• Authors:
    • Peterson, G. A.
    • Westfall, D. G.
    • Ortega, R. A.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 36
  • Issue: 19/20
  • Year: 2005
  • Summary: In the West Central Great Plains of the United States, no-till management has allowed for increased cropping intensity under dryland conditions. This, in turn, has affected the carbon (C) and nitrogen (N) mineralization dynamics of these systems. In this region, moisture stress increases from north to south due to an increase in evapotranspiration (ET), resulting in a climatic gradient that affects cropping system management. The objectives of this study were to determine the interaction of cropping system intensification and climatic gradient (ET) on C and N mineralization and to determine if the presence or absence of crop residue on the soil surface affects C and net N mineralization. Two cropping systems, winter wheat-fallow (WF) ( Triticum aestivium L.) and winter wheat-corn (sorghum)-millet-fallow (WCMF) [ Zea mays (L.), Sorghum bicolor (L.) Moench, Panicum milaceum (L.)] were studied at three locations across this aforementioned ET gradient. The treatments had been in place for 8 yrs prior to sampling in the study. These results showed that the more intense cropping system (WCMF) had a higher laboratory C mineralization rate at two of the three locations, which the study concluded resulted from larger residue biomass additions and larger quantities of surface residue and soil residue at these locations (Soil residue is defined as recognizable crop residue in the soil that is retained on a 0.6 mm screen). However, no differences in N mineralization occurred. This is most likely due to more N immobilization under WCMF as compared to WF. Presence or absence of crop residue on the surface of undisturbed soil cores during incubation affected potential C and net N mineralization more than either cropping system or location. Soil cores with the surface residue intact mineralized as much as 270% more C than the same soils where the surface crop residue had been removed. In laboratory studies evaluating the relative differences in cropping systems effects on C and N mineralization, the retention of crop residue on the soil surface may more accurately access the cropping system effects.
  • Authors:
    • Spiridon, C.
    • Rotarescu, M.
    • Raranciuc, S.
    • Guran, M.
    • Popov, C.
    • Vasilescu, S.
    • Gogu, F.
  • Source: Probleme de Protectia Plantelor
  • Volume: 33
  • Issue: 1/2
  • Year: 2005
  • Summary: The paper presents the harmful organisms which attacked the field crops in 2004. It is emphasized the occurrence and spreading of the most important pathogens and harmful insects in cereals, grain legumes, industrial and fodder crops as well as their role on yield quality and quantity. In Romania, the most important issues of plant protection in 2004, by the economic impact and applied chemical measures were those determined by the following pathogens and harmful insects. The soil and seed pathogens were: Tilletia spp., Fusarium spp. in wheat; Ustilago nuda [ U. segetum var. nuda], Pyrenophora graminea in barley; Pythium spp., Fusarium spp. in maize; Sclerotinia sclerotiorum, Botrytis cinerea, Plasmopara helianthi [ Plasmopara halstedii], Orobanche cumana in sunflower; Fusarium spp., Pythium spp. in pea, beans and soyabean foliar and ear diseases were: Erysiphe spp., Septoria spp., Pyrenophora graminea, Puccinia spp., Fusarium spp. in wheat and barley; Ustilago maydis [ Ustilago zeae], Helminthosporium turcicum [ Setosphaeria turcica], Fusarium spp., Nigrospora oryzae [ Khuskia oryzae] in maize; Sclerotinia sclerotiorum, Botrytis cinerea, Alternaria spp., Phomopsis spp. in sunflower; Erysiphe spp., Septoria spp. in rape. The soil pests were: Zabrus tenebrioides, Agriotes spp. in spiked cereals; Tanymecus dilaticollis, Agriotes spp. in maize and sunflower; Delia platura in beans; Phyllotreta atra in rape and mustard; Aphthona euphorbiae in linseed; Sitona spp., Agriotes spp. in lucerne and clover. The pests which attack aerial part of plants and seeds were: Eurygaster integriceps, Lema melanopa [ Oulema melanopus], Anisoplia spp. in wheat, barley and oats; Ostrinia nubilalis, Diabrotica virgifera virgifera in maize; Thrips linarius in linseed; Athalia rosae, Meligethes aeneus, Brevicoryne brassicae in rape and mustard; Hypera variabilis [ Hypera postica], Semiothisa clathrata [ Chiasmia clathrata], Bruchophagus roddi, Subcoccinella 24- punctata in lucerne and clover. Based on evaluation of the attack potential of these harmful organisms in 2004, the potential for the future manifestation was also estimated.
