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The government of Nepal has recommended blanket fertilizer application for rice cultivation, which results in lower nutrient use efficiency (NUE) particularly under rainfed conditions. With the aim of finding an appropriate nutrient management practices concerning rice production and profitability, a field experiment was conducted during rainy season of 2017 and 2018 at Kavrepalanchowk and Dang district of Nepal. Altogether, five treatments comprising various nutrient management practices viz. Nutrient Expert Model (NE), use of Leaf Color Chart (LCC), Government Recommended Fertilizer Dose (GON), Farm Yard Manure (FYM), and Farmers’ Field Practice (FFP), were laid out in RCBD with four replications in farmers’ fields. The analysis of variance showed significant difference between treatments for test weight and grain yield in Kavrepalanchowk whereas all traits except number of effective tillers were significant in Dang. The significantly higher grain yield and harvest index were obtained in NE, followed by LCC; and the overall straw yield was highest in LCC, followed by NE in both the locations. Also, yield gap analysis suggested the NE had 44.44% and 23.97% increase in yield as compared to FPP in Kavrepalanchowk and Dang, respectively. The combined analysis with Best Linear Unbiased Estimator revealed the interaction of nutrient management and location significantly effects the straw yield and harvest index across both the locations. The estimated mean straw yield and harvest index were 10.93 t/ha and 34.98%, respectively. Both correlation study and biplot of principal component analysis signaled grain yield had positive correlation with all other traits. Furthermore, the net revenue was maximum for NE, followed by LCC in both the locations. The benefit: cost ratio was highest for NE which was 1.55 in Kavrepalanchowk and 2.61 in Dang. On the basis of these findings, NE and LCC can be effectively used as nutrient management practice by the farmers to obtain maximum production and profitability in Rice.

Rice (Oryza sativa L.) is a dominant staple food crop of Nepal which production and productivity is significantly declining compared to several years due to inappropriate nutrient management practices. A field experiment was conducted at Lamahi, Dang to evaluate the performance of hybrid rice(US-305) under rain fed condition with five precision nutrient management practices [Viz: Nutrient Expert® -Rice (NE) recommendation; Leaf Color Chart (LCC) N and Nutrient Expert (P and K); Nutrient Expert (N) and Farmers Fertilizer Practices (P and K); Farmers Fertilizer Practices (FFP) and Government Recommendation (GR)] replicated four times in RCBD design during June to October, 2018. The experimental finding showed that SSNM based Nutrient Expert® -Rice (NE) recommendation gave higher grain yield (6.36 ton ha-1) and straw yield (12.62 ton ha-1) which leads to highest gross return (NRs 242,498) and B: C ratio(3.08). Between the treatments Nutrient Expert® -Rice (NE) recommendation was excellent to growth parameters like plant height, crop growth rate, relative growth rate and leaf area index over FFP. Further, Nutrient Expert® -Rice (NE) recommendation gave significantly higher effective tiller m-2(354.50), panicle length (26.31), panicle weight (81.50), filled grain (390) and fertility (87.56%) over FFP. Nutrient Expert® -Rice (NE) recommendation has increased the grain yield by 23.97% with yield difference of 1.23 ton ha-1 and straw yield by 39.44 % with yield difference of 3.57 ton ha-1 in comparison with FFP. Hence the experiment concluded that site specific nutrient management recommendation that accounts Nutrient Expert® -Rice and leaf color chart could be the practical decision tool for making authentic fertilizer recommendation.

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The physicochemical behaviour of dodecyltrimethylammonium bromide (DTAB) in water and ethanol-water mixture in the presence and absence of ZnSO4 were studied by measuring the conductivity at 298.15 K. The pre-micellar (S1) and post-micellar slopes (S2) were obtained and calculated the degree of dissociation (α) and the critical micelle concentration (cmc). With an increase in ethanol content, the cmc and α of DTAB increased whereas, in the presence of ZnSO4, the cmc and α decreased. By using cmc and α, thermodynamic properties as the standard free energy of micellization ( ) were evaluated. With an increase in ethanol content, the negative values of  are decreased indicating less spontaneous in the micellization which makes micellization less favourable. The correlation of the pre-micellar and post-micellar slopes with the volume fraction of ethanol were discussed. DTAB micellization was tested in contexts of specific solvent parameters and solvophobic parameter.