Changes in the status of organic and inorganic pools of soil sulfur (S), total nitrogen (N), and organic carbon, and their interrelationships and S mineralisation were examined on a Typic Haplustert soil after a 27-year long-term cropping. The results indicated that NPK(+S) applied for 27 years at 50%, 100%, and 150% of optimum recommended rates and 100% NPK(+S) with farmyard manure (FYM) increased the organic C and total N status of soil compared with the control and the initial status of the soil. Intensive cropping with continuous use of 100% NPK without S resulted in depletion of total, organic, and inorganic S concentrations by 18.13%, 17.80%, and 21.72%, respectively, over the control, while the status of total, organic and inorganic S improved in plots that received graded rates of S with NPK and NPK plus FYM. Intensive cropping with continuous use of S-free NPK fertiliser (100% NPK-S) resulted in the widest C: N: S ratio in the soil. NaHCO 3 -extractable total, inorganic, and organic S fractions and NaOH-extractable total and inorganic S fractions were found to be better indices of soil S mineralisation than CaCl 2 -extractable inorganic S. Cumulative amounts of S mineralised during a 14-week incubation period varied between 2.3 and 21.3 mg S/kg soil and increased with an increase in the rates of S applied, along with NPK fertilisers. Incorporation of FYM with 100% NPK(+S) resulted in greater cumulative mineralised S over 100% NPK(+S) alone. The cumulative mineralised S showed a quadratic relationship with the duration of incubation in all the treatments.

In this work, we report the synthesis of Cu nanoparticles (NPs) by laser ablation technique using 532 nm and 1064 nm wavelength in ethylene glycol. The optical and morphological studies of as-prepared NP colloids were characterized using UV–Visible absorption , photoluminescence spectrometers and transmission electron microscope (TEM) techniques. Cu NPs synthesized at 532 nm and 1064 nm were spherical with an average size of $3.2\pm 0.1$ nm and $4.3\pm 0.1$ nm respectively. Furthermore, surface-enhanced Raman scattering (SERS) studies were performed on methylene blue (MB) using Cu NPs as SERS platform. In addition, the effects of size, shape and localized surface plasmon resonance (LSPR) of Cu NPs as well as the Raman excitation wavelength used for SERS measurement were investigated and discussed to give insight into the factors affecting their SERS enhancement factor.