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Use of nitrogen (N) fertilizers is gaining popularity to meet crop nutrient requirement for sustaining the food security of the increasing global population. However, improper management of N fertilizers in acid soils causes leaching and surface runoff because of excessive rainfalls and poor N retention in the tropics in particular. This results in N pollution in water bodies (also known as eutrophication), which degrades water quality to the detriment of aquatic ecosystems near farms. Thus, there is a need for using inorganic soil amendments such as Calciprill and sodium silicate to improve soil N adsorption because of the alkalinity and ability of these amendments to retain N for mitigating excessive N contamination in water bodies. To this end, this N sorption study was conducted to determine the effects of Calciprill and sodium silicate on ammonium (NH4+) adsorption and desorption in an acid soil (Bekenu series, Typic Paleudults). The soil was co-applied with different rates of Calciprill (80 %, 90 %, and 100 % Ca saturations) and sodium silicate (90, 105, 120, 135, and 150 kg ha-1), followed by the NH4+ adsorption capacity determination through the additions of NH4+ isonormal solutions at the five concentrations (0, 25, 50, 75, and 100 mg L-1) to establish a linear relationship between the amount of NH4+ absorbed (qe) and the amount of NH4+ left in the solution (Ce) after 24 h of equilibration. Apart from the soil only without any amendment (C0S0), there were another two additional treatments where the soil was added with Calciprill (100 % Ca saturation) (C3) and sodium silicate only (150 kg ha-1) (S5) to determine their respectively effects on N sorption. The collected data were fitted to the Langmuir and Freundlich isotherms. Thereafter, NH4+ desorption was determined using the same soil samples added with 2 mol dm-3. Compared with the soil without any amendment (C0S0), the Calcirpill alone (C3) and the combined use of Calciprill and sodium silicate significantly increased NH4+ adsorption at the NH4+ addition of 250 mg L-1, suggesting that Calciprill is the amendment which dominantly increases NH4+ adsorption and the effects of amendments are more pronounced at the lower soil NH4+ concentration. The results also revealed that the NH4+ adsorption in the soils following the co-application of Calciprill and sodium silicate followed the assumption of Freundlich isotherm. Regardless of the NH4+ concentration used, the effects of Calciprill and sodium silicate on the NH4+ desorption remain unclear, which could be because of the ability of sodium silicate to stabilize the soil structure. This stabilization reaction might have impeded the dissolution of Calciprill and temporarily fixed the absorbed NH4+. These findings suggest that it is possible to use the amendments to amend NH4+ sorption in Bekenu series for mitigating NH4+ leaching and runoff to prevent eutrophication. [ABSTRACT FROM AUTHOR]

In the tropics, high rainfalls and hot temperatures cause the formation of highly weathered acid soils with low pH buffering capacity (pHBC). Such soils are prone to nutrient losses via leaching, surface runoff, and volatilization. The poor nutrient retention of the highly weathered soils can cause environmental pollution in water bodies and detrimentally affect aquatic ecosystem. A preliminary study was conducted by mixing an acid soil (Bekenu series, Typic Paleudults) with Calciprill (80 %, 90 %, and 100 % Ca saturation) and sodium silicate (90, 105, 120, 135, and 150 kg ha-1) to determine the effects of the amendments on pH and pHBC of Bekenu series. Furthermore, a soil incubation study was carried out to determine the relationship between pH, pHBC, and effective cation exchange capacity (ECEC) after the soil was applied with Calciprill and sodium silicate and incubated for 40, 80, and 120 days. After the soil was harvested, the relationship between pHBC with soil exchangeable ammonium (NH4+), available nitrate (NO3- ), and available phosphorus (P) to determine whether the combined use of Calciprill and sodium silicate is able to mitigate N and P losses through surface runoff and leaching to contaminate the surface and underground water bodies. The results from the studies showed that Calciprill and sodium silicate significantly increased soil pH and pHBC of Bekenu series. Notably, in the soil incubation study, the treatments with Calciprill and sodium silicate consistently improved pHBC compared with the soil without these amendments, suggesting that C2S4 (Calciprill at 90 % Ca saturation and sodium silicate at 135 kg ha-1) is the minimum amount of the amendments required to improve the pHBC of Bekenu series. The significant positive correlation between pH, pHBC, and ECEC throughout the soil incubation study indicates that the amendments are capable of improving pHBC of the Bekenu series when the pH and ECEC increase because of their alkalinity in addition to the presence of carbonate and silicate minerals. The significant positive correlations between pHBC with exchangeable NH4+ and available P at 40 and 80 DAI suggest that the Calciprill and sodium silicate can improve NH4+ and P availability for crop uptake. On the contrary, the significant negative correlation between pHBC and available NO3- at 80 DAI also suggests that the combined use of amendments can significantly reduce the NO3- contamination in water bodies because of improved pHBC. The most suitable combination for improving soil pH, ECEC, and pHBC is C2S4 (Calciprill at 90 % Ca saturation and sodium silicate at 135 kg ha-1) and it is possible to co-apply Calciprill and sodium silicate to mitigate NO3- contamination in water bodies. To further validate the findings of this study, greenhouse study is recommended to elucidate the plant-soil interactions. [ABSTRACT FROM AUTHOR]

