• Authors:
    • Saggin, A.
    • Santos, D.
    • Gatiboni, L.
    • Brunetto, G.
    • Kaminski, J.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 29
  • Issue: 4
  • Year: 2005
  • Summary: The critical potassium level for fertilizer recommendation for soils in the State of Rio Grande do Sul (RS) and Santa Catarina (SC), Brazil, with cation exchange capacity (CEC) from 5.1 to 15 cmol c dm -3 is 60 mg dm -3. However, until 2002 concentrations of 80 mg dm -3 had been used. Two experiments were carried out on an experimental area of the Department of Soil Science of the Federal University of Santa Maria (RS-Brazil) on a sandy Typic Hapludalf under no-tillage. The objective of the study was to evaluate critical potassium levels for fertilizer recommendations for soyabean, maize and sorghum. The first experiment was set up in 1991 and carried out until 2002. The main plot treatments were the application of 0, 60, 120, and 180 kg ha -1 K 2O every four years, and split-plot treatments were the reapplication of 60 kg of K 2O in 0, 1, 2, or 3 years. The second experiment was carried out from 1995 to 2002 and the treatments were 0, 50, 100, 150, and 200 kg ha -1 year -1 K 2O. Results showed that the critical potassium level extracted with Mehlich-1 solution is 42 mg dm -3. When using the critical potassium level established by the Regional Soil Chemistry and Fertility Commission in these soils it is possible to reach over 95% of the maximum crop yield.
  • Authors:
    • Rodrigues, L.
    • Lazarini, E.
    • Leal, A.
    • Muraishi, C.
    • Gomes Junior, F.
  • Source: Acta Scientiarum Agronomy
  • Volume: 27
  • Issue: 2
  • Year: 2005
  • Summary: This experiment aimed to verify the reaction of soyabean and maize cultures sown 38 days near or after chemical or mechanical handling of different soil coverings. The experiment was carried out at the experimental Station of Unesp, Ilha Solteira Campus, in the municipality of Selviria, state of Mato Grosso do Sul, Brazil, during the agricultural year of 2001/02. The covering cultures used were: rice, sorghum, Brachiaria decumbens [ Urochloa decumbens] and B. brizantha [ U. brizantha], millet [ Pennisetum glaucum] and Eleusine coracana. It was observed that the covering cultures showed good environment adaptation in dry mass production. The maize productivity was larger when the covering cultures handling was mechanically accomplished. The interval between handling and sowing of soyabean and maize culture is important only for rice or Brachiaria decumbens covering cultures; in this case, a 38-day previous handling is recommended. Maize yield was inferior when sown on sorghum residues.
  • Authors:
    • Klepker, D.
    • Yamada, M.
    • Hitsuda, K.
  • Source: Agronomy Journal
  • Volume: 97
  • Issue: 1
  • Year: 2005
  • Summary: Sulfur deficiency symptoms are more often observed in crops at early stages of growth since S can be easily leached from the surface soil. The objectives of this study were to evaluate some of the popular rotation crops grown in Brazil for tolerance to low external S levels and to determine the critical tissue concentration for S deficiency during early stages of growth. Germinated seedlings of soybean [ Glycine max (L.) Merr.], rice ( Oryza sativa L.), maize ( Zea mays L.), field bean ( Phaseolus vulgaris L.), wheat ( Triticum aestivum L.), cotton ( Gossypium spp.), sorghum ( Sorghum bicolor L.), and sunflower ( Helianthus annuus L.) were transferred to water culture with 0.0 to 32.0 mg S L -1 and were grown for 29 d. The minimum S concentration required in nutrient solutions was 2.0 mg L -1 for sunflower; 1.0 mg L -1 for cotton, sorghum, wheat, and soybean; and 0.5 mg L -1 or less for field bean, rice, and maize. All crops achieved optimum growth at 2.0 mg S L -1. Critical shoot S concentration at early stages of growth was 0.8 g kg -1 in maize and soybean; 1.1 to 1.3 g kg -1 in cotton, sorghum, and rice; and 1.4 to 1.6 g kg -1 in wheat, sunflower, and field bean. Our results demonstrate that the tolerance to low external S (
  • Authors:
    • Trein, C.
    • Herzog, R.
    • Levien, R.
