Mature Oil Palm Research Articles

Importance of CO2 production in subsoil layers of drained tropical peatland under mature oil palm plantation

Expansion of oil palm (Elaeis guineensis Jacq.) plantations in tropical peatlands is always followed by a lowering groundwater level, which exposes peat to oxidic condition and releases large amounts of carbon dioxide (CO2) to atmosphere. This study is concerned with decomposition of organic matter in the soil profile of tropical peatland under oil palm plantation. For 2 years, CO2 fluxes were measured from the soil surface (CO2-efflux) and from the surface where peat was removed to the depths of 10, 30 and 50 cm (CO2 efflux potential/CO2-EP). CO2-EP is a potential estimation of organic matter decomposition from subsoil. Groundwater level, soil moisture and soil temperature were measured as soil environmental factors. The annual CO2 efflux was 139 mg m–2 h–1 while CO2-EP increased with depth which were 1032, 1209, 2304 mg m–2 h–1 from 10, 30, 50 cm depths, respectively. CO2 efflux did not significantly correlated with soil environmental factors. CO2-EP had a significant negative correlation with groundwater level and soil moisture at depths of 30 cm and 50 cm. There are significant correlations among CO2 released from 0, 10, 30, and 50 cm depths. These results indicated that the formation of CO2 in the deeper peat contributes greatly to the emission of CO2, and that keeping the groundwater level at a high level will greatly contribute to the suppression of CO2 emissions from peatland. The subsoil of cultivated peatland is considered to be vulnerable, and its exploitation should be avoided.

Inorganic and organic fertilizer packages for growth acceleration and productivity enhancement on a four-year-old mature oil palm

Fertilization is one of the efforts to increase the productivity of oil palm. This study aimed to determine the best combination of fertilizer packages and to find out the rate of organic fertilizers to reduce the use of inorganic fertilizers on 1st mature oil palm. This study used one factor of randomized complete block design that consisted of 11 treatment levels with three replications. The treatment levels were: control (P0), 1500 g urea+ 1000 g SP-36+ 1500 g KCl+ 50 g borate + 50 g CuSO4.5H2O per palm (P1), 3000 gurea + 2000 g SP-36 + 3000 g KCl + 50 g borate + 50 g CuSO4.5H2O per palm (P2), 4500 g urea + 3000 g SP-36 + 4500 g KCl + 50 g borate + 50 g CuSO4.5H2O per palm (P3), 2000 g NPK+ 50 g borate + 50 g CuSO4.5H2O per palm (P4), 4000 g NPK+ 50 g borate + 50 g CuSO4.5H2O per palm (P5), 6000 gNPK + 50 g borate + 50 g CuSO4.5H2O per palm (P6), 3000 g urea + 2000 g SP-36 + 3000 g KCl per palm (P7), 4000 g NPKper palm (P8), 3000 g urea + 2000 g SP-36 + 3000 g KCl per palm + 50 kg organic fertilizer per palm (P9), 3000 g urea + 2000 g SP-36 + 3000 g KCl per palm + 100 kg organic fertilizer per palm (P10). Fertilizer package (P3) is the best combination of fertilizer packages to increase the growth and yield such as trunk girth, bunch number, and productivity. Fertilizer package (P3) could increase the bunch number by 37.31% and productivity by 72.97% compared to control (P0). Application of 50 kg organic fertilizer year−1 (P9) could reduce by 30% of the use of a single package of inorganic fertilizers (P3).

Embryogenic callus induction and fatty acid composition analysis of oil palm (Elaeis guineensis cv. Tenera)

Embryogenic callus (EC) induction and plantlet regeneration of oil palm (Elaeis guineensis) are essential platforms for the propagation of uniform hybrid cultivars in large-scale cultivation. In this paper, an embryogenic callus was successfully induced from leaf tissue from the ‘Tenera’ varieties of oil palm and regenerated into plantlets via secondary embryogenesis. The total lipid and separated triacylglycerol (TAG) contents of the EC were determined using GC–MS. The results showed that the EC had a total lipid content of approximately 9.46%, while TAG accounted for 32% of the total lipid content. Considering that the TAG content was more than 95% of the total fatty acids (FAs) in the mesocarp of ripe oil palm fruit, the FA profile of the TAG content in the EC was compared with the total lipid content in the mesocarp of oil palm. The results indicated that the FA profile of the TAG content in the EC was similar to that in the mesocarp, even though there were still significant differences in the content of individual FAs. The similar FA composition in the EC and mesocarp of oil palm will be a valuable marker for predicting FA profiles in the mesocarp of the mature transgenic oil palm fruit obtained from transformation and embryogenesis.

