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Articles by Osumanu Haruna Ahmed
Total Records ( 33 ) for Osumanu Haruna Ahmed
  Muyang Tawie Sulok Kevin , Osumanu Haruna Ahmed , Wan Yahaya Wan Asrina , Amartalingam Rajan and Mohamad Ahzam
  A pot study was carried with the following objectives: (i) To investigate N and K uptake of Bario rice on Bekenu series (Tipik Tualemkuts), and (ii) To investigate N and K use efficiency of Bario rice on Bekenu series. Treatments evaluated were: (i) Bario rice under fertilized condition (T1), and (ii) Bario rice under unfertilized condition (T0). The experiment was conducted in a glasshouse at Universiti Putra Malaysia Bintulu Campus, Sarawak, Malaysia. Altogether 18 pots were used. The experimental design was completely randomized design (CRD) with 9 replications. Nitrogen and K were applied in the forms of urea (46 % N) and muriate of potash (60 % K2O) at the rates of 0.52 g N g and 0.60 g K2O per pot respectively at specific times. The fertilizers applications were done 20 and 45 days after seeding (for T1 only). However, P was applied to T1 pots only in the form of Christmas Island Rock Phosphate (36 % P2O5) at a rate of 0.54 g P2O5 per pot. At 65 days after planting, the Bario rice plants were sampled and partitioned into roots and stem. Their dry weight, N, and K concentrations determined using standard procedures. Soil sampling was done before and after fertilization stages. Soil total N was determined using the Kjeldahl method while exchangeable K, Ca, Na, and Mg were extracted using the double acid method and their concentrations determined using atomic absorption spectrophotometry. Dry ashing method was used for the determination of K, Ca, Na, and Mg concentrations in plant tissues while the Kjeldahl method was used to determine total N in plant tissues. The concentrations multiplied by the oven dried weight of roots and stem provided N, K, Ca, Na, and Mg uptake in these plant parts. The N and K use efficiency were then calculated using the subtraction method. With the exception of Ca, urea and KCl (MOP) application significantly increased soil N, K, Mg, and Na concentrations. Total dry weight for both stem and roots showed no significant difference under T1 and T0. Except for Mg concentration in stem and roots, K concentration in stem and that of N in roots were significantly higher under T1 than under T0. The other comparisons showed no significant difference. Due to N and K fertilization, there was significant increase in plant height and number of panicles under T1 compared to T0. Nitrogen, K, Na, and Mg uptake in stem were significantly higher for T1 than T0. However, those of roots were not significantly different. The overall N and K use-efficiency of the Bario rice were 9.90 % and 4.23 % respectively, and were considered low, indicating that rice grown within the time frame of this study did not efficiently utilize these nutrients. This was partly attributed to low N and K recovery during reduced condition and low organic matter status of Bekenu series as Bario rice is noted for being cultivated organically. Additionally, slow adaptation to inorganic fertilizers and sudden climatic change involved in this study cannot be ruled out as one of the reasons for the low efficiency because the rice is traditionally cultivated in the highlands of Sarawak, Malaysia. However, with appropriate fertilization and soil maintenance (through further research), Bekenu series could be used for Bario rice production. Probably supplementing inorganic fertilizers with organic ones may help to improve growth and development of this rice on Bekenu series. Future studies may consider mimicking or modifying the environment to suit Bario rice growth and development at lower elevations. Certainly, the quality of Bario rice at lower elevations should also be considered in future fertilization programmes or trials.
  Mohd. Taufik Mohd. Yusuff , Osumanu Haruna Ahmed , Wan Asrina Wan Yahaya and Nik Muhamad Ab. Majid
  A field study was carried with the following objectives: (i) To investigate the effect of compost, N, and K fertilizers on selected chemical properties of Bekenu series (Tipik Tualemkuts), and (ii) To investigate the effect of compost, N and K fertilizers on N and K uptake and yield of Masmadu variety cultivated on Bekenu series. Treatments evaluated were: (i) No fertilization (T1), (ii) Hundred percent inorganic fertilizer application (T2), (iii) Eighty percent of N fertilizer plus twenty percent of N from compost application (T3), (iv) Sixty percent of N fertilizer plus forty percent of N from compost (T4), and (v) Application of hundred percent compost (T5). The experiment was conducted at the share farm of Universiti Putra Malaysia Bintulu Campus, Sarawak, Malaysia. The experimental design was a randomized complete block design (RCBD) with 4 replications. Nitrogen and K were applied in the forms of urea (46 % N) and muriate of potash (60 % K2O) in split i.e., at 15 days after planting (DAP) and 36 DAP, respectively. At 73 DAP, plants were harvested. The fresh weight of cobs excluding guard rows was recorded. Dry weight (stem and leaves), N, K, Ca, and Mg concentrations were determined by standard procedures. Soil sampling was done before and after fertilization. Soil total N was determined using the Kjeldahl method while exchangeable K, Ca, and Mg were extracted using the double acid method and their concentrations determined using atomic absorption spectrophotometry. Dry ashing method was used for the determination of K, Ca, and Mg concentrations in plant tissues while the Kjeldahl method was used to determine total N in plant tissues. The concentrations multiplied by the oven dried weight of roots and stem provided N, K, Ca and Mg uptake in these plant parts. T2, T3, T4 and T5 affected soil bulk density, CEC, pH, total N, exchangeable K, Ca and Mg. The dry weight of Masmadu leaf was not affected by fertilization and so was N and K uptake in this plant part. T2 was superior to the other treatments in terms of stem dry weight and cob production although the uptake of N and K in Masmadu stem under T2 was statistically not different from T3, and T4. Isotopic studies to quantify the amount of N and K contributed by compost in relation N and K uptake and yield may help to conclusively explain why T2 was superior to T3 and T4 in particular.
