Ahmad Husni Mohd Hanif

Ammonia volatilization and ammonium accumulation from urea mixed with zeolite and triple superphosphate

Abstract Ammonia volatilization from surface-applied urea fertilizer reduces N fertilizer use efficiency by crops. Beneficial formation of NH4 over NH3 leading to reduction of NH3 loss may be possible through addition of zeolite and acidic materials. The objective of this laboratory study was to evaluate the effect of four different urea-triple superphosphate (TSP)-zeolite mixtures on NH3 volatilization and NH4 and NO3 contents in soil, compared with surface-applied urea without additives. The soil was a sandy clay loam Typic Kandiudults (Bungor Series). The mixtures significantly reduced NH3 loss by 34 to 49% compared with urea (straight urea, 46% N) and larger reductions were obtained with higher rates of zeolite (0.75 and 1 g kg−1 of soil). All the mixtures of acidic P fertilizer and zeolite with urea significantly increased soil NH4 content but not NO3 content. The mixtures with acidic P fertilizer and zeolite also significantly increased soil-exchangeable Ca, K and Mg, and benefited the formation of NH4 over NH3 compared with urea without additives. The increase in soil-exchangeable cations, and temporary reduction of soil pH, might have impeded urea hydrolysis in the microsite immediately around the fertilizer. It could be possible to improve the efficiency of urea surface-applied to high value crops by addition of TSP and zeolite.

Multivariate statistical techniques for the assessment of seasonal variations in surface water quality of pasture ecosystems

This study investigates the applicability of multivariate statistical techniques including cluster analysis (CA), discriminant analysis (DA), and factor analysis (FA) for the assessment of seasonal variations in the surface water quality of tropical pastures. The study was carried out in the TPU catchment, Kuala Lumpur, Malaysia. The dataset consisted of 1-year monitoring of 14 parameters at six sampling sites. The CA yielded two groups of similarity between the sampling sites, i.e., less polluted (LP) and moderately polluted (MP) at temporal scale. Fecal coliform (FC), NO3, DO, and pH were significantly related to the stream grouping in the dry season, whereas NH3, BOD, Escherichia coli, and FC were significantly related to the stream grouping in the rainy season. The best predictors for distinguishing clusters in temporal scale were FC, NH3, and E. coli, respectively. FC, E. coli, and BOD with strong positive loadings were introduced as the first varifactors in the dry season which indicates the biological source of variability. EC with a strong positive loading and DO with a strong negative loading were introduced as the first varifactors in the rainy season, which represents the physiochemical source of variability. Multivariate statistical techniques were effective analytical techniques for classification and processing of large datasets of water quality and the identification of major sources of water pollution in tropical pastures.

Effect of Particle Size on Direct Compaction of Urea Fertilizer

The effect of particle size on compaction properties and characteristics of urea tablets manufactured from available urea granules (TG tablets) and ground urea powders (TP tablets) was investigated. The compaction properties, namely, plastic work, elastic work, friction work, and maximum ejection pressure were analyzed from the force-displacement profile of the compaction process. Five applied pressures ranging between 37.67 MPa and 188.35 MPa were used to compact the materials using a universal testing machine. Characteristics of the tablets tested were mechanical strength and the release of ammonium ion through dissolution test. The results demonstrated that TG tablets underwent high plastic work and elastic work but low friction work compared to the TP tablets. TG tablets released lower amount of ammonium ion compared to the TP tablets at almost all applied pressures, except at 75.34 MPa. This study provides a valuable data for evaluating the behavior of urea in the form of granules and powders during the compaction process as well as the suitability in choosing the form of raw material for the production of urea tablets.

Determination of optimum harvest maturity and non-destructive evaluation of pod development and maturity in cacao (Theobroma cacao L.) using a multiparametric fluorescence sensor: Maturity in cacao (Theobroma cacao L.) using a multiparametric fluorescence sensor

BACKGROUND A series of fluorescence indices (anthocyanin, flavonol, chlorophyll and nitrogen balance) were deployed to detect the pigments and colourless flavonoids in cacao pods of three commercial cacao (Theobroma cacao L.) genotypes (QH1003, KKM22 and MCBC1) using a fast and non-destructive multiparametric fluorescence sensor. The aim was to determine optimum harvest periods (either 4 or 5 months after pod emergence) of commercial cacao based on fluorescence indices of cacao development and bean quality. RESULTS As pod developed, cacao exhibited a rise with the peak of flavonol occurring at months 4 and 5 after pod maturity was initiated while nitrogen balance showed a decreasing trend during maturity. Cacao pods contained high chlorophyll as they developed but chlorophyll content declined significantly on pods that ripened at month 5. CONCLUSION Cacao pods harvested at months 4 and 5 can be considered as commercially-ready as the beans have developed good quality and comply with the Malaysian standard on cacao bean specification. Thus, cacao pods can be harvested earlier when they reach maturity at month 4 after pod emergence to avoid germinated beans and over fermentation in ripe pods harvested at month 5.