Spatial and seasonal distribution of nitrate-N in groundwater beneath the rice–wheat cropping system of India: a geospatial analysis

Abstract

Increased use of nitrogenous fertilizers in the intensively cultivated rice (Oryza sativa)-wheat (Triticum aestivum) cropping system (covers a 13.5-ha m area in South Asia) has led to the concentration of nitrates (NO(3)-N) in the groundwater (GW) in Haryana State of India. Six districts from the freshwater zone were selected to identify factors affecting NO(3)-N enrichment in GW. Water and soil samples were collected from 1,580 locations and analyzed for their chemical properties. About 3% (26,796, and 10,588 ha) of the area was estimated to be under moderately high (7.5-10 mg l( -1)) and high (>10 mg l( -1)) risk categories, respectively. The results revealed that NO(3)-N was 10-50% higher during the pre-monsoon season than in the monsoon season. Nitrate-N decreased with the increase in aquifer depth (r (2) = 0.99). Spatial and proximity analyses using ArcGIS (9.2) revealed that (1) clay material in surface and sub-surface texture restricts N leaching, (2) piedmont and rolling plains act as an N sink, and (3) perennial rivers bring a dilution effect whereas seasonal rivers provide favorable conditions for NO(3) (-) enrichment. The study concludes that chemical N fertilizers applied in agro-ecosystems are not the sole factor determining the NO(3) in groundwater; rather, it is an integrated process governed by several other factors including physical and chemical properties of soils, proximity and type of river, and geomorphologic and geographical aspects. Therefore, future studies should adopt larger area (at least watershed scale) to understand the mechanistic pathways of NO(3) enrichment in groundwater and interactive role of the natural drainage system and surrounding physical features. In addition, the study also presents a conceptual framework to describe the process of nitrate formation and leaching in piedmont plains and its transportation to the mid-plain zone.

Assessment of Nutrient Leaching in Flooded Paddy Rice Field Experiment Using Hydrus-1D

“…Subsurface losses (kg ha −1 ) = 0.01 DP (1) where C = solute concentration (mg/L) and DP = deep percolation depth (mm).…”

“…The nutrient concentration of surface and subsurface waters has changed into a dangerous worldwide environmental and ecological problem [1], which has tremendously accelerated the potential risks of the eutrophication of surface water and toxic contamination of groundwater. Most chemical fertiliser loads primarily originate from agricultural fields, especially during the rice growing seasons, in which a tremendous amount of fertilisers are utilised within agricultural crops.…”

Evaluation of nitrogen balance in a direct-seeded-rice field experiment using Hydrus-1D

“…Nitrogen (N) contamination of surface and ground waters has become a serious, global environmental problem (Chandna et al, 2011). The risk of groundwater contamination by N depends largely on the N input to agricultural fields in the form of inorganic fertilizers and on its effective use by agricultural crops (Becker et al, 2007).…”

Molecular Characterization of Stress Tolerant Plant Growth Promoting Rhizobacteria (PGPR) for Growth Enhancement of Rice

“…Farmers usually rely on agrochemicals to maintain the crop productivity (Wang et al, 2010;Zaman et al, 2010). However, excessive use of agrochemicals to crop fields has been reported to increase nitrate, nitrite, ammonium and phosphate and other reactive chemical species in groundwater and surface water bodies, which causes serious environmental and health hazards (Emilsson et al, 2007;Chandna et al, 2011;Rawat et al, 2010Rawat et al, , 2012.…”