  • Authors:
    • Dhyani, S. K.
    • Singh, R.
    • Sharma, A. R.
  • Source: Indian journal of soil conservation
  • Volume: 33
  • Issue: 1
  • Year: 2005
  • Summary: Maize and wheat are the most important crop grown in sequence largely under rainfed conditions, with low inputs and traditional practices in the outer western Himalayan region of India. Deficiency of moisture and nutrients is primarily responsible for low productivity of these crops. The conventional practices for alleviating these stresses such as summer ploughing, use of organics, intercropping with legumes, mulching, haloding (interculturing), earthing-up and ploughing immediately after harvesting of maize are gradually being discontinued by the farmers due to various emerging problems. This article reviews the effects of tillage and mulching on moisture conservation and nutrient use in the maize-wheat cropping system. Field studies at different locations of this region have shown the beneficial effects of resource conserving technologies for improving productivity of maize and following wheat. The results have suggested that the conventional repetitive tillage operations including deep ploughing can be dispensed with, and equally good or even higher yields can be obtained with minimum or zero tillage along with mulching or residue management practices over a period due to improved soil environment. Live mulching with weeds, annual legumes or pruned biomass of perennial legumes in alley cropping systems are beneficial for efficient conservation of soil, moisture and nutrients for higher productivity in maize-wheat cropping system. There is a need for adopting diversified farming systems approach for improving productivity of crops as well as other enterprises for greater livelihood security of the farming community in this region.
  • Authors:
    • Rosenberg, N. J.
    • Brown, R. A.
    • Thomson, A. M.
    • Izaurralde, R. C.
    • Benson, V.
  • Source: Climatic Change
  • Volume: 69
  • Issue: 1
  • Year: 2005
  • Summary: Here we simulate dryland agriculture in the United States in order to assess potential future agricultural production under a set of general circulation model (GCM)-based climate change scenarios. The total national production of three major grain crops - corn, soybeans, and winter wheat - and two forage crops - alfalfa and clover hay - is calculated for the actual present day core production area (CPA) of each of these crops. In general, higher global mean temperature (GMT) reduces production and higher atmospheric carbon dioxide concentration ([CO 2]) increases production. Depending on the climatic change scenarios employed overall national production of the crops studied changes by up to plus or minus 25% from present-day levels. Impacts are more significant regionally, with crop production varying by greater than 50% from baseline levels. Analysis of currently possible production areas (CPPAs) for each crop indicates that the regions most likely to be affected by climate change are those on the margins of the areas in which they are currently grown. Crop yield variability was found to be primarily influenced by local weather and geographic features rather than by large-scale changes in climate patterns and atmospheric composition. Future US agronomic potential will be significantly affected by the changes in climate projected here. The nature of the crop response will depend primarily on to what extent precipitation patterns change and also on the degree of warming experienced.
  • Authors:
    • Li, Y. S.
    • Shao, M. A.
    • Zhong, L. P.
  • Source: Agricultural Sciences in China
  • Volume: 4
  • Issue: 1
  • Year: 2005
  • Summary: Based on the experimental data of crop yield, soil water and fertility of a dryland farming ecosystem in northwest China, a systematic analysis is carried out using spring maize and winter wheat to study the dynamics of dryland farming ecosystem productivity and its limiting factors. This paper also discusses which of the two limiting factors, i.e., soil water or fertility, is the primary factor and their dynamics. The result shows that fertility is the primary limiting factor when the productivity is rather low. As chemical fertilizer input increases and the productivity promotes, water gradually becomes the primary limiting factor. Chemical fertilizers and plastic film mulching are the two major driving forces that determine the crop productivity and its stability in these areas.