  Shajarutulwardah Mohd Yusob , Osumanu Haruna Ahmed , Wan Asrina Wan Yahaya and Nik Muhamad Ab. Majid
  A pot study was carried with the following objectives: (i) To investigate N and K uptake of MR 220 and ARC 2 rice varieties grown on Bekenu series (Tipik Tualemkuts), and (ii) To investigate N and K use efficiency of MR 220 and ARC 2 grown on Bekenu series. Treatments evaluated were: (i) MR 220 and ARC 2 under fertilized condition (T1), and (ii) MR 220 and ARC 2 under unfertilized condition (T0). The experiment was conducted in a glasshouse at Universiti Putra Malaysia Bintulu Campus, Sarawak, Malaysia. Altogether 24 pots were used having a completely randomized design (CRD) with 6 replications (for each treatment and each variety). Nitrogen and K were applied in the forms of urea (46 % N) and muriate of potash (60 % K2O) for the two varieties. For T1 of MR 220, N, K, and P were applied at the rates of 4.0 g N, 1.10 g K2O and 2.13 g P2O5 per pot, respectively in split. In the case of T1 of ARC 2, N, K, and P rates used were 1.30 g N, 0.8 g K2O, and 1.70 g P2O5 per pot, respectively in split. At 65 days (ARC 2) and 70 days (MR 220) after planting, plants were sampled and partitioned into roots and stem, and their dry weight, N, and K concentrations determined using standard procedures. Soil sampling was done before and after fertilization. Soil total N was determined using the Kjeldahl method while exchangeable K, Ca, Mg, and Na were extracted by the double acid method and their concentrations determined by atomic absorption spectrophotometry. The dry ashing method was used for the determination of K, Ca, Mg and Na concentrations in plant tissues while the Kjeldahl method was used to determine total N in plant tissues. The concentrations multiplied by the oven dried weight of roots and stem provided N, K, Ca, Mg and Na uptake in these plant parts. The N and K use efficiency was then calculated using the subtraction method. With the exception of Ca, urea and KCl application significantly increased soil N, K, Mg, and Na concentrations. Application of K fertilizer significantly increased soil exchangeable K under MR 220 and ARC 2 cultivations. But this accumulation did not reflect in plant height, number of panicles, dry matter production, K uptake and K use efficiency. Urea application significantly increased N concentration in both roots and stem of MR 220 but the significant effect of N uptake reflected in stem only. Urea application however, did not affect N accumulation, plant height, number of panicles, and dry matter production. Nitrogen use efficiency was also low. As the results showed inefficient nutrient use, series of trials on Bekenu series on the interaction between inorganic and organic fertilizers (e.g. compost) should be carried out as this is likely to improve the inherent low exchange properties of this soil which partly contributes to poor fertility properties.
  Susilawati Kasim , Osumanu Haruna Ahmed , Nik Muhamad Ab. Majid and Khanif Yusop
  The isolation of humic acids from soils is laborious and time consuming. Factors that affect the yield of humic acids isolated from soils include extraction, fractionation and purification periods. This study was conducted to investigate whether a relationship could be separately established between extraction time, fractionation time, and the yield of humic acids of a tropical peat soil (Hemists), as well as the relationship between both variables on the yield of humic acids of this soil. Modified standard procedures using 0.1 M KOH were used to isolate humic acids from a tropical peat soil. Even though there was a quadratic relationship between extraction period and yield of humic acids, there was no relationship between fractionation period and yield of humic acids. There was negative correlation between the yields of extraction and fractionation periods. This finding enables the isolation of humic acids of Hemists in less than 10 h instead of the existing average period of 48 h, therefore helping in facilitating the idea of producing for instance ammonium-humate or K-humate (N and K foliar organic fertilizers) from peat soils.
  Mohd Ramzan Nur Hanisah , Osumanu Haruna Ahmed , Kasim Susilawati , Nik Muhamad Ab. Majid and Mohamadu Boyie Jalloh
  This study was conducted to investigate whether a simple and rapid method could be developed for extracting, fractionating and purifying soil HA in forest rehabilitation programmes. Humic acids from 10 g of soil were extracted with 100 mL of 0.10 M NaOH. Different extraction periods (4, 8, 12, 16, 20 and 24 h) were tested. Samples were centrifuged (16,211 G for 15 min) at the end of each extraction period. The dark-coloured supernatant liquor containing HA was decanted and the pH of the solution adjusted to 1.0 using 6 M HCl. After acidification, the fractionation periods evaluated were 4, 8, 12, 16, 20 and 24 h. After each fractionation period, the sample was transferred to a polyethylene bottle and centrifuged (16,211 G for 10 min). The HA were purified by suspending them in 100 mL distilled water, centrifuged (16,211 G for 10 min). After repeating this procedure three times, the supernatant was analyzed for Na, Mg and K. Standard procedures were used to characterize the HA (C, E4/E6, phenolic OH, carboxylic COOH, total acidity) and soil (pH, C, organic matter). Although there was significant effect of different extraction periods on yield of HA, there was no significant relationship between fractionation period and yield of HA. There was also no significant relationship between fractionation periods and yield of HA for different extraction periods studied. In terms of purification, the distilled water used in this study was able to effectively purify HA (e.g., reduction in mineral matter such as Na+) of the soil without altering the true nature of HA as C, E4/E6, phenolic OH, carboxylic COOH, total acidity values of the acids were consistent with those reported in the literature. The significance of this work is that it enables the isolation of HA from soil within 9 h (4 h extraction period, 4 h fractionation period and 1 h purification period) instead of the existing range of 2-7 days, hence helping in facilitating the idea of producing for instance ammonium and potassium-humates from soils, a practice that could have less undesirable environmental effects.
  Susilawati Kasim , Osumanu Haruna Ahmed , Nik Muhamad Ab. Majid , Mohd Khanif Yusop and Mohamadu Boyie Jalloh
  Problem statement: Fertilizer N use efficiency is reduced by ammonia volatilization. Under low soil CEC and high pH, N from soil solution is released to the atmosphere. Ammonia loss due to low worldwide N use efficiency (33%) has been implicated in global warming. Thus, the objectives of this laboratory study were to evaluate the effectiveness of liquid humic and fulvic acids, isolated from tropical peat soils in reducing N loss from urea fertilizer as well as to investigate the ability of these acids to retain NH4+ and NO3¯ or reduce soil pH.
Approach: Formulated liquid N fertilizers consisting of urea and different types of humic molecules (HA or FA or mixture of both), solid and liquid urea were surface applied to 250 g of soil. A closed dynamic air flow system was used to trap NH3 loss in boric acid after which samples were titrated with 0.01 M HCl to estimate NH3 loss. After 30 days of incubation, the soil was air dried and analysed for pH, exchangeable NH4+, available NO3¯ and exchangeable cations. The results were analysed using SAS and treatments means were compared using Duncan’s New Multiple Range Test (DNMRT).
Results:
The use of humic molecules reduced NH3 loss and increased exchangeable NH4+. The high CEC of Humic Acids (HA) made the LHA treatment the best in reducing N loss after surface application. The presence of HA and Fulvic Acids (FA) increased NH4+ recovery. Even though, the soil pH of all the treatments were high, significant reduction of N loss was observed for humic molecules treatments.
Conclusion:
The use of liquid organic N fertilizer has the ability to reduce NH3 volatilization in acid soil. The use of both humic and fulvic acids could be effective in promoting NH4+ retention. Thus, it can be concluding that, humic substances, in general, have great ability in controlling NH3 loss and retaining NH4+ in acid soils. It could be a cheapest, practical and easiest way to control N loss.
  Ch`ng Huck Ywih , Osumanu Haruna Ahmed , Nik Muhamad Ab. Majid and Mohamadu Boyie Jalloh
  Problem statement: Peat has been identified as one of the major groups of soils found in Malaysia. Sarawak as the largest state in Malaysia has the biggest reserve of peat-land. There are about 1.5 million ha of peat-land in Sarawak, which are relatively under developed. As is the case with any plant, oil palm trees do sequester carbon as they grow. Nevertheless, the process of clearing forest in order to establish a plantation may release carbon. Little studies have been done on the comparison of soil organic matter, soil organic carbon and yield of humic acids when secondary forest on peat soil is converted to oil palm plantation. The objective of this study was to compare carbon storage of secondary forest and early stages of oil palm plantations on a tropical peat soil.