Sustainability of African Oil Palm Agriculture in a Changing Climatic Environment

Non-governmental organizations often claim that those countries growing oil palm are responsible for deforestation, biodiversity loss, and climate change. Nevertheless, demand for palm oil has kept on growing in Africa and worldwide due to the ever-growing populations and to the high demand for palm oil numerous food and non-food uses. In 2018, African demands for oils and fats are estimated at 30.64 million tonnes. Assuming that 50% of the continent’s demands were to be satisfied with palm oil, mature oil palm areas would have to be 7.547 million hectares at the current palm oil yield of 2.03 t/ha. Growing demand for palm oil will result in expansion of oil palm plantation in new forest areas. In Africa, further challenges facing oil palm agriculture are poor yields of oil palm resulting from (i) limited technical knowhow on the establishment and management of plantations, (ii) a marked dry season of 2-5 months per year, and (iii) unambitious oil palm development programmes. Fortunately, oil palm ranked first in oil production per unit area with a high theoretical oil yield potential (18 t/ha). High-yield oil palm agriculture could be harnessed to meet the growing demand for food without destroying more natural habitat. In 2016, 609 000 ha would have been enough for the 9 recorded African oil palm-growing countries to produce their 2.434 million tonnes of palm oil production at 4 t/ha against 1.198 million hectares effectively harvested with an average yield of 2.031 t/ha. High-yield on-farm activities are recommended, from the site selection to the harvest of ripe fresh fruit bunch to (i) ensure economic and environmental sustainability of oil palm fields, (ii) consolidate the African oil palm sector, and (iii) prepare its shift to an African oil palm industry, an ambitious vision on which sustainability of the palm oil business depends.

Hydrological dynamics of tropical streams on a gradient of land-use disturbance and recovery: A multi-catchment experiment

Although erosional impacts of rainforest logging are well established, changes in hydrological dynamics have been less explored especially in the post-logging recovery phase following repeat-logging cycles and mature phase of oil palm plantation cycles. This study addresses this gap by comparing hydrological characteristics of five catchments in a steep land area of Sabah, Malaysian Borneo on a gradient of disturbance and recovery – twice-logged forest, 22 years recovery (LF2); multiple-logged forest, 8 years recovery (LF3); mature oil palm, 20 years old (OP); and two primary forests (PF and VJR) as controls. Each catchment was instrumented with water depth (converted to discharge), conductivity, temperature, and turbidity sensors, and a raingauge connected to a solar-powered datalogger recording data at 5-minute intervals from November 2011 to August 2013. Data were analysed via the flow-duration curve (FDC) supplemented by the runoff coefficient (RR) and coefficient of variation in discharge (QVAR) for aggregated characteristics, as well as via a combination of the Dunn's test and multiple-regression at the storm event scale for focused hydrological dynamics. Results show that OP is characterised by a relatively low RR (0.357) but with high responsiveness during storm events and very low baseflow (38.4% of total discharge). Discharge in the LF3 (RR = 0.796) is always the highest while having an intermediate level of responsiveness. LF2 with longer-term recovery shown a reduction in terms of discharge (RR = 0.640). Being the benchmark, the undisturbed forest (PF) has the most buffered storm response with the highest baseflow (67.9% of total discharge). Stormflow and baseflow are anomalously high and low respectively in the near-primary VJR catchment, but this probably reflects the shallow soils and short-stature rainforest associated with its igneous and metamorphic lithology. From a management aspect, although hydrological recovery is more advanced in the 22 years than in the 8-years post-logging catchment, full recovery is yet to be achieved and might be hastened by enrichment planting of the degraded forest. The low baseflow and flashy nature of the mature oil palm have major implications for downstream water supply in ENSO periods and flooding in La Nina periods. Steep lands in the humid tropics are best avoided from any form of landscape disturbance.

