Effects of shifting cultivation on soil ecosystems in Sarawak,Malaysia

Experimental shifting cultivation was conducted at the Balai Ringin (B. Ringin) and Sabal sites in Sarawak, Malaysia. At the sites, plots (10 x 10 m²) were burned with the fuel of aboveground biomass amounting to 0 (control), 100, 200, and 300 Mg ha^-1. At the B. Ringin site, the soils were clayey and strongly weathered with a strongly acidic characteristic. Ash addition enabled to alleviate the soil acidity and to increase the amounts of nutrients of the soils, especially the surface soils. It was indicated that 1) N addition from ash to the soils was negligible, 2) the losses of nutrients by runoff water were not substantial compared with the amounts of nutrients contained in ash, 3) ash alkalinity seemed to be consumed for inactivating exchangeable AI mainly in the surface soils, and 4) development of variable negative charges could contribute to the retention of inorganic bases derived from ash. After harvest of upland rice, the soil chemical properties in the plots treated with 100 and 200 Mg ha-1 fuel returned to the levels before burning, indicating the rapid loss of nutrients due to leaching and erosion as well as the uptake by plants. However, the soils treated with 300 Mg ha^-1 fuel still showed high contents of exchangeable bases and a low content of exchangeable AI. On the other hand, the soils at the Sabal site were sandy and were characterized by a very low nutrient status. The changes in the amounts of nutrients by ash addition were similar to those at the B. Ringin site. However, the changes in the level of exchangeable AI which were not appreciable were probably due to the low AI content. It was postulated that because of the sandy texture and low CEC of the soils, inorganic bases contained in ash were only suspended in the soil solution. Taking into account the low yield of rice and low level of secondary biomass, it appeared that most of the nutrients were lost downward in soils by leaching.     

Adsorption mechanisms of thiazafluron in mineral soil clay components

The adsorption of the herbicide thiazafluron, 1,3-dimethyl-1-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)urea, by three smectites, illite, kaolinite, ferrihydrite and the clay fraction of an illitic soil (54.9% illite, 17.0% montmorillonite and 24.9% kaolinite) and a montmorillonitic soil (33.9% illite, 55.0% montmorillonite and 11.1% kaolinite) has been determined. Thiazafluron adsorbed on neither kaolinite nor iron oxide. The adsorption isotherms on smectites and illite conformed to the Freundlich equation. Values of K_f-obtained for smectites were larger than for the illite and increased as the layer charge of the smectite decreased. Desorption of thiazafluron on smectites was shown to be highly irreversible. Adsorption isotherms of thiazafluron on different homoionic montmorillonite samples suggest an important role of the exchangeable cations in the adsorption. Infrared spectra and X-ray diffraction analysis of the complexes of thiazafluron with homoionic montmorillonites indicated that thiazafluron adsorbs in the interlamellar space of the smectites, mainly by substitution of water molecules associated with the exchangeable cations through the carbonyl-amide group and formation of H-bonds or waterbridge between the NH group of the amide and the basal oxygens of the montmorillonite. The illitic soil clay adsorbed more of the herbicide than the montmorillonitic one did, suggesting that illite and montmorillonite may be present in soils in altered forms giving rise to different adsorption capacities from those of the pure minerals.     

Methane fluxes from three ecosystems in tropical peatland of Sarawak, Malaysia

Methane fluxes were measured monthly over a year from tropical peatland of Sarawak, Malaysia using a closed-chamber technique. The CH₄ fluxes in forest ecosystem ranged from −4.53 to 8.40 μg C m⁻² h⁻¹, in the oil palm ecosystem from −32.78 to 4.17 μg C m⁻² h⁻¹ and in the sago ecosystem from −7.44 to 102.06 μg C m⁻² h⁻¹. A regression tree approach showed that CH₄ fluxes in each ecosystem were related to different underlying environmental factors. They were relative humidity for forest and water table for both sago and oil palm ecosystems. On an annual basis, both forest and sago were CH₄ source with an emission of 18.34 mg C m⁻² yr⁻¹ for forest and 180 mg C m⁻² yr⁻¹ for sago. Only oil palm ecosystem was a CH₄ sink with an uptake rate of −15.14 mg C m⁻² yr⁻¹. These results suggest that different dominant underlying environmental factors among the studied ecosystems affected the exchange of CH₄ between tropical peatland and the atmosphere.     

