• Authors:
    • HongYeng, L.
    • Agamuthu, P.
  • Source: Article
  • Volume: 103
  • Issue: 2
  • Year: 2015
  • Summary: High levels of nitrogen (N) are typically used in leafy vegetable farms to maximize production. However, such practice often leads to nutrient pollution. Hence, N balance in intensive leafy vegetable farm production must be explored to improve current farm management practices and to avoid environmental pollution. This study aimed to generate partial N balance in two organic (OF1 and OF2) and two conventional (CF1 and CF2) vegetable farms by employing material flow analysis/substance flow analysis in the STAN modeling software. Results showed that 31,556, 32,798, 19,498, and 19,337 t ha(-1) y(-1) of materials entered CF1, CF2, OF1, and OF2, respectively, and contributed to the nitrogen surplus levels of 1577, 1667, 2953, and 961 kg N ha(-1) y(-1), respectively. The STAN model revealed the presence of N surplus in the organic and conventional systems used in the study.
  • Authors:
    • Meyer-Aurich, A.
    • Salleh, M. A. M.
    • Hansen, A.
    • Lau, Lek H.
    • Grundman, P.
    • Harsono, S. S.
    • Idris, A.
    • Ghazi, T. I. M.
  • Source: Resources, Conservation and Recycling
  • Volume: 77
  • Year: 2013
  • Summary: This paper presents results from a gate-to-gate analysis of the energy balance, greenhouse gas (GHG) emissions and economic efficiency of biochar production from palm oil empty fruit bunches (EFB). The analysis is based on data obtained from EFB combustion in a slow pyrolysis plant in Selangor, Malaysia. The outputs of the slow pyrolysis plant are biochar, syngas, bio-oil and water vapor. The net energy yield of the biochar produced in the Selangor plant is 11.47 MJ kg(-1) EFB. The energy content of the biochar produced is higher than the energy required for producing the biochar, i.e. the energy balance of biochar production is positive. The combustion of EFB using diesel fuel has the largest energy demand of 2.31 MJ kg(-1) EFB in the pyrolysis process. Comparatively smaller amounts of energy are required as electricity (0.39 MJ kg(-1) EFB) and for transportation of biochar to the warehouse and the field (0.13 MJ kg(-1) EFB). The net greenhouse gas emissions of the studied biochar production account for 0.046 kg CO2-equiv.kg(-1) EFB yr(-1) without considering fertilizer substitution effects and carbon accumulation from biochar in the soil. The studied biochar production is profitable where biochar can be sold for at least 533 US-$t(-1). Potential measures for improvement are discussed, including higher productivity of biochar production, reduced energy consumption and efficient use of the byproducts from the slow pyrolysis.
  • Authors:
    • Melling, L.
  • Source: Planter
  • Volume: 89
  • Issue: 1051
  • Year: 2013
  • Summary: Arable land is among one of the world's most important resources that influences a nation's wealth. In Sarawak, tropical peatland is the last frontier of arable land available for industrial agriculture development. Being the last exploited land resources, it is the least researched soil type among the tropical soils and making it the most least understood. Tropical peats that co-existed with the tropical ecosystem are liken to mineral soils of the tropics and are quite different from temperate peats because they are formed under contrasting climatic (wet and dry seasons) and edaphic conditions. Temperate peats are mainly derived from the remains of low growing plants ( Sphagnum spp., Gramineae spp. and Cyperaceae spp.) which are more cellulosic in nature. Tropical peats, on the other hand, are formed from forest species and hence tend to have large amounts of undecomposed and partially decomposed logs, branches and other plant remains which are more lignified. Recently, there has been an increasing trend in oil palm cultivations on tropical peatland. Conversion of tropical peatland into oil palm plantation in South East Asia has been assumed to enhance decomposition process via peat oxidation due to drainage and water management, which leads to the raising level of greenhouse gas (GHG) emission. It has also been postulated that this process will increase in time with oil palm cultivation. However, the management has its contributing factor towards GHG emission from an oil palm plantation and its after effect of climate change due to peatland conversion. Drainage, compaction and water management formed a part of the development process for oil palm peat planting. To