• Authors:
    • May, W. E.
    • Brandt, S. A.
    • Lafond, G. P.
    • Holzapfel, C. B.
    • Johnston, A. M.
  • Source: Canadian Journal of Plant Science
  • Volume: 87
  • Issue: 2
  • Year: 2007
  • Summary: Delaying nitrogen (N) applications into the growing season as a risk management tool is a concept that has received considerable attention in recent years. A 3-yr field study with spring wheat ( Triticum aestivum L.) and canola ( Brassica napus L.) was conducted at two Saskatchewan locations, Indian Head and Scott. The effects of postponing N applications for up to 30 d after seeding and several application methods were evaluated against mid-row banded urea at seeding. Liquid urea ammonium-nitrate (UAN) was applied at four separate times relative to seeding, either as an in-soil coulter band or a surface band. The surface band applications were applied either with or without the addition of 5% ammonium thiosulphate (ATS), a potential urease inhibitor. The dependent variables considered included plant density and grain yield for both crops, and grain protein in wheat. The only effect on plant density occurred in canola, where the post-seeding coulter applications slightly reduced stands compared with the other treatments. Postponing N fertilization for up to 30 d after seeding compared with N fertilization at seeding did not affect the yield of canola or protein in spring wheat, but reduced the yield of spring wheat at Indian Head in 2003, which was a very dry growing season. The coulter applications only showed a slight advantage over the surface band applications. For the surface band applications, the addition of 5% ATS did not provide a noticeable advantage over UAN alone. Canola appeared to be less sensitive to post-seeding applications than spring wheat. Deferring the entire amount of fertilizer N into the growing season appears to be a viable option but it is not without risk, especially when dry conditions are encountered.
  • Authors:
    • Lares, M. T.
    • Liebig, M. A.
    • Tanaka, D. L.
    • Merrill, S. D.
    • Krupinsky, J. M.
    • Hanson, J. D.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 4
  • Year: 2007
  • Summary: Field research was conducted to determine the influence of crop and crop sequencing on crop residue coverage of soil with 10 crops [buckwheat (Fagopyrum esculentum Moench), canola (Brassica napus L.), chickpea (Cicer arietinum L.), corn (Zea mays L.), dry pea (Pisum sativum L.), grain sorghum [Sorghum bicolor (L.) Moench], lentil (Lens culinaris Medik.), oil seed sunflower (Helianthus annuus L.), proso millet (Panicum miliaceum L.), and hard red spring wheat (Triticum aestivum L.)]. Crop residue production was obtained. Crop residue coverage of the soil surface was measured with a transect technique at the time of seeding spring wheat. Crop residue coverage varied and was more clearly associated with the second-year crop than with the first-year crop of a 2-yr crop sequence. Crop sequences composed of spring wheat, proso millet, and grain sorghum had higher crop residue coverage compared with sequences composed of the other crops. When these three crops and three crops that provide lower crop residue coverage of soil the subsequent year (lentil, chickpea, and sunflower) were analyzed as a subset to compare various sequences of crops providing a range of residue coverage, for example, lower (first yr)/lower (second yr), the surface residue coverage ranged from 65% for the lower/lower combination to 93% for the higher/higher combination in 2004 and from 56 to 94% in 2005, respectively. A producer operating on more fragile soil and concerned about reducing soil erosion hazards would be advised to grow crops that provide higher residue coverage in the year before crops that provide lower residue coverage.
  • Authors:
    • Lares, M. T.
    • Liebig, M. A.
    • Merrill, S. D.
    • Tanaka, D. L.
    • Krupinsky, J. M.
    • Hanson, J. D.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 4
  • Year: 2007
  • Summary: Crop sequence is an important management practice that may lower the risk for leaf spot diseases of spring wheat ( Triticum aestivum L.). Field research was conducted near Mandan, ND, to determine the impact of crop sequences on leaf spot diseases of hard red spring wheat early in the growing season. Spring wheat was evaluated for disease severity following crop sequence combinations of 10 crops [buckwheat ( Fagopyrum esculentum Moench)], canola ( Brassica napus L.), chickpea ( Cicer arietinum L.), corn ( Zea mays L.), dry pea ( Pisum sativum L.), grain sorghum [ Sorghum bicolor (L.) Moench], lentil ( Lens culinaris Medik.), oil seed sunflower ( Helianthus annuus L.), proso millet ( Panicum miliaceum L.), and hard red spring wheat. Spring wheat leaves with distinct lesions were collected for determination of lesion number and percentage necrosis data, which were used to estimate leaf spot disease severity. Pyrenophora tritici-repentis (Died.) Drechs., the cause of tan spot, and Phaeosphaeria nodorum (E. Muller) Hedjaroude, the cause of Stagonospora nodorum blotch, were the major leaf spot diseases and consistently present throughout the growing season. The frequency of isolation following alternative crops was generally lower compared with spring wheat following wheat. Leaf spot diseases on spring wheat were impacted by crop sequencing. Spring wheat following crop sequences with alternative crops for 1 or 2 yr had lower levels of disease severity compared with a continuous spring wheat treatment early in the growing season. Disease severity was apparently not related to the percentage of crop residue coverage on the soil surface associated with various crop sequence combinations. New alternative crops preceding spring wheat reduce levels of leaf spot diseases.