Basidiospores as sources of inoculum in the spread of Ganoderma boninense in oil palm plantations in Papua New Guinea

Basal and upper stem rot of oil palm is caused by the agaricomycete Ganoderma boninense. This study investigated the transmission of basal stem rot from Ganoderma‐infected oil palm stumps to young oil palm seedlings. Low seedling mortalities (2.5%) were observed in a field trial after 24 months, but G. boninense could be detected in the rachis, bole and roots of a significant proportion of seedlings that were outwardly healthy. A high level of genetic heterogeneity amongst G. boninense isolates within the trial area was revealed. Furthermore, germinated seedlings growing in close proximity to infected palms in a mature oil palm field contained multiple isolates of G. boninense indicating that colonization of roots by basidiospores and dikaryons, arising from mating between basidiospores, is a common occurrence in oil palm plantations. The probability that basidiospores are a direct source of inoculum in addition to diseased trunk tissue is discussed as a means of explaining the observed heterogeneity in populations of G. boninense on oil palm. Such a scenario presents challenges for the long‐term management of basal stem rot.

Classification for non infected and infected ganoderma boninense of oil palm trees using ALOS PALSAR-2 backscattering coefficient

Malaysia’s monthly export of oil palm product in 2015 was 25,370,294 tonnes valued at about RM60 million. Consequently, Malaysia is now one of the leading manufacturers and exporters of palm oil and its derivatives in the world. However, oil palm plantations in Malaysia are now facing the threat of a Basal Stem Rot (BSR) disease that is caused by fungus called the Ganoderma boninense. This disease reduces oil palm production as an infected mature oil palm dies after 2-3 years of being infected. A decision tree classification approach is proposed in this study for discriminating between non infected and infected of G. boninense in oil palm tree using backscatter values of ALOS PALSAR 2 in FELCRA Seberang Perak 10, Kampung Gajah, Perak. The methodology involves (1) collection of ALOS PALSAR 2 image which include dual polarization HH (Horizontal - transmit and Horizontal - receive) and HV (Horizontal - transmit and Vertical - receive); (2) infection status of the oil palm trees in the study area that comprise 92 trees; and (3) image pre-processing that includes radiometric calibration, speckle filtering and linear conversion to dB. The final stage is the backscatter classification of G. boninense health status using the Decision Tree classifier. The overall accuracy for HH and HV backscatter classification were 45.65% and 56.52% respectively. Further investigations may need to be carried out to improve existing accuracy.

A STUDY OF RAT SPECIES, THEIR POPULATIONS AND CROP DAMAGE IN MATURE OIL PALM PLANTATIONS IN CENTRAL KALIMANTAN

Rats are the most important amongst the many vertebrate pests of oil palm. They occur in nurseries, immature and mature oilpalm plantation areas and can cause substantial economic loses to the plantations. A study was conducted to determine the species and population of the rats as well as to assess the crop damage in a mature oil palm area in Central Kalimantan province. Five study plots were established at randomly selected fields in five oil palm estates and the rat populations were estimated using the 'catch, marked and recapture' (CMR) technique. The house rat, Rattus rattus diardii, was the only rat species found from live-trapping using wire mesh drop door traps. Using the CMR technique, the population of the Rattus rattus diardii was estimated; it ranged from 185 to 718 rats per hectare among the five trapping plots. The average rat population was 384 rats per hectare over the five estates. The percentage of palms with fresh rat damage on fresh fruit bunches (FFB), ranged from low to moderate, i.e. 5 -15 per cent. Generally, it was observed that high rat population amounted to high number of palms with fresh damage on FFB. The potential crop losses were calculated for the five estates and it ranged from USD 201.48 to USD 779.64 per hectare per year. At the average potential crop loss of USD 417.42 per hectare per year, the combined potential loss for the five estates with a total area of about 20 000 ha amounted to USD 8.35 million. This study also indicated that the house rat, Rattus rattus diardii, was the sole rat species found to be well established in the mature oil palm plantation areas of Central Kalimantan. Side observation from this study indicated that barn owl population augmentation did not result in the desired level of rat control. Hence, the need for a pragmatic integrated approach incorporating both judicious rat baiting together with biological control of rats using barn owls. Keywords: Oil palm, rat species, rat population, catch, marked and recapture (CMR), Rattus rattus diardii, crop losses.