Approach:
Soil samples were collected from the secondary forest, 1, 3, 4 and 5 year old oil palm plantations in Tatau district, Sarawak. Ten samples were taken at random with a peat auger at 0-25 and 25-50 cm depths. The bulk densities at these depths were determined by the coring method. The bulk density method was used to quantify the total carbon, total organic matter, total nitrogen, humic acids and stable carbon at the stated sampling depths on per hectare basis.
Results:
There were no significant differences in the amounts of stable C of both secondary forest and different ages of the oil palm plantations at 0-25 and 25-50 cm soil depth. The amounts of stable C in the secondary forest, 1, 3, 4 and 5 year old oil palm plantations at 0-25 cm depth were generally higher than those in the 25-50 cm depth. This was attributed to higher yield of HA in the secondary forest, 1, 3, 4 and 5 year old oil palm plantations soil partly due to better humification at the 0-25 cm soil depth.
Conclusion:
Conversion of secondary forest on peat to initial stages of oil palm plantation seems to not exert any significant difference on carbon storage in tropical peat soil.
  Seca Gandaseca , John Sabang , Osumanu Haruna Ahmed and Nik Muhamad Ab. Majid
  Problem statement: Peat covers 1.6 million ha (13%) of the 12.4 million ha land area of Sarawak and some of peat swamp forests have been logged. The objective of this study was to assess the impact of logging operation on peat swamp forest in this area.
Approach:
The study used a remote sensing technique to assess vegetation cover in a peat swamp forest areas in Sarawak as result of logging practice and land clearing activities for oil palm plantation. Vegetation Index was used to assess impact of timber harvesting system and land clearing activities on remaining peat swamp forest in two sites which were logged previously and the possible relationship of change in hydrology.
Results:
The timber harvesting system was a combination of rail system for log transportation and excavator crawler for log skidding. Drainage work was probably carried out prior to logging activities which was followed up by land preparation for the establishment of the oil palm plantations. There was a general decrease in the level of greenness from 2002-2007. Between the two sites, the level of greenness was relatively lower in the West Site. The high green level of both sites was reduced remarkably in 2007 especially for the West Site and this corresponded to increase in the percentage of medium green level. The changed in the level of greenness in the remnant peat swamp forest could suggest that soil and other conditions such as vegetation structure and floristic composition are unfavorable for the expected rate of forest regeneration.
Conclusion:
The remnant logged peat swamp forest of the area declined due to a poor state of growth as shown by the dramatically decrease in the level of greenness. The peat swamp forest types strongly related to the hydrological conditions and the associated flow of nutrients and mineral elements. The surrounding hydrology was presumed to have influence the physical and chemical characteristics of the peat.
  Zuraidah Yahya , Aminuddin Husin , Jamal Talib , Jamarei Othman , Osumanu Haruna Ahmed and Mohamadu Boyie Jalloh
  Problem statement: The impacts of soil compaction on crop yields have been studied extensively by soil scientists due to declining soil productivity associated with mechanisation. However, a relationship between machine-induced soil compaction and oil palm (Elaeis guineensis) yield is unclear. Therefore, the objectives of this study were to determine the effects of mechanization on soil physical properties and the influence on oil palm yield. Approach: The palms were planted in Bernam series soil which is clay textured. Compaction treatments were imposed for 6 consecutive years. Comparisons were made between the effects of soil compaction caused by different trailer weights and monthly transportation frequency. Results: The results showed a beneficial effect of soil compaction on the oil palm yield. It significantly increased the yield with increased mean soil bulk density. The transportation frequency played a greater role than the trailer weight. After six years of soil compaction, there was a positive relationship between mean soil bulk density, porosity and oil palm yield. Conclusion: Thus compaction may not often be a problem.
  Roland Kueh Jui Heng , Nik Muhamad Abd. Majid , Seca Gandaseca , Osumanu Haruna Ahmed , Silvester Jemat and Melvin Ku Kin Kin
  Problem statement: Forest structure assessment provides information on forest succession, dynamics, biodiversity and health which are important but only few information is available on rehabilitated forest. The objective of this study was to assess the forest structure of selected age stands at a rehabilitated forest situated in Universiti Putra Malaysia Bintulu Sarawak Campus, Sarawak, Malaysia. Approach: Four 20x20 m plots were established in stands planted in 1991, 1999, 2008 and an adjacent natural regenerating secondary forest (±22years) and all stands were measured for Diameter Breast Height (DBH) and height and identified. Results: Forest structural analysis showed better performance in the structural characteristics mainly the mean basal area (61%), mean Dbh (56%) and mean height (60%) of the trees as compared to the adjacent natural regenerating secondary forest. Conclusion: It can be concluded that after 18 years, rehabilitated forest using accelerating natural regeneration technique showed better structural dimension. This can help to promote the reforestation and restoration activities on degraded forest. Overall, rehabilitated forest areas have yet recovered in terms of size and height.
  Shamsuddin Rosliza , Osumanu Haruna Ahmed , Kasim Susilawati , Nik Muhamad Ab. Majid and Mohamadu Boyie Jalloh
  Abstract: Problem Statement: The isolation (extraction, fractionation and purification) of humic acids (HA) from soils is laborious, time consuming and expensive. The extraction, fractionation and purification periods of these substances vary from 12 h-7 days. In order to facilitate production of HA at competitive cost, this study was conducted to investigate whether a simple and rapid procedure could be developed for isolation of HA from well decomposed tropical peat soils (Saprists). Approach: A 0.1 M KOH was used to isolate HA of air dry peat soil at 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24 h extraction periods after which samples (liquid obtained after centrifugation at 16,211 G for 15 min) were fractionated (using 6 M HCl) at 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24 h. Samples were purified by washing them five times using distilled water instead of using HCl, HF, and an expensive process called dialysis that requires 1 to 7 days to purify HA. Each washing time was 10 min. Standard procedures were used to ascertain the purity (Ash, C, E4/E6, carboxylic, phenolic, total acidity, and K, Ca, Mg, and Na) and quantity of HA yield. Statistical Analysis System (SAS) was used for statistical analysis. Results: Although there was a linear relationship between extraction period and HA yield, there was no relationship between fractionation period and yield of HA. Distilled water used in this study was effective in purifying HA of the Saprists within 1 h without altering the true chemical nature of HA as it significantly reduced the mineral content of HA. Besides, C, E4/E6, carboxylic, phenolic, and total acidity of the isolated HA were typical of standard ones. Conclusion: The isolation of HA from peat soils can be reduced to 9 h (4 h extraction period, 4 h fractionation period and 1 h purification period) instead of the existing range of 1-7 days.