Adsorption complex,pH relationships in some acid mediterranean forest soil profiles

Acid soils in some mediterranean forests were investigated for the composition of the adsorption complex and the gradients in soil pH. The effective CEC (235–838 mmol_c kg^?1) and base saturation (93–98 %) are highest in ectorganic horizons. In the mineral horizons the effective CEC (23–52 mmol_c kg^?1) and base saturation (11–40 %) are much lower. The exchange complex of mineral horizons consists for 90 (AEh) to 40 percent (Bw2) of organic matter. The effective CEC of the mineral clay fraction is low (60 mmol_c kg^?1 clay). The clear trends in soil pH within the ectorganic layer of deciduous and sclerophyllous oak forests are attributed to vertical spatial separation of nitrogen mineralization (ammonification and strongly impeded nitrification) and nutrient uptake by roots (mainly NH₄). This leads to a high effective CEC in the fermentation layer and acidification of the uppermost part of the mineral soil. In contrast to the situation in temperate forests this process is impeded in mediterranean coniferous forests, where litter decomposition is extremely slow and both proton production and consumption take place in the organic rich mineral horizon.     

Nitrous oxide emissions from three ecosystems in tropical peatland of Sarawak,Malaysia

Abstract

Nitrous oxide (N₂O) emissions were measured monthly over 1 year in three ecosystems on tropical peatland of Sarawak, Malaysia, using a closed-chamber technique. The three ecosystems investigated were mixed peat swamp forest, sago (Metroxylon sagu) and oil palm (Elaeis guineensis) plantations. The highest annual N₂O emissions were observed in the sago ecosystem with a production rate of 3.3 kg N ha^?1 year^?1, followed by the oil palm ecosystem at 1.2 kg N ha^?1 year^?1 and the forest ecosystem at 0.7 kg N ha^?1 year^?1. The N₂O emissions ranged from –3.4 to 19.7 µg N m^?2 h^?1 for the forest ecosystem, from 1.0 to 176.3 µg N m^?2 h^?1 for the sago ecosystem and from 0.9 to 58.4 µg N m^?2 h^?1 for the oil palm ecosystem. Multiple regression analysis showed that N₂O production in each ecosystem was regulated by different variables. The key factors influencing N₂O emissions in the forest ecosystem were the water table and the NH⁺ ₄ concentration at 25–50 cm, soil temperature at 5 cm and nitrate concentration at 0–25 cm in the sago ecosystem, and water-filled pore space, soil temperature at 5 cm and NH⁺ ₄ concentrations at 0–25 cm in the oil palm ecosystem. R² values for the above regression equations were 0.57, 0.63 and 0.48 for forest, sago and oil palm, respectively. The results suggest that the conversion of tropical peat swamp forest to agricultural crops, which causes substantial changes to the environment and soil properties, will significantly affect the exchange of N₂O between the tropical peatland and the atmosphere. Thus, the estimation of net N₂O production from tropical peatland for the global N₂O budget should take into consideration ecosystem type.     

The parent rock effect in the genesis of soil

Weathering trends emanating from the compositional field of the common igneous rocks, can be shown graphically to converge on compositions relatively rich in SiO₂, Al₂O₃ and Fe₂O₃. This convergence means that in chemical terms, the effect of the composition of igneous parent rock on the composition of the resulting soil, is an inverse function of time. Given enough time the chemical effect of parent rock would be nullified. The consequences of this to “state factor equations” are indicated.     

Nutritional Environment of Tropical Peat Soils in Sarawak,Malaysia Based on Soil Solution Composition

It has been considered that natural peat soils and swamp forest ecosystems in the tropics are quite oligotrophic. This concept seems to be related to the low mineral contents in the soil solid phase of the peat soils. However, some nutritional elements such as K, Mg, Ca, and/or P may be abundant in the soil solution phase and could easily migrate in peat soils. In order to analyze the nutritional environment of peat soils, chemical composition of the soil solid phase and soil solution was compared.

This study was carried out in Naman Forest Reserve, Sibu and in/around Sg. Talau Peat Research Station, Mukah, Sarawak, Malaysia. In both areas, each of the three study sites with a different depth of underlying mineral layer was selected for sampling of soil and soil solution. All the soils studied except for one shallow peat profile were classified into Oligotrophic peat based on Fleischer’s criteria. The soil solution collected monthly showed the following characteristics in its composition.

