Slow Release Behavior Of Biodegradable Starch Polyvinyl Alcohol Urea Fertilizer

By the year 2050,the world population will be projected to reach 9 billion.The world arable land areas are reported to decline in the past years with potentially disastrous consequences as global demand of food soars. There will be absolutely need that the use of nitrogen fertilizers as the primary vital nutrients in crop output must be increased.The most widely used is urea due to its high nitrogen content,46% by weight which has surpassed other nitrogen fertilizer.However,approximately 70% of the high soluble urea fertilizer may be lost into the environment through surface runoff,leaching,and volatilization,thereby reduce farmer’s profit and lead to serious environmental pollution.The slow release fertilizer is most often suggested to avoid losses of nitrogen from agricultural land.Nevertheless,the cost of producing slow release fertilizer has limited its development and accumulation of hydrophobic matrix is a menace to environment.The objective of this study were to examine the performance of synthesized biodegradable matrix based urea fertilizer compared to conventional urea fertilizer in relation to slow release properties, ammonium retention and ammonia loss under flooded condition.Tapioca starch was crosslinked with polyvinyl alcohol by using boric acid to form a matrix having slow release characteristic when immersed in water.The experiments were arranged in a two-level factorial design with three replications. Treatments were two levels of concentration of boric acid (-1: 1 %; +1: 4%),reaction time (-1: 1 hour; +1: 4 hours) and heating temperature (-1:60℃; +1: 90℃) in the synthesis formulation and condition of crosslinked matrix.The soil burial degradation data showed that synthesized matrix were still able to degrade in the range of 35.81% to 56.48% even in the presence of boric acid crosslinking.Compared to conventional urea fertilizer which was dissolved within seconds in water,the synthesized matrix slowly released the urea completely during the 8 hours soaking period at 30ºC with the rotation speed of 100 rpm.The release mechanism of the urea from the synthesized matrix obeyed the Korsmeyer-Peppas model with a quasi-Fickian diffusion mechanism.Soil incubation experiments showed that the matrix could retain the soil exchangeable ammonium due to partially negatively charged sites after ionization of matrix. Urea encapsulated with matrix significantly reduced ammonia loss from urea by 40% up to 55% compared with pure urea alone.Hence,there was a widely potential utility of matrix in agricultural industry as fertilizer carrier due to its simple step in manufacturing process,environmental friendly,and high nitrogen use efficiency

Boric Acid Modified Starch Polyvinyl Alcohol Matrix For Slow Release Fertilizer

The slow release urea fertilizer was prepared by the boric acid crosslinked starch/polyvinyl alcohol (SPB) matrix as biodegradable carrier material. Using a two level factorial design of experiment, a comprehensive understanding of the concentration of boric acid, reaction time and heating temperature in the preparation of SPB matrix was obtained. The swelling ratio, release profile of urea in water, and crushing strength were selected as the response. The interaction between the variables and response was analyzed using the ANOVA model. The system was confirmed using the constant determination,R2 with values above 0.99.The high concentration of boric acid with a prolonged reaction time at high temperature gave relative good results of swelling ratio, dissolution rate of urea and crushing strength. In the 28-day soil incubation experiment, the retention of exchangeable ammonium ion 4 (NH ) + was significant higher in SPB urea as compared to pure urea. There was a potential for SPB matrix to improve nitrogen efficiency by increasing the accumulation of exchangeable 4 NH+ and decreasing the dissolution rate of urea in the flooded condition

The effect of chitosan content to physical and degradation properties of biodegradable urea fertilizer

Chitosan has been widely used in many applications due to its biodegradability and non-toxicity. This article discusses the effect of different chitosan loadings on properties of ureafertilizer which prepared through direct wet mixing process. Absorption and soil degradationtests were performed to measure the amount of water intakes and the life-cycle of the fertilizer.The chemical interaction and thermal properties were analyzed using FTIR and DSC,respectively. It was found that water absorbency and degradation rate increases with chitosanloading, and FTIR confirms the presence of urea in as-produced fertilizers from a unique –NHand amide C=O functional groups

Slow Release Of Urea Encapsulated By Starch PVA Matrix

The hydrophobicity of starch/PVA blend was improved by crosslinking with boric acid.It was found that the swelling ratio of the boric acid modified starch/PVA matrix decreased as function of boric acid concentration. FTIR spectra and SEM images demonstrated that the urea had been encapsulated in polymer matrix successfully.The urea release characteristic was explained with respect to the swelling ratio and crosslinking density of polymer matrix.In addition,the matrix displayed a good barrier for controlling the release rate of urea from pellet

Erratum to: Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition) (Autophagy, 12, 1, 1-222, 10.1080/15548627.2015.1100356

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