  Susilawati Kasim , Osumanu Haruna Ahmed , Nik Muhamad Ab. Majid and Mohd Khanif Yusop
  The objectives of this study were: To investigate whether a purification period of HA isolated from Hemists peat soils could be reduced and to investigate whether distilled water could be used to purify HA isolated from Hemists peat soils. Standard procedures were used to extract and fractionate HA in a Hemists peat soil. The isolated HA was purified by suspending the HA 50 mL distilled water, centrifuged for 10 minutes, supernatant decanted and the liquor analyzed for K, Ca, Mg and Na by atomic absorption spectrophotometry. The entire procedure was repeated five times after which the purified HA samples were oven dried at 40ºC to a constant weight. Washing HA for 5 consecutive times (10 min for each washing) reduced the ash (mineral matter) content of the HA to an acceptance level of 2%. This finding was associated with significant decrease in K, Ca, Mg and Na contents with increased washing time. This observation also suggests that the distilled water used during the purification process served as Bronsted-Lowry acid thereby donating more H+ which may have replaced some of K+, Ca2+, Mg2+ and Na+ at the exchange sites of the HA. The C, carboxylic COOH, phenolic OH, total acidity and E4/E6 values of the purified HA were consistent with standard values, a further indication of the effectiveness of using distilled water in purifying HA from Hemists peat soil. Humic acids isolated from Hemists peat soil can be purified within one hour using distilled water without altering the true nature of HA.
  Rajeswari A.P. Murugayah , Seca Gandaseca , Osumanu Haruna Ahmed and Nik Muhamad Ab. Majid
  Problem statement: This research was important because of still lack of information about rehabilitated tropical forest age effect on infiltration rate. The objectives of this study were to determine the influence of age of forest on soil water infiltration rate and to evaluate the influence of forest age on the relationship between water infiltration rate, soil organic matter and soil texture. Approach: This study was conducted under a rehabilitated forest at Bukit Nyabau (University Putra Malaysia Bintulu Campus, UPMKB) Forest. Soil organic matter, soil texture and infiltration rate were investigated in randomly selected blocks representing different age classes, namely two, four, six, eight and ten years. Results: The results indicated that 2, 4, 6 and 8 year old forest were not significantly different in organic matter content with the mean of 8.10+2.75, 9.32+3.50, 9.55+1.71 and 8.10+2.75% respectively. Besides, 10 year forest showed no significant differences compared with two and eight year forests. Soil texture for all the forests was sandy loam, except for the 4 year old forest which was a sandy clay loam. The lowest value of sand content was observed in four year forest. However, the clay content in this forest was statistically the highest compared with 2, 4, 8 and 10 year old forest. The infiltration rate of 6 years old forest was significantly greater in soil water infiltration rate with the mean of 5.0±0.02 mm m-1, compared with 2, 4, 8 and 10 years old forest with the means of 2.6±0.02, 4.2±0.03, 3.6±0.03 and 3.5±0.03 mm m-1 respectively. Eight and 10 year old forests showed no significant differences in terms of soil water infiltration rate and the lowest value of water infiltration rate was observed in the two year old forest. Conclusion: From the results, it can be concluded that the soil water infiltration rate in the forest is mainly influenced by soil texture and organic matter content, but not by forest age. However, the effect of soil texture was significant compared to organic matter which facilitates water movement into soil. Soil texture with higher percentage of sand and lower percentage of clay had higher infiltration rate.
  Susilawati Kasim , Osumanu Haruna Ahmed , Nik Muhamad Ab. Majid , Mohd Khanif Yusop and Mohamadu Boyie Jalloh
 

Problem statement:Exchangeable ammonium (NH4+) could be recovered by humic and fulvic acids from humic substances. The ability of these acids in fixing or retaining NH4+ has been demonstrated in many findings and reports. Both acids could affect the plant growth, nutrients uptake by enhancing photosynthesis rate and root growth among others. Thus, in this study, the effect of both acids (in liquid form) on soil exchangeable NH4+, dry matter production and available nitrate (NO3¯) was investigated.
Approach: Humic molecules were isolated using standard procedures, followed by liquid organic N fertilizers formulation. Organic based N fertilizers were applied to soil in pots at 10 Days After Planting (DAP) and 28 DAP. Treated soils and plant parts were sampled at 54 DAP or at tasselling stage. Soil samples were analyzed for pH, ammonium and nitrate content. The plant samples were weighed to assess dry matter production.
Results: Under acid condition, organic based liquid N fertilizers (fulvic acid or both, humic and fulvic acids) increased accumulation of NH4+in soil. The presence of carboxylic groups in humic molecules increased NH4+ retention with increasing soil’s stock labile carbon. However, low percentage of these acids reduced their full effect on dry matter production. The availability of nitrate was not statistically different for all treatments. Low soil pH could had reduced nitrification processes and simultaneously soil NO3¯ content.
Conclusion:
Liquid form of humic and/or fulvic acids could play an important role in enhancing urea efficiency. However, their contribution needs to be studied in detail in relation to humic molecules characteristics. This study had a potential in the development of liquid and foliar organic fertilizers.

  Claudia Hui Hui Chen , Osumanu Haruna Ahmed , Nik Muhamad Ab. Majid and Mohamadu Boyie Jalloh
 

Problem statement:The isolation of Humic Acids (HA) from coal is laborious, costly and time consuming. The extraction and fractionation periods of HA vary from 4 h to 7 days. Fractionation period ranges from 12-24 h. However, most studies use 24 h as extraction period and also 24 h as fractionation period. This study was conducted to investigate whether the isolation period for HA of coals could be reduced.
Approach: Different extraction periods using 0.1 M NaOH (4, 8, 12, 16, 20 and 24 h) were tested. Samples were centrifuged (16,211 G for 15 min) at the end of each extraction period. The dark-colored supernatant liquor containing HA was decanted and the pH of solution was adjusted to 1.0 using 6 M HCl. After acidification, the fractionation periods evaluated were 4, 8, 12, 16, 20 and 24 h. The samples were transferred to a polyethylene bottle and centrifuged (16, 211 G for 10 min) after each fractionation period. The HA purification was done by suspending them in 50 mL distilled water and centrifuged (16,211 G for 10 min). HA samples were dried in an oven at 40°C to a constant weight. Standard procedures were used to characterized the HA (total carbon, E4/E6, phenolic OH, carboxylic COOH and total acidity).
Results: There was significant effect of both extraction and fractionation periods on the isolation of HA from coal. The optimum period for Na ions to saturate the exchange complex of HA during the extraction process was 8 h while the optimum period for the exchanges sites of the HA to be saturated with H ions during the fractionation process was 20 h. The distilled water used in this study was able to purify HA within 1 h because it served as Bronsted-Lowry acid. Additionally, carbon, E4/E6, phenolic OH, carboxylic COOH and total acidity of the HA were typical of those reported in the literature, suggesting that that the isolation process of the HA was successful.
Conclusion:
The isolation period of HA from coal can be reduced to 29 h (8 h extraction, 20 h fractionation period and 1 h purification period) instead of the existing range of 2-7 days.