Parasitic infections caused by nematode parasites are a challenge which causes significant threats to animal health, which results in economic losses. Medicinal plants have been utilised for generations as traditional remedies against various diseases due to the presence of bioactive compounds in the plants. This article reviews four selected plant species in Brunei: Azadirachta indica, Andrographis paniculata, Clitoria ternatea, and Litsea elliptica to unravel their potential in combating helminthic infections, considering both their historical significance and known therapeutic values. The phytochemical compounds present in each species that exhibit potential anthelmintic properties are discussed and evaluated. The selected medicinal plants from Brunei have shown their potential as an alternative anthelmintic source, particularly noting their effectiveness against nematode parasites due to the presence of phytochemicals in the plants. Caenorhabditis elegans can be used as a model organism to explore the exact active compounds having anthelmintic ability and elucidate its mechanism of action to enhance a better understanding of plant-based anthelmintics and their potential in combating nematode parasitic infections. Hence, the identification and understanding of the phytochemical constituents of these plants can offer promising avenues for the development of novel interventions to combat parasitic infections in livestock, promoting sustainable agricultural practices and securing food production. [ABSTRACT FROM AUTHOR]

Abstract The use of N fertilizers on tropical acid soils is increasing because of their low native fertility. Chicken litter biochar was used to improve N use efficiency and rice yield. The objective of this study was to determine the effects of chicken litter biochar on selected chemical properties of a tropical acid soil under rice (MR219) cultivation. Treatments evaluated were in this study were as follows: (1) T1, soil only, (2) T2, existing recommended fertilization, (3) T3, chicken litter biochar alone, and (4) T4, chicken litter biochar + existing recommended fertilization. Plant and soil analyses were conducted using standard procedures. The use of chicken litter biochar increased soil pH, total carbon, total P, available P, total N, and exchangeable N. Also, this practice decreased soil total acidity and exchangeable Al3+. Compared with T2, T4 significantly increased Crop Recovery Efficiency and Agronomic Recovery Efficiency of N. This resulted in a significant increase in the grain yield (11 t ha−1) of MR219 (Malaysia hybrid rice) for T4 compared with the existing rice grain yield of 5.9 t ha−1 (T2). Moreover, application of chicken litter biochar (5 t ha−1) to tropical acid soil suggested that N application can be reduced to 26.67%, 30.03%, 30.15%, and 14.15% of the recommended rates by MADA on days 10, 30, 50, and 70 after transplanting, respectively. Chicken litter biochar can improve the chemical properties of tropical acid soils and rice (MR219) grain yield.

Densification of biochar can reduce transportation and handling costs, as well as significantly decrease loss of biochar during soil application. Although the nutrient-rich biochar tablets may be a potential cost-effective slow-release fertilizer in soil, there is a lack of information on characterization of mixtures of rubber tree twigs and rice residues tablets with embedded NPK fertilizer. Objective of this work was to determine the physical and chemical properties of biochar tablets with and without embedded fertilizer. Biochar tablets were produced by blending of charred rice husk, rice straw, rubber tree twigs, and starch and followed by tableting. Their production with embedded fertilizer was similar to production process of tablets without it, except adding the NPK fertilizer to blending phase prior to tableting. Fourier-transform infrared spectra analysis indicates was utilized for determination of presence of ammonium and phosphorus substances in the biochar tablets with embedded fertilizer (BFs). The NPK fertilizer significantly increased tablet density and total contents of nitrogen, phosphorus, potassium, calcium and magnesium. The presence of higher amount of nutrients in BFs suggests that it could release nutrients for plant use.

