• Authors:
    • Göksoy, A. T.
    • Sincik, M.
    • Candogan, B. N.
    • Yazgan, S.
    • Bükükcangaz, H.
    • Demirtaş, Ç.
  • Source: African Journal of Biotechnology
  • Volume: 9
  • Issue: 41
  • Year: 2010
  • Summary: The aim of the study was to determine the response of soybean [ Glycine max (L.) Merr.] to drought at various stages of development in a sub-humid environment of Turkey. Drought-stress treatments was applied to plants in 2005 and 2006 by withholding irrigation at six critical stages: completely vegetative (fifth trifoliate) (T 2), flowering (T 3), podding (T 4), seed fill (T 5), full bloom+podding (T 6), and podding+seed fill (T 7). Growth and production was compared in each treatment to full irrigated (T 1) and non-irrigated (T 8) controls. Each drought treatment reduced shoot biomass and seed yield compared to well-watered plants, but only non-irrigated plants or plants droughted at vegetative or flowering stages produced fewer seed pods and seeds. Seed protein and oil content was highest among treatments when plants were droughted during the seed filling stage. Yield increased exponentially with crop water use and ranged from 2.1-2.5 tons ha -1 in non-irrigated plants to 3.5-4.0 tons ha -1 in the well-watered controls. However, plants droughted during the vegetative stage of development produced the highest yield per unit of irrigation water applied (that is, irrigation water use efficiency). This research results will be useful for maximizing soybean production and/or seed quality when irrigation water is limited.
  • Authors:
    • de Cara Garcia, M.
    • Roubtsova, T.
    • Antonio Lopez-Perez, J.
    • Ploeg, Antoon
  • Source: Journal of Nematology
  • Volume: 42
  • Issue: 2
  • Year: 2010
  • Summary: Broccoli (Brassica oleracea), carrot (Daucus carob), marigold (Tagetes patula), nematode-resistant tomato (Solanum lycopersicum), and strawberry (Fragaria ananassa) were grown for three years during the winter in a root-knot nematode (Meloidogyne incognita) infested field in Southern California. Each year in the spring, the tops of all crops were shredded and incorporated in the soil. Amendment with poultry litter was included as a sub-treatment. The soil was then covered with clear plastic for six weeks and M. incognita:susceptible tomato was grown during the summer season. Plastic tarping raised the average soil temperature at 13 cm depth by 7 degrees C. The different winter-grown crops or the poultry litter did not affect M. incognita soil population levels. However, root galling on summer tomato was reduced by 36%, and tomato yields increased by 19% after incorporating broccoli compared to the fallow control. This crop also produced the highest amount of biomass of the five winter-grown crops. Over the three-year trial period, poultry litter increased tomato yields, but did not affect root galling caused by M. incognita. We conclude that cultivation followed by soil incorporation of broccoli reduced M. incognita damage to tomato. This effect is possibly due to delaying or preventing a portion of the nematodes to reach the host roots. We also observed that M. incognita populations did not increase under a host crop during the cool season when soil temperatures remained low (< 18 degrees C).
  • Authors:
    • Catania, C. D.
    • Parera, C. A.
    • Monte, R. F. del
    • Uliarte, E. M.
    • Monte, M. S. A. de del
  • Source: Bulletin de l'OIV
  • Volume: 82
  • Issue: 938/939/940
  • Year: 2009
  • Summary: The aim of this work was to assess the effects of a cover crop, on the vegetative growth and production of grapevine. Three permanent cover crops: Agropyron elongatum (Host) Beauv. (tall wheatgrass), Trifolium pratense L. (red clover), the association Secale cereale L. - Bromus catharticus Vahl (cereal rye-rescuegrass) and two annual species: Sorghum sudanense (Piper) Stapf (Sudangrass), X Triticosecale Wittmack (triticosecale) were compared, with respect to no till soil management by herbicides application. The study was developed in a cv. Malbec vineyard with surface irrigation and in a vertical shoot positioning trellis system, located in Mendoza, Argentina. Parameters related to vegetative expression, grape production and its oenological potential were determined. Permanent covers of red clover, tall wheatgrass and the mixture cereal rye-rescuegrass restricted grapevine vigour compared to open soil (control), diminishing shoot growth, size of leaves and pruning weight. A lower yield production was also observed, with smaller clusters and a reduction of clusters per vine; with greater amounts of total anthocyanins and polyphenols. Permanent cover crops decreased titratable acidity and free amino nitrogen in the must; which slightly delayed alcoholic fermentation, although without stuck fermentation. In the wine tasting evaluation, wines coming from the three treatments with permanent cover crops were preferred by tasters and they appear with greater varietals authenticity. The introduction of a permanent cover crop reduced vegetative growth and yields of the grapevine, modifying the balance vigour/production of the vineyard, and therefore the composition of grapes and wine, without the need to conduct specific cultural operations.