  • Authors:
    • Warland, J.
    • von Bertoldi, P.
    • Parkin, G.
    • Jayasundara, S.
    • Barbeau, J.
    • Lee, I.
    • McLaughlin, N. L.
    • Furon, A.
    • Wagner-Riddle, C.
  • Source: Global Change Biology
  • Volume: 13
  • Issue: 8
  • Year: 2007
  • Summary: No-tillage (NT), a practice that has been shown to increase carbon sequestration in soils, has resulted in contradictory effects on nitrous oxide (N2O) emissions. Moreover, it is not clear how mitigation practices for N2O emission reduction, such as applying nitrogen (N) fertilizer according to soil N reserves and matching the time of application to crop uptake, interact with NT practices. N2O fluxes from two management systems [conventional (CP), and best management practices: NT + reduced fertilizer (BMP)] applied to a corn (Zea mays L.), soybean (Glycine max L.), winter-wheat (Triticum aestivum L.) rotation in Ontario, Canada, were measured from January 2000 to April 2005, using a micrometeorological method. The superimposition of interannual variability of weather and management resulted in mean monthly N2O fluxes ranging from - 1.9 to 61.3 g N ha(-1) day(-1). Mean annual N2O emissions over the 5-year period decreased significantly by 0.79 from 2.19 kg N ha(-1) for CP to 1.41 kg N ha(-1) for BMP. Growing season (May-October) N2O emissions were reduced on average by 0.16 kg N ha(-1) (20% of total reduction), and this decrease only occurred in the corn year of the rotation. Nongrowing season (November-April) emissions, comprised between 30% and 90% of the annual emissions, mostly due to increased N2O fluxes during soil thawing. These emissions were well correlated (r(2) = 0.90) to the accumulated degree-hours below 0 degrees C at 5 cm depth, a measure of duration and intensity of soil freezing. Soil management in BMP (NT) significantly reduced N2O emissions during thaw (80% of total reduction) by reducing soil freezing due to the insulating effects of the larger snow cover plus corn and wheat residue during winter. In conclusion, significant reductions in net greenhouse gas emissions can be obtained when NT is combined with a strategy that matches N application rate and timing to crop needs.
  • Authors:
    • Ascough, J. C.,II
    • McMaster, G. S.
    • Andales, A. A.
    • Hansen, N. C.
    • Sherrod, L. A.
  • Source: Transactions of the ASABE
  • Volume: 50
  • Issue: 5
  • Year: 2007
  • Summary: Alternative agricultural management systems in the semi-arid Great Plains are receiving increasing attention. GPFARM is a farm/ranch decision support system (DSS) designed to assist in strategic management planning for land units from the field to the whole-farm level. This study evaluated the regional applicability and efficacy of GPFARM based on simulation model performance for dry mass grain yield, total soil profile water content, crop residue, and total soil profile residual NO 3-N across a range of dryland no-till experimental sites in eastern Colorado, USA. Field data were collected from 1987 through 1999 from an on-going, long-term experiment at three locations in eastern Colorado along a gradient of low (Sterling), medium (Stratton), and high (Walsh) potential evapotranspiration. Simulated crop alternatives were winter wheat ( Triticum aestivum), maize ( Zea mays), sorghum ( Sorghum bicolor), proso millet ( Panicum miliaceum), and fallow. Relative error (RE) of simulated mean, root mean square error (RMSE), and index of agreement (d) model evaluation statistics were calculated to compare modelled results to measured data. A one-way, fixed-effect ANOVA was also performed to determine differences among experimental locations. GPFARM simulated versus observed REs ranged from -3 to 35% for crop yield, 6 to 8% for total soil profile water content, -4 to 32% for crop residue, and -7 to -25% for total soil profile residual NO 3-N. For trend analysis (magnitudes and location differences), GPFARM simulations generally agreed with observed trends and showed that the model was able to simulate location differences for the majority of model output responses. GPFARM appears to be adequate for use in strategic planning of alternative cropping systems across eastern Colorado dryland locations; however, further improvements in the crop growth and environmental components of the simulation model (including improved parameterization) would improve its applicability for short-term tactical planning scenarios.