Agroecological integration of shade- and drought-tolerant food/feed crops for year-round productivity in banana-based systems under rain-fed conditions in Central Africa

Yield gaps in banana-based production systems have increased in the past two decades due to declining soil fertility, drought and biotic stresses. Sustainable, environmentally sound and economically viable strategies for intensification in these systems are urgently needed. Agroecological practices, such as the integration of shade- and drought-tolerant crops, nitrogen-fixing and cover crops could potentially improve soil fertility and moisture retention, reduce the weed burden, narrow yield gaps and increase overall plot/farm productivity in these systems. In Malaysia, leguminous crops like Pueraria phaseoloides, Calopogonium caeruleum and Centrosema pubescens are often cultivated as cover crops (to suppress weeds, and reduce moisture loss and soil erosion) in young rubber and oil palm plantations with low shade levels. Even in mature oil palm plantations with less than 30% light intensity, various shade-tolerant crops are grown, e.g., elephant foot yam, turmeric and arrow root. In humid tropical Africa, Colocasia (taro) and Xanthosoma (cocoyam) are reported to tolerate shade conditions and hence often planted under perennial banana/plantain plantations. Drought tolerance is a less common feature of most annual crops grown in the humid tropics. A few root and tuber crops (e.g., cassava, taro, yam and sweetpotato) remain in the field during the dry season in Central Africa and are then harvested according to household needs. This paper also reports on crops (Mucuna, lablab and chickpea) with potential for integration into banana-based systems during the dry season, if planted during the last month of the rainy season. These crops are reported to use the residual soil moisture content for continued growth during the dry season months. The paper concludes with detailed descriptions (from a literature review) on drought- and shade-tolerance characteristics of various crops which have long been integrated in Central African banana-based cropping systems, crops with a more recent cultivation history and crops with potential for system integration.

Evaluation of linear discriminant and support vector machine classifiers for classification of nitrogen status in mature oil palm from SPOT-6 satellite images: analysis of raw spectral bands and spectral indices

Nitrogen (N) management is important in sustaining oil palm production. Remote sensing-based approaches via spectral index have promise in assessing the N nutrition content. The objectives of this study are; (i) to examine the N classification capability of three spectral indices (SI) such as visible (Vis), near infrared (NIR) and a combination of visible and NIR (Vis + NIR) from the SPOT-6 satellite, and (ii) to compare the performance of linear discriminant analysis (LDA) and support vector machine (SVM) in discriminating foliar N content of mature oil palms. Nitrogen treatments varied from 0 to 2 kg per palm. The N-sensitive SIs tested in this study were age-dependent. The Vis index (BGRI1) (CVA = 79.55%) and Vis + NIR index (NDVI, NG, IPVI and GNDVI) (CVA = 81.82%) were the best indices to assess N status of young and prime mature palms through the SVM classifier.

Simplifying understory complexity in oil palm plantations is associated with a reduction in the density of a cleptoparasitic spider, Argyrodes miniaceus (Araneae: Theridiidae), in host (Araneae: Nephilinae) webs.