  • Authors:
    • Smith, R. F.
    • Boyd, N. S.
    • Brennan, E. B.
    • Foster, P.
  • Source: Agronomy Journal
  • Volume: 101
  • Issue: 4
  • Year: 2009
  • Summary: Winter cover crops can add soil organic matter, improve nutrient cycling, and suppress weeds in organic vegetable systems. A 2-yr study was conducted on organic farms in Salinas and Hollister, CA, to evaluate the effect of seeding rate (SR) and planting arrangement on cover crop density, ground cover, and cover crop and weed dry matter (DM) with a mixed cover crop. The mix contained legumes (35% Vicia faba L., bell bean; 15% Vicia dasycarpa Ten., woolypod vetch; 15% Vicia benghalensis L., purple vetch; and 25% Pisum sativum L., pea) and 10% oat ( Avena sativa L.) by seed weight. Three SRs (112, 224, and 336 kg ha -1) and two planting arrangements (one-way versus grid pattern) were evaluated. Planting arrangement had no effect on the variables measured. When weeds were abundant, weed DM declined linearly with increasing SR from approximately 300 kg ha -1 at the low SR to
  • Authors:
    • Ferris, H.
    • DuPont, S. T.
    • Horn, M. van
  • Source: Applied Soil Ecology
  • Volume: 41
  • Issue: 2
  • Year: 2009
  • Summary: Soil food webs cycle nutrients and regulate parasites and pathogens, services essential for both agricultural productivity and ecosystem health. Nematodes provide useful indicators of soil food web dynamics. This study was conducted to determine if nematode soil food web indicators and crop yield can be enhanced by combinations of cover crops in a conservation tillage system. The effects of three cover crop treatments (vetch/pea, oat/wheat and oat/wheat/pea/vetch) with low, medium and high C:N and a bare fallow control were investigated in Davis, CA. Nematode fauna, soil properties and plant productivity were measured. Soil food web indices, including the Enrichment Index (EI), Structure Index (SI), Basal Index (BI), and Channel Index (CI), based on the composition of nematode assemblages, were calculated to infer soil food web condition. Cover cropped tomato/corn rotations had twice the number of enrichment opportunist bacterial feeding nematodes, active participants in nitrogen mineralization, than fallowed tomato/corn rotations (opportunist bacterial feeders=163 versus 98). In winter fallowed plots food webs were basal, common in disturbed, nutrient-poor conditions (BI=37). Total number of enrichment opportunist nematodes, soil NH 4-N levels, and inferred nitrogen mineralization, were higher in cover crop treatments with low to mid C:N ratios. Omnivore and predator nematodes were scarce, averaging less than 6 nematodes 100 g -1 in all treatments. In year one, plant productivity was highest after fallow. In contrast, in year two productivity was highest after cover crops with high nitrogen content and productivity significantly correlated with the structure of the soil fauna. Monitoring the abundance of enrichment opportunists may provide managers with a new tool to evaluate soil food web nitrogen mineralization and plant productivity.
  • Authors:
    • Ngouajio, M.
    • Kaya, E.
    • Isik, D.
    • Mennan, H.
  • Source: Crop Protection
  • Volume: 28
  • Issue: 4
  • Year: 2009
  • Summary: Weed control is a major constraint for organic production around the world. Field studies were conducted in pepper ( Capsicum annuum L.) from 2004 to 2006 at the Black Sea Agricultural Research Institute experimental field in Turkey to determine the weed suppressive effects of winter cover crops. Treatments consisted of ryegrass ( Lolium multiflorum L.), oat ( Avena sativa L.), rye ( Secale cereale L.), wheat ( Triticum aestivum L.), gelemen clover ( Trifolium meneghinianum Clem.), Egyptian clover ( Trifolium alexsandrinum L.), common vetch ( Vicia sativa L.), hairy vetch ( Vicia villosa Roth.) and a bare fallow with no cover crop. Weed density and total weed dry biomass were assessed at 14, 28, and 56 days after incorporation to quantify effects of cover crops during a subsequent pepper crop. Cover crop establishment was similar in both growing seasons and individual species produced in the range of 1800-3500 kg/ha biomass. Ryegrass produced the greatest biomass compared with other species. Weed dry biomass production just before cover crop incorporation varied with year and cover crop species. Hairy vetch, ryegrass, oat and common vetch were the most competitive cover crops based on total weed dry biomass. Hairy vetch was the most promising cover crop and reduced weed density by 73% and 70% at 28 and 56 DAI, respectively. Pepper yields were higher following all cover crops except Egyptian clover. The highest yield was obtained from hairy vetch plots in both years. This research indicates that cover crops such as hairy vetch, ryegrass, oat and common vetch could be used in integrated weed management programs to reduce weed infestation in organic pepper.
