• Authors:
    • Passos, A. M. A. dos
    • Albuquerque, A. de
    • Resende, P. M. de
    • Baliza, D. P.
    • Reis, W. P.
    • Botrel, E. P.
  • Source: Revista de Agricultura
  • Volume: 86
  • Issue: 1
  • Year: 2011
  • Summary: The objective of this work was to compare the potential of the irrigated wheat under no tillage and conventional cropping systems, as well as to evaluate the performance of fifteen wheat cultivars in the two cropping systems, in succession to soybean crop, in the South of Minas Gerais. The experiment was carried out in the Federal University of Lavras (UFLA), in Lavras, MG, in the years of 2006/07 and 2007/08, in a split-block-designed scheme in a randomized complete block design, with three replications. The cropping systems (conventional and no-tillage) were installed in the rows and, in the columns, the fifteen wheat cultivars were distributed. The wheat yield and others agronomic characteristics were evaluated. The no-tillage provided an average increase of 25% in the organic matter levels in the topsoil layer in relation to previous levels and to conventional cropping system. The cultivars tested, independent of the agricultural year, significantly altered the grain yields and the agronomic characteristics. The high yield presented by the cultivars evaluated in this study indicates the high potential of the irrigated wheat cropped in succession to soybean crops, under similar climatic and soil conditions used in this study.
  • Authors:
    • Isla, R.
    • Salmeron, M.
    • Cavero, J.
  • Source: Field Crops Research
  • Volume: 123
  • Issue: 2
  • Year: 2011
  • Summary: Under semiarid Mediterranean conditions irrigated maize has been associated to diffuse nitrate pollution of surface and groundwater. Cover crops grown during winter combined with reduced N fertilization to maize could reduce N leaching risks while maintaining maize productivity. A field experiment was conducted testing two different cover crop planting methods (direct seeding versus seeding after conventional tillage operations) and four different cover crops species (barley, oilseed rape, winter rape, and common vetch), and a control (bare soil). The experiment started in November 2006 after a maize crop fertilized with 300 kg N ha(-1) and included two complete cover crop-maize rotations. Maize was fertilized with 300 kg N ha(-1) at the control treatment, and this amount was reduced to 250 kg N ha(-1) in maize after a cover crop. Direct seeding of the cover crops allowed earlier planting dates than seeding after conventional tillage, producing greater cover crop biomass and N uptake of all species in the first year. In the following year, direct seeding did not increase cover crop biomass due to a poorer plant establishment. Barley produced more biomass than the other species but its N concentration was much lower than in the other cover crops, resulting in higher C:N ratio (> 26). Cover crops reduced the N leaching risks as soil N content in spring and at maize harvest was reduced compared to the control treatment. Maize yield was reduced by 4 Mg ha(-1) after barley in 2007 and by 1 Mg ha(-1) after barley and oilseed rape in 2008. The maize yield reduction was due to an N deficiency caused by insufficient N mineralization from the cover crops due to a high C:N ratio (barley) or low biomass N content (oilseed rape) and/or lack of synchronization with maize N uptake. Indirect chlorophyll measurements in maize leaves were useful to detect N deficiency in maize after cover crops. The use of vetch, winter rape and oilseed rape cover crops combined with a reduced N fertilization to maize was efficient for reducing N leaching risks while maintaining maize productivity. However, the reduction of maize yield after barley makes difficult its use as cover crop. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Amarasekera, P.
    • Sangakkara, U. R.
    • Stamp, P.
