• Authors:
    • Miyao, G.
    • Jackson, J.
    • Mitchell, J. P.
    • Horwath, W. R.
    • Doane, T. A.
    • Brittan, K.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 85
  • Issue: 3
  • Year: 2009
  • Summary: In spite of potential benefits and positive assessments of reducing primary tillage operations, only a small part of irrigated row crops is currently managed using reduced tillage, for reasons that include concerns about its agronomic suitability for certain crop rotations. Three years of a tomato/corn rotation under standard and no-tillage management were used to understand the fate of a fertilizer and cover crop nitrogen (N) application. Uptake of both inputs was reduced under no-tillage during the year of application, in this case a tomato crop. As a result, more input N was retained in the soil in this system. The initial challenge of reduced tomato yields diminished as no-tillage management remained in place and the soil N reservoir developed. Corn production was not affected by tillage treatment. Inclusion of a legume cover crop increased the amount of fertilizer N retained in the soil over time, more so under no-tillage than under standard tillage, emphasizing the benefit of cover crops in reducing the amount of fertilizer required to maintain productivity. While acceptance of reduced tillage ultimately depends on economic performance, the results of this study support its agronomic viability for irrigated row crops.
  • Authors:
    • Suhag, K. S.
    • Kumar, S.
    • Kumar, D.
    • Kumar, N.
  • Source: Haryana Journal of Agronomy
  • Volume: 25
  • Issue: 1/2
  • Year: 2009
  • Summary: The analysis of secondary data of various districts of Haryana for the period 1996-97 to 2005-06 revealed that both bullock and camel population declined in the wake of farm mechanization across districts, regions and state, while he-buffaloes population increased due to the increased use of carts for transport. The number of both wooden and iron ploughs declined, while those of sugarcane crushers, combine harvesters and bullock carts increased both at intra and inter-regions including state. The use of NPK fertilizers, credit disbursed through primary agricultural cooperative credit societies as well as irrigation intensity though increased across districts, regions and state, yet pesticides consumption declined in eastern region including state. The area under cereals had positive growth rates across districts, regions and state even but at the cost of pulses and oilseeds. Likewise, the area under fruits and vegetables though marginally declined across regions and state yet both increasing and decreasing trends existed across districts and the compound growth rates both for production and productivity of cereals have increased across districts, regions and state. Furthermore, the oilseeds production has declined across districts, regions and state but except for eastern region, the oilseeds productivity increased both in western region and state.
  • 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:
    • Rosa, D. M.
    • Mauli, M. M.
    • Nobrega, L. H. P.
    • Piccolo, G.
    • Smanhotto, A.
  • Source: Central theme, technology for all: sharing the knowledge for development
  • Year: 2008
  • Summary: It was analyzed a possible allelopathic action of black oat ( Avena strigosa Schreb) (BO) in a consortium (CO) with BO, forage turnip ( Raphanus sativus L.) (FT) and vetch ( Vicia sativa L.) (V) in relation to seedling emergency (SE), emergency speed (ES), seedling emergency speed (SES) plants heights and soybean productivity, in interval between covering desiccation with Glyphosate 480 (3 L ha -1) and the cultivar BRS 232 sowing (IDS). Plots of 5*2.5 m were randomly prepared with 1 m of border, four treatments of BO and CO and two control treatments, with five replications of 0.15 among rows. At bloom term, the plots were desiccated in an IDS, of one, ten, twenty and thirty days. The soybean was sown in November 2006, with 0.45 m among rows, thirteen sowing lines and 14 seeds by linear m -1. The harvest was manual and productivity was adjusted to 13% of water content. The experimental design was completely randomized, subdivided in plots. The data were submitted to normality, while averages were compared by Scott and Knott test at 5% of significance. There was a possible effect of BO and CO on SES, with higher SES to CO. The coverings did not influence on the other parameters however, IDS interfered in all of them. Thus, it is recommended CO use with IDS from ten days.
  • Authors:
    • Souza Filho, A. P. da S.
    • Nobrega, L. H. P.
    • Piccolo, G.
    • Fortes, A. M. T.
    • Uribe-Opazo, M.