  • Authors:
    • Migliorini, P.
    • Mazzoncini, M.
    • Bigongiali, F.
    • Antichi, D.
    • Lenzi, A.
    • Tesi, R.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 24
  • Issue: 2
  • Year: 2009
  • Summary: When animal husbandry is not included in organic farming systems, green manure may be crucial to preserve or increase soil organic matter content and to ensure an adequate N supply to crops. Different species, both legumes and nonlegumes, may be used as cover crops. The present research was carried out to investigate the effect of different green manure crops [oats and barley mixture ( Avena sativa L. and Hordeum vulgare L.), rye ( Secale cereale L.), brown mustard ( Brassica juncea L.), flax ( Linum usitatissimum L.), pigeon bean ( Vicia faba L. var. minor)] on the production of the following tomato crop. A field trial was conducted for two cropping seasons (2003-2004 and 2004-2005) in a commercial organic farm. The yield of tomato crop was positively affected by pigeon bean, although statistically significant differences in comparison with the other treatments were observed only in 2004-2005, when the experiment was conducted in a less fertile soil. This was probably due mainly to the effect of the pigeon bean cover crop on N availability. In fact, this species, in spite of a lower biomass production than the other cover crops considered in the study, provided the highest N supply and a more evident increase of soil N-NO 3. Also, cover crop efficiency, evaluated using the N recovery index, reached higher values in pigeon bean, especially in the second year. The quality of tomato fruits was little influenced by the preceding cover crops. Nevertheless, when tomato followed pigeon bean, fruits showed a lower firmness compared to other cover crops, and in the second year this was associated with a higher fruit N content.
  • Authors:
    • Ben-Hammouda, M.
    • Errouissi, F.
    • Moussa-Machraoui, S.
    • Nouira, S.
  • Source: Soil & Tillage Research
  • Volume: 106
  • Issue: 2
  • Year: 2009
  • Summary: No-tillage (NT) is becoming increasingly attractive to farmers worldwide because it clearly reduces production costs relative to conventional tillage (CT) and improves soil properties and crop yield. Currently, under semi-arid conditions in North Africa, modern no-tillage techniques are being practiced on several hectares of land. The effect of NT and CT management and crop rotation on soil properties under semi-arid Mediterranean conditions was studied, over a 4-year period at two locations in northern Tunisia. Data from a short-term (2000-2004) use of both no-tillage (NT) and conventional tillage (CT) at the ESAK (Tunisia) were used to evaluate the influence of the tillage systems on the physicochemical properties of soil at the 0-20 cm depth layers. Trial was set up in 2000, where the two tillage systems (CT and NT), and four crop types (durum wheat, barley, pea and oats) were implemented in two distinct sites close to two governorates: Kef (silt/clayey) and Siliana (sand/clay) in northwestern Tunisia. Four years after implementing the two different tillage systems, soil parameters (N, NO 32-, NH 4+ P, P 2O 5, K, K 2O, SOC, SOM and CEC) were determined and comparison between the two tillage systems was made. Our results showed that after 4 years the contents of some parameters for most crop types were greater under NT than under CT at 0-20 cm depth layers, the results varied depending on crop type and site. NT significantly improved soil content especially for K, K 2O, P 2O 5 and N. Under NT system SOM and SOC were enhanced, but without significant results. These enhancements were accompanied by the enhancement of the CEC and the decrease of the C/N ratio. Thus the mineralization process was slightly quicker under NT. Our results also indicate that residue cover combined with no-tillage appears to improve some agronomic parameters and biomass production (grain yield). Multivariate analyses indicate that the improvement of soil properties was dependant on tillage management, sites (climate and soil type) and crop succession (species and cover residue). It must be pointed out that a 4-year period was not sufficient to clearly establish some parameters used in the effects of the NT system on soil properties under semi-arid conditions in northwestern Tunisia.