The reaction of H2PO42- and HPO4- with Al and Fe in acid soils to form a precipitate reduces P availability. Chicken litter biochar has been used to improve soil P availability for maize production but with limited information on optimum rates of biochar and Triple Superphosphate (TSP) to increase P availability. This study determined the optimum amount of chicken litter biochar and TSP that could increase P availability. Different rates of chicken litter biochar and TSP were evaluated in an incubation study for 30, 60, and 90 days. Selected soil chemical properties before and after incubation were determined using standard procedures. Soil pH, total P, available P, and water soluble P increased in treatments with 75% and 50% biochar. Total acidity, exchangeable Al3+, and Fe2+ were significantly reduced by the chicken litter biochar. The chicken litter biochar also increased soil CEC and exchangeable cations (K, Ca, Mg and Na). The use of 75% and 50% of 5 t ha-1 biochar with 25% TSP of the existing recommendation can be used to increase P availability whilst minimizing soil Al and Fe content. This rates can be used to optimize chicken litter biochar and TSP use in acid soils for crop production especially maize and short term vegetables.

Ultisols and Oxisols are the two dominant soils in the tropics. These soils are mostly infertile and have low cation exchange capacity because of their low pH (4 to 5). They are composed of kaolinite and sesquioxides which are prone to potassium (K) leaching. To make these soils arable, liming and fertilization are required. Nevertheless, this conventional practice alone does not mitigate K availability in such soils because of their low pH buffering capacity and low K adsorption capacity. The alkalinity of sago (Metroxylon sagu) bark ash and charcoal and the deprotonation of charcoal’s functional groups by the carbonates and oxides of sago bark ash have potential benefits. Due to these characteristics of sago bark ash and charcoal, they could be utilized to improve soil pH buffering capacity and K adsorption capacity to prevent the leaching of K and the pollution of water bodies. Moreover, the use of charcoal and sago bark ash to amend soils is a good way of utilizing agro-wastes sustainably. Thus, the objective of this study was to determine the effects of amending tropical acid soils with charcoal and sago bark on K sorption and pH buffering capacity. The treatments evaluated were: (i) 300 g soil only, (ii) 250 g charcoal only, (iii) 250 g sago bark ash only, (iv) 300 g soil + 15.42 g charcoal, (v) 300 g soil + 7.71 g sago bark ash, and (vi) 300 g soil + 15.42 g charcoal + 7.71 g sago bark ash. Langmuir bonding energy constant (KL), Maximum K buffering capacity (MBC), and maximum adsorption capacity (qmax) of the soil with charcoal and sago bark ash were higher than that of soil alone. However, desorption of K was not significantly affected after application of the amendments. On the other hand, the combined use of charcoal and sago bark ash improved the soil’s pH buffering capacity in comparison to the untreated soil because of the inherently high CEC and alkalinity of these amendments. Therefore, this intervention could contribute to improving K fertilizer use and prevent environmental pollution and economical loss to farmers. [ABSTRACT FROM AUTHOR]

Oligotrophic tropical peat soils are usually deemed unsuitable for cropping common crops such as maize due to low pH and nutrient deficiency. This research aims to compare potassium, calcium, and magnesium uptake between different varieties of maize planted in two types of peat materials. This study investigated the growth of selected maize varieties by comparing the nutrient uptake between three different varieties of maize (V1-Asia Manis, V2-Super A, and V3-Pearl Waxy) planted on hemic and sapric, respectively, without any application of fertilisers. Significant interactions were found where different maize varieties responded differently in the nutrient uptake when planted in different peat materials. Super A (V2) significantly recorded the highest uptake for all nutrients (679.71 mg) when planted in hemic, followed by V1 (422.03 mg) and V3 (314.77 mg) when planted in sapric. Super A was found to be superior to the two varieties, where it was more efficient in absorbing nutrients from the peat materials, having significantly higher dry matter weight (26.37 g) than V1 (19.26 g) and V3 (13.67 g). Hemic and sapric could support the growth of all three maize varieties up till the tasselling stage without any fertiliser application. [ABSTRACT FROM AUTHOR]