further understand the role of water table on soil carbon (C) flux in tropical peatland, a study on GHG from three different ecosystems on tropical peatland was commissioned i.e. oil palm plantation, secondary forest and tropical peat swamp forest for 12 months using a closed chamber method. The mean water table levels at these three ecosystems were -67.6 cm, -14.7 cm and -3.9 cm, respectively. Mean soil CH 4 flux was lowest at the oil palm plantation (0.003 t CH 4/ha/yr), followed by secondary forest (0.067 t CH 4/ha/yr) and tropical peat swamp forest (0.179 t CH 4/ha/yr). However, even though the mean water table levels in the three ecosystems differed by an average of 42.5 cm, the mean soil CO 2 fluxes were quite similar: oil palm plantation (32.89 t CO 2/ha/yr), secondary forest (41.10 t CO 2/ha/yr) and tropical peat swamp forest (45.08 t CO 2/ha/yr). These findings indicated that on tropical peatland soil CH 4 flux was highly influenced by water table but not soil CO 2 flux. Since the total soil CH 4 flux was much lower compared with soil CO 2 flux, it was concluded that water table was not the most important factor influencing the soil C flux in tropical peatland.
  • Authors:
    • Harun, M. H.
  • Source: Oil Palm Bulletin
  • Issue: 65
  • Year: 2012
  • Summary: Measurements of actual greenhouse gases (GHG) like CO 2, CH 4 and N 2O emissions from tropical peatlands in Malaysia are needed to understand the role of peatlands as carbon sequesters (sink) or source when establishing oil palm plantations on tropical peatland. Long-term eddy covariance (EC) measurements, together with carefully focused ecological measurements of meteorological and flux data, can potentially identify the relevant climatic factors and partition of the net GHG flux from the whole ecosystem into contributions from the various major components, and quantify the effects of climatic variations on seasonal and annual net uptake of CO 2. Direct measurements of CO 2 flux using the EC method involving air temperature, precipitation, windspeed, vapour pressure deficit (VPD), net radiation, photosynthetically active radiation (PAR) fluxes, sensible heat flux, latent heat and net ecosystem CO 2 exchange (NEE), can define the magnitude of net CO 2 fluxes and net ecosystem production on time scales ranging from hourly to seasonal, annual and inter-annual, for comparing intact and converted forest ecosystems into oil palm plantations. These observations are capable of elucidating the relationships between net CO 2 sequestration and underlying environmental and ecosystem parameters, on time scales long enough to be highly relevant to climate issues. Therefore, the flux measurements provide unique fundamental mechanistic, process and environmental data for evaluating ecosystem models, and for assessing the role of terrestrial ecosystems in the global carbon balance. A sequence of actions are needed for a successful EC experimental set-up, data collection and processing, such as design of the experiment, implementation and data processing. A multi-disciplinary, fully integrated and focused study team is needed for each site in order to obtain the full suite of observations, and to acquire an understanding of the underlying processes through the correct data collection, processing and interpretation. Some problems are anticipated during installation of an EC system on peatland, such as peat subsidence, varying peat depths and low bulk density as a result of the existence of a water table. The tower design should not obstruct air flow and affect the instruments' sensors. The tower should be suitably placed at the study site so that the useful footprint from all winds is maximised. Instruments should be placed at a maximum height that still allows for a useful footprint. The maintenance plan should include periodic sensor cleaning and replacement, a calibration schedule, planned replacement of damaged cables and other repairs to the instrument system. Direct measurements of GHG such as CO 2, CH 4 and N 2O fluxes from tropical peatlands in Malaysia can be done using the EC method, which must be supported by the chamber method to measure the influence of soil respiration on GHG emission and uptake rate from peatland converted to oil palm plantation. A suitable tower design with a strong tower foundation support can minimise damage to the study site. Together with a strict maintenance programme implemented during the duration of the study can ensure the successful collection of good data.
