Rural
  • Volume: 38
  • Issue: 3
  • Year: 2008
  • Summary: The growing of winter crop species results in benefits on soil characteristics, and can present economic advantages. Thus, it is important to introduce winter species that, besides straw, produce grains to increase the performance and the sustainability of agricultural activity. The objective of this research was to evaluate, in three growing seasons, the agronomic and economic performance of maize crop grown in succession to five winter cover crops and/or for grain production, cultivated under two rates of side dressing N fertilization. The experiment was carried out in the growing seasons of 2003/04, 2004/05 and 2005/06, in the state of Rio Grande do Sul, Brazil. In the three years, the treatments consisted of irrigated maize crop grown in succession to five winter cover crops species and to a control without cover crop. The maize cost production in succession to common vetch is lower than in succession to black oat and to wild radish. Comparing the winter cover crops for grain production, the gross income was higher when wheat was grown in relation to oat. The economic advantages of the use of wild radish and common vetch as previous crops to irrigated maize in relation to the poaceae species are only evident under conditions of low N availability in the soil.
  • Authors:
    • Jandrey, D.
    • Strieder, M.
    • Piana, A.
    • Sangoi, L.
    • Silva, P.
    • Silva, A.
    • Endrigo, P.
  • Source: PESQUISA AGROPECUARIA BRASILEIRA
  • Volume: 43
  • Issue: 8
  • Year: 2008
  • Summary: The objective of this work was to evaluate the productivity of irrigated maize, grown using several rates of nitrogen sidedress, in succession to different winter crops. The experiment was carried out in Eldorado do Sul, RS, Southern Brazil, during the 2003/2004, 2004/2005 and 2005/2006 growing seasons. Maize was sown in succession to five winter crops: black oat, common vetch, wild radish (straw production), white oat and wheat (grain and straw production), and to a control treatment, where the spontaneous vegetation was controlled by successive desiccant application. Maize grain yield was higher than 8 Mg ha -1 and was not affected by the specie of preceding winter crop, when nitrogen sidedress was applied. Maize grain yield was higher, when it succeeded wild radish and in the treatment without N in side-dressing. White oat and wheat added more than 3 Mg ha -1 of straw and produced more than 1.5 Mg ha -1 of grain. With supplementary irrigation and side-dress nitrogen application, it is possible to obtain high grain yield, when corn is cultivated as a sequential crop, independently of winter cover species.