https://jopr.mpob.gov.my Wed, 17 Nov 2021 06:48:48 +0000 en-US hourly 1 https://wordpress.org/?v=7.0 https://jopr.mpob.gov.my/best-management-practices-for-oil-palm-cultivation-on-peat-ground-water-table-maintenance-in-relation-to-peat-subsidence-and-estimation-of-co2-emissions-at-sessang-sarawak/ Sat, 13 Nov 2021 08:09:40 +0000 https://jopr.mpob.gov.my/V2/?p=9073 The study on peat subsidence was carried out in an area of shallow and deep peat in MPOB Research Station in Sessang, Sarawak. Upon completion of the latest phase of peat development for oil palm planting in 2001, water management was improved to maintain the ground water-table at 30 to 50 cm over the whole plantation. Data on peat subsidence and oil palm yields were collected from 10 blocks of oil palm of different ages planted on peat of different depths ranging from shallow to deep peat. A regression equation was established with subsidence data as a dependent variable, while ground water-table and time with quadratic effects were independent variables. Two separate equations were developed for the different depths of peat. The study shows that the subsidence rate was very much related to the age of peat development, i.e. the number of years after oil palm had been planted. The subsidence rate over the years declined and stabilised after 15 years of peat development. A relationship between bulk density of the peat and age of peat development was also established. The CO₂ emission was estimated using the method based on depth of ground water-table. From the current study, it was found that maintaining high ground water-table was better for oil palm agronomics, while at the same time, it reduced the decomposition and mineralisation rates of peat, and hence prevented excessive CO₂ emission.

]]> https://jopr.mpob.gov.my/greenhouse-gas-exchange-of-tropical-peatlands-a-review/ Sat, 13 Nov 2021 08:09:40 +0000 https://jopr.mpob.gov.my/V2/?p=9072 This article presents data on greenhouse gas (GHG) exchange of tropical peat soils with emphasis on changes in emissions of gases during and following the conversion of native tropical peatlands to plantations of oil palm and other crops. The relevant GHGs are carbon dioxide (CO₂), methane (CH₄) and nitrous oxide _(N2O). Establishment of plantations on peat requires drainage, which, even if controlled, results in peat aeration and subsidence. Subsidence is mainly due to natural consolidation, often augmented by mechanical compaction, and is manifested as increased bulk density. Aeration causes carbon to be released as CO₂. Methods for distinguishing and quantifying these processes are discussed. Exchanges of CH₄ and N₂O are also changed by plantation development and are influenced by management practices but the quantities involved are small and in some cases peat soils even act as a sink and not a source, of these gases. There are seasonal changes in the GHG fluxes related to both water table depth and rainfall, and emissions of CH₄ and N₂O can be promoted by nitrogen application. GHG exchange of reclaimed peat is dominated by CO₂ despite the higher global warming potential of CH₄ and N₂O. Methods for estimating CO₂ fluxes are reviewed and their shortcomings are examined. The importance of adequately distinguishing between emission sources, e.g. root and microbial respiration when evaluating carbon fluxes at the surface of peat soils is emphasised.

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