• Authors:
    • Inubushi, K.
    • Bakar, R.
    • Affandi, D.
    • Hadi, A.
  • Source: Jurnal Tanah Tropika (Journal of Tropical Soils)
  • Volume: 17
  • Issue: 2
  • Year: 2012
  • Summary: Presently, about 20% of oil palm ( Elaeis guineensis Jacq) fields in Indonesia are on peat soil, in addition to that other area of peat soil has been conventionally used for rice field and vegetables. To elucidate the global warming potentials of peat soils cultivated to oil palm, vegetable or rice field, field experiment has been carried out in South Kalimantan. Air samples were taken from rice field, oil palm and vegetable fields in weekly basis for six month period and analyzed for concentrations of N 2O, CH 4 and CO 2. The global warming potentials (GWP) of the three gases were calculated by multiplying the emission of each gas with their respective mole warming potential. This step was followed by the addition of the three gases' GWP to have the total GWP. The results showed that the emissions of greenhouse gases from peat soils changed seasonally and varied with the crops cultivated. Oil palm has resulted the highest GWP, mostly contributed by N 2O. There was no statistical different in total GWP of paddy and vegetable fields. The annual N 2O emission from oil palm field was 4,582 g N ha -1 yr -1. Water, nutrients and organic matter managements are among the potential techniques to minimize gas emissions from oil palm field which need field trials.
  • Authors:
    • Ruiz R., R.
    • Henson, I.
    • Romero, H.
  • Source: Agronomia Colombiana
  • Volume: 30
  • Issue: 3
  • Year: 2012
  • Summary: Colombia is currently the world's fifth largest producer of palm oil and the largest producer in South and Central America. It has substantial areas of land that could be used for additional oil palm production and there is considerable scope for increasing yields of existing planted areas. Much of the vegetation on land suitable for conversion to oil palm has a low biomass, and so establishing oil palm plantations on such land should lead to an increase in carbon stock, thereby counteracting greenhouse gas (GHG) emissions responsible for global warming. The first part of this study examines changes in carbon stock in Colombia resulting from expansion of oil palm cultivation together with factors (offsets) that act to minimize carbon emissions. The results are subsequently used to construct a net GHG balance.
  • Authors:
    • Romero, H.
    • Ruiz R., R.
    • Henson, I.
  • Source: Agronomia Colombiana
  • Volume: 30
  • Issue: 3
  • Year: 2012
  • Summary: In the preceding paper we examined carbon sequestration in oil palm plantations and in mill products and by-products as part of a study of the greenhouse gas balance of palm oil production in Colombia, showing how this has changed over time. Here, we look at the opposing processes of greenhouse gas (GHG) emission and calculate the resulting net carbon budget for the industry. The main emission sources, in decreasing order of magnitude, assessed using "default" or "most probable" options, were found to be land use change (40.9% of total), mill methane production (21.4%), direct use of fossil fuel (18.5%), indirect use of fossil fuel (11.9%) and nitrous oxide production (7.3%). The total (gross) emissions, expressed in carbon equivalents (Ceq.), were less than the amount of sequestered carbon, resulting in a positive net Ceq. balance. All oil palm growing regions showed a net gain with the exception of the western zone, where emissions due to land-use change were judged to be substantial. Of the 11 alternative scenarios tested, only three resulted in Ceq. balances lower than the default and only two gave a negative balance.
  • Authors:
    • Harmand, J.
    • Henault, C.
    • Skiba, U.
    • Blanchart, E.