  • Authors:
    • Mielniczuk, J.
    • Vieira, F. C. B.
    • Dieckow, J.
    • Bayer, C.
    • Zanatta, J. A.
  • Source: Soil & Tillage Research
  • Volume: 94
  • Issue: 2
  • Year: 2007
  • Summary: Conservation management systems can improve soil organic matter stocks and contribute to atmospheric C mitigation. This study was carried out in a 18-year long-term experiment conducted on a subtropical Acrisol in Southern Brazil to assess the potential of tillage systems [conventional tillage (CT) and no-till (NT)], cropping systems [oat/maize (O/M), vetch/maize (V/M) and oat + vetch/maize + cowpea (OV/MC)] and N fertilization [0 kg N ha-1 year-1 (0 N) and 180 kg N ha-1 year-1 (180 N)] for mitigating atmospheric C. For that, the soil organic carbon (SOC) accumulation and the C equivalent (CE) costs of the investigated management systems were taken into account in comparison to the CT O/M 0 N used as reference system. No-till is known to produce a less oxidative environment than CT and resulted in SOC accumulation, mainly in the 0-5 cm soil layer, at rates related to the addition of crop residues, which were increased by legume cover crops and N fertilization. Considering the reference treatment, the SOC accumulation rates in the 0-20 cm layer varied from 0.09 to 0.34 Mg ha-1 year-1 in CT and from 0.19 to 0.65 Mg ha-1 year-1 in NT. However, the SOC accumulation rates peaked during the first years (5th to 9th) after the adoption of the management practices and decreased exponentially over time, indicating that conservation soil management was a short-term strategy for atmospheric C mitigation. On the other hand, when the CE costs of tillage operations were taken into account, the benefits of NT to C mitigation compared to CT were enhanced. When CE costs related to N-based fertilizers were taken into account, the increases in SOC accumulation due to N did not necessarily improve atmospheric C mitigation, although this does not diminish the agricultural and economic importance of inorganic N fertilization.
  • Authors:
    • Amado, T. J. C.
    • Pontelli, C. B.
    • Santi, A. L.
    • Viana, J. H. M.
    • Sulzbach, L. A. de S.
  • Source: Brazilian Journal of Agricultural Research (PAB)
  • Volume: 42
  • Issue: 8
  • Year: 2007
  • Summary: The objective of this work was to analyze the spatial and temporal yield variability of soybean, corn and wheat in a 57 ha cropland, without irrigation, under no-till for more than ten years in a Typic Hapludox, located in Palmeira das Missões, RS. Yield data of crops from 2000 to 2005 were collected using a combine equipped with yield monitor. Statistical and geostatistical analysis were performed to monitor the range of the spatial variability and its spatial dependence, as well as its behavior over the years. Soybean, corn and wheat yield present spatial variability, which is maintained over time. In dry years, yield variance coefficient increases compared to wet years. Corn was more efficient than soybean to identify spatial yield variability in the cropland.
  • Authors:
    • Fan, T.
    • Xu, M.
    • Zhou, G.
    • Ding, L.
  • Source: American-Eurasian Journal of Agricultural and Environmental Science
  • Volume: 2
  • Issue: 5
  • Year: 2007
  • Summary: Grain yield trends and changes in Soil Organic Carbon (SOC) from a 26-yr rainfed fertilization trial in Pingliang, Gansu, China, were recorded. Mean wheat ( Triticum aestivum L.) yields for the 18-yr ranged from 1.72 t ha -1 for the unfertilized plots (CK) to 4.65 t ha -1 for the plots that received Manure (M) annually with inorganic Nitrogen (N) and Phosphorus (P) fertilizers (MNP). Corn ( Zea mays L.) yields for the 6-yr averaged 2.43 and 5.35 t ha -1 in the same treatments. Yields declined with year except the CK for wheat. Wheat yields for the N only declined 117.8 kg ha -1 yr -1 that was the highest among all treatments and that for the NP declined 84.7 kg ha -1 yr -1, similar to that of 77.4 kg ha -1 yr -1 for the treatment receiving straw and N annually and P every second year (SNP). Likewise, the corn yields declined highly for all treatments and the declined amounts ranged from 108 to 258 kg ha -1 yr -1 that was much higher than in wheat. SOC gradually increased with time except the CK and N treatments, in which SOC remained almost stable. The SOC increases of 190.1, 166.8 and 164.5 mg C kg -1 yr -1 occurred in MNP and SNP and M treated soils, respectively. About 24% of the total C-input from manure and root residue and about 14% of the total C-input from straw and root residue remained in the soil as organic matter. Losses of 1 t SOM ha -1 were associated with a decrease in wheat yield of approximately 80 kg ha -1, showing the importance of using management practices that minimize losses of SOC in the China Loess Plateau. Grain yield declines were likely related to gradual dry weather and soil available N decline. It is concluded that C sequestration can be enhanced by increasing manure and straw additions in these dryland soils.