  • Source: Engenharia Agricola
  • Volume: 24
  • Issue: 3
  • Year: 2004
  • Summary: To evaluate soyabean productivity on natural pasture fields, grown once with oats to produce grain and straw for soil cover, an experiment was conducted on a Typic Paleudult Soil in Eldorado do Sul, Rio Grande do Sul, Brazil. After mechanically harvesting oats, the straw was returned to plots in amounts of 0, 2, 3, 4, 5 and 6 mg/ha and were divided according to the furrow opening depth (0.06 and 0.12 m). The area was divided in 2, with and without irrigation. The volume of soil mobilized by the fertilizer furrow openers was 53% higher when the working depth reached 0.12 m compared to 0.06 m, but no difference due to the amount of cover crop residues was attained. Grain yield, crop biomass and root mass up to 0.15 cm depth did not differ with both soil working depth and crop residue cover. Irrigation increased grain yield and total biomass of soyabeans. Even without irrigation, soyabean productivity was higher than the Rio Grande do Sul State average, showing its suitability to be grown on native pastures under the no-till system.
  • Authors:
    • Dale, B. E.
    • Kim, S.
  • Source: Biomass and Bioenergy
  • Volume: 26
  • Issue: 4
  • Year: 2004
  • Summary: The global annual potential bioethanol production from the major crops, corn, barley, oat, rice, wheat, sorghum, and sugar cane, is estimated. To avoid conflicts between human food use and industrial use of crops, only the wasted crop, which is defined as crop lost in distribution, is considered as feedstock. Lignocellulosic biomass such as crop residues and sugar cane bagasse are included in feedstock for producing bioethanol as well. There are about 73:9 Tg of dry wasted crops in the world that could potentially produce 49:1 GL year-1 of bioethanol. About 1:5 Pg year-1 of dry lignocellulosic biomass from these seven crops is also available for conversion to bioethanol. Lignocellulosic biomass could produce up to 442 GL year-1 of bioethanol. Thus, the total potential bioethanol production from crop residues and wasted crops is 491 GL year-1, about 16 times higher than the current world ethanol production. The potential bioethanol production could replace 353 GL of gasoline (32% of the global gasoline consumption) when bioethanol is used in E85 fuel for a midsize passenger vehicle. Furthermore, lignin-rich fermentation residue, which is the coproduct of bioethanol made from crop residues and sugar cane bagasse, can potentially generate both 458 TWh of electricity (about 3.6% of world electricity production) and 2:6EJ of steam. Asia is the largest potential producer of bioethanol from crop residues and wasted crops, and could produce up to 291 GL year -1 of bioethanol. Rice straw, wheat straw, and corn stover are the most favorable bioethanol feedstocks in Asia. The next highest potential region is Europe (69:2 GL ofbioethanol), in which most bioethanol comes from wheat straw. Corn stover is the main feedstock in North America, from which about 38:4 GL year -1 of bioethanol can potentially be produced. Globally rice straw can produce 205 GL of bioethanol, which is the largest amount from single biomass feedstock. The next highest potential feedstock is wheat straw, which can produce 104 GL of bioethanol. This paper is intended to give some perspective on the size ofthe bioethanol feedstock resource, globally and by region, and to summarize relevant data that we believe others will 0nd useful, for example, those who are interested in producing biobased products such as lactic acid, rather than ethanol, from crops and wastes. The paper does not attempt to indicate how much, if any, of this waste material could actually be converted to bioethanol.
  • Authors:
    • Moreira, A.
    • Martins, G.
    • Mccann, J.
    • German, L.
    • Kern, D.
    • Lehmann, J.
  • Source: Amazonian Dark Earths
  • Volume: Part 2
  • Year: 2004
  • Authors:
    • Sathaye, J. A.
    • Makundi, W. R.
  • Source: Environment, Development and Sustainability
  • Volume: 6
  • Issue: 1-2
  • Year: 2004
  • Summary: This paper summarizes studies of carbon mitigation potential (MP) and costs of forestry options in seven developing countries with a focus on the role of agroforestry. A common methodological approach known as comprehensive mitigation assessment process (COMAP) was used in each study to estimate the potential and costs between 2000 and 2030. The approach requires the projection of baseline and mitigation land-use scenarios derived from the demand for forest products and forestland for other uses such as agriculture and pasture. By using data on estimated carbon sequestration, emission avoidance, costs and benefits, the model enables one to estimate cost effectiveness indicators based on monetary benefit per tC, as well as estimates of total mitigation costs and potential when the activities are implemented at equilibrium level. The results show that about half the MP of 6.9 GtC (an average of 223 MtC per year) between 2000 and 2030 in the seven countries could be achieved at a negative cost, and the other half at costs not exceeding $100 per tC. Negative cost indicates that non-carbon revenue is sufficient to offset direct costs of about half of the options. The agroforestry options analyzed bear a significant proportion of the potential at medium to low cost per tC when compared to other options. The role of agroforestry in these countries varied between 6% and 21% of the MP, though the options are much more cost effective than most due to the low wage or opportunity cost of rural labor. Agroforestry options are attractive due to the large number of people and potential area currently engaged in agriculture, but they pose unique challenges for carbon and cost accounting due to the dispersed nature of agricultural activities in the tropics, as well as specific difficulties arising from requirements for monitoring, verification, leakage assessment and the establishment of credible baselines.