  • Source: Acta Agronomica Hungarica
  • Volume: 59
  • Issue: 2
  • Year: 2011
  • Summary: Maize is the most important upland cereal in tropical Asia, grown in both major and minor seasons under rainfed conditions. Due to the inadequate rainfall in the minor season, the crop is subjected to water stress, and irrigation helps to produce high yields. Smallholders who grow maize on flat beds in their allotments often use surface flood irrigation whenever irrigation water is available, which leads in most instances to inefficient use of this valuable resource. A field study was carried out over two minor seasons in Sri Lanka to determine the impact of different schedules of irrigation, developed on the basis of time intervals (3-, 7-, 14- or 21-day intervals or no irrigation as a control), which can easily be practised by smallholders, on the root development, shoot growth, seed yield and water use efficiency of maize. Irrigation at 3-day intervals produced fine roots in the top layers of the soil. Increasing the time interval between irrigation schedules to 7, 14 or 21 days reduced the percentage of fine roots, but developed more, heavier roots in the lower soil layers, as determined by root length densities (RLD) and root weight densities (RWD). Longer irrigation intervals or lack of irrigation resulted in a smaller number of heavier roots in the soil profile. The leaf water potential was affected to a greater degree than shoot water content or relative water content. The seed yield and harvest index were highest when maize was irrigated at 7-day intervals. In contrast, irrigation water use efficiency (IWUE) was highest at an irrigation interval of 14 days. The potential for optimizing water use in surface irrigation in flat beds while obtaining high yields in a tropical Asian minor season, when maize is subjected to moisture stress under smallholding conditions, is presented on the basis of this study.
  • Authors:
    • Prabhakaran, N. K.
    • Chinnusamy, C.
    • Sangeetha, C.
  • Source: Madras Agricultural Journal
  • Volume: 98
  • Issue: 4/6
  • Year: 2011
  • Summary: A study was carried out to evaluate the effect of early post emergence herbicide, imazethapyr against weeds in irrigated soybean (Glycine max (L.) Merill) at Agricultural Research Station, Bhavanisagar. Weeds, viz., Dactyloctenium aegypticum, Acrach ne racemosa, Cyperus rotundus, Boerhaavia diffusa, Digera arvensis, Parthenium hysterophorous were the dominant weeds in the experimental field. Imazethapyr at 100 and 200 g ha -1 applied on 15 DAS provided 87 to 91% weed control efficiency compared to unweeded control. However, imazethapyr at 200 g ha -1 had slight phytotoxicity on soybean in the initial stages. Higher grain yield of 1645 kg ha -1 was obtained with application of imazethapyr 100 g ha -1.
  • Authors:
    • Prasad, T. V. R.
    • Kumar, V. K. K.
    • Sanjay, M. T.
    • Gowda, P. T.
  • Source: Journal of Crop and Weed
  • Volume: 7
  • Issue: 1
  • Year: 2011
  • Summary: A field experiment was conducted during Kharif 2007 and summer 2008 on sandy loam soil of Hebbal, Bangalore, University of Agricultural Sciences, Bangalore, to know the comparative performance of tank mix application of chlorimuron ethyl (Kloben 25% WP)+quizalofop-p-terfuryl (Pantera 4% EC) on controlling weeds in soybean and seed yield Tank mix combination of chlorimuron ethyl 9 g+quizalofop-p-tefuryl 40 g ai/ha -20 DAS with surfactant (1598 kg/ha) or without surfactant (1518 kg/ha) gave seed yield similar to hand weeding twice (1720 kg/ha), as result of good control of grasses, broad leaf weeds and sedge. Unweeded control lowered the yield by 61% mainly due to severe competition offered by grasses. Thus, use of chlorimuron ethyl 9 g+quizalofop-p-terfuryl 40 g ai/ha+0.2% surfactant (as tank mix) at 20 DAS can be used safely for broad spectrum weed control in irrigated soybean.
  • Authors:
    • Cella, A. J. S.
    • Ferraz, E. de C.
    • Barros, H. B.
    • Santos, E. R. dos
    • Capone, A.
    • Santos, A. F. dos
    • Fidelis, R. R.