  • Authors:
    • Bandyopadhyay, K. K.
    • Wanjari, R. H.
    • Manna, M. C.
    • Misra, A. K.
    • Mohanty, M.
    • Rao, A. S.
    • Ghosh, P. K.
  • Source: Journal of Sustainable Agriculture
  • Volume: 30
  • Issue: 1
  • Year: 2007
  • Summary: This article deals with the beneficial effect of important legumes on increasing productivity and nutrient use efficiency in various systems. Sorghum, pearl millet, maize, and castor are mainstay in dry lands and marginal and sub-marginal lands. Sorghum yield increased when sown after cowpea, green gram, and groundnut. Grain legumes like groundnut or cowpea provide an equivalent to 60 kg N ha on the subsequent crop of pearl millet. Various studies have shown that among legume/cereal intercropping system, the combination of maize/pigeon pea is considered to be highly suitable with a minimum competition for nutrients, while legume/legume intercropping system, pigeon pea/groundnut system is the most efficient one in terms of resource use-efficiency. In alley cropping system, Leucaena leucocephala (Subabul) prunings provide N to the extent of 75 kg, which benefits the intercrop castor and sorghum. Nitrogen economy through intercropped legume is still a researchable issue because the key point for leguminous crop grown in intercropping system is the problem of nodulation. Incorporation of whole plant of summer green gram/black gram into soil (after picking pods) before transplanting rice resulted in the economizing (40-60 kg N ha -1, 30 kg P 2O 5, and 15 kg K 2O per ha) of rice in rice-wheat system. Similarly, 6-8 weeks old green manure crop of sunhemp or dhaincha accumulates approximately 3-4 t ha -1 dry matter and 100-120 kg N ha -1 which, when incorporated in situ, supplements up to 50% of the total N requirement of rice. Legumes with indeterminate growth are more efficient in N 2 fixation than determinate types. Fodder legumes in general are more potent in increasing the productivity of succeeding cereals. The carryover of N for succeeding crops may be 60-120 kg in berseem, 75 kg in Indian clover, 75 kg in cluster bean, 35-60 kg in fodder cowpea, 68 kg in chickpea, 55 kg in black gram, 54-58 kg in groundnut, 50-51 kg in soyabean, 50 kg in Lathyrus, and 36-42 kg per ha in pigeon pea. Direct and residual effect of partially acidulated material and mixture of rock phosphate + single superphosphate were observed to be better when these were applied to green gram in winter season than to rice in rainy season simply because of legume effect.
  • Authors:
    • Goswami, S. B.
    • Saha, S.
    • Dutta, S.
  • Source: National Seminar on Ecorestoration of Soil and Water Resources Towards Efficient Crop Production
  • Year: 2007
  • Summary: On-farm field experiments were undertaken in Chakdah Block, West Bengal, India, to study the impact of surface sowing, sowing by zero till seed drill (ZT) and conventional sowing with normal tillage (CT) in lowland rice fields on the growth and yield performances of wheat cv. 'UP 262', sown in the 1st, 3rd and 4th weeks of November during 2005-06 and 2006-07. For sowing under zero till, the seed rate was high (150 kg/ha). The depth of irrigation for ZT was 4 cm (3 h/bigha) compared to CT of 6 cm (4.5 h/bigha). Three irrigations were applied at crown root initiation, maximum tillering and flowering stages. The wheat plant height, tillering, panicle length, grains per spike and test weight were significantly affected by ZT and surface sowing compared to CT. Effective tiller production was higher under ZT with 3 irrigations than ZT with 2 irrigations or surface sowing. ZT with 3 irrigations (226 mm total water use) recorded the highest grain yield of 24.6 q/ha, which was a 21.8% yield increase over CT with 3 irrigations (243 mm total water use). ZT with 2 irrigations (189 mm total water use) decreased the grain yield by 111.8% over ZT with 3 irrigations. The water use efficiency was higher (8.5-8.71 kg ha -1 mma -1) under ZT with 3 irrigations over ZT with 2 irrigations or CT with 3 irrigations.