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Advisor: S.C. Datta
Title: Clay-Polymer Interactions With Reference to Retention and Release of Phosphorus in Soils
Publisher: Division of Soil Science and Agricultural Chemistry ICAR-Indian Agricultural Research Institute New Delhi
Language: en
Type: Thesis
Agrotags: null
Keywords: Clay-Polymer Interactions With Reference to Retention and Release of Phosphorus in Soils
Abstract: Phosphorus (P) availability in soil is abysmally low due to its high reactivity with soil constituents. Use of nanoclay-polymer composites (NCPCs) as a fertilizer carrier is the new avenue of research in the field of agriculture due to their role in controlled release of nutrients synchronizing with crop demand. A series of NCPCs were prepared using nano-bentonite and modified nanobentonite with varying neutralization degree and cross linker level. Phosphorus was loaded as diammonium phosphate (DAP) after polymerization of NCPCs. Bentonites as well as NCPCs were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The XRD patterns confirmed an increase in interlayer spacing from 13.0Å in nano-bentonite to 19.2Å in modified nanobentonite (treated with cetyl trimethyl ammonium bromide). Disappearance of –OH stretching vibration of clays and weakening of Si-O stretching vibration in NCPCs as shown by FTIR spectra confirmed the interaction between functional groups of clay and polymer. The TEM image of nanoclay and modified nanoclay confirmed that the average diameter of particles was <100 nm. Phosphorus loaded NCPCs were evaluated for P release rates in two P deficient soils (Alfisol and Inceptisol) under laboratory incubation experiment and the best product was selected (NCPC prepared from modified nano-bentonite at the rate of 60% neutralization and 0.5% cross linker) for pot culture study using wheat as a test crop. Phosphorus uptake increased from 3.32 mgkg-1 in DAP treatment to 8.71 mgkg-1 in NCPC treatment in red soil, the corresponding values for alluvial soils being 4.45 to 9.78 mgkg-1 at flowering stage of wheat. Soil P fixation percentage was reduced from 60 to 19 in red soil at flowering stage by changing conventional DAP application to P-loaded NCPC application. The corresponding data in case of alluvial soil was from 50 to 0. Fertilizer P use efficiency at increased from 16 to 47 % by changing P application from DAP to P-loaded NCPC in case of red soil and the corresponding increase in efficiency in alluvial soil was from 21 to 51 %. Increase in dehydrogenase as well as phosphatase activity in NCPC treated soil over control indicated stimulation of microbial activity by adding NCPC. Hence use of P loaded, modified clayNCPC emerged as a promising option not only in increasing P use efficiency but also for stimulating microbial activity.
Description: t-9165
Subject: Soil Sciences
Theme: Clay-Polymer Interactions With Reference to Retention and Release of Phosphorus in Soils
These Type: M.Sc
Issue Date: 2015
Appears in Collections:Theses

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