  • Source: Central theme, technology for all: sharing the knowledge for development
  • Year: 2008
  • Summary: It was analyzed the possible allelopathic action of vegetal remains of black oat ( Avena strigosa Schreb) (BO) and a consortium (CO) of BO with forage turnip ( Raphanus sativus L.) and vetch ( Vicia sativa L.) in relation to the incidence of weed plants on soybean culture; in intervals (IDS) between covering desiccation with Glyphosate 480 (3 L ha -1) and the cultivar BRS 232 sowing; 5*2.5 m parcels with 1 m of border; four treatments of BO and CO and two control treatments, with five randomized replications, in August, 2006, with 0.15 m among rows. At bloom term, the plots were desiccated in an IDS, of one, ten, twenty and thirty days. The soybean was sown in November 2006, with 0.45 m among rows, thirteen sowing lines and 14 seeds by linear m -1. The incidence of weed plants was evaluated with a 0.5*0.5 m metal frame. The plants were counted and classified by narrow leaf (NL) and large leaf (LL). The soybean harvest was manual and its productivity was adjusted to 13% of water content. The experimental design was completely randomized, in split plot. The data were submitted to normality, while averages were compared by Scott and Knott test at 5% of significance. There was a possible suppressor allelopathic effect of BO and CO coverings on weed plants. The interval between desiccation and sowing interfered on weed population.
  • Authors:
    • Balkcom, K. S.
    • Arriaga, F. J.
    • Bergtold, J. S.
    • Stoll, M. E.
    • Price, A. J.
    • Kornecki, T. S.
    • Rap, R. L.
  • Source: Communications in Biometry and Crop Science
  • Volume: 3
  • Issue: 1
  • Year: 2008
  • Summary: Research has shown that some cover crops are allelopathic and can inhibit weed germination and growth. Additionally, negative allelopathic effects have been documented in cash crops planted into cover crop residue. However, little literature exists comparing relative the allelopathic potential of cover crops producers utilize in conservation-agriculture systems. This study assessed the effects of twelve cover crop extracts on radish ( Raphanus sativus L.) and cotton ( Gossypium hirsutum L.) radicle elongation, in three trials, using an extract-agar bioassay. In Trial 1 the cover crops were black oat ( Avena strigosa Schreb) cv. SoilSaver, crimson clover ( Trifolium incarnatum L.) cv. AU Robin, white lupin ( Lupinus albus L.) cvs. AU Homer and AU Alpha, rye ( Secale cereale L.) cv. Elbon, wheat ( Triticum aestivum L.) cv. Vigoro Grazer, and triticale (* Triticosecale Wittmack) cv. Trical 2700. In Trial 2 the cover crops were forage rape ( Brassica napus L. var. napus) cv. Licapo, sunn hemp ( Crotalaria juncea L.), Austrian winter field pea ( Pisum sativum spp. arvense L. Poir), black medic ( Medicago lupilina L.), hairy vetch ( Vicia villosa Roth), black oat cv. SoilSaver, and crimson clover cv. AU Robin. Cotton was evaluated using the same bioassay and all of the cover crops mentioned above in a single trial (Trial 3). All cover crop extracts inhibited radicle elongation compared to water. Allelopathic potential was highly variable among cultivars within a cover crop species, and within a cultivar. Allelopathic differences among cover crops give an additional weed control tool in conservation systems. However, winter cover selection may impact on cash crop performance if producers plant their crop into green residue.
  • Authors:
    • Paspatis, E.
    • Travlos, I.
    • Psomadeli, E.
  • Source: Journal of Agronomy
  • Volume: 7
  • Issue: 2
  • Year: 2008
  • Summary: Laboratory and greenhouse pot experiments were conducted to evaluate the potential usefulness of Oxalis pes-caprae L. as allelopathic ground-cover species for integrated weed management. The effects of the extracts of several tissues and the exudates from living roots of O. pes-caprae plants were tested for their allelopathic activity on several plants. Duckweed fresh weight was significantly inhibited from phytotoxic activity of petiole tissues (and secondly leaves and stems) of O. pes-caprae. For all the kinds of tissues duckweed fresh weight was reduced with increasing extract concentrations. Besides, root exudates of Bermuda buttercup caused 62, 58 and 42% inhibition of the dry biomass production of tomato, oat and lettuce plants, respectively, confirming the remarkable allelopathic activity of this weed.
  • Authors:
    • Kang, J.