  Abdul Rahim Anuar , Kah Joh Goh , Tee Bee Heoh and Osumanu Haruna Ahmed
  One of the major challenges in oil palm (Elaeis guineensis Jacq.) plantations today is proper interpretation of yield maps for site-specific management and identification and understanding of the causal factors influencing the variability of oil palm yields. A study was conducted to examine the structural yield variation in order to assess the spatial and temporal yield trends so as to interpret multi-year yield maps of oil palm as influenced by the long-term N fertilizer applications in the palm circle in fertilizer response trial in Sabah, Malaysia. Two clusters of palms were selected for the study; with and without N fertilizer applications for the past 10 years. Fresh fruit bunch (ffb) yields were recorded and summarized on an annual basis. Geostatistical analysis was used to characterize the spatial structure of the semivariogram while point kriging was used to interpolate the ffb yields at unsampled locations. A classified management zone map was developed based on the spatial and temporal stability yield maps from 1992-1999. Semivariance analysis revealed that the yield variations between plots and within plots could be distinguished from the structural semivariogram. The variability between plots was relatively higher compared with within plots. The maximum range of the semivariance of both fertilizer treatments was about 6-palm distance which corresponded well to the experimental plot size of 30 (5x6) palms. It was also observed that the structure of the semivariogram was governed by the sampling pattern and the experimental plot size. The annual yield maps suggested that the application of N could sustain ffb yields above 30 t ha-1 year-1 whereas its removal could result in a drastic decline in ffb yields after 1992. Long-term N fertilizer applications reduced the annual ffb yield fluctuations to between 35 and 45% based on the coefficient of variations between years obtained from individual palms. The results further demonstrate the potential of integrating spatial and temporal stability of ffb yields from multi-year yield data to classify management zones for site-specific oil palm management particularly for fertilizer application. However, the potential of misinterpretation of yield maps can be high if limited data are available. Further work is necessary to ascertain the minimum number of palms and years required for the generation of meaningful yield maps and management zones.
  Abdul Rahim Anuar , Kah Joh Goh , Tee Bee Heoh and Osumanu Haruna Ahmed
  The identification and understanding of soil factors influencing yield variability of oil palm enable their efficient management. Soil samples were therefore collected from a fertilizer response trial on oil palm to study the spatial inorganic N distribution and some selected soil chemical properties as affected by long-term N fertilizer applications. The experiment was conducted on mature oil palms grown on Kumansi family (Typic Paleudults) soil in Tawau, Sabah, Malaysia. The soil samples were taken from 2 areas; with and without N treatments for 8 years. They were analyzed for total N, NH4+-N, NO3--N, exchangeable K, and pH. Semivariance analysis was used to characterize the spatial variance of soil NH4+-N and NO3--N while point kriging method was used to illustrate their spatial distributions. Results showed that application of N in the palm circle increased soil NH4+-N above 150 mg kg-1 at 0 to 15 cm depth. In unmanured plot, the NH4+-N contents were similar in the different sites within a palm area although the frond heap area tended to have higher NH4+-N probably due to the N return from the decaying cut fronds. The coefficient of variations for both soil NH4+-N and NO3--N exceeded 30% even within each microsite of palm circle, interrow, frond heaps, and harvesting path. Semivariance analysis showed that the maximum range of soil NH4+-N could be reached at 10 m and 90 m in areas with and without N respectively, indicating that the application of N fertilizer reduced its spatial variability in mature oil palm agroecosystem. The kriged soil map showed localized spots of high NH4+-N content, which corresponded to the palm circles where N fertilizer was applied. Gradual changes in soil fertility were observed in area without N, moving from northern to southern portion of the field. Long-term applications of N caused significant downward movement of NH4+-N and NO3--N to the lower soil depth. They also decreased the soil pH from 4.2 to 3.7, and caused leaching of K to the lower depth. Fertilizer should be broadcast in the interrow in mature oil palm agroecosystem to reduce spatial N variation and other detrimental effects.
  Ellyfa Kon , Osumanu Haruna Ahmed , Shaharudin Saamin and Nik Muhamad Ab. Majid
  This study was conducted to determine the LD50 and effect of gamma ray on germination percentage, plant height, survival percentage, root length, root dry weight and shoot dry weight of seedlings derived from seeds of long bean (Vigna sesquipedalis). Seeds of this crop were treated with 300, 400, 500, 600 and 800 Gy gamma rays at Malaysian Institute of Nuclear Technology (MINT). The treated seeds including control were sown in sand beds in size 4.6 x 0.7 m2 in a greenhouse at Horticulture Unit, Universiti Putra Malaysia Bintulu Campus (UPMKB). After germination, plants were transferred into polybags. Each polybag contained 1.2 kg blended growth medium with top soil, sand, and processed chicken dung ratio of 3:2:1. Standard procedures were used to observe and record the variables studied in this research. The experiment was designed as a 4 x 6 factorial Completely Randomized Design with 3 replications. Lethal dose 50 % of population (LD50) was assayed. The study revealed that germination percentage, plant height, survival percentage, root length, root dry weight and shoot dry weight decreased with increasing dose of gamma ray. The 800 Gy gamma ray dose in particular had a pronounced effect on these morphological characteristics probably because of injury it might have caused to the seeds of the long bean. As a result, poor growth and development was noticed. The LD50 for survival and height ranged between 600-800 Gy and 400-500 Gy, respectively. Generally, higher gamma ray doses particularly 800 Gy significantly affected the morphological characteristics of long bean seedlings obtained from irradiated seeds.
  Shairul Rizdiyandi Omar , Osumanu Haruna Ahmed , Shaharudin Saamin and Nik Muhamad Ab. Majid
  Induced mutation by gamma irradiation has been found to be a very useful technique for crop improvement. Apart from this, the proper use of induced mutation in plant breeding has become a profitable approach. This investigation was carried out to determine the LD50 and effect of gamma rays on germination, plant height, survival percentage, root length, root dry weight and shoot dry weight of seedlings derived from irradiated seeds of chili (Capsicum annuum). Seeds of chili were treated with 300, 400, 500, 600 and 800 Gy gamma rays at Malaysian Institute of Nuclear Technology (MINT). The treated seeds including control were sown in sand beds in size 4.6 x 0.7 m2 in a greenhouse at Horticulture Unit, UPMKB. Water was applied manually to maintain the soil moisture at field capacity as well as weed was manually controlled. The experiment was designed as 5 x 6 factorial in completely randomized design (CRD) with three replications. Lethal dose 50 % of population (LD50) was assayed. Observation showed that germination percentage, plant height, survival percentage, root length, root weight and shoot dry weight decreased with increasing dose of gamma rays. The 800 Gy gamma ray dose had a profound effect on these variables perhaps due to injury the higher doses may have caused to the seeds of chili. This resulted in poor growth and development of chili seedlings. The LD50 for chili (survival percentage) was estimated at 445 Gy. Loan contracts performance determines the profitability and stability of the financial institutions and screening the loan applications is a key process in minimizing credit risk. Before making any credit In general, higher gamma ray doses particularly 600 and 800 Gy had negative effect on the morphological characteristics of chili seedlings derived from irradiated seeds.