  • Authors:
    • Hill, J.
    • Jacobs, J. L.
    • Jenkin, T.
  • Source: Animal Production Science
  • Volume: 49
  • Issue: 7
  • Year: 2009
  • Summary: The efficient production and subsequent utilisation of home-grown forage is seen as the cornerstone of profitability of the dairy industry as it leads to lower unit costs of milk production compared with purchased forage or grain supplements. Cereals such as wheat ( Triticum aestivum L.), oats ( Avena sativa L.) and triticale ( Triticum * Triticosecale) all have the potential to produce high forage dry matter (DM) yields. These forages are not widely grown within dryland Australian dairy systems and there is a paucity of information on both the agronomic requirements and subsequent ensiling and feed-out management under these conditions. The experiment reported in this paper examines the DM yield, nutritive and ensiling characteristics of three small-grain cereals (triticale, wheat and oats) cut at various stages of development and ensiled with or without silage additives. We hypothesised that: (1) delaying harvesting until later stages of growth would result in higher DM yields, but negatively impact on both nutritive and fermentation characteristics of subsequent silages; (2) ensiling wilted material at earlier harvests would improve fermentation characteristics compared with direct ensiled material; and (3) the use of silage additives at all harvests would improve fermentation characteristics of resultant silages compared with untreated silages. Apart from winter oats, the estimated metabolisable energy of forages was highest at the boot stage of growth, declined during anthesis and then rose again during milk and soft-dough stage of growth. The crude protein content of forages declined with maturity, with final values at soft dough below 90 g/kg DM. Neutral detergent fibre content was highest at anthesis and then declined, with lowest values observed at soft dough (497-555 g/kg DM). In the majority of cases silages were well preserved, with direct ensiled material having pH values generally below 4.5 and wilted material below 5.0, with limited proteolysis as assessed by ammonia-N contents in the range of 5-15% of total-N. The production of volatile fatty acids and lactic acid was influenced by wilting and the use of additives. Generally, wilted silages fermented less than the corresponding direct ensiled forages, whereas the use of Sil-All 4*4 additive resulted in a lactic acid-dominant fermentation compared with LaSil additive, which resulted in a greater proportion of acetic acid as an end product of fermentation. The findings of the present study highlight the potential of forage cereals to produce high DM yields for whole crop cereal silage. The timing of harvest directly influences nutritive characteristics of forages for ensiling. The use of silage additives can assist in controlling fermentation pathways during ensilage, ensuring the production of silages with fermentation attributes more likely to lead to higher intakes when fed to animals.
  • Authors:
    • Vanderlinden, K.
    • Murillo, J. M.
    • Madejon, E.
    • Lopez-Garrido, R.
    • Melero, S.
    • Ordonez, R.
    • Moreno, F.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 133
  • Issue: 1-2
  • Year: 2009
  • Summary: Long-term field experiments can provide relevant information regarding soil organic carbon sequestration under different soil tillage systems. Especially, conservation tillage (CT) has been proved to be a practice that highly contributes to improve soil quality. For that reason, the study of soil quality indicators, such as organic fractions, are useful tools to assess changes caused by different soil tillage systems in long-term field experiments. We evaluated long-term effects of conservation tillage on soil carbon fractions and biological properties in a sandy clay loam Entisol (soil A) and in a clay Vertisol (soil B) located in semi-arid SW Spain. Cereal-sunflower-legume rotations under rainfed conditions were used in both soils in which conservation tillage (CT) was compared to traditional tillage (TT). Soil samples were collected at three depths (0-5, 5-10 and 10-20 cm) four months after sowing a pea crop ( Pisum arvense L.) in the Entisol and a wheat crop ( Triticum aestivum L.) in the Vertisol. Labile fractions of the total organic carbon (TOC) were determined as active carbon (AC) and water soluble carbon (WSC). Biological status was evaluated using soil microbial biomass carbon (MBC) and enzymatic activities [dehydrogenase activity (DHA), o-diphenol oxidase activity (Dphox), and beta-glucosidase activity (beta-glu)]. As a rule, the contents of AC, WSC, MBC, beta-glu and Dphox in soil A and contents of TOC, AC and DHA in soil B were higher in CT than in TT, at the 0-5 cm depth. In both soils, the studied parameters decreased with depth under both tillage treatments (TT and CT). Values of AC, TOC, MBC and beta-glu were positively correlated with each other ( p