• Authors:
    • Ferrari, S.
    • Picoli, P.
    • Lazarini, E.
    • Barbosa, C.
  • Source: Cientifica (Jaboticabal)
  • Volume: 39
  • Issue: 1/2
  • Year: 2011
  • Summary: The objective of this study was to evaluate the straw effect of four cover crops [grain sorghum ( Sorghum bicolor L. Moench), sun hemp ( Crotalaria juncea L.), pearl millet ( Penisetum americanum L.), and brachiaria ( Brachiaria brizantha cv. Marandu)] sown at two different times and a fallow area and its effects on soybean cultivated in succession in a no tillage system. The study was carried out from march/08 to april/09 in the experimental farm of the College of Engineering, a unit of the Universidade Estadual Paulista (UNESP), located in Selviria, a county of the state of Mato Grosso do Sul, (51degrees22′W and 20degrees22′S, with 335 m altitude), Brazil, in an Oxisol. The treatments consisted in the sowing of the four cover crops on March 27 and April 23 of 2008 and in the use of a fallow area. The experiment was set in the field according to a randomized complete block design with eight repetitions. Forage crops (sunhemp and B. brizantha) sown in two seasons do not change the soybean yield. Soybean yield on sorghum and millet sown in March was higher than that observed for the same crops sown in April. The grasses used are shown as a viable option for the production of dry matter for soybean sown in March.
  • Authors:
    • Brennan, E.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 3
  • Year: 2011
  • Summary: Cone planters (CP) uniformly distribute seed over research plots; however, preparing seed for CP by weighing is time-consuming. This study evaluated (i) the effect of seed preparation method (scooping with a calibrated cup vs. weighing) on population density of monoculture cover crops planted with a CP, (ii) time required for scooping vs. weighing, and (iii) the effect of scooping on segregation of pre-made cover crop mixtures. Monocultures included mustard [ Brassica juncea (L.) Czern.], rye ( Secale cereale L.), common vetch ( Vicia sativa L.), and faba bean ( Vicia faba L.) planted at 1*, 2*, and 4* seeding rates; 1* rates in pure live seed m -2 were 24 (faba bean), 43 (common vetch), 291 (rye), and 310 (mustard). Mixtures contained rye, oat ( Avena sativa L.), barley ( Hordeum vulgare L.), faba bean, common vetch, or pea ( Pisum sativum L.), and by weight included: Mix 1 (10% rye, 90% faba bean), Mix 2 (10% oat, 90% faba bean), Mix 3 (10% barley, 90% faba bean), Mix 4 (10% common vetch, 90% rye), and Mix 5 (10% rye, 25% pea, 30% common vetch, 35% faba bean). Seed preparation method did not affect the population densities of the monocultures. Preparing seed packets was at least two times more time-consuming with the weighing than scooping method. Calibrating cups to scoop within 1% of the desired seed packet weight was not difficult. However, segregation occurred while scooping some mixtures from a bucket whereby smaller-seeded components increased with scooping depth. Simple methods to detect seed segregation in mixtures are discussed.
  • Authors:
    • Degrande, P.
    • Soria, M.
  • Source: Revista Brasileira de Milho e Sorgo
  • Volume: 10
  • Issue: 2
  • Year: 2011
  • Summary: Pest species that are enhanced by cover crops used in no-tillage farming can cause damages to subsequent crops of economic importance planted into cover crops stubble. In the 2006/2007 growing season, in Dourados, MS, Brazil, a study was carried out to assess the arthropod fauna in three soybean no-tillage systems: unseeded vegetation-soybean, pearl millet-soybean and sorghum-soybean. During the soybean pre-planting season and the early soybean season, the incidence of pests and natural enemies was assessed in 1 m 2 of the cover crops and later on their respective stubble with soybean seedlings in development using a wood made frame square ("wood square" sampling method). The most abundant species at the soybean pre-planting season were caterpillars of Mythimna ( Pseudaletia) sequax and Mocis latipes (Lepidoptera: Noctuidae), and adults and nymphs of the predator Doru luteipes (Dermaptera: Forficulidae), showing a significant population increase on the pearl millet green cover crop. After the cover crops desiccation the incidence of Lagria villosa (Coleoptera: Lagriidae) species was significant on sorghum and pearl millet stubble and the genus Agrotis sp. (Lepidoptera: Noctuidae) on sorghum cover. Thus, the bioecology of pests and natural enemies associated with pearl millet as cover crop might be considered on the development of Integrated Pest Management (IPM) programs in conservation farming systems.
  • Authors:
    • Costa, M.
    • Castoldi, G.
    • Pivetta, L.
    • Steiner, F.
    • Costa, L.