  • Authors:
    • Cakmak, I.
  • Source: Turkish Journal of Agriculture and Forestry
  • Volume: 29
  • Issue: 2
  • Year: 2005
  • Summary: These proceedings contain 8 papers on: the impact of genomics and genetics on wheat quality improvement; the role of conventional plant breeding and biotechnology in future wheat production; biotechnology applications for wheat improvement at CIMMYT; genetics and breeding for durable resistance to leaf stripe rusts ( Pyrenophora graminea) in wheat; controlling foliar blight ( Cochliobolus sativus) of wheat in South Asia: a holistic approach; international cooperation for winter wheat improvement in Central Asia: results and perspectives; the role of wheat in diversified cropping systems in dryland agriculture of Central Asia; and breeding of winter wheat ( Triticum aestivum) for different adaptation types in multifunctional agricultural production.
  • Authors:
    • Prado A., R. del
    • Diaz S., J.
    • Espinoza N., N.
  • Source: XVII Congreso de la Asociación Latinoamericana de Malezas (ALAM) I Congreso Iberoamericano de Ciencia de las Malezas, IV Congreso Nacional de Ciencia de Malezas, Matanzas, Cuba, 8 al 11 de noviembre del 2005, pp. 326
  • Year: 2005
  • Summary: Eight biotypes of herbicide-resistant weeds have been described in Chile. All belong to grass weeds, specifically wild oat ( Avena fatua), ryegrass ( Lolium rigidum), Italian ryegrass ( L. multiflorum) and crested dogtailgrass ( Cynosurus echinatus), which are the most common in the main wheat, barley, oats, lupin and canola producing area (36degreesS to 39degreesS). The biotypes have shown resistance to ACCasa, ALS and EPSP inhibitors. Most biotypes have appeared in farm fields subjected to intensive land use, with annual crops, with a trend to wheat monoculture in some cases, and with intense use of no-till and herbicides with similar mode of action. Herbicides most frequently used have been glyphosate (EPSP), diclofop-methyl and clodinafop-propargyl (ACCasa). Cross-resistance to ACCasa was found in some biotypes of wild oat and ryegrass, with greater resistance to aryloxyphenoxypropionates than to cyclohexanediones. All ACCasaresistant biotypes were susceptible to iodosulfuron and flucarbazone Na (ALS). These two herbicides are recommended for wheat and began to be used just recently in the country. Two biotypes of Italian ryegrass were found resistant to glyphosate. One of these biotypes showed, in addition, resistance to ALS; that is to say, showed multiple resistance. Also the crested dogtailgrass biotype showed multiple resistance to ACCasa and ALS.
  • Authors:
    • Zhou, G. Y.
    • Luo, J. J.
    • Stewart, B. A.
    • Yong, W.
    • Fan, T. L.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 106
  • Issue: 4
  • Year: 2005
  • Summary: Wheat ( Triticum aestivum L.) and corn ( Zea mays L.) rotation system is important for food security in the Loess Plateau of China. Grain yield and water-use efficiency (WUE: grain yield per unit of water consumed) trends, and changes in soil properties during a 24-year fertilization experiment in Pingliang, Gansu, China, were recorded. Mean yields of wheat for the 16 years started in 1981 ranged from 1.29 t ha -1 for the unfertilized plots (CK) to 4.71 t ha -1 for the plots that received manure (M) annually with inorganic nitrogen (N) and phosphorus (P) fertilizers (MNP). Corn yields for the 6 years started in 1979 averaged 2.29 and 5.61 t ha -1 in the same treatments. Yields and WUEs declined significantly with lapse of time except CK and MNP for wheat. Wheat yields with the N and M declined at rate of 77 and 81 kg ha -1 year -1, but the decline of 57 kg ha -1 year -1 for NP was similar to that of 61 ha -1 year -1 for straw with N annually and P every second year (SNP). Likewise, the corn yields and WUEs declined from 160 to 250 kg ha -1 year -1 and from 0.01 to 0.03 kg m -3 year -1 among treatments, respectively. These declines were likely to loss of soil fertility and gradual dry weather. Yields were significantly correlated with seasonal evapotranspiration with slopes ranging from 0.5 to 1.27 kg m -3 for wheat and from 1.15 to 2.03 kg m -3 for corn. Soil organic carbon (SOC), total N (TN), and total P (TP) gradually built up with time except the CK, in which TN and TP remained unchanged but SOC and available P (AP) decreased. Soil AP decreased in the N. Soil available K declined rapidly without straw or manure. Balanced fertilization should be encouraged to ensure sustainable productivity in this intensive cropping system. The greatest SOC increases of about 160 mg ha -1 year -1 occurred in the SNP and MNP, suggesting that long-term additions of organic materials to soil could increase soil water-holding capacity which, in return, improves water availability to plants and arrests yield declines, and decrease CO 2 emission from agricultural soils and sustain land productivity.
