• Authors:
    • Giacomini, S.
    • Aita, C.
  • Source: Revista Brasileira de Ciencia do Solo
  • Volume: 32
  • Issue: 5
  • Year: 2008
  • Summary: This study was conducted to evaluate the accumulation and displacement of N-NO 3- in the soil after pig slurry application in no-tillage maize in southern Brazil. The doses of 0, 40 and 80 m 3/ha pig slurry were applied annually, for three years, on the mulch of cover crop of black oats [ Avena nuda] and of winter spontaneous vegetation, preceding maize sowing. The N-NO 3- concentration was evaluated in different soil layers to a depth of 60 cm and on six dates, from the slurry application until maize tasseling. The amount of N-NO 3- increased quickly in the soil surface layer with the pig slurry application, evidencing the high nitrification rates of ammoniacal N in the slurry. N-NO 3- produced in the surface layers moved down quickly in the soil profile. At a dose of 80 m 3/ha slurry the amounts of N-NO 3- in the 30-60 cm soil layer on the 30th day of the first year, 29th day in the second and 36th day in the third year were higher than the average of the treatments without slurry in 9, 21 and 32 kg N-NO 3-/ha, respectively. In the first two years the amount of soil N-NO 3- in the surface layer did not differ with slurry application on mulch of oats or spontaneous vegetation, indicating the low potential of grass mulch in promoting microbial N immobilization. The high rate of nitrification of ammoniacal N in the slurry and the fast displacement of N-NO 3- in the soil profile when maize N demand was still small indicate a greater susceptibility of N-NO 3- losses by leaching with slurry application, especially at a dose of 80 m 3/ha, where the average amount of total applied N in the three years was 244 kg/ha per year.
  • Authors:
    • Cargnin, R.
    • Inomoto, M.
    • Asmus, G.
  • Source: Tropical Plant Pathology
  • Volume: 33
  • Issue: 2
  • Year: 2008
  • Summary: Two greenhouse and one field experiment were carried out to evaluate the reaction of cover crops to reniform nematode, Rotylenchulus reniformis, and their effect on nematode populations in a naturally infested soil (2,359 nematodes/200 cm 3) and on cotton yield. Oil radish ( Raphanus sativus), Mulato grass ( Brachiaria ruziziensis * B. brizantha), forage sorghum ( Sorghum bicolor), tef ( Eragrostis tef), foxtail millet ( Setaria italica), Algerian ( Avena byzantina) and black ( A. strigosa) oats, pearl millet ( Pennisetum glaucum), and finger millet ( Eleusine coracana) were determined to be poor hosts for R. reniformis in greenhouse experiments. Grain amaranth ( Amaranthus cruentus) and quinoa ( Chenopodium quinoa) were good hosts to R. reniformis. In the field, lower nematode densities were observed after Mulato grass, oil radish and forage sorghum. Higher cotton fiber yields were obtained from plots cultivated with Mulato grass or sorghum during the winter compared to clean fallow. Cotton yield was inversely correlated with both reproduction factor (p
  • Authors:
    • Baker, B.
  • Source: Proceedings of the 5th Organic Seed Growers Conference, Salem, Oregon, USA
  • Year: 2008
  • Summary: The market for organic seed poses a great opportunity for both organic producers who want to diversify into new crops as well as for seed producers who want to enter into the rapidly growing organic market. While organic standards in the United States require the use of organic seed, organic producers are not able to find organic seed in sufficient quantity and of suitable quality to meet their production needs. Because commercial availability must be evaluated as part of the certification process, the certifying agents play an important role in assessing both the supply and demand for organic seed. Certifying agents were surveyed to identify how they assess commercial availability, what information resources are used, and what crops and varieties are considered commercially unavailable. More research is needed to forecast organic seed demand and overcome production obstacles.
  • Authors:
    • Blackshaw, R. E.
  • Source: Crop Protection
  • Volume: 27
  • Issue: 2
  • Year: 2008
  • Summary: Cover crops may have a valuable role to play in developing improved dry bean production systems. A field experiment was conducted to determine the agronomic benefits of including various fall-seeded and spring-seeded cereal cover crops with and without in-crop herbicides in dry bean. Main plot treatments included fall-seeded winter rye, barley, oat, and spring rye; spring-seeded barley, oat, and spring rye; and a no-cover crop control. Subplot treatments consisted of in-crop sethoxydim/bentazon and an untreated control. Fall-seeded cover crops were often superior to spring-seeded cover crops in terms of providing sufficient ground cover to reduce the risk of soil erosion and reducing weed emergence and growth. Among the fall-seeded cover crops, winter rye provided the greatest ground cover and often resulted in the greatest weed suppression. Dry bean density was not affected by any of the cover crops, but fall-seeded cover crops delayed emergence by up to 5 days and delayed maturity by up to 4 days. Cover crop effects on dry bean yield were most evident in the absence of in-crop herbicides, where fall-seeded cover crops increased dry bean yield by 20-90%. Cover crops also increased dry bean yield in 2 of 3 years when in-crop herbicides were used but yield increases were much smaller, ranging from 5% to 13%. These yield increases occurred with fall-seed cover crops that aided in weed management but also with spring-seeded cover crops where weed suppression was not evident, suggesting that cover crops provided additional benefits beyond weed management. Information gained in this study will be utilized to advise farmers on the most suitable use of cover crops in sustainable dry bean production systems.