1. Concentrations of Al, Si, and Fe were higher in the soil solution from the shallow peat than in that from the deep peat, reflecting the effect of underlying mineral layers on the soil solution composition.

2. Concentrations of Na, Mg, and Cl in the soil solution and Na and Mg contents in the soil solid phase reflected the distance from the sea. In the Naman series, accumulation of K and Ca in the soil solution was larger in the surface layer in the deep peat than in the shallow peat, though such clear trend was not observed for the K content in the soil solid phase.

3. The concentrations of N and P were fairly high in the soil solution in all the profiles except for P in the profile near the center of the peat dome. Dissolved P consisted mostly of ortho-phosphate, whereas a larger part of N was in the organic form.

4. At the Sago plantation farm on deep peat, depletion of K and P was observed during the rainy season. Such instability in the concentrations in the soil solution was attributed to forest clear-cutting and subsequent disturbance of nutrient cycling.

In general, the concentrations of N, P, K, and Ca in the soil solution were not low even in the Oligotrophic peat. However, in taking account of the fact that the peat soils showed low mineral contents in the available forms and that the bulk density was also quite low, the potential capacity to supply K, Ca, and/ or P was not necessarily high in spite of the apparent high intensity observed for the soil solution composition. Therefore, from the viewpoint of nutrient dynamics, the potential for the use of reclaimed peat land was considered to be rather limited especially under low input management.     

Potassium behavior and clay mineral composition in the soil with low effectiveness of potassium application

ABSTRACT

Increasing exchangeable potassium (ExK) content in soil to an appropriate level is important to mitigate the transfer of radioactive cesium to crops. We focused on a buckwheat (Fagopyrum esculentum Moench) field with a low ExK content, despite the application of K, in Fukushima Prefecture, Japan (Field A), following the Tokyo Electric Power Company Fukushima Dai-ichi (No. 1) Nuclear Power Plant accident in March 2011. We examined the relationship between K concentration and clay mineral composition in the soil of Field A and compared the findings with another field in Fukushima Prefecture (Field B) to clarify whether K applied to the soil was leached or remaining fixed. Pot experiments showed that K concentration in water seepage from pots following irrigation was significantly lower in pots from Field A than in those from Field B. Soil ExK content after soybean cultivation was lower in soils of Field A than those of Field B. These results indicate that K applied to Field A was fixed in the soil. Analysis of clay mineral composition confirmed the distinctive vermiculitic nature of Field A soils. This clay mineralogy would be associated with the higher K fixation ability of Field A than Field B soils. This study demonstrated that K fixation in vermiculite was a factor preventing the increase in ExK content from K application to Field A.     

Soil clay mineralogies in relation to fertility management: Effect of soil clay mineral compositions on potassium fixation under conditions of wetland rice culture

Abstract

To evaluate the impact of soil clay mineralogy on the utilization efficiency of potassium fertilizers by rice, potassium fixation studies were made on fourteen soil clays having a range of mineralogical compositions. Soil clay with monomineralic beidellite fixed the highest proportion (76%) of the added potash, followed by clays containing either dominant or major vermiculite (51–66%). Fixation was significantly less severe (<35%) in vermiculitic clays containing hydrous mica. All the clays with mineralogical suites without beidellite or vermiculite, but consisting of montmorillonite, chlorite, hydrous mica, halloysite, kaolinite, and x‐ray amorphous material did not fix appreciable amounts (<18%) of the applied potassium.     

Performance of Pot-Grown Seedlings of the Dipterocarp Dryobalanops lanceolata with Controlled-Release Fertilizer after Transplantation to the Shifting Cultivation Land in Sarawak, Malaysia

In the present study, the focus was placed on the survival, growth, nutrient status, and ectomycorrhizal formation of pot-grown dipterocarps treated with a controlled-release fertilizer or a chemical fertilizer when transplanted to abandoned shifting cultivation land. Either a chemical fertilizer (CF) or a 700-day controlled-release fertilizer (CRF) had been applied to Dryobalanops lanceolata seedlings at the rates of 0, 2, 5, and 10 g fertilizers per pot in the nursery of the Forest Research Station Niah (FRSN), Miri, Sarawak, Malaysia. The seedlings were cultivated for 18 months in the nursery, and then transplanted to abandoned shifting cultivation land around the FRSN. At 16 months after transplantation, the plants in the CRF treatments showed a good performance in terms of growth and survival ability, because of the sufficient amounts of nutrients accumulated in plants with a sound shoot form and high photosynthetic activity at the nursery stage. On the other hand, many saplings in the CF treatments at the rates of 5 g and 10 g died in the field due to their spindly shoot form and low photosynthetic activity in the nursery, even though the saplings that survived showed on adequate growth. Therefore, the application of slow-release type CRF in the nursery was considered to be feasible and suitable for successful establishment of a dipterocarp plantation in the field. Ectomycorrhizal fungus present in the nursery would sustain and be correlated with P uptake of the saplings after transplantation.     