    • Osmond, D. L.
  • Year: 2008
  • Authors:
    • Smith, R. F.
    • Koike, S. T.
    • Yokota, R.
    • Murphree, L.
    • Jackson, L. E.
    • Smukler, S. M.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 126
  • Issue: 3-4
  • Year: 2008
  • Summary: Studying the management strategies suited to large-scale organic production, particularly during the mandated 3-year transition period from conventional management, is a unique research challenge. Organic production traditionally relies on small, diverse plantings and complex management responses to cope with soil fertility and pest pressures, so research should represent decision-making options of an organic grower at the farm scale. This study analyzes crop, soil, pest and management changes during the organic transition period on two ranches (40 and 47 ha) in the Salinas Valley, California in cooperation with a large conventional vegetable producer, Tanimura and Antle, Inc. Permanent transects were established across the two ranches at the onset of adoption of organic practices, and soil and plants were sampled at harvest of almost all crops, while all management operations were recorded by the co-operator. The similar to 10 ha blocks were divided into many small plantings, and 17 different cash crop and cover crop species were planted during the transition period. Management inputs consisted of a range of organic fertilizers and amendments, sprinkler and drip irrigation, cultivation and hand-hoeing, and several types of organic pesticides. Results from the 3-year period followed these general trends: increase in soil biological indicators (microbial biomass and arbuscular mycorrhizae), low soil nitrate pools, adequate crop nutrients, minor disease and weed problems, and sporadic mild insect damage. Multivariate statistical analyses indicated that some crops and cultivars consistently produced higher yields than others, relative to the maximum yield for a given crop. Multi-factor contingency tables showed clear differences in insect and disease damage between crop taxa. Although Tanimura and Antle, Inc. used some of the principles of organic farming (e.g., crop diversity, crop rotation, and organic matter (OM) management), they also relied on substitution-based management, such as fertigation with soluble nutrients, initially heavy applications of organic pesticides, and use of inputs derived from off-farm sources. Their initial production of a large number of crop taxa in small plantings at staggered intervals proved to be an effective strategy for avoiding risks from low yields or crop failure and allowed them to move towards a smaller number of select, successful crops towards the end of the transition. This study demonstrates the feasibility of large-scale producers to transition to organic practices in a manner that was conducive to both production goals and environmental quality, i.e., increased soil C pools, low soil nitrate, and absence of synthetic pesticides. (C) 2008 Elsevier B.V. All rights reserved.
  • Authors:
    • Berrada, A.
    • Reule, C. A.
    • Bartolo, M. E.
    • Halvorson, A. D.
  • Source: Agronomy Journal
  • Volume: 100
  • Issue: 4
  • Year: 2008
  • Summary: Onion (Allium cepa L.) is a high cash value crop with a very shallow root system that is frequently irrigated and fertilized with high N rates to maximize yield. Converting from furrow-irrigated to drip-irrigatcd onion production may reduce N fertilizer needs, water inputs, and NO3-N leaching potential. Onion growth and N uptake, fresh yield, and residual soil NO3-N were determined under drip and furrow irrigation on a clay loam soil with N fertilizer rates from 0 to 224 kg N ha(-1). Onions were sampled bi-weekly from 25 May to 30 August in 2005 and 2006 from each treatment. In 2005, 72% less water was applied with the drip system compared with furrow system, and 57% less in 2006. Onion yields were significantly greater with the drip system. Total marketable fresh onion yield increasedwith increasing N rate in 2005 only.The drip system had more colossal and jumbo sized onions and less medium sized onions than the furrow system. Biomass production and N accumulation accelerated in mid-June each year with an average total N accumulation (leaves + bulbs) of 121 kg N ha(-1) at final harvest. Irrigation water use efficiency (IWUE) and N use efficiency (NUE) were higher with the drip system than with the furrow system. Residual soil NO3-N levels were greater in the drip-irrigated treatments after onion harvest in 2005 than in the furrow-irrigated treatments, but soil NO3-N levels were similar after harvest in 2006. Adjusted gross economic returns (less the cost of N, water, and drip system) were greater with drip irrigation than with furrow irrigation. This study demonstrates that fresh onion yields, potential economic returns, IWUE, and NUE can be improved in Colorado by using drip irrigation for onion production rather than furrow irrigation.