S. Rajendiran

Enhancing N Use Efficiency and Reducing N 2 O Emission by Coating Urea with Newly Identified Bio-Molecule (C 20 H 30 O 2 ), Nano-Zn Oxide and Nano-rock Phosphate

The increasing use of nitrogenous fertilizer and its importance in Indian agriculture has attracted the attention of environmentalists. There is a greater concern that nearly 30–60% of applied N is lost in the form of ammonia from the agricultural soils through volatilization. To reduce such loss, urea can be coated with pine oleoresin, a novel coating material, for making slow release urea with minimal cost using the solvents like petrol. The POR-coated urea releases N slowly by the action of a physical barrier and increase N availability by inhibiting urease activity through antibacterial properties and reduces volatilization loss by acidifying alkaline micro-sites in soil. It also improves the biomass yield, nitrogen uptake and nitrogen use efficiency. Keeping in view of the above, the current investigation was aimed to coat urea with nano-ZnO (<100 nm) and nano-rock phosphate (<48.6 nm) using pine oleoresin (POR) as a coating agent and to study their effect on nitrous oxide (N2O) emission. Significant improvement in N use efficiency ranging 10–20% was observed in greenhouse studies. Further, the results clearly demonstrated that further encapsulation of POR coated urea with nano-Zn oxide (<50 nm) and nano-rock phosphate (<100 nm) reduced nitrous oxide emission by 30–40%. Nano-ZnO coated urea showed the least N2O emission (0.28 μg N2O mg−1 N) followed by 35% nano-RP coated urea (0.30 μg N2O mg−1 N). The results thus indicated that coating urea with 2% nano-ZnO and 35% nano-rock phosphate could be used as a potential means to reduce N2O emission from fertilizer N.

Spatial Distribution and Baseline Concentration of Heavy Metals in Swell–Shrink Soils of Madhya Pradesh, India

Defining and understanding the current abundance and spatial distribution of metals in soils are essential and reliable information on this aspect are needed for proper legislation. To estimate the baseline concentrations and spatial distribution of heavy metals (HMs) in Swell–shrink soils Sehore and Vidisha districts, 100 surface soil samples (0–20 cm) were randomly collected across the two districts and their physico-chemical properties and total HM contents were analysed. Spatial distribution maps of HMs were prepared and influence of soil parameters on HMs was studied. Most of the soils in the region had neutral to alkaline pH (6.58–8.60), non saline (EC 0.11–1.3 dS/m), medium organic carbon (0.6%), CaCO3 0.2–11.5% and clay >40%. The baseline concentrations of HMs (mg kg−1) were Cu, 178.1; Cd, 0.7; Pb, 24.4; Cr, 116.9; Ni, 81.8; and Zn, 85.2; respectively. The concentrations of Cd, Pb and Zn in all the samples were within the safe range but the concentrations of Cr, Cu and Ni were a little high.

Relative Contribution of Phosphorus from Various Sources to the Upper Lake, Bhopal

An investigation on phosphorus loading from the point and non point sources to the Upper Lake, Bhopal and its contribution on eutrophication was undertaken at Indian Institute of Soil Science, Bhopal. Geo-referenced water samples from different entry points (15 locations), where water from different sources (agriculture and municipal water) enters to the Upper Lake, were collected and analyzed for various P fractions. The results showed that the total phosphorus (TP) content varied from 0.30 to 0.73 mg/L with a mean value of 0.47 mg/L having lowest and highest content from Kholukhedi (agriculture source) and Bhadbada (domestic wastewater), respectively. Among the P fractions, the bioavailable P fraction (total dissolved phosphorus-TDP) was highest in the water sample from the domestic source, whereas, the dominant P fractions in the water samples from agricultural source was particulate P (PP). The results shows that the total P in the sediment of post-monsoon stage samples ranges from 0.03 to 0.07% with a mean value of 0.04%. The mean sediment inorganic phosphorus (SIP) and the sediment organic phosphorus (SOP) is 68.01 and 31.98% of total phosphorus (TP), respectively. Among the inorganic P fractions in the sediment, Ca bound P was maximum and found to be in the range of 86.32–96.97% of total sediment inorganic P followed by Fe bound P (2.10–11.51%) and loosely sorbed P (LSP) (0.39–5.66%). To summarize, the source of water from the city (domestic wastewater) and at idol immersion location contains relatively higher total phosphorus (TP) and dissolved reactive phosphorus (DRP).

A novel urea coated with pine oleoresin for enhancing yield and nitrogen uptake by maize crop

ABSTRACT A study was conducted with maize in Vertisol, Inceptisol, Alfisol and Aridisol to evaluate the efficacy of the pine oleoresin coated urea fertilizers (coated with 1.25, 2.50, 3.75 and 5.00% pine oleoresin). Significant increase in biomass yield was observed in all the soils when urea was coated with pine oleoresin at 3.75% or more. All the pine oleoresin coated urea in Inceptisol and Aridisol; and 3.75% and 5% pine oleoresin coated urea in Vertisol and Alfisol significantly increased nitrogen (N) uptake as compared to uncoated urea. Nitrogen use efficiency increased from 19.34% to 32.80% in Vertisol, 13.06% to 28.27% in Alfisol, 13.87% to 23.86% in Inceptisol and 10.68% to 20.23% in Aridisol, as a result of coating urea with pine oleoresin. Thus the results indicate that there is a beneficial effect of coating urea with pine oleoresin with respect to yield, N uptake and use efficiency in maize crop.