Impact of Nitrogen Containing Nano Clay Polymer Composite (N-NCPC), Nano Urea and Other Nitrogen Carriers on Soil Nitrogen Fractions and Nitrogen Use Efficiency in Wheat Grown in a Typic Haplustepts

One of the biggest threats to world agriculture right now is the subsiding nitrogen (N) use efficiency (< 40%) which limits agricultural productivity. To tackle this, various innovative N-sources have been designed. However, their effectiveness remained ambiguous and their contribution to soil N-fractions in a growing season is largely undocumented. To put light on this, a pot experiment was conducted with KMnO₄-N deficient soil to examine the effect of nitrogen nano clay polymer composite (N-NCPC, a laboratory synthesized N-fertilizer with slow-release property) with 100%, 75% and 50% of recommended dose of N (RDN), neem coated urea (NCU), nano urea, and vermicompost on soil mineral N availability, organic N fractions, nutrient use efficiency (NUE) of applied N and soil enzymatic activity. The KMnO₄-N content in the post-harvest soil was highest in the N-NCPC @ 100% RDN treated soil (91.7 mg kg^− 1) which was significantly higher than NCU and nano urea. The same was true for nitrate (69.7 mg kg^− 1) and ammonium- N (40.0 mg kg^− 1). N-NCPC maintained at par value of the hydrolysable ammoniacal-N (HAN), amino acid-N (AAN) and amino sugar-N (ASN) with NCU, but a significant reduction in these fractions occurred with nano urea. Moreover, it was also found that N-NCPC significantly increased the DHA (Dehydrogenase), and Urease activity over NCU and nano urea. The highest apparent N recovery (ANR) was observed (74.4%) in the case of N-NCPC @ 50% RDN followed by Nano urea (71.5%). A significant increase in plant N recovery was revealed with N-NCPC and nano urea. N-NCPC can curtail 50% RDN without any drop in crop yield as well as soil properties. However, these novel N- carriers need to be evaluated under long-term experiments involving diverse types of soil and cropping systems.