  Anton Eko Satrio , Seca Gandaseca , Osumanu Haruna Ahmed and Nik Muhamad Ab. Majid
  Problem statement: It is important to investigate the seriousness of degradation of peat swamp forest caused by skidding system in terms of its function as a carbon sink. In this study, we formulated assumptions that conditions of our research site before the introduction of skidding system were in their natural states, thus that changes measured are clearly caused by skidding system. The objective of this study was to determine soil carbon storage of a tropical peat swamp forest in their natural state. Approach: Peat soil samples and bulk density were taken at 0-15 cm in a 0.3 ha plot at Sibu, Sarawak, Malaysia. The soil samples were analyzed for acidity, organic matter content, total carbon and total nitrogen. The humic acid extraction was also done and soil carbon storage values obtained by calculation. The calculation of carbon storage was by the bulk density method. Correlation analysis was used where applicable using Statistical Analysis System (SAS) version 9.1. Results: The results indicated that this tropical peat swamp forest rich in soil organic matter (97.645 %) but had extreme acidic environment (pH 3.737), thereby inhibiting organic matter decomposition rates. This tropical peat swamp forest also had large amounts of total carbon (48.823 %), low mineral nitrogen (0.896 %) and high C/N ratio (58.427). Stable carbon (soil carbon storage) positively correlated with unstable carbon (p<0.01, r = 0.43). The value of soil carbon storage was found to be 67.550 Mg Ha-1 (±61.49 % of unstable carbon). Furthermore, soil carbon storage positively correlated with soil organic matter (p<0.01, r = 0.43), total carbon (p<0.01, r = 0.43) and humic acid yield (p<0.01, r = 1.00). However, soil carbon storage negatively correlated with soil acidity (p<0.01, r = -0.55). Conclusion: From the results, it can be concluded that the tropical peat swamp forest indicates its specific natural state. This natural tropical peat swamp forest plays an important role as a sink rather than a source of carbon. The soil carbon storage in this natural tropical peat swamp forest was derived from unstable carbon and sensitive to soil acidity.
  Auldry Chaddy Petrus , Osumanu Haruna Ahmed , Ab Majid Nik Muhamad , Hassan Mohammad Nasir , Make Jiwan and Michael Gregory Banta
  Problem statement: Agriculture waste such as Sago Waste (SW) has a potential to cause pollution either on land or in water. In order to reduce this problem, a study was conducted to investigate the effect of three different treatments on the chemical characteristics of compost and humic acid from SW. Approach: The study had three treatments which were: T1: SW (80%) + chicken feed (5%) + chicken dung slurry (5%) + molasses (5%) + urea (5%), T2: SW (80%) + chicken feed (10%) + chicken dung slurry (5%) + molasses (5%) and T3: SW (80%) + chicken feed (10%) + chicken dung slurry (5%) + urea (5%). Composting was done for 60 days in a white polystyrene box with a size of 61.5x49x33.5 cm. The composts were analyzed for pH, total nitrogen, organic carbon, organic matter, ash, Cation Exchange Capacity (CEC), phosphorus and HA using standard procedures. Results: All treatments did not reach thermophilic phase. Compost of T2 had high quality (pH, total nitrogen, organic carbon, organic matter, ash, Cation Exchange Capacity (CEC), phosphorus and HA) compared to T1 and T3. The yield of HA of T2 was also significantly higher compared to those of T1 and T3. The compost characteristics of T1 and T3 were similar. The chemical characteristics of HA the 3 treatments were within the standard range reported by other researchers. Conclusion: T2 is more efficient in producing mature and good quality compost in 60 days compared to T1 and T3.
  Mohd Taufik Mohd Yusuff , Osumanu Haruna Ahmed and Nik Muhamad Ab. Majid
  Problem statement: Acid Sulphate Soil (ASS) is a problem soil partly because of its high acidity. This low pH could be exploited to reduce ammonia loss from urea by reducing soil microsite pH. The use Humic Acid (HA) to control ammonia loss from urea has been reported but the cost of this material is high. This laboratory study compared the effect of enhancing urea-humic acid mixtures with acid sulphate soil on NH3 loss, pH, exchangeable ammonium and available nitrate contents. Approach: Humic acid, acid sulfate soil and soil used in the incubation study were analyzed for selected soil physical-chemical properties using standard procedures. Urea-HA-ASS mixtures were prepared and ammonia volatilization of the mixtures was evaluated by the closed-dynamic air flow system. The treatments were evaluated in a randomized complete block design with 3 replications. Standard procedures were used to determine ammonia loss, soil pH, exchangeable ammonium and available nitrate at 22 days of incubation. Data obtained were analyzed using analysis of variance and Duncan’s test using Statistical Analysis System (SAS) version 9.2. Results: Urea amended with 0.75 g ASS significantly reduced ammonia volatilization. Although the use of appropriate amount of acid sulphate soil to control ammonia loss is possible, excessive use of this material is not recommended because of Fe in it. Conclusion: Urea amended with 0.75 g ASS reduced ammonia.
  Shamsuddin Rosliza , Osumanu Haruna Ahmed , Nik Muhamad Ab. Majid and Mohamadu Boyie Jalloh
  Problem statement: Ammonia volatilization from surface-applied urea may be substantial but it is possible to control it by mixing urea with acidic substances such as Humic Acids (HA) and Fulvic Acids (FA). The objective of this study was to compare the effects of urea-HA, urea-FA, urea-acidified (HA+FA) mixtures on ammonia loss, soil pH, soil exchangeable ammonium and available nitrate accumulation compared to urea alone. Approach: The effects of urea amended with or without HA and FA were evaluated in a laboratory condition using a closed-dynamic air flow system. Ammonia loss, soil pH, soil exchangeable ammonium and available nitrate were determined using standard procedures. Results: Humic acid alone was not effective in controlling ammonia volatilization even though ammonium retention was found to be significantly higher compared to urea alone. Fulvic acid significantly reduced ammonia volatilization by 50% compared to urea alone. It also caused the highest retention of soil exchangeable ammonium and available nitrate. However, there was no ammonia volatilization with acidified HA and FA. Ammonium and nitrate accumulation for FA was better than acidified HA and FA. Ammonia loss could be reduced by improving ammonium retention. It must be stressed that results obtained in the incubation experiment using an acidic (pHwater 6.32) soil of Typic Paleudults (Bekenu series) may only be applicable to similar acid soils. Conclusion: Urea amended with HA or HA and FA significantly reduced ammonia loss. The outcome of this study might be contributed to the improvement of urea N use efficiency as well as reducing environmental pollution.
