• Authors:
    • Ulmer, M. G.
    • Cihacek, L. J.
  • Source: Agriculture Practices and Policies for Carbon Sequestration in Soil
  • Year: 2002
  • Summary: from summary: "The significance of soils in sequestering greenhouse gases and reducing global warming may be greater due to C sequestration as inorganic C. Soil IC is a sink for atmospheric CO 2 , which may be more resistant to cropping and tillage effects on sequestered soil C and is likely to persist for decades and perhaps centuries after sequestration."
  • Authors:
    • Grove, J. H.
    • Dí­az-Zorita, M.
  • Source: Soil & Tillage Research
  • Volume: 66
  • Issue: 2
  • Year: 2002
  • Summary: Surface accumulation of soil organic carbon (SOC) under conservation tillage has significant effects on stratification of other nutrients, on crop productivity and in ameliorating the greenhouse effect via atmospheric CO, sequestration. A measure of SOC stratification relative to deeper soil layers has been proposed as a soil quality index. Our objective was to determine the effects of the duration of tillage practices upon the SOC and extractable P distribution with depth in Maury silt loams (Typic Paleudalfs) at similar levels of corn (Zea mays L.) productivity without P fertilization. Soil samples (0-20.0 cm in 2.5 cm increments) were collected under moldboard tillage (MT), chisel tillage (CT) and no-tillage (NT) and in surrounding tall fescue (Festuca arundinacea L.) sods selected from three tillage experiments (1-2-, 8- and 29-year durations) in Kentucky. SOC stratification was greater under conservation tillage (CT and NT) and sods than under MT. SOC and soil-test-extractable P stratification were positively related. Increasing the duration under NT caused the thickness of C stratification to increase. In NT soils, C stratification ratio (CSR) approached CSR in the nearby long-term sods with time. Conservation tillage rapidly promoted the occurrence of CSR greater than 2 while MT always resulted in values lower than 2. The rapid initial change in CSR suggests characterization of thin soil layers (i.e. 2.5 cm depth increments) is desirable under conservation tillage. (C) 2002 Elsevier Science B.V. All rights reserved.
  • Authors:
    • Azooz, R.
    • Soon, Y.
    • Arshad, M.
  • Source: Soil & Tillage Research
  • Volume: 65
  • Issue: 1
  • Year: 2002
  • Summary: In recent years, crop rotation and no-till farming have become common practices in Alberta, Canada, and are widely recommended to maintain and/or enhance soil quality for sustained crop production, and improve environmental quality. This study was undertaken to evaluate the effects of rape ( Brassica rapa [ B. napus var. oleifera]) and field pea ( Pisum sativum) as replacements for summer fallow on wheat ( Triticum aestivum) production, and to determine the role of tillage (no-till versus modified no-till) on crop production on an Albright silt loam (Mollic Cryoboralf) near Beaverlodge, Alta. Spring wheat was grown for 2 years of the 3-year cropping cycle. Crop sequences studied were: rape-wheat-wheat (RWW), field pea-wheat-wheat (PWW) and fallow-wheat-wheat (FWW). The control was continuous wheat, i.e. wheat-wheat-wheat or monoculture wheat (MW). In modified no-till, sweeps attached to the seed drill pushed crop residues aside from the centre 7.5 cm of the seed row. Wheat yield following field pea increased by an average (1997-99) of 10.5% compared to monoculture wheat. Our data showed no measurable effect of rape on succeeding wheat yields compared to monoculture wheat. Wheat yields following fallow were intermediate between the RWW and PWW cropping systems. Residue management through the modified no-till system resulted in a warmer seedbed during spring and improved wheat production in all crop rotations studied, especially the first succeeding wheat. Modified no-till also resulted in higher yields of rape but not pea. Our data indicate that in a 3-year rotation with wheat, the preferred break crop would be field pea for the cold semiarid region of Alberta.
  • Authors:
    • Rice, CW
  • Source: Geotimes
  • Volume: 47
  • Issue: 1
  • Year: 2002
  • Authors:
    • Li, X. Y.
    • Zhao, H. L.
    • Gao, C. Y.