Expansion of oil palm agriculture is currently one of the main drivers of habitat modification in Southeast Asia. Habitat modification can have significant effects on biodiversity, ecosystem function, and interactions between species by altering species abundances or the available resources in an ecosystem. Increasing complexity within modified habitats has the potential to maintain biodiversity and preserve species interactions. We investigated trophic interactions between Argyrodes miniaceus, a cleptoparasitic spider, and its Nephila spp. spider hosts in mature oil palm plantations in Sumatra, Indonesia. A. miniaceus co‐occupy the webs of Nephila spp. females and survive by stealing prey items caught in the web. We examined the effects of experimentally manipulated understory vegetation complexity on the density and abundance of A. miniaceus in Nephila spp. webs. Experimental understory treatments included enhanced complexity, standard complexity, and reduced complexity understory vegetation, which had been established as part of the ongoing Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Project. A. miniaceus density ranged from 14.4 to 31.4 spiders per square meter of web, with significantly lower densities found in reduced vegetation complexity treatments compared with both enhanced and standard treatment plots. A. miniaceus abundance per plot was also significantly lower in reduced complexity than in standard and enhanced complexity plots. Synthesis and applications: Maintenance of understory vegetation complexity contributes to the preservation of spider host–cleptoparasite relationships in oil palm plantations. Understory structural complexity in these simplified agroecosystems therefore helps to support abundant spider populations, a functionally important taxon in agricultural landscapes. In addition, management for more structurally complex agricultural habitats can support more complex trophic interactions in tropical agroecosystems.

IMPACTS OF WATER TABLE AND SOIL AMELIORANT ON SOIL MOISTURE, CO2 EMISSION, AND OIL PALM YIELD ON PEAT SOIL

A field study on peat soil to investigate impacts of soil water table depth and soil ameliorant (steel sludge) had been carried out on mature oil palm. Three treatments of soil water table management and four rates of steel sludge application were applied in this study. Treatments of soil water table management were WLM1, WLM-2, and WLM-3, where soil water table depth was maintained at 35-50 cm, 60-75 cm, and >75 cm below the soil surface, respectively. Treatments of steel sludge were application of this soil ameliorant at the rate of 0; 3.15; 6.51; 9.86 kg tree-1. The study was arranged as split plot randomized block design by assigning soil water table management as main plot and rate of steel sludge as sub plot. Soil Data observed were actual soil water content, peat soil properties, CO2 emission, vegetative growth, and palm yield. The results showed that maintaining soil water table depth at < 75 cm could maintain actual soil moisture up to top parts of peat soil. On the other hand, deeper soil water table (>75 cm, WLM-3) caused significant effects on decreasing of soil moisture in the 0-10 cm layer of peat soil. CO2 emission was 37, 40, dan 45 ton ha-1 year-1 under WLM-1, WLM-2, and WLM-3, respectively. The drop of soil water table to >75 cm (WLM-3) significantly increased CO2 emission to about 11-18% higher than that on WLM-1 and WLM-2. Steel sludge application did not significantly decrease CO2 emission. The highest FFB yield was observed under WLM-1, then followed by WLM-2 and WLM-3. FFB yield was significantly higher when soil water depth was maintained at 35-75 cm than that at > 75 cm, it was 7-10% and 36-60% higher in 2014 and 2015, respectively. There were no significant effects of steel sludge application on FFB yield, but there was improvement on average bunch weight.

IMPACTS OF WATER TABLE AND SOIL AMELIORANT ON SOIL MOISTURE, CO2 EMISSION, AND OIL PALM YIELD ON PEAT SOIL

A field study on peat soil to investigate impacts of soil water table depth and soil ameliorant (steel sludge) had been carried out on mature oil palm. Three treatments of soil water table management and four rates of steel sludge application were applied in this study. Treatments of soil water table management were WLM1, WLM-2, and WLM-3, where soil water table depth was maintained at 35-50 cm, 60-75 cm, and >75 cm below the soil surface, respectively. Treatments of steel sludge were application of this soil ameliorant at the rate of 0; 3.15; 6.51; 9.86 kg tree-1. The study was arranged as split plot randomized block design by assigning soil water table management as main plot and rate of steel sludge as sub plot. Soil Data observed were actual soil water content, peat soil properties, CO2 emission, vegetative growth, and palm yield. The results showed that maintaining soil water table depth at < 75 cm could maintain actual soil moisture up to top parts of peat soil. On the other hand, deeper soil water table (>75 cm, WLM-3) caused significant effects on decreasing of soil moisture in the 0-10 cm layer of peat soil. CO2 emission was 37, 40, dan 45 ton ha-1 year-1 under WLM-1, WLM-2, and WLM-3, respectively. The drop of soil water table to >75 cm (WLM-3) significantly increased CO2 emission to about 11-18% higher than that on WLM-1 and WLM-2. Steel sludge application did not significantly decrease CO2 emission. The highest FFB yield was observed under WLM-1, then followed by WLM-2 and WLM-3. FFB yield was significantly higher when soil water depth was maintained at 35-75 cm than that at > 75 cm, it was 7-10% and 36-60% higher in 2014 and 2015, respectively. There were no significant effects of steel sludge application on FFB yield, but there was improvement on average bunch weight.