  • Source: Revista Ceres
  • Volume: 58
  • Issue: 6
  • Year: 2011
  • Summary: The genetic diversity is one of the most important parameters evaluated by plant breeders in the early stages of a genetic improvement program. The objective of this paper was to evaluate the genetic divergence by means of multivariate techniques, among 48 soybean genotypes grown in irrigated lowland in the State of Tocantins, in order to select parents of hybrids for the production of oil and meal, as well as varieties of the panel, intended for human consumption. The experiment was conducted in the county Formoso do Araguaia - Tocantins, Brazil, in the cultivation of irrigated lowland, in the inter-cropping 2010. The experimental design was a randomized block with four replications. There was observed variability among the genotype tested. The Tocher's method, UPGMA and Canonic Variables agreed among themselves, and found four distinct groups. The following hybrids are promising for the production of soybean oil and meal for the M-Soy 8766, M-Soy 9144, A-7002 and M-soy 9056 with Amaralina RR crosses between and M-Soy 8766, M-Soy 9144 and Amaralina RR with BRSMG 790A, BRS 257, BRS 216 and BRS 213, are listed in order especially soybeans for human consumption.
  • Authors:
    • Munkhtsetseg, E.
    • Kimura, R.
    • Şaylan, L.
    • Kamichika, M.
  • Source: Theoretical and Applied Climatology
  • Volume: 105
  • Issue: 1/2
  • Year: 2011
  • Summary: In this study, variations in carbon dioxide (CO 2) fluxes resulting from gross primary production (GPP), net ecosystem exchange (NEE), and respiration ( Re) of soybean ( Glycine max L.) were investigated by the Eddy Covariance method during the growing period from June to November 2005 on an irrigated sand field at the Arid Land Research Center, Tottori University in Tottori, Japan. Although climatic conditions were humid and temperate, the soybeans required frequent irrigation because of the low water holding capacity of the sandy soil at the field site. Finally, it has been found that the accumulated NEE, GPP, and Re fluxes of soybean over 126 days amount to -93, 319, and 226 gC m -2, respectively. Furthermore, the average ratio of GPP to Re was 1.4 and the average ratio of NEE to GPP was about -0.29 for the growth period of soybean. Daily maximum NEE of -3.8 gC m -2 occurred when LAI was 1.1.
  • Authors:
    • Fahandezh-Saadi, S.
    • Sepaskhah, A. R.
    • Zand-Parsa, S.
  • Source: Agricultural Water Management
  • Volume: 99
  • Issue: 1
  • Year: 2011
  • Summary: Simulation of crop yield allows better planning and efficient management under different environmental inputs such as water and nitrogen application. However, most of the models are complicated and difficult to understand. Furthermore, input data are not readily available. The objectives of this investigation were to use logistic equation to quantify the influence of seasonal water and nitrogen application on maize biomass accumulation and grain yield and to develop empirical models for prediction of maize biomass and grain yield. Logistic equations were fitted to dray matter (DM) yield at different times in the growing season at different irrigation water and nitrogen levels. The parameters of the logistic equations were then fitted to irrigation water and nitrogen as empirical functions. Further, the harvest index (HI) was related to the applied water and nitrogen as another empirical model. The empirical logistic models were used to estimate the DM and grain yield based on data from another experiment in the same area. Results indicated that the empirical models predicted the DM yield during the growing season with an acceptable accuracy, but dry matter (DM) prediction at harvest was very good. The grain yield also was predicted with a very good accuracy. It is concluded that logistic equation along with the presented empirical models for prediction of constants in logistic equation and HI are appropriate for accurate prediction of DM and grain yield of maize at the study region.
  • Authors:
    • Dobermann, A.
    • Weiss, A.
    • Cassman, K. G.
    • Bastidas, A. M.
    • Setiyono, T. D.