  • 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:
    • Butkuviene, E.
  • Source: Biodiversity and animal feed: future challenges for grassland production. Proceedings of the 22nd General Meeting of the European Grassland Federation, Uppsala, Sweden, 9-12 June 2008
  • Year: 2008
  • Summary: Pasture sward improvement investigations were conducted during the period 1980-2003 at the Vezaiciai Branch of the Lithuanian Institute of Agriculture. The focus was on the effects of pasture turf cultivation and resowing time, different cover and catch crops, and herbicide use in combination with pasture resowing. Cover crops, catch crops and pasture resowing time all affected dry matter (DM) yield. The most suitable time for turf cultivation was August-September and spring was most suitable for grass sowing. The best cover crops were barley for grain and oat-vetch mixture for green forage/silage. Potato and cereals were the best catch crops for pasture resowing. DM yield of resown pasture increased by 0.04-2.181 ha -1 compared with old untreated pasture. Resowing led to increased proportions of legumes in the sward by 1.1-9.2%, while the proportions of forbs decreased by 9.1-14.9%.
  • Authors:
    • Mbuya, O.
    • Chase, C.
  • Source: Weed Technology
  • Volume: 22
  • Issue: 2
  • Year: 2008
  • Summary: Twelve winter cover crops were planted in Citra and Live Oak, FL, in 2004, to evaluate their potential for use as living mulches in organic vegetable production: black oat, rye, annual ryegrass, hard fescue, two cultivars of white clover, berseem clover, crimson clover, subterranean clover, arrowleaf clover, barrel medic, and a hybrid disc * strand medic cultivar. The best canopy development and weed suppression occurred with black oat, rye, and annual ryegrass. In 2005, black oat, two rye cultivars, and annual ryegrass were evaluated as living mulches in broccoli at Citra and Live Oak, using organic production methods. 'Florida 401' (FL 401) rye was tallest, black oat was intermediate, and 'Wrens Abruzzi' (WA) rye and 'Gulf' ryegrass were of similar height and were the shortest living mulches. Biomass harvested at 12 and 13 wk after planting at Citra and Live Oak, respectively, was greatest with FL 401 rye. At Live Oak, the three other mulches had similar amounts of biomass; however, at Citra, black oat biomass was greater than that of WA rye, and biomass of ryegrass was lowest. The greatest weed infestation occurred with the weedy control. Weed biomass was highest with the weedy control, intermediate with ryegrass, and lowest with rye and black oat. However, the biomass of the weedy control was lower than that of the living mulches plus any associated weeds. Marketable broccoli yield was highest with the weed-free control. Yields with black oat, WA rye, and ryegrass were similar to that of the weedy control, whereas yield with the FL 401 rye was lower than with the weedy control. Suppression of living mulches by mowing at 3 and 7 wk after planting had no effect on broccoli growth or yield.
  • Authors:
    • Souza, J.
    • Finger, J.
    • Gobbi, F.
    • Vanin, J.
    • Fey, E.
    • Conti, C.
  • Source: Central theme, technology for all: sharing the knowledge for development. Proceedings of the International Conference of Agricultural Engineering, XXXVII Brazilian Congress of Agricultural Engineering, International Livestock Environment Symposium
  • Year: 2008
  • Summary: The cassava has great ability to adapt and better develop in deep soils without compaction and aeration well. To achieve these characteristics, this work was carried out by subjecting the culture to eight formats furrows and three separate roofs of soil under the tillage system. The work was conducted in a farm located in the district of Pearl Independent municipality of Maripa - Parana - Brazil, which has Latosol red eutrophic. The experiment went installed in randomized blocks with split plot, in the plots main the different furrow in the subplots the coverages. Effectuate up assessments of moisture, penetrometro of impact, breakup of soil in the furrow, depth of maniva and groove, population of plants, stalks per plant and percentage of plants fallings. The coverages of forage turnip and oats had higher humidity and lower resistance to penetration in the layer of up to 8.75 cm. For sulcadores are obtained different breakup of soil, influencing the depth of furrow and maniva. The coverage of oats presented grooves and manivas most deeper, lower breakup soil, providing conditions for less plants fallings.
  • 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:
    • Lima, E. do V.
    • Moro, E.
    • Crusciol, C. A. C.
    • Andreotti, M.
  • Source: Bragantia
  • Volume: 67
  • Issue: 2
  • Year: 2008
  • Summary: The objective of this research work was to evaluate black oat decomposition and release of nutrients. The experiment was carried out during the 1998 cropping season in an experimental area located in Marechal Candido Rondon, Parana State, Brazil. A randomized block design with four replications was used. The cover crop was rolled over thirty days after emergence. The persistence and release of nutrients were evaluated at 0, 13, 35 and, 53 days after rolling and desiccation. The decomposition rate of oat residue was constant during this period (remaining 34% of the initial amount) and inversely proportional to the C:N ratio that showed an initial value of 34 and a final value of 50. Most K was released soon after oat management, remaining only 2% of the initial content in the last sampling time. N, P, Ca and S were gradually released, and in the last evaluation the remaining amount of these nutrients was 55, 42, 48, and 47% of the total accumulated amount, respectively. Compared to other plant nutrients, K followed by N were the nutrients available in higher amount in the soil, reaching maximum release speed between 10 and 20 days after rolling and dessication of black oat.