Tropical soils such as Ultisols fix phosphorus (P) because of their characteristically high contents of aluminium and iron. Organic amendments could be used to mitigate P fixation. This study aimed to: i) improve soil P availability, nutrients uptake, and yield of Zea mays L. using biochar and pineapple leaf residues compost; and ii) determine if the use of biochar and pineapple leaf residues compost could exert a residual effect on P. Two cycles of field trials were carried out and the test crop used was Zea mays L. hybrid F1. At harvest, the plants were harvested, partitioned into leaves and stems, and analysed. Soil samples were also collected and analysed. The results suggest that the soil total P, available P, inorganic P, and organic P recovered from the treatments with the organic amendments were higher compared with the nonorganic amendments. The availability of soil macro-nutrients in the soils and Zea mays L. yield were higher in the treatments with the organic amendments in the first and second field trials. Amending chemical fertilisers with organic amendments have a larger residual effect than chemical fertilisers only and can be used to ameliorate P fixation of acid soils to improve maize production on acid soils.

Sugarcane is an important industrial crop because it is the major source of white sugar. It is also one of the crops for the alcohol and biofuel industries. Disease-causing organisms can significantly decrease the productivity of sugarcane plants and sugar quality. Among the disease-causing organisms, Colletotrichum falcatum Went causes the most significant economic loss (5–50%) in the sugarcane production due to red rot disease. This loss results in only 31% sugar recovery. It is reported that C. falcatum can kill sugarcane plants. Currently, there is no sustainable way of preventing red rot disease from spreading in sugarcane plantations. Many popular sugarcane varieties are no longer used in sugarcane cultivation because of their susceptibility to C. falcatum. The objectives of this manuscript were to: (i) summarize existing approaches for the early detection of red rot disease and controlling techniques of red rot disease in the field and laboratory and (ii) assess red rot disease control effectiveness so as to propose better methods for mitigating the spread C. falcatum. If our proposition is adopted or practiced, it could significantly contribute to the mitigation of C. falcatum infection in the sugarcane industry. This could enable achieving sustainable cultivation of sugarcanes to guarantee the sustainability of the sugar industry in the tropics and the subtropics.

Plant growth-promoting rhizobacteria (PGPR), which include isolates from genera Paraburkholderia, Burkholderia and Serratia, have received attention due to their numerous plant growth-promoting mechanisms such as their ability to solubilize insoluble phosphates and nitrogen-fixation. However, there is a dearth of information on the potential plant growth-promoting effects of these three groups of bacteria on non-legumes such as maize. This study determined the influences of the aforementioned strains on soil properties, maize growth, nutrient uptake and nutrient use efficiency. A pot trial using maize as a test crop was done using a randomized complete block design with 7 treatments each replicated 7 times. The treatments used in this study were: Control (no fertilizer), chemical fertilizer (CF), organic-chemical fertilizers combination without inoculum (OCF) and with inocula consisting of single strains [cellulolytic bacteria (TC), organic fertilizer and chemical fertilizer with N-fixing bacteria (TN), organic fertilizer and chemical fertilizer with P-solubilizing bacteria (TP)) and three-strain inocula (TCNP), respectively. The variables measured included plant growth and nutrient content, soil nutrient content and functional rhizospheric bacterial populations. Paraburkholderia nodosa NB1 and Burkholderia cepacia PB3 showed comparable effects on maize biomass and also improved N and P use efficiencies when compared to full chemical fertilization. Nitrogen-fixing rhizobacteria had a positive effect on above-ground biomass of maize. Paraburkholderia nodosa NB1 improved soil total C and organic matter contents, besides being the only bacterial treatment that improved K use efficiency compared to OCF. The results suggest that P. nodosa NB1 and B. cepacia PB3 have potential usage in bio-fertilizers. In contrast, treatments with Serratia nematodiphila C46d and consortium strains showed poorer maize nutrient uptake and use efficiency than the other single strain treatments. Bacterial treatments generally showed comparable or higher overall N and P use efficiencies than full chemical fertilization. These findings suggest that at least half the amounts of N and P fertilizers could be reduced through the use of combined fertilization together with beneficial bacteria.