    • Specht, J. E.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 4
  • Year: 2011
  • Summary: At any given time, the leaf area index (LAI) of a soybean [Glycine max (L.) Merr.] crop consists of the summed contributions of each trifoliolate leaf present at each main stem node and on branches. No data are available on nodal LAI distributions in modern indeterminate (IN) or semi-determinate (SD) cultivars grown in irrigated, early-planted, high-yield production systems. The impact of stem termination type and row spacing on that distribution was investigated in such environments at Lincoln, NE in 2003, 2004, and 2005. Trifoliolate LAI at each stem node followed a temporal pattern of rapid increase (after leaf initiation) to a peak before declining due to senescence-driven leaf abscission, thus emulating, on a shorter time-scale, the canopy LAI pattern. The post-peak decline in nodal LAI was rapid in nodes initiated prebloom (i.e., nearly 100% abscission before seed-fill), but was gradual in nodes initiated after pod initiation (i.e., little abscission before plant maturity). Nodal LAI peaked at the eighth node of the IN cultivar, but rapid leaf expansion at preflowering nodes of the SD cultivar led to a broad peak spanning the fifth to eighth node. Simulation of the Beer-Lambert law of light attenuation in both canopies revealed that light penetration was deeper in the IN canopy than in the SD canopy. Although higher plant density suppressed branching (and thus branch leaf area) in the SD cultivar, this was not observed in the IN cultivar. These findings suggested that nodal LAI development can be used to mechanistically model canopy LAI.
  • Authors:
    • Kabenge, I.
    • Irmak, S.
    • Sharma, V.
    • Kilic, A.
  • Source: Transactions of the ASABE
  • Volume: 54
  • Issue: 3
  • Year: 2011
  • Summary: Understanding the relationship between the spatial distribution of precipitation and crop yields on large scales (i.e., county, state, regional) while accounting for the spatial non-stationarity can help managers to better evaluate the long-term trends in agricultural productivity to make better assessments in food security, policy decisions, resource assessments, land and water resources enhancement, and management decisions. A relatively new technique, geographically weighted regression (GWR), has the ability to account for spatial non-stationarity with space. While its application is growing in other scientific disciplines (i.e., social sciences), the application of this new technique in agricultural settings has not been practiced. The geographic information system (GIS), along with two different statistical techniques [GWR and conventional ordinary least square regression (OLS)], was utilized to analyze the relationships between various precipitation categories and irrigated and rainfed maize and soybean yields for all 93 counties in Nebraska from 1996 to 2008. Precipitation was spatially interpolated in ArcGIS using a spline interpolation technique with zonal statistics. Both measured and GWR- and OLS-predicted yields were correlated to spatially interpolated annual (January 1 to December 31), seasonal (May 1 to September 30), and monthly (May, June, July, August, and September) precipitation for each county. Statewide average annual precipitation in Nebraska from 1996 to 2008 was 564 mm, with a maximum of 762 mm and minimum of 300 mm. Mean precipitation decreased gradually from May to September during the growing season. County average yields followed the same temporal trends as precipitation. When the OLS regression model was used, there was a general trend of linear correlation between observed yield and long-term average mean annual total precipitation with a varying coefficient of determination (R 2). For rainfed crops, 67% of the variability in mean yield was explained by the mean annual precipitation. About 23% and 17% of the variability in mean yield was explained by mean annual precipitation for irrigated maize and soybean, respectively. However, the performance of the GWR technique in predicting the yields from spatially interpolated precipitation for irrigated and rainfed maize and soybean was significantly better than the performance of the OLS model. For both rainfed maize and soybean, 77% to 80% of the variation in yield was explained by the mean annual precipitation alone. For irrigated crops, 42% of the variation in the yield was explained by the mean annual precipitation. For rainfed crops, there was a strong correlation between seasonal precipitation and yield, with R 2 values of 0.73 and 0.76 for maize and soybean, respectively. The mean annual total precipitation was a better predictor of rainfed maize yield than rainfed soybean yield. On a statewide average, July precipitation as a predictor had the greatest correlation with yields of both maize and soybean. June, July, and August precipitation had greater impact on maize yield than on soybean under rainfed conditions due to more sensitivity of maize to water stress than soybean. For irrigated yields, July precipitation had more impact on soybean yield than on maize. The performance of the GWR technique was superior to the OLS model in analyzing the relationship between yield and precipitation. The superiority of the GWR technique to OLS is mainly due to its ability to account for the impact of spatial non-stationarity on the precipitation vs. yield relationships.