Improving mineral nitrogen control by combining catch crops,fertilisation, and straw management in a clay loam soil

This experiment was conducted on a clay loam Cambisol and set out to determine the effects of combining catch crops, variable fertilisation levels, and straw management on the productivity of a spring barley-catch crop agrosystem, on the enrichment of soil with organic matter and nitrogen (N), and on soil mineral N control. Research was carried out in a spring barley (Hordeum vulgare L.) crop without catch crops, with undersown red clover (Trifolium pratense L.), and with post-crop white mustard (Sinapis alba L.). The barley was unfertilised, fertilised at moderate rates or at high rates. Straw was managed by either removing it from the field or chopping and spreading it. The quantity of organic matter and N incorporated into the soil depended on the fertilisation level of the barley crop. Soil mineral N stocks in the spring were reduced when straw was used together with red clover. When white mustard mass was incorporated alone in the autumn during ploughing, soil mineral N was reduced in the spring; however, when it was incorporated with straw, the effect was the opposite. Soil mineral N content is controllable when organic matter components are combined according to their decomposition rates, masses, and incorporation times.     

Iron oxides and clay minerals within profiles as indicators of soil age in Northern Italy

Nine profiles representing the Alfisol, Inceptisol and Entisol orders were sampled on three terraces forming a chronosequence. Total iron, dithionite-extractable iron and oxalate-extractable iron were determined for all horizons of all profiles, and the clay mineralogy for horizons of three profiles. The percentage of total Fe (Fe_t) extracted by dithionite (Fe_d) increased with age of terraces, as did the difference between Fe_d and Fe_o (oxalate-extractable). Analysis of variance (ANOVA) of the horizon data showed that the ratios Fe_d/Fe_t and Fe_dFe_o/Fe_t were closely related to the ages of the terraces. Clay minerals were also related to terrace ages, with 2:1 minerals dominant in the profiles on the youngest and mixed-layer minerals and kaolinite more abundant in profiles on the older terraces.     

The inheritance of soil fabric from joints in the parent rock

The origin of ped faces in subsoils has been variously ascribed to the activities of organisms, stress-strain history and to alternating wetting and drying cycles. At three sites in the Sydney Basin the orientation of ped faces in the in situ B horizons of soils developed in dolerite and shale were measured and found to be similar to the orientation of planar joints in the parent rock. Joints in the rock, when inherited by the soil material, provided flaws which could be exploited by shrink and swell phenomena, gradually becoming permanent features. Horizontal ped faces appeared to be inherited joint or bedding planes, affected by the slope of the site to the extent that their dip increased in a downslope direction. This work confirmed previous soil fabric studies by Lafeber (1965) and demonstrated fabric anisotropy and inheritance from the parent rock.     

Influence of Volcanic Ash Deposition on the Classification,Fertility, and Suitability of Some Soils of West Sarawak,Malaysia

Abstract

A study was conducted to determine the influence of the volcanic ash deposition on the physicochemical characteristics of some soils of West Sarawak and to evaluate their suitability for some common crops. A total of seven common soil series of different geology and locations from West Sarawak were collected and analyzed for their physicochemical and dissolution analysis. For comparison, similar analytical procedures were conducted on selected volcanic ash soils of Indonesia and the Philippines. The Sarawak soils were classified as Inceptisol, Ultisol, and Oxisol. The soils were acidic and had relatively low CEC and exchangeable bases. The other laboratory analysis, however, were not conclusive in the results. The soils were evaluated for crops such as rubber, oil palm, rice, pepper, banana and tapioca. Most of these soils were rated as moderate (S₂) to marginally suitable (S₃), indicating insignificant contribution of volcanic ash into the fertility status of soils of west Sarawak regions.     