  • Authors:
    • Sjoegersten, S.
    • Hardy, I. C. W.
    • Choy, A. W. K.
    • Townsend, T. J.
    • Smith, D. R.
  • Source: GCB Bioenergy
  • Volume: 4
  • Issue: 5
  • Year: 2012
  • Summary: Oil palm plantations cover similar to 14.6 similar to million similar to ha worldwide and the total area under cultivation is expected to increase during the 21st century . Indonesia and Malaysia together account for 87% of global palm oil production and the combined harvested area in these countries has expanded by 6.5 similar to million similar to ha since 1990. Despite this, soil C cycling in oil palm systems is not well quantified but such information is needed for C budget inventories. We quantified soil C storage (root biomass, soil organic matter (SOM) and microbial biomass) and losses [potential soil respiration (Rs) and soil surface CO2 flux (Fs)] in mineral soils from an oil palm plantation chronosequence (1134 similar to years since planting) in Selangor, Malaysia. There were no significant effects of plantation age on SOM, microbial biomass, Rs or Fs, implying soil C was in dynamic equilibrium over the chronosequence. However, there was a significant increase in root biomass with plantation age, indicating a short-term C sink. Across the chronosequence, Rs was driven by soil moisture, soil particle size, root biomass and soil microbial biomass N but not microbial biomass C. This suggests that the nutrient status of the microbial community may be of equal or greater importance for soil CO2 losses than substrate availability and also raises particular concerns regarding the addition of nitrogenous fertilizer, i.e. increased yields will be associated with increased soil CO2 emissions. To fully assess the impact of oil palm plantations on soil C storage, initial soil C losses following land conversion (e.g. from native forest or other previous plantations) must be accounted for. If initial soil C losses are large, our data show that there is no accumulation of stable C in the soil as the plantation matures and hence the conversion to oil palm would probably represent a net loss of soil C.
  • 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:
    • Manzur, C. L.
    • Cai, D.
    • Zhang, G.
    • Wu, H.
    • Wu, X.
    • Zheng, Y.
    • Hu, Y.
    • Zhao, Q.
    • Wang, X.
  • Source: Irrigation Science
  • Volume: 30
  • Issue: 3
  • Year: 2012
  • Summary: The field experiment for cotton crop (Gossypium hirsutum L.) was conducted at the Zhongjie Farm, Huanghua city of Hebei province in the coastal salinity-affected areas in North China Plain, to determine the effects of an alternative of irrigation water sources/methods and agronomic practices on seedling emergence and yields of cotton, soil water-salt distributions, and soil pH changes during cotton growth stages. The experiment was setup using split-plot design with two water sources as main treatments (well water/desalinized sea-ice water); two irrigation methods (+PAM (Polyacrylamide)/-PAM); and four fertilization modes: check (CK), mineral fertilizer (F), mineral + organic fertilizer (FM), and mineral fertilizer + gypsum (FG). Using desalinized sea-ice water irrigation showed the same effects on top-soil salt leaching and desalinization as using well water did. There was no significant difference in seedling emergence and cotton yields between two irrigation water sources for cotton irrigation. Using PAM-treated irrigation, the 10-cm top-soil salinity significantly decreased to about 2.3-3.9 g kg(-1) from 4.6 to 8.6 g kg(-1) (PAM untreated). The PAM-treated irrigation increased seedling emergence by about 13, 29 and 36% and yields by about 50, 49, and 70%, with F, FM, and FG, respectively, as compared with CK. PAM-treated irrigation, either using well water or desalinized sea ice, especially in combination with gypsum-fertilization, shows the best practice for both seedling emergence and cotton yields. In conclusion, the desalinized sea-ice water used as an alternative water source, integrated with better agronomic practices of soil water-salt management could be acceptable for cotton irrigation in the coastal saline areas.