    • Li, F. R.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 91
  • Issue: 1-3
  • Year: 2002
  • Summary: Winter wheat (Triticum aestivum L.) monoculture is common in wheat-growing areas of the Loess Plateau of northwest China. This system is characterized by nearly 3-month summer fallow from wheat harvest at the end of June or early July to sowing in late September. It not only lowers the overall precipitation-use efficiency because of the large amount of evaporation from the bare soil surface during the fallow period but also entails high risk of erosion by summer rainstorms. There is a need to develop more effective cropping systems to replace the current production system. Seven alternative rotations, mainly using wheat, rapeseed, corn, potato, pearl millet, linseed, alfalfa and sweetclover, were established and their use of environmental resources, production performance, energy efficiency, soil fertility sustainability, and soil conservation effectiveness were compared with continuous wheat cropping. The rotations had greater potential use of environmental resources. Despite showing no clear advantage in grain yields, all rotations were significantly higher in total above-ground biomass production and more efficient in energy transformation compared with continuous wheat cropping. After a 3-year cycle, the rotations did not adversely affect soil bulk density but some rotations significantly increased soil water-stable aggregates compared with the initial measurement. For the rotations based on the inclusion of legumes, the availability of N was apparently improved but the total P was substantially reduced compared with the initial measurement and continuous wheat cropping. An assessment of soil conservation effectiveness with a weighted soil conservation effectiveness index (WSCEI) indicated that the rotations performed much better than continuous wheat cropping in conserving soil and water resources. This study also strongly recommend that it is feasible to cultivate winter wheat followed by a 3-month legume fallow crop in year I and then a summer crop cultivation in the next. This system provides a soil cover during both erosion-prone rainy periods while leaving the soil bare for about 7 months (October-April) every 2 years. Another alternative is to cultivate winter wheat followed by a 15-month legume crop cultivation in years I and 2 and then a summer crop in year 3. This system allows the soil to be covered during three rainy periods while leaving the soil bare for about 7 months every 3 years. As most of this 7-month period is winter with low rainfall (snow) and temperatures below 0degreesC, not only is soil evaporation very low but the risk of erosion is also low. (C) 2002 Elsevier Science B.V. All rights reserved.
  • Authors:
    • Ulrich, D.
    • Brandt, S. A.
    • Malhi, S. S.
    • Lemke, R.
    • Gill, K. S.
  • Source: Journal of Plant Nutrition
  • Volume: 25
  • Issue: 11
  • Year: 2002
  • Summary: Cropping systems can influence the accumulation and distribution of plant nutrients in the soil profile, which can affect their utilization efficiency by crops and pollution potential in the environment. A field experiment was conducted on a Dark Brown loam soil at Scott, Saskatchewan, Canada to assess the effects of input level, cropping diversity and crop phase on the accumulation and distribution of nitrate-nitrogen (N) and extractable phosphorus (P) in the soil profile at the end of 1995 to 2000 growing seasons. The 54 treatments were combinations of three input levels (organic-ORG, reduced-RED and high-HIGH), three cropping diversities (low diversity-LOW, diversified annual grains-DAG, and diversified annual and perennials-DAP), and six crop phases chosen from fallow (tillage-fallow or chemfallow), green manure [lentil-Lens culinaris Medicus or sweet clover-Melilotus officinalis (L.) Lam], spring wheat (Triticum aestivum L.), canola (Brassica napus L. and Brassica rapa L.), fall rye (Secale cereale L.), field pea (Pisum sativum L.), spring barley (Hordeum vulgare L.), flax (Linum usitatissimum L.), oats (Avena sativa L.), and bromegrass (Bromus inermis Leyss), alfalfa (Medicago sativa Leyss) mixture hay. Soil was sampled from the 0-15, 15-30, 30-60, and 60-90cm depths in each crop phase from 1995 to 2000, with additional depths 90-120, 120-150, 150-180, 180-210, and 210-240cm taken from the wheat phase in 2000. In general, there were greater amounts of nitrate-N with HIGH input compared to ORG or BID inputs, especially under LOW diversity. The nitrate-N in various soil depths suggested some downward movement of nitrate-N to the deeper soil depths when HIGH input was compared to ORG input. In LOW cropping diversity, green manure or fallow usually had more nitrate-N in soil than other crop phases. In DAG and DAP cropping diversities, nitrate-N varied with crops and on average it had maximum concentration after wheat or canola in DAG and after hay followed closely by wheat in DAP. The ORG input level had greater nitrate-N than RED or HIGH inputs in some instances, most likely due to relatively low extractable P in soil for optimum crop growth under ORG input. Extractable P in the 0-15 and 15-30 cm soil depths tended to be greater under HIGH or RED inputs compared to the ORG input level in many cases. In summary there was no consistent effect of cropping diversity on extractable P in soil under ORG input, but LOW diversity tended to show more extractable 13 compared to DAG and DAP diversities in some cases of RED and HIGH inputs. The green manure/fallow, HIGH input and LOW diversity treatments tended to result in higher nitrate-N and extractable P levels compared to the corresponding treatments, and the effects were more pronounced on nitrate-N than extractable P and in shallow compared to deeper soil layers.
