RESIDUAL INFLUENCE OF NANO UREA AND BORON NUTRITION ON POST-HARVEST SOIL PHYSICAL AND CHEMICAL PROPERTIES UNDER INDIAN MUSTARD

Abstract

Keeping soil healthy while still pushing crop productivity upward is one of the quiet, ongoing challenges of Indian mustard (Brassica juncea L.) cultivation, especially in tracts such as the Kymore Plateau of Madhya Pradesh where nitrogen-use efficiency is often poor and boron deficiency is common. To examine this issue from the soil's point of view rather than only the crop's, a two-factor factorial field experiment in a randomized block design was carried out over two Rabi seasons (2022–23 and 2023–24) at the Rajaula Research Farm, Chitrakoot–Satna. The trial combined three levels of foliar nano urea (N0: two water sprays; N1: one nano urea spray at 20 DAS followed by a water spray at 40 DAS; N2: nano urea sprays at both 20 and 40 DAS) with five levels of soil-applied boron (0, 0.5, 1.0, 1.5 and 2.0 kg ha⁻¹), replicated three times, and the post-harvest soil in every plot was analysed each season for pH, electrical conductivity (EC), organic carbon (OC), and the available status of nitrogen, phosphorus, potassium, sulphur and boron. Across both years and on a pooled basis, neither nano urea nor boron altered soil pH, EC or organic carbon to a statistically detectable degree, so the soil's basic chemical character stayed essentially where it started. Available nitrogen, phosphorus, potassium, sulphur and boron, however, rose significantly (p ≤ 0.05) as the level of either input increased, with the strongest residual enrichment recorded under the twin nano urea spray (N2) and the highest boron dose (B4, 2.0 kg ha⁻¹); their interaction remained statistically non-significant for every soil parameter studied, indicating that the two nutrients act largely independently rather than reinforcing or dampening one another's effect on the soil. On a pooled basis, available N, P, K, S and B increased from 218.06, 15.20, 155.04, 18.24 kg ha⁻¹ and 0.52 mg kg⁻¹ under N0 to 231.66, 16.77, 171.42, 19.52 kg ha⁻¹ and 0.56 mg kg⁻¹ under N2, and from 212.56, 14.69, 149.74, 17.71 kg ha⁻¹ and 0.39 mg kg⁻¹ under B0 to 233.44, 17.03, 174.10, 19.76 kg ha⁻¹ and 0.68 mg kg⁻¹ under B4. Read together, these numbers describe a fertilization strategy that quietly builds up the soil's available-nutrient reserve without disturbing its pH, salinity or organic matter balance — a combination that appears well suited to the sustainable nutrient management of mustard-based cropping systems on sandy loam soils of central India.