    • Hergoualc'h, K.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 148
  • Year: 2012
  • Summary: Agroforestry represents an opportunity to reduce CO2 concentrations in the atmosphere by increasing carbon (C) stocks in agricultural lands. Agroforestry practices may also promote mineral N fertilization and the use of N-2-fixing legumes that favor the emission of non-CO2 greenhouse gases (GHG) (N2O and CH4). The present study evaluates the net GHG balance in two adjacent coffee plantations, both highly fertilized (250 kg N ha(-1) year(-1)): a monoculture (CM) and a culture shaded by the N-2-fixing legume tree species Inga densiflora (CIn). C stocks, soil N2O emissions and CH4 uptakes were measured during the first cycle of both plantations. During a 3-year period (6-9 years after the establishment of the systems), soil C in the upper 10 cm remained constant in the CIn plantation (+0.09 +/- 0.58 Mg C ha(-1) year(-1)) and decreased slightly but not significantly in the CM plantation (-0.43 +/- 0.53 Mg C ha(-1) year(-1)). Above-ground carbon stocks in the coffee monoculture and the agroforestry system amounted to 9.8 +/- 0.4 and 25.2 +/- 0.6 Mg C ha(-1), respectively, at 7 years after establishment. C storage rate in the phytomass was more than twice as large in the CIn compared to the CM system (4.6 +/- 0.1 and 2.0 +/- 0.1 Mg C ha(-1) year(-1), respectively). Annual soil N2O emissions were 1.3 times larger in the CIn than in the CM plantation (5.8 +/- 0.5 and 4.3 +/- 0.3 kg N-N2O ha(-1) year(-1), respectively). The net GHG balance at the soil scale calculated from the changes in soil C stocks and N2O emissions, expressed in CO2 equivalent, was negative in both coffee plantations indicating that the soil was a net source of GHG. Nevertheless this balance was in favor of the agroforestry system. The net GHG balance at the plantation scale, which includes additionally C storage in the phytomass, was positive and about 4 times larger in the CIn (14.59 +/- 2.20 Mg CO2 eq ha(-1) year(-1)) than in the CM plantation (3.83 +/- 1.98 Mg CO2 eq ha(-1) year(-1)). Thus converting the coffee monoculture to the coffee agroforestry plantation shaded by the N-2-fixing tree species I. densiflora would increase net atmospheric GHG removals by 10.76 +/- 2.96 Mg CO2 eq ha(-1) year(-1) during the first cycle of 8-9 years. (c) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Melling, L.
    • Kimura, S. D.
    • Goh, K. J.
  • Source: Geoderma
  • Volume: 185-186
  • Year: 2012
  • Summary: The influence of oil palm development on tropical peat soil decomposition rate was investigated by an incubation experiment. Soil samples from soil surface and around underground water table were taken from forest site, and oil palm site at 1st and 9th year after development. The soil samples were sieved into 0-2 mm, 2-8 mm and 8-20 mm and analyzed for carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes. The development of oil palm did not change the CO2 emissions and showed inconsistent influence on CH4 flux according to aggregate size, while significantly higher N2O emissions were found for aggregates 0-2 mm at high moisture of oil palm plantation soils compared with the original forest Nitrous oxide fluxes showed significant positive correlation with the CO2 flux, which indicated that soil organic matter decomposition was closely related to the N2O production. On the other hand, CH4 flux showed clear emission for aggregates bigger than 2 mm, while aggregates size 0-2 mm showed consistent CH4 uptake. These results showed that investigation of greenhouse gas emissions in tropical peat soil must take into account the aggregate characteristics of the soil, which are inhomogeneous and mixed with fresh organic matter.
  • Authors:
    • Ferreira, R.
    • Galvao, R.
    • Miranda Junior, E.
    • Araujo Neto, S.
    • Negreiros, J.
    • Parmejiani, R.
  • Source: Horticultura Brasileira
  • Volume: 29
  • Issue: 3
  • Year: 2011
  • Summary: The use of volunteer plants and live coverage of peanut ( Arachis pintoi) was evaluated, associating the application of organic compost in organic production of radish in no-till. The experiment was carried out at Federal University of Acre, in Rio Branco, Acre State, Brazil. A randomized complete block design with a split plot arrangement (4*3) and four replications was used. The plots consisted of the no-tillage systems with live coverage of peanut, with live coverage of spontaneous plants (weeds), with mulching of spontaneous plants, and conventional soil tillage with no-mulching soil. The subplots were composed of the doses of organic compost of 5, 10 and 15 t ha -1 in dry basis. The no-tillage with straw weed mulch had similar performance to the conventional soil tillage, both superior to the crop on the no-tillage with live mulch. The productivity of the radish cv. Cometa, was not affected by increasing doses of organic compost, being possible to apply only 5 t ha -1, whereas in the conventional tillage, the increasing productivity was higher compared to the direct planting only in the higher dose of compost (15 t ha -1).
  • Authors:
    • Backiyavathy, M. R.
