Precision nitrogen management for improved root architecture, micronutrient acquisition, and rice productivity in the northeastern hill region of India

Abstract

Agriculture is the primary source of livelihood in the North-Eastern Hill (NEH) region of India, where rice, the staple food crop, holds paramount importance for farmers. However, declining productivity and low nutrient use efficiency have emerged as major constraints in the region. Most farmers continue to follow blanket fertilizer application practices, particularly for nitrogen (N), resulting in uneven and inefficient nutrient use. Precision nitrogen management (PNM), through the use of N-stress sensing tools, offers a promising solution by synchronizing N supply with crop demand. Further enhancement in N use efficiency (NUE) can be achieved by integrating nano-fertilizers, which to some extent allow for reduced N application rates without compromising crop performance. In this context, a field experiment was conducted at the ICAR Research Complex, Meghalaya, to evaluate the effects of PNM and nano-urea (NU) on rice productivity, root dynamics and micronutrient uptake. Results indicated that SPAD (Soil plant analysis development) and LCC (Leaf color chart) based N management save N, improves root quality, micronutrient uptake and grain yield, which was comparable to soil test crop response (STCR) based recommendations, where maximum N was applied. Notably, in the treatment 75% RDN+ 2NU spray, a 25% reduction in the recommended dose of N (RDN) was achievable, as the reduced N dose was effectively supplemented through two foliar sprays of NU, resulting in crop performance comparable to that obtained with 100% RDN. Overall, the study demonstrates that PNM and NU, to some extent, offer a sustainable and efficient strategy for improving rice productivity, root parameters and micronutrient uptake in the NEH region of India.