Estimation the Amount of Oil Palm Trees Production Using Remote Sensing Technique

Currently, fossil fuels were used as the main source of power supply to generate energy including electricity. Depletion in the amount of fossil fuels has been causing the increasing price of crude petroleum and the demand for alternative energy which is renewable and environment-friendly and it is defined from vegetable oils such palm oil, rapeseed and soybean. Indonesia known as the big palm oil producer which is the largest agricultural industry with total harvested oil palm area which is estimated grew until 8.9 million ha in 2015. On the other hand, lack of information about the age of oil palm trees and changes also their spatial distribution is mainly problem for energy planning. This research conducted to estimate fresh fruit bunch (FFB) of oil palm and their distribution using remote sensing technique. Cimulang oil palm plantation was choose as study area. First step, estimated the age of oil palm trees based on their canopy density as the result from Landsat 8 OLI analysis and classified into five class. From this result, we correlated oil palm age with their average FFB production per six months and classified into seed (0-3 years, 0kg), young (4-8 years, 68.77kg), teen (9-14 years, 109.08kg), and mature (14-25 years, 73.91kg). The result from satellite image analysis shows if Cimulang plantation area consist of teen old oil palm trees that it is covers around 81.5% of that area, followed by mature oil palm trees with 18.5% or corresponding to 100 hectares and have total production of FFB every six months around 7,974,787.24 kg.

EFFECT OF DIFFERENT INSECTICIDES ON THE SURVIVAL OF THE OIL PALM POLLINATOR, ELAEIDOBIUS KAMERUNICUS (COLEOPTERA:CURCULIONIDAE)

This study investigated the effects of nine insecticides used in young mature oil palm plantations for bunch moth control and their effect on the survival of the oil palm pollinating weevils especially on the newly emerged young adult weevils from the spent male inflorescence spikelets. Ten male inflorescences were randomly selected from an eight-year-old oil palm field and sprayed with 1 litre each of selected insecticides five days before anthesis. Field sampling of the male inflorescence spikelets for weevil counting was conducted when the flowers began to open from the base of the spikelets and continued until pollen shedding is over and no more aniseed smell was detected. Results show that three insecticides namely Dinotefuran, Fipronil and Cypermethrin at 0.0056 per cent ai, 0.0048 per cent ai and 0.015 per cent ai respectively at 1 litre spray solution per inflorescence showed significantly detrimental effects on both survival of adult weevils and newly emerged adult weevils per spikelet. The mean percentages of survival weevil per spikelet for Dinotefuran, Fipronil and Cypermethrin were at 20.48 per cent, 12.09 per cent and 55.18 per cent respectively. The mean number of newly emerged adult weevil count per spikelet for male inflorescence treated with Dinotefuran, Fipronil and Cypermethrin at 0.58, 4.74 and 6.05 respectively were significantly lower as compared to control (43.06). There were no significant differences in both mean percentages of survival adult weevil and newly emerged adult weevil per spikelet by the other six insecticides as compared to control. The study concludes that prolonged usage of these three insecticides in the young mature oil palm plantation to control bunch moth will inevitably lead to detrimental effects on the survival and proliferation of the oil palm pollinators in the oil palm ecosystem in the long run. Extra precaution is therefore required when handling these insecticides in the fields in order to have more sustainable way of controlling oil palm bunch moth in peat. Keywords: Bunch moth, insecticides, Elaeidobius kamerunicus, oil palm.

Oil palm monoculture induces drastic erosion of an Amazonian forest mammal fauna.