  • Authors:
    • Thomas, R. J.
    • Fisher, M. J.
  • Source: Environment, Development and Sustainability
  • Volume: 6
  • Issue: 1-2
  • Year: 2004
  • Summary: Three of the nine physiographic regions that comprise the 8.2 million km2 (Mkm2) of the central lowlands of tropical South America have undergone substantial conversion from the native vegetation in the last 30 years, a good deal of it to introduced pastures. The converted lands were either formerly treeless grasslands of the Brazilian Shield and the Orinoco Basin, or semi-evergreen seasonal forest mainly in the east and southwest of the Amazon Basin in Brazil. There are about 0.44Mkm2 of introduced Brachiaria pastures in the former grasslands and we estimate that there are 0.096Mkm2 of introduced pastures in the Amazon Basin, mostly Brachiaria species. Based on extensive descriptions of the land systems of the central lowlands by Cochrane et al. (1985) we extrapolated data of carbon (C) accumulation in the soil under introduced pastures on the eastern plains of Colombia (about 3 t Cha-1 yr-1), which are treeless grasslands of the Orinoco Basin, to estimate the probable change in C stocks as a result of conversion to pasture elsewhere. Losses of above-ground C on conversion of the former grasslands is negligible, while in contrast the forests probably lose about 115 t C for each ha converted. We estimated the mean time since conversion started and allowed for the degradation of the pastures that commonly occurs. We concluded that introduced pastures on the former grasslands have been a net sink for about 900 million t (Mt) C, while conversion of the forest has been a net source of about 980 Mt C, leading to a net source of about 80 Mt C for the central lowlands as a whole. We identify a number of issues and possible methodologies that would improve precision of the estimates of the changes in C stocks on conversion of native vegetation to pasture.
  • Authors:
    • Carmo, C.
    • Lhamby, J.
    • Ambrosi, I.
    • Santos, H.
  • Source: Ciencia Rural
  • Volume: 34
  • Issue: 1
  • Year: 2004
  • Summary: Soil tillage and crop rotation and succession systems were assessed in Passo Fundo, Rio Grande do Sul, Brazil, from 1994/95 to 1997/98. Four soil tillage systems, i.e. no-tillage, minimum tillage, conventional tillage using a disc plough, and conventional tillage using a mouldboard plough, and three crop rotation and succession systems, i.e. system I (wheat/soyabean), system II (wheat/soyabean and common vetch [ Vicia sativa]/sorghum or maize) and system III (wheat/soyabean, common vetch/sorghum or maize, and white oats/soyabean), were compared. An experimental design of randomized blocks with split-plots and three replications was used. The main plot was formed by the soil tillage systems, while the split-plots consisted of the crop rotation and succession systems. Two types of analysis were applied to the net return of soil tillage and crop rotation and succession systems: mean-variance and risk analysis. By the mean-variance analysis, no-tillage and minimum tillage, which presented higher net returns, were the best alternatives to be offered to the farmer. By the stochastic dominance analysis, no-tillage and crop rotation with two winters without wheat showed the highest profit and the lowest risk.
  • Authors:
    • Sharma, R. D.
    • Corrêa, J. C.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 39
  • Issue: 1
  • Year: 2004
  • Summary: An experiment was carried out on a heavy red yellow latosol to evaluate crop rotation on herbaceous cotton ( Gossypium hirsutum) yields in no-till system under rainfed Savannah conditions. The treatments were: soyabean-millet ( Pennisetum glaucum)-soyabean-millet-cotton; soyabean-amaranth ( Amaranthus hypochondriacus)-soyabean-forage radish-soyabean-cotton; soyabean-grain sorghum ( Sorghum vulgare [ S. bicolor])-soyabean-grain sorghum-cotton; soyabean-black rye ( Avena strigosa [ A. nuda])-soyabean-black rye-cotton and soyabean-soyabean-cotton. The highest cotton seed yield and best weed control were recorded in the sequence soyabean-millet-soyabean-millet-cotton.