  • Authors:
    • Haqqani, A. M.
    • Munir, M.
    • Mann, R. A.
  • Source: Pakistan Journal of Agricultural Research
  • Volume: 18
  • Issue: 1
  • Year: 2002
  • Summary: Rice-wheat cropping system is the most important one in Pakistan. The system provides food and livelihood for more than 15 million people in the country. The productivity of the system is much lower than the potential yields of both rice and wheat crops. With the traditional methods, rice-wheat system is not a profitable one to many farmers. Hence, Cost of cultivation must be reduced and at the same time, efficiency of resources like irrigation water, fuel, and fertilizers must be improved to make the crop production system more viable and ecofriendly. Resource conserving technology (RCT) must figure highly in this equation, since they play a major role in achieving the above goals. The RCT include laser land leveling, zero-tillage, bed furrow irrigation method and crop residue management. These technologies were evaluated in irrigated areas of Punjab where rice follows wheat. The results showed that paddy yield was not affected by the new methods. Direct seeding of rice crop saved irrigation water by 13% over the conventionally planted crop. Weeds were the major problem indirect seeded crop, which could be eliminated through cultural, mechanical and chemical means. Wheat crop on beds produced the highest yield but cost of production was minimum in the zero-till wheat crop. Planting of wheat on raised beds in making headway in lowlying and poorly drained areas. Thus, resource conserving tillage technology provides a tool for making progress towards improving and sustaining wheat production system, helping with food security and poverty alleviation in Pakistan in the next few decades.
  • Authors:
    • Chanasyk, D. S.
    • Mathison, M. N.
    • Naeth, M. A.
  • Source: Canadian Journal of Soil Science
  • Volume: 82
  • Issue: 2
  • Year: 2002
  • Summary: The longevity of deep ripping effects on Solonetzic soils was investigated at 11 field sites in east-central Alberta after a period of 15 to 20 yr. Select soil properties and crop yield of deep-ripped and non-ripped control plots were analyzed. Dryland yield data of wheat, barley, oats and canola were assessed for 10 of the 11 sites over a 16-yr time period. Select soil properties were analyzed once in 1998 with penetration resistance (PR) evaluated again in 1999. A significant difference in penetration resistance was found between the deep ripped versus control treatments ( P≤0.05). There were no significant treatment differences for soil texture, bulk density (Db), pH, electrical conductivity (EC) or sodium adsorption ratio (SAR). A significant yield difference between the deep ripping and control treatments (for all crop species) was found for 6 of 10 sites ( P≤0.10), with all sites having an increase in mean yield for the majority of years evaluated. Generally, sites in the drier ecoregions had smaller yield increases than those in the wetter ones. Hence some beneficial effects from deep ripping remain for a long time period.
  • Authors:
    • Michalski, T.
    • Bartos, M.
  • Source: Progress in Plant Protection
  • Volume: 42
  • Issue: 2
  • Year: 2002
  • Summary: Experiments were conducted during 1996-99 in Poland to study the effect of sowing density on barley, oat, wheat and triticale weed infestation. The cereals were sown in 4 densities, starting from 400 grains of barley and 650 grains of the other species (100%) and consequently reduced to 80, 60 and 40%. Number and weight of weeds in each year was seriously diverse. Weed infestation was the smallest (mean 27 weeds/m 2) at high sowing density and increased with a decrease in sowing density, reaching 88 weeds at the smallest density of cereals. The reduction of sowing density by 20% increased weed density 40-50%. The most frequent weeds were Setaria viridis and cultivated rape ( Brassica napus var. oleifera).
  • Authors:
    • Tonkin, C. J.
    • Francis, R. J.
    • Dellow, J. J.
    • Mullen, C. L.
  • Source: Weed control in winter crops 2002
  • Year: 2002
  • Summary: This bulletin provides a list of the most important weeds of winter crops, and identifies the herbicides that should be used for optimum weed control in fallows, wheat, barley, oat, rye, triticale, rape, sunflower, lentil, linseed, lupin, chickpea, faba bean and field pea.