In the midst of the major soil degradation and erosion faced by tropical ecosystems, rehabilitated forests are being established to avoid the further deterioration of forest lands. In this context, cellulolytic, nitrogen-fixing (N-fixing), phosphate-solubilizing bacteria are very important functional groups in regulating the elemental cycle and plant nutrition, hence replenishing the nutrient content in forest soils. As is the case for other potential plant growth-promoting (PGP) rhizobacteria, these functional bacteria could have cross-functional abilities or beneficial traits that are essential for plants and can improve their growth. This study was conducted to isolate, identify, and characterize selected PGP properties of these three functional groups of bacteria from tropical rehabilitated forest soils at Universiti Putra Malaysia Bintulu Sarawak Campus, Malaysia. The bacteria were isolated based on their colonial growth on respective functional media, identified using both molecular and selected biochemical properties, and were assessed for their functional quantitative activities as well as PGP properties based on seed germination tests and indole-3-acetic acid (IAA) production. Out of the 15 identified bacterial isolates that exhibited beneficial phenotypic traits, a third belong to the genus Burkholderia and a fifth to Stenotrophomonas sp., with both genera consisting of members from two different functional groups. The results of the experiments confirm the multiple PGP traits of some selected bacterial isolates based on their respective high functional activities, root and shoot lengths, and seedling vigor improvements when bacterized on mung bean seeds, as well as significant IAA production. The results of this study suggest that these functional bacterial strains could potentially be included in bio-fertilizer formulations for crop growth on acid soils.

Phosphorus is a macronutrient which plays an important role in plant metabolism, growth, and development. However, in tropical acid soils, P fixation is high because of significant amounts of Al and Fe ions. Al and Fe ions can reduce diffusion of P into plant roots. Low absorption of P at initial growth of most plants causes stunting and slow growth of plant leaves. This process reduces photosynthesis. Chicken litter biochar (CLB) had been used on tropical acid soils to improve total P, available P, organic P, and inorganic fractions of P. Moreover, CLB is able to reduce exchangeable acidity, Fe, and Al ions in mineral acid soils because of the reactive surfaces of this organic amendment. However, there is dearth of information on the effects of the right combination of CLB and triple superphosphate (TSP) on the aforementioned soil chemical properties and crop productivity. To this end, the objectives of this study were to improve P: (i) Availability in a mineral acid soil and (ii) uptake, agronomic efficiency, and dry matter yield of Zea mays L. using the right amounts of TSP and CLB. Combinations of 75%, 50%, and 25% CLB (based on recommended 5 t ha−1) and TSP (based on recommended P fertilization for maize) were evaluated in a pot study. Selected soil chemical properties, maize plants nutrient uptake, growth variables, and dry matter yield were determined using standard measures. Results showed that 25% and 50% biochar of 5 t ha−1 with 75% TSP can increase soil P availability, recovery, agronomic use efficiency, and dry matter yield of maize plants. These optimum rates can also reduce P fixation by Al and Fe ions. Therefore, soil and maize productivity can be improved by using CLB (25% and 50% of 5 t ha−1) and TSP (75% of conventional rate) to increase nutrients availability especially P.

This study was carried out in an area cultivated with durian in Gua Musang, Kelantan with a soil series of Rengam-Jerangau. The objective of this study was to determine the physicochemical properties of soil cultivated with durian at different elevations and samplings. The soil composite sampling was determined at three elevations (top, middle and bottom elevation) marked using GPS coordinate with two different depths (0-15 cm and 15-30 cm). The United States Department of Agriculture (USDA) of the soil texture is clay with bulk density ranging between 0.98 to 1.11 g/cm3. Significant parameters at alpha value of 95% include total carbon content (0.903% until 1.389%), total sulphur content (0.059% to 0.100%), exchangeable bases calcium, potassium and sodium at 3.520 cmolc/kg to 5.582 cmolc/kg, 0.380 to 0.581 cmolc/kg and 0.101 to 0.155 cmolc/kg respectively. From the significant parameters, only exchangeable potassium was affected by the by both elevation and depth of the sampling while the other parameters were only affected by the elevation. As some of the nutrients had been classified as low, extensive measures need to be done for healthy growth performance. [ABSTRACT FROM AUTHOR]