  • Source: Revista Brasileira de Ciencias Agrarias
  • Volume: 6
  • Issue: 3
  • Year: 2011
  • Summary: The organic carbon is a major component of the soil organic matter, and its stock is influenced by the type of management system used. This study aimed to evaluate the effect of two cropping systems, with and without cover crop rotation, associated to three fertilization sources (mineral, organic and mineral+organic) in the organic and residual carbon contents of an Oxisol, in no-tillage system. Soil samples were collected at 0.0-0.10, 0.10-0.20 and 0.20-0.40 m depth in the first, second and third years of the experiment, installed in 2006. The crops sequence in the rotation system with cover crops was oat+vetch+turnip/corn/wheat/mucuna+brachiaria+crotalaria/corn/soybean, and in the following system it was wheat/corn/wheat/soybean/corn/soybean. The organic and mineral+organic fertilizers consisted in the sole application of organic fertilizers and combined with mineral fertilizer. The organic and residual carbon contents were not affected by the different cropping systems. The organic and mineral+organic fertilizers promoted increases in the organic and residual carbon contents. The system of crop succession fertilized with mineral fertilizer resulted in higher losses of soil carbon.
  • Authors:
    • Provance-Bowley, M.
    • Wyenandt, C. A.
    • Heckman, J. R.
  • Source: Journal of Sustainable Agriculture
  • Volume: 35
  • Issue: 6
  • Year: 2011
  • Summary: When municipal shade tree leaves (MCST-leaf) are used as mulch the residues impact soil fertility for crops in the rotation. Pumpkin (Cucurbita pepo L.), grown near Pittstown, New Jersey, using leaf mulch, was followed in the next year by sweet corn (Zea mays L.) and by a fall-seeded rye (Secale cereale L.) cover crop. A 15 cm layer of MCST-leaf mulch adds an estimated 448 kg ha(-1) of N organically bound within 45 Mg ha(-1) of leaf dry matter. Because of the high C/N ratio, little of this N becomes available in the first growing season as was apparent from the N immobilization and N deficiency temporarily observed when the land was initially cropped to pumpkin. Sweet corn ear size was increased on amended soil compared to unamended soil. Crop responses with both sweet corn and rye indicated that significant amounts of nitrogen became plant available from leaf mulch decomposition. Leaf mulch improves soil fertility for several years after incorporation but in ways not apparent through soil nitrate testing. Besides enhanced N nutrition, sweet corn ear size on MCST-leaf amended soil may be related to other improvements in soil quality such as increased water holding capacity.
  • Authors:
    • Lenssen, A. W.
    • Sainju, U. M.
    • Jabro, J. D.
    • Evans, R. G.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 42
  • Issue: 18
  • Year: 2011
  • Summary: We evaluated the effect of no tillage (NT) and conventional tillage (CT) on soil penetration resistance (PR), bulk density (BD), gravimetric moisture content (MC), and saturated hydraulic conductivity (Ks) during the fallow phase of a spring wheat-fallow rotation. The study was conducted on two soils mapped as Williams loam at the Froid and Sidney sites. Soil measurements were made on 19 May, 23 June, and 4 August 2005 at the Froid site and on 6 June and 8 July 2005 at the Sidney site. Tillage had no effect on either soil properties except on the PR at Sidney. However, soil PR, MC, and BD varied significantly with depth regardless of tillage and location. Further, soil PR and MC varied with the date of sampling at both locations, and PR generally increased with decreased MC at all soil depths. Soil Ks was slightly influenced by tillage at both locations.
  • Authors:
    • Uygur, F. N.
    • Koloren, O.
    • Kitis, Y. E.
  • Source: African Journal of Agricultural Research
  • Volume: 6
  • Issue: 5
  • Year: 2011
  • Summary: Weeds are one of the most important problems in newly established orchards. Especially in organic orcharding, the importance of weed management is much more than conventional orcharding. Therefore, importance of alternative methods to chemical control of weeds is increasing. This study was conducted to quantify the effects of common vetch (Vicia sativa L.) as living mulch on weeds and evaluate the availability of common vetch in organic citrus production. The study was carried out in Mandarin orchard which was established specially for this research in research and implementation area of the Plant Protection Department of Cukurova University in Turkey, in a three-year-period. Living mulch and control plots were placed between rows in newly established mandarin orchard and plots were maintained at the same locations until the end of the experiment. In this study, effects of the living mulch application on density, cover proportion, biomass, dry weight and similarity index of weed species were investigated. Overall three-years results of the study were evaluated, living mulch application reduced weed density and cover proportion average of 42.8% and 45.9% respectively compare to control. Biomass and dry weight of weeds were also reduced by living mulch in all years of the experiment. The results indicate that living mulch application by common vetch is an important alternative weed suppression method for ecological weed management.
  • Authors:
    • Brandenburg, R. L.