  Regis Bernard , Osumanu Haruna Ahmed , Nik Muhamad Ab. Majid and Mohamadu Boyie Jalloh
  Problem Statement: Application of urea as a source of nitrogen fertilizer has an adverse effect on ammoniacal loss to the environment. This study was conducted to reduce ammonia loss from urea by mixing with Humic Acids (HA) isolated from Saprists peat. Approach: The effects of urea amended with four different amounts of humic acids, 0.25, 0.50, 0.75 and 1.00 g were evaluated in laboratory conditions using a closed dynamic air flow system. The mineral soil that was used as medium for the study was Bekenu series (typic paleudults). Amnonia loss, soil pH, exchangeable ammonium, available nitrate, exchangeable K, Ca, Mg and Na were determined using standard procedures. Results: All the treatments with HA significantly reduced ammoinia loss compared to urea alone. Increasing the amount of HA also significantly retained soil exchangeable ammonium and available nitrate. Treatments with HA had no significant effect on the concentrations of Mg, K and Ca, except for Na. The effect of HA in the mixtures on ammonia loss was related to their effect on the formation of ammonium over ammonia. Conclusion: Surface-applied urea fertilizer efficiency could be increased when coated with 1.00 g of HA.
  Makilan Muniandy , Osumanu Haruna Ahmed , Nik Muhamad Ab. Majid and Mohd Khanif Yusop
  Problem Statement: Peatlands are natural sequesters of carbon and nitrogen. Once they are disturbed the tendency to lose carbon and nitrogen to the environment is very high. This study investigated the effect of converting peat land forest into oil palm plantation on soil chemical properties with particular emphasis on carbon and nitrogen storage. Approach: Soil samples were collected randomly at depths 0-25 and 25-50 cm from a secondary forest and from four different ages of oil palm plantations at woodman oil palm plantation located in Sarawak, Malaysia. Soil pH in water and KCl, Organic Matter (OM), Organic Carbon (OC), Total Nitrogen (TN), Organic Nitrogen (ON), ammonium, nitrate, available phosphorous, carbon to nitrogen ratio, carbon to phosphorous ratio and bulk density were determined using standard procedures. The bulk density method was used to quantify Carbon (C), Nitrogen (N), ammonium, nitrate and available phosphorous storage on per hectare basis. Results: Statistical analysis showed that the OC content was statistically similar for all soil depths and vegetation types (forest or plantation). The TN content was statistically higher for secondary forest. Conclusion: Regardless of depth, C sequestration was not altered due to land use change but the secondary forest had higher stores of soil N.
  Ameera Abdul Reeza , Osumanu Haruna Ahmed , Nik Muhamad Nik Ab. Majid and Mohamadu Boyie Jalloh
  Problem Statement: Ammonia volatilization is a major pathway for nitrogen loss from surface applied urea. While all top-dressed ammonia and ammonium based N fertilizers can volatilize, the potential loss is greatest with urea and fluids containing urea. As much as 20-50% of N applied to soils is lost through volatilization alone. Thus, the objective of this laboratory study was to reduce ammonia loss from urea via mixing with humic and fulvic acids isolated from coal. Approach: This study compared four different types of treatments which were urea without additives (T1), urea with humic acid-powdered form (T2), urea with fulvic acid-liquid form (T3) and urea with humic and fulvic acids-liquid form (T4). Comparisons were made based on ammonia loss, soil NH4 and NO3- contents as well as exchangeable cations in the treated soils. Soil samples from typic paleudults (Bekenu series) were used. Humic substances were isolated using standard procedures. Daily ammonia loss from soil was measured using a modified closed-dynamic air flow system method. Results: All of the treatments with humic substances significantly reduced ammonia loss ranging between 13 and 25% compared to urea alone. The treatment with both humic and fulvic acids (T4) showed pronounced ammonia loss reduction. All treatments with humic substances significantly increased NH4+ and NO3- content in soil samples compared to urea alone except for treatment having humic acid alone (T2). Treatments with fulvic acid (T3 and T4) also showed significant increase in exchangeable K+ and Na+ compared to urea alone. The increase in the formation of NH4+ over NH3, soil exchangeable cations and temporary reduction of soil pH may had retarded urea hydrolysis in the immediate vicinity of the fertilizer. Conclusion: Surface applied urea fertilizer efficiency could be increased if applied together with humic and fulvic acids.
  Mohd Taufik Mohd Yusuff , Osumanu Haruna Ahmed and Nik Muhamad Ab Majid
  Problem statement: Ammonia loss due to rapid hydrolysis of urea in soil following surface application can be substantial. Ammonia loss in agriculture is estimated to be 1 to 60%. This laboratory study compared the effect of three different urea-humic acid-acid sulphate soil mixtures on NH3 loss and soil ammonium and nitrate contents, with loss from surface applied urea without additives (urea alone). Approach: Humic acid, acid sulfate soil and soil use in the incubation study was analyzed for selected soil physical-chemical properties. The fertilizers mixture and ammonia loss was done using standard methods. The treatments were evaluated in Randomized Complete block Design with 3 replications. The data obtained at the end of the study on total ammonia loss, soil pH, exchangeable ammonium and available nitrate were analyzed using analysis of variance and the means were compared using Duncan’s test using Statistical Analysis System (SAS) version 9.2. Results: The soil used to test treatments was a sandy clay loam Typic Paleudults (Nyalau series). The mixture significantly reduced NH3 loss by between 31.5 and 36.7% compare with urea alone with larger reductions with higher rate of humic acid (0.75 and 1 g Kg-1 of soil) and acid sulphate soil (0.75 g Kg-1 of soil). The impact of the treatment also showed significant effect on the soil pH and ammonium content at the end of study. Conclusion: Amending urea with acid sulphate soil and humic acid can reduce ammonia loss in acid soils by improving ammonium retention. This may in effect improve urea-N use efficiency as well as reducing environmental pollution in agriculture.
  Shamsuddin Rosliza , Osumanu Haruna Ahmed and Nik Muhamad Ab. Majid
  Problem statement: Inefficient use of inorganic fertilizer such as urea is caused by substantial losses of ammonia when urea is surface-applied. Ammonia losses can be controlled by adding acidic material such as TSP, HA or FA. In order to reduce ammonia loss and retain soil exchangeable ammonium and available nitrate as well as producing complete organic based fertilizer, this study was conducted to compare the effects of urea-TSP-MOP, urea-TSP-MOP-HA, urea-TSP-MOP-FA, urea-TSP-MOP-acidified (HA + FA) mixtures on ammonia loss, soil pH, soil exchangeable ammonium and available nitrate accumulation compared to urea alone. Approach: The effects of urea amended with or without TSP, MOP, HA and FA were evaluated in a laboratory condition using a closed-dynamic air flow system. Ammonia loss, soil pH, soil exchangeable ammonium and available nitrate were determined using standard procedures. Results: Urea-TSP-MOP-HA, Urea-TSP-MOP, Urea-TSP-MOP-FA and Urea-TSP-MOP-Acidified (HA + FA) mixtures significantly reduces ammonia loss by 12.92, 20.12, 29.54 up to 100 % compared to urea alone. The same observation was made for soil exchangeable ammonium. From all the treatments, only Urea-TSP-MOP-FA and Urea-TSP-MOP-Acidified (HA + FA) significantly retained soil available nitrate accumulation and the findings were consistent with pH found in the study. It must be stressed that results obtained in the incubation experiment using an acidic (pHwater 6.32) soil of Typic Paleudults (Bekenu series) might only be applicable to similar acid soils. Conclusion: Urea, TSP and MOP amended with HA or HA and FA significantly reduced ammonia loss. The outcome of this study may contribute to the improvement of urea N, P and K use efficiency as well as reducing environmental pollution.