Oil palm monoculture comprises one of the most financially attractive land-use options in tropical forests, but cropland suitability overlaps the distribution of many highly threatened vertebrate species. We investigated how forest mammals respond to a landscape mosaic, including mature oil palm plantations and primary forest patches in Eastern Amazonia. Using both line-transect censuses (LTC) and camera-trapping (CT), we quantified the general patterns of mammal community structure and attempted to identify both species life-history traits and the environmental and spatial covariates that govern species intolerance to oil palm monoculture. Considering mammal species richness, abundance, and species composition, oil palm plantations were consistently depauperate compared to the adjacent primary forest, but responses differed between functional groups. The degree of forest habitat dependency was a leading trait, determining compositional dissimilarities across habitats. Considering both the LTC and CT data, distance from the forest-plantation interface had a significant effect on mammal assemblages within each habitat type. Approximately 87% of all species detected within oil palm were never farther than 1300 m from the forest edge. Our study clearly reinforces the notion that conventional oil palm plantations are extremely hostile to native tropical forest biodiversity, which does not bode well given prospects for oil palm expansion in both aging and new Amazonian deforestation frontiers.

Evaluation of ground-level and space-borne sensor as tools in monitoring nitrogen nutrition status in immature and mature oil palm

ABSTRACTMonitoring nitrogen (N) in oil palm is crucial for the production sustainability. The objective of this study is to examine the capability of visible (Vis), near infrared (NIR) and a combination of Vis and NIR (Vis + NIR) spectral indices acquired from different sensors for predicting foliar N content of different palm age groups. The N treatments varied from 0 to 2 kg per palm, subjected according to immature, young mature and prime mature classes. The Vis + NIR indices from the ground level-sensor that is green + red + NIR (G + R + NIR) was the best index for predicting N for immature palms (R2 = 0.91), while Vis indices blue + red (B + R) and Green Red Index from the space-borne sensor were significantly useful for N assessment of young and prime mature palms (R2 = 0.70 and 0.50), respectively. The application of vegetation indices for monitoring N status of oil palm is beneficial to examine extensive plantation areas.

Expansion of oil palm and other cash crops causes an increase of the land surface temperature in the Jambi province in Indonesia

Abstract. Indonesia is currently one of the regions with the highest transformation rate of land surface worldwide related to the expansion of oil palm plantations and other cash crops replacing forests on large scales. Land cover changes, which modify land surface properties, have a direct effect on the land surface temperature (LST), a key driver for many ecological functions. Despite the large historic land transformation in Indonesia toward oil palm and other cash crops and governmental plans for future expansion, this is the first study so far to quantify the impacts of land transformation on the LST in Indonesia. We analyze LST from the thermal band of a Landsat image and produce a high-resolution surface temperature map (30 m) for the lowlands of the Jambi province in Sumatra (Indonesia), a region which suffered large land transformation towards oil palm and other cash crops over the past decades. The comparison of LST, albedo, normalized differenced vegetation index (NDVI) and evapotranspiration (ET) between seven different land cover types (forest, urban areas, clear-cut land, young and mature oil palm plantations, acacia and rubber plantations) shows that forests have lower surface temperatures than the other land cover types, indicating a local warming effect after forest conversion. LST differences were up to 10.1 ± 2.6 °C (mean ± SD) between forest and clear-cut land. The differences in surface temperatures are explained by an evaporative cooling effect, which offsets the albedo warming effect. Our analysis of the LST trend of the past 16 years based on MODIS data shows that the average daytime surface temperature in the Jambi province increased by 1.05 °C, which followed the trend of observed land cover changes and exceeded the effects of climate warming. This study provides evidence that the expansion of oil palm plantations and other cash crops leads to changes in biophysical variables, warming the land surface and thus enhancing the increase of the air temperature because of climate change.

Nitrogen Effects on Growth and Spectral Characteristics of Immature and Mature Oil Palms

Nitrogen Effects on Growth and Spectral Characteristics of Immature and Mature Oil Palms

Study of Asystasia gangetica (L.) T. Anderson as Cover Crop Against Soil Water Content in Mature Oil Palm Plantation

Study of Asystasia gangetica (L.) T. Anderson as Cover Crop Against Soil Water Content in Mature Oil Palm Plantation