  • Source: Advances in Plant Sciences
  • Volume: 24
  • Issue: 1
  • Year: 2011
  • Summary: A field experiment was conducted to evaluate the effect of different organic manures and its sources at different levels (FYM - 20, 25 & 30 t ha -1, vermicompost - 2.5, 5.0 & 7.5 t ha -1, poultry manure - 2.5, 5.0 & 7.5 t ha -1 and pig manure - 2.5, 5.0 & 7.5 t ha -1) on yield and quality of fodder in perennial fodder crops. The field experiment was conducted at New Area Farm, Department of Forage Crops, TNAU, Coimbatore. The experiment was laid out in randomized block design replicated twice with 14 treatments. Perennial fodder crops viz., cumbu napier hybrid grass CO 3, guinea grass CO 2, sorghum COFS 29, lucerne CO 1 and hedge lucerne were studied under this investigation. The results revealed that the organic manure treatments were compared with recommended dose of inorganic fertilizers with respect to each fodder crop. Among different organics, application of FYM @ 30 t ha -1 registered the maximum green fodder, dry fodder and crude protein yields in all perennial fodders. However the maximum green, dry fodder and crude protein yields were recorded in RDF treatment over the rest of the other treatments.
  • 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:
    • Elazegui, D. D.
    • Chupungco, A. R.
    • Nguyen, M. R.
  • Source: Philippine Journal of Crop Science
  • Volume: 36
  • Issue: 2
  • Year: 2011
  • Summary: This study discusses the seed system, production and marketing of eggplant, Solanum melongena L., considered as one of the most important vegetable crops in the Philippines. Data analyzed were obtained from focus group discussions in major eggplant producing provinces of Pangasinan, Batangas and Quezon; key informant interviews with representatives of government agencies and seed companies, and traders; and secondary sources such as government reports and other publications. The eggplant seed system is generally organized, involving public and private sectors. There are different varieties available in the market but seed developers do not opt for seed registration nor plant variety protection because of the rigorous process involved. Instead, seed companies adopt well-established seed production and quality control strategies and vigorous marketing and promotion to improve sales. Commercial growers of eggplant adopt hybrid seeds, while open-pollinated varieties (OPVs) are mainly used for small-scale production. Between 2000 and 2009, eggplant production increased by 21% despite a relatively lower increase (6%) in area planted. Average yield ranged 8-10 mt ha -1. Eggplant production is profitable, but major problems include fruit and shoot borer (FSB) infestation, bacterial wilt, irrigation supply and climate-related problems. Production involves intensive use of pesticides, bearing some implications on human health and environment. This should call the attention of Local Government Units which are in the forefront of providing extension services. Moreover, research and development should continuously receive adequate support to address these concerns. Research and development thrusts could include varietal improvement of eggplant and alternative pest control strategies such as integrated pest management (IPM) technology and intercropping. The current effort on R & D of Bt eggplant addresses the problem of FSB and heavy dependence of farmers on pesticides. With the stringent regulatory system of the Philippines on the commercial propagation of GM crops, adverse impact on human health and environment will be curtailed.
  • Authors:
    • Rao, I. M.
    • Schmidt, A.
    • van der Hoek, R.
    • Bernasconi, S. M.
    • Frossard, E.
    • Douxchamps, S.
    • Oberson, A.
  • Source: Plant and Soil
  • Volume: 341
  • Issue: 1-2
  • Year: 2011
  • Summary: The integration of multipurpose legumes into low-input tropical agricultural systems is needed because they are a nitrogen (N) input through symbiotic fixation. The drought-tolerant cover legume canavalia (Canavalia brasiliensis) has been introduced for use either as forage or as a green manure into the crop-livestock system of the Nicaraguan hillsides. To evaluate its impact on the subsequent maize crop, an in-depth study on N dynamics in the soil-plant system was conducted. Microplots were installed in a 6-year old field experiment with maize-canavalia rotation. Direct and indirect (15)N-labelling techniques were used to determine N uptake by maize from canavalia residues and canavalia-fed cows' manure compared to mineral fertilizer. Litter bags were used to determine the N release from canavalia residues. The incorporation of N from the amendment into different soil N pools (total N, mineral N, microbial biomass) was followed during the maize cropping season. Maize took up an average of 13.3 g N m(-2), within which 1.0 g N m(-2) was from canavalia residues and 2.6 g N m(-2) was from mineral fertilizer, corresponding to an amendment N recovery of 12% and 32%, respectively. Recoveries in maize would probably be higher at a site with lower soil available N content. Most of the amendment N remained in the soil. Mineral N and microbial N were composed mainly of N derived from the soil. Combined total (15)N recovery in maize and soil at harvest was highest for the canavalia residue treatment with 98% recovery, followed by the mineral fertilizer treatment with 83% recovery. Despite similar initial enrichment of soil microbial and mineral N pools, the indirect labelling technique failed to assess the N fertilizer value of mineral and organic amendments due to a high N mineralization from the soil organic matter.