  Osumanu Haruna Ahmed , Nik Muhamad Ab. Majid and Mohamadu Boyie Jalloh
  Problem statement: Mixture of the right proportion of expanding and non-expanding clays to improve plasticity (moldability) of clays used in the pot industry of Malaysia is yet to be well investigated. In addition, little is known about the choice of the right clay size to eliminate or reduce the content of undesirable compounds such as Fe2O3, Al2O3 to improve the strength of pots and roofing tiles in the country. The objective of this study was to investigate how selected physico-chemical properties of pottery clay relate to grain size of Nyalau series ((Typic Paleudults). Approach: Soil samples were refined into 25, 20 and 63 μm using size grading method. The mineralogical composition of the samples was determined using X-Ray Diffraction (XRD). The chemical composition of the samples was also determined using standard procedures. Firing was done at 800°C) in a muffle furnace and the cracks of the samples recorded. Results: The clay particles with sizes 20 and 25 μm were higher in LOI and total C than that those of 63 μm regardless of grain size, the clay investigated had quartz (SiO2), illite-montmorillonite, Anatase ((TiO2) and kaolinite. Grading affected the concentrations of Fe, Al and Si as clays with particle sizes 20 and 25 μm had higher contents of the aforementioned elements compared with those of 63 μm. The clay with particles 63 μm had the best strength and this was so because the clay particles had the lowest amount of Fe, Al and Si. Conclusion: The strength of Malaysian pots could be improved upon proper grading of the clay particles.
  Muhamad Ismawi Salimin , Seca Gandaseca , Osumanu Haruna Ahmed and Nik Muhamad Ab. Majid
  Problem statement: Peat swamp is an important component of the world’s wetlands. Once they are disturbed the tendency for the soil degradation is very high. This study compared selected chemical properties of a peat swamp soil before and after timber harvesting. Approach: Peat soil samples were taken at 0-15 cm depth in 6 plots with 0.1 ha each plot at Batang Igan forest at Sibu Sarawak, Malaysia. The soil samples were analyzed for selected soil chemical properties. Data were analyzed by using Statistical Analysis System (SAS) version 9.2. Results: The tropical peat swamp forest indicate its specific natural state such as rich in soil pH KCl and except for C/N ratio, the selected chemical properties such as soil pH water, cation exchange capacity, soil organic matter, total carbon, total nitrogen, total phosphorus and exchangeable potassium were significantly different between before and after timber harvesting. Conclusion: Timber harvesting has significant effect on chemical properties of peat swamp.
  Mohd Suffian Firdaus , Seca Gandaseca , Osumanu Haruna Ahmed and Nik Muhamad Ab. Majid
  Problem statement: The conversion of forest land into oil palm plantation is considered to be one of the causes of soil degradation and loss of tropical land forest in Southeast Asia. The objective of this study was to compare selected peat soil physical properties of secondary tropical peat swamp forest and oil palm plantation to determine the effect of forest conversion. Approach: Peat soil samples were collected from secondary tropical peat swamp forest and oil palm plantation at Batang Igan, Sibu, Sarawak, Malaysia. Experimental plots of 300 m3 were set up in both sites and thirty peat soil samples were collected randomly in both sites at 0-15 cm depth using a peat auger. Undisturbed cores and bulk samples were collected for analysis of bulk density and moisture content. Fiber content of the total mass of organic materials was determined by wet sieving method. Soil bulk density, moisture content, organic matter, mineral content, soil porosity and particle density were determined by standard procedures. Hydraulic conductivity was measured in the field using Model 2800K1 Guelph Permeameter and soil strength was determined using Hand Operated Cone Penetrometer Eijkelkemp. Unpaired T-test was used to compare the variables of the two sites. Results: Both sites had similar degree of decomposition classified as hemic peat. No significant differences in fiber content, moisture content and particle density. Bulk density, mineral content and soil strength were significantly higher in the oil palm plantation while organic matter content, porosity and saturated hydraulic conductivity were significantly higher in the secondary tropical peat swamp forest. Conclusion: Conversion of secondary tropical peat swamp forest to oil palm plantation has significantly increased soil bulk density, mineral content and soil strength but significantly decreased organic matter content, porosity and saturated hydraulic conductivity. However, degree of decomposition, fiber content, moisture content and particle density were not affected by the conversion.
  Hasbullah Nur Aainaa , Osumanu Haruna Ahmed , Susilawati Kasim and Nik Muhamad Ab. Majid
  In acid soils of the humid tropics, Phosphorus (P) deficiency due to its fixation by Al and Fe is common. It is therefore important to ensure adequate supply of P for optimum crop production. The use of zeolite on acid soils could fix Al and Fe and thus, rendering P readily available for crop use. The objective of the study was to determine the effects of including clinoptilolite zeolite in Zea mays cultivation on an acid soil on selected soil chemical properties, dry matter production, nutrient uptake and use efficiency of Zea mays. Triple Super Phosphate (TSP), urea and Muriate of Potash (MOP) were used in this study. Twenty five percent of the recommended N, P and K fertilizers for Zea mays were replaced with Clinoptilolite zeolite. Standard procedures were used to determine soil pH, exchangeable ammonium, available nitrate, available phosphorus, exchangeable aluminium, iron, cations and organic matter before and after planting. The plants were harvested at tasselling stage and measured for dry matter production, nutrients uptake and use efficiency. The effect of zeolite application with 75% of fertilization (T2) and 100% fertilization (T1) on soil chemical properties were statistically similar. Similar observation was made on dry matter production, nutrients concentration, nutrients uptake and nutrients use efficiency. The findings reported in this paper indicate that Clinoptilolite zeolite could be used to reduce the use of N, P and K fertilizers use of Zea mays on acid soils. At least three cropping cycles are recommended to confirm the findings of this study. It is also essential to estimate the economic benefits of including zeolite in Zea mays cultivation. These aspects are being investigated in on-going field trial.
  Hasbullah Nur Aainaa , Osumanu Haruna Ahmed , Susilawati Kasim and Nik Muhamad Ab. Majid
  This study was conducted to (i) Determine dry matter production, nutrients concentration, nutrients uptake and use efficiency of Zea mays by including clinoptilolite zeolite in the fertilization program of Zea mays planted on an acid soil and (ii) Determine the effect of including Clinoptilolite zeolite in the fertilization program of Zea mays on selected chemical properties of an acid soil. The effect of Clinoptilolite zeolite application with 75% of fertilizers (C2) and 100% fertilizers (C1) on soil chemical properties were statistically similar. Similar observation was made for dry matter production, nutrients concentration, nutrients uptake and nutrients use efficiency. These suggest that substituting 25% of N, P and K fertilizers with Clinoptilolite zeolite is more beneficial compared to 100% application of these fertilizers. Clinoptilolite zeolite strong affinity for monovalent cations ensured timely availability of P by exerting more soil exchange sites to occupy Al3+ and Fe2+.
 
 
 
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