    • Shew, B. B.
    • Wilkerson, G. G.
    • Jordan, D. L.
    • Lassiter, B. R.
  • Source: Weed Technology
  • Volume: 25
  • Issue: 4
  • Year: 2011
  • Summary: Experiments were conducted in North Carolina during 2005, 2006, and 2007 to determine peanut and weed response when peanut was planted in strip tillage after desiccation of cereal rye, Italian ryegrass, oats, triticale, wheat, and native vegetation by glyphosate and paraquat before planting with three in-season herbicide programs. Control of common ragweed and yellow nutsedge did not differ among cover crop treatments when compared within a specific herbicide program. Applying dimethenamid or S-metolachlor plus diclosulam PRE followed by imazapic POST was more effective than a chloroacetamide herbicide PRE followed by acifluorfen, bentazon, and paraquat POST. Incidence of spotted wilt in peanut (caused by a Tospovirus) did not differ when comparing cover crop treatments, regardless of herbicide program. Peanut yield increased in all 3 yr when herbicides were applied POST, compared with clethodim only. Peanut yield was not affected by cover crop treatment. Response to cover crop treatments was comparable, suggesting that growers can select cereal rye, Italian ryegrass, oats, or triticale as an alternative to wheat as a cover crop in peanut systems without experiencing differences associated with in-season weed management.
  • Authors:
    • Nzokou, P.
    • Wilson, A. R.
    • Lin, Y.
  • Source: HortScience
  • Volume: 46
  • Issue: 3
  • Year: 2011
  • Summary: High rates of inorganic fertilizers are used in conventional intensive production systems such as Abies fraseri (fraser fir) cropping systems for Christmas trees. Groundcovers can be used as green mulches, help reduce the use of farm chemicals, and provide several environmental benefits. We investigated the performance of a low-input cropping system by combining two legume cover crops [Dutch white clover (Trifolium repens) and alfalfa (Medicago sativa)] in combination with low rates of inorganic fertilizers as a step toward a more sustainable production system. The randomized block design comprised one cover crop and one of three applications of reduced rate inorganic fertilizer (75%, 50%, and 25% of the recommended rate). A conventional system using herbicides for weed control and the 100% rate of inorganic fertilizer was used as a control. Parameters measured included tree morphology, foliar nitrogen concentration, soil mineral nitrogen, and nitrate-N leaching below the root zone. A significant positive growth response (height and diameter) was obtained in all alfalfa-based cropping systems. This was accompanied by foliar nutrient concentrations similar to conventional plots and a reduction in nitrate-N leaching. However, in white clover-based cropping systems, the growth response was reduced (both height and diameter), suggesting competition for soil resources. In addition, the total nitrate-N leaching was higher in this system, suggesting an imbalance between mineral nitrogen availability and use in white clover-based cropping systems. We conclude that if the potential competition between cover crops and trees can be properly managed, legume cover crops can be effectively used to make intensive production tree-based systems more sustainable. Further studies related to mineralization and macronutrient flows are needed before any definite recommendation can be made about the use of these systems in large-scale production systems.
  • Authors:
    • Trond M. Henriksen, T. M.
    • Anne-Kristin Løes, A.-K.
    • Sjursen, H.
    • Ragnar Eltun, R.
  • Source: Acta Agriculturae Scandinavica, Section B - Soil & Plant Science
  • Volume: 61
  • Issue: 2
  • Year: 2011
  • Summary: By restricted access to manure, nitrogen (N) supply in organic agriculture relies on biological N-fixation. This study compares grain yields after one full-season green manure (FSGM) to yields with repeated use of a green-manure catch crop. At two sites in south-eastern Norway, in a simple 4-year rotation (oats/wheat/oats/wheat), the repeated use of ryegrass, clover, or a mixture of ryegrass and clover as catch crops was compared with an FSGM established as a catch crop in year 1. The FSGM treatments had no subsequent catch crops. In year 5, the final residual effects were measured in barley. The yield levels were about equal for grains with no catch crop and a ryegrass catch crop. On average, the green-manure catch crops increased subsequent cereal yields close to 30%. The FSGM increased subsequent cereal yields significantly in two years, but across the rotation the yields were comparable to those of the treatments without green-manure catch crop. To achieve acceptable yields under Norwegian conditions, more than 25% of the land should be used for full-season green manure, or this method combined with green-manure catch crops. The accumulated amount of N in aboveground biomass in late autumn did not compensate for the N removed by cereal yields. To account for the deficiency, the roots of the green-manure catch crops would have to contain about 60% of the total N (tot-N) required to balance the cereal yields. Such high average values for root N are likely not realistic to achieve. However, measurement of biomass in late autumn may not reflect all N made available to concurrent or subsequent main crops.