  • Authors:
    • McRae, F. J.
    • Brooke, G.
    • Francis, R. J.
    • Dellow, J. J.
  • Source: Weed control in winter crops 2005
  • Year: 2005
  • Summary: This publication provides a guide to chemical weed control during different growth stages of fallow, wheat, barley, oats, rye, triticale, rape, safflower, lentil, linseed, lupin, chickpea, faba bean and field pea in New South Wales, Australia. Recommended timing of herbicide application is given. Sensitivity of winter crop cultivars to herbicides is outlined. Information is also included on crop rotation, use of surfactants and oils, water quality for herbicide application, spray equipment clean-up, herbicide spray drift, compatibility of winter crop herbicides and insecticides, and common retail prices of chemicals used on winter crops.
  • Authors:
    • Sayre, K. D.
    • Govaerts, B.
    • Deckers, J.
  • Source: Field Crops Research
  • Volume: 94
  • Issue: 1
  • Year: 2005
  • Summary: Subtropical highlands of the world have been densely populated and intensively cropped. Agricultural sustainability problems resulting from soil erosion and fertility decline have arisen throughout this agro-ecological zone. This article considers practices that would sustain higher and stable yields for wheat and maize in such region. A long-term field experiment under rainfed conditions was started at El Batan, Mexico (2240 m a.s.l.; 19.31 degrees N, 98.50 degrees W;fine, mixed, thermic, Cumulic Haplustoll) in 1991. It included treatments varying in: (1) rotation (continuous maize (Zea mays) or wheat (Triticum aestivum) and the rotation of both); (2) tillage (conventional, zero and permanent beds); (3) crop residue management (full, partial or no retention). Small-scale maize and wheat farmers may expect yield improvements through zero tillage, appropriate rotations and retention of sufficient residues (average maize and wheat yield of 5285 and 5591 kg ha(-1)), compared to the common practices of heavy tillage before seeding, monocropping and crop residue removal (average maize and wheat yield of 3570 and 4414 kg ha(-1)). Leaving residue on the field is critical for zero tillage practices. However, it can take some time-roughly 5 years-before the benefits are evident. After that, zero tillage with residue retention resulted in higher and more stable yields than alternative management. Conventional tillage with or without residue incorporation resulted in intermediate yields. Zero tillage without residue drastically reduced yields, except in the case of continuous wheat which, although not high yielding, still performed better than the other treatments with zero tillage and residue removal. Zero tillage treatments with partial residue removal gave yields equivalent to treatments with full residue retention (average maize and wheat yield of 5868 and 5250 kg ha(-1)). There may be scope to remove part of the residues for fodder and still retain adequate amounts to provide the necessary ground cover. This could make the adoption of zero tillage more acceptable for the small-scale, subsistence farmer whose livelihood strategies include livestock as a key component. Raised-bed cultivation systems allow both dramatic reductions in tillage and opportunities to retain crop residues on the soil surface. Permanent bed treatments combined with rotation and residue retention yielded the same as the zero tillage treatments, with the advantage that more varied weeding and fertilizer application practices are possible. It is important small-scale farmers have access to, and are trained in the use of these technologies. (c) 2004 Elsevier B.V. All rights reserved.