The influence of soil macroporosity on water retention, transmission and drainage in a clay soil

Abstract. Reductions in hydraulic conductivity and specific yield (drainable porosity) of large cores of Evesham clay soil were observed for periods up to 40 days under continuous ponding. A strong linear relationship ( r ²= 0.94) found between these two variables was used as parameter input to a layered drainage model for mole drained soils. Model results indicated that soils of lower drainable porosity and hydraulic conductivity produced higher peaked hydrographs widi faster recessions. These results are discussed in relation to the effects of soil loosening on drain response in heavy clay soils.     

Mineralogies of silt and clay fractions of twelve soil profiles in the Bolivian Andes (Callavaya Region)

Mineralogies of a soil catena in the Pampa of Ulla Ulla (4,300–4,600 m) and the soils of the steep slopes of the Cordillera de las Muñecas (“steep area”) were investigated. The latter area includes three altitudinal zones: herbaceous zone (3,900–4,800 m), shrub zone (2,700–3,900 m), and mountain forest zone (up to 2,700/2,800 m). The soils were classified according to Soil Taxonomy as Entisols, Mollisols, and Inceptisols. They were mainly derived from quartzitic schists and slope debris. Each horizon of each profile was representatively sampled for analyses.Muscovites and illites were the dominant minerals in the fine silt and clay fraction, respectively. Besides kaolinite, pyrophyllite and vermiculite, regular illite/vermiculite mixed layers, chlorite, feldspar and quartz were detected in both fractions. In a Typic Cryaquent from the Pampa of Ulla Ulla, smectites had been formed. Pyrophyllite, illite/vermiculite mixed layers and chlorite seemed to be unstable under acid conditions in most of these soils.     

Crystallinity of soil kaolinites in relation to clay particle-size and soil age

The crystallinity of soil kaolinites as a function of clay particle-size and soil age was investigated in soil chronosequences of the Shingle House Creek and Hawkesbury River alluvial terraces in south-eastern Australia. The youngest soils (late Holocene) in each sequence are texturally uniform Entisols containing kaolinite and illite. The oldest soils (Pleistocene to late Tertiary) are Ustalfs with strong textural differentiation and are predominantly kaolinitic. With increasing age, textural B horizons are increasingly enriched in kaolinite and in particles of fine clay (< 0.2 μm) size. In two sub-fractions of the fine clay (0.2-0.06 μm; < 0.03 μm), no corresponding changes were observed in the crystallinity of kaolinites (as measured by the index, C _k) with age. However, values of C _k were significantly higher in the coarse clay (2-0.2 μm) than for both fine clay fractions in all except the Ultic Paleustalf of the oldest, possibly late Tertiary, terrace of the Hawkesbury River sequence. In this soil, C _k values are low in all three clay-size fractions.
In these sequences, the effects of both clay particle-size and soil age were identified in the crystallinity of kaolinites. Disorder as a result of pedogenesis, however, was associated only with the most prolonged weathering and the strongest soil textural differentiation.     

The importance of secondary forest blocks for terrestrial mammals within an Acacia/secondary forest matrix in Sarawak, Malaysia

With the rapid conversion of tropical forests in Asia to plantation forests for timber or biofuel production there is a need to determine if these forests serve any viable role in wildlife conservation. We used infra-red trip cameras to survey for large terrestrial mammals within an Acacia/secondary forest matrix being created for pulpwood production in Sarawak, Malaysia. We detected at least 27 species of mammals within the matrix and 18 species were detected in both Acacia and secondary forest. Using occupancy modeling to determine important covariates for seven mammal species within the project area, six of these species were sensitive to forest type, and most were sensitive to the amount of secondary forest within 1 km of the sample point. For four species (sun bear, Helarctos melayanus; common porcupine, Hystrix brachyura; mousedeer, Tragulus spp.; and pig-tailed macaque, Macaca nemestrina), the mean distance of detection from large secondary forest blocks was significantly closer than expected from the distribution of sample points. Most species used Acacia forest less frequently than secondary forest, possibly for transit or foraging, with the exception of bearded pigs (Sus barbatus), sambar (Rucervus unicolor), and civets which were more common in Acacia stands. The amount of secondary forest preserved within forest plantations seems to be the best measure of conservation potential for these industrial forests. Forest plantations can provide a conservation value if managed properly and those retaining significant amounts of secondary forest should be eligible for a base level of certification as they comprise a significant portion of the landscape in this region.