Yields, nutrient-use efficiencies and production economics of wheat (Triticum aestivum) as influenced by foliar nano urea

The nano fertilizers are becoming popular in crop production sector due to their higher nutrient use efficiency and also enhance the productivity and quality while requiring less input and being environmentally safe. In order to assess the effect of foliar application of nano urea on growth and yield performances of wheat (Triticum aestivum L.) and to evaluate nitrogen-use efficiency under integrated use of nano urea, this study was undertaken during the rabi seasons of 2021–22 and 2022–23 at the Uttar Banga Krishi Viswavidyalaya, Pundibari, West Bengal. The experiment was laid-out in a randomized block design (RBD) having 13 treatments consisting of foliar application of water, nano urea (once at tillering and twice at tillering and jointing) and 5% urea in combination with each of 50,75 and 100% of recommended nitrogen doses (RDN) along with a control (without N), and each treatment was replicated thrice. It was observed that foliar application of nano urea (0.4%) twice at tillering and jointing stages with 100% (RDN 5,759 kg/ha) was statistically at par with 100% RDN + 5% foliar spray of urea twice at tillering and jointing stage (5,985 kg/ha) in terms of grain yield, the latter being the highest yielder. Foliar application of either urea or nano urea by curtailing 25-50% RDN did not brought about superior growth and yield performances. Under each level of RDN (100%, 75% and 50%), foliar application of 5% urea was a bit superior to nano urea, though the difference was not statistically significant. However, nano urea reflected higher nitrogen-use efficiency under all levels RDN; partial factor productivity of nitrogen (PFPN) and agronomic nitrogen-use efficiency (ANUE) values be- ing the highest under 50% RDN along with two spraying of nano urea (56.76 and 24.50 kg grain/kg N). The treat- ment comprising 100% RDN+ 5% spray of urea at tillering and jointing stages resulted in the highest net return (69608 `/ha) and B: C ratio (2.58), closely followed by the treatment comprising nano urea application twice (gross return, net return and B: C ratio of 109,426 `/ha, 63,748 `/ha and 2.40, respectively) with 100% RDN, being statis- tically at par with each other. It can be concluded from this two-year trial that only foliar application of nano urea by curtailing soil nitrogen application to 25-50% resulted in reduced yield performances of wheat; nano urea had pro- motive effects on yields when it was applied along with 100% RDN.