Spatial and Temporal Assessment of Nitrate-N under Rice-Wheat System in Riparian Wetlands of Punjab, North-Western India

Abstract

The nitrate (NO3−) leaching assessment from extensive fertilizer nitrogen (N) applications to croplands is crucial to optimize fertilizer-N recommendations that do not threaten the quality of drinking groundwater. SWAP (Soil Water Atmosphere Plant), a water balance model, was linked with ANIMO (Agricultural NItrogen MOdel), a nitrate leaching model and the Geographical Information System (GIS) to assess the spatial and temporal leaching of NO3−-N from fields under rice-wheat cropping system in the riparian wetlands in the Punjab in north-western India. The results revealed that NO3−-N concentration in the groundwater exceeded the 10 mg NO3−-N L−1 limit set by the World Health Organization (WHO) for drinking water only during December–January. The verification of these results using measured values indicated that the SWAP-ANIMO model satisfactorily predicted NO3−-N concentrations in the leachate in the vadose zone. A low value of the mean absolute error (0.5–1.4) and a root mean square error (0.6–1.5) was observed between the measured and the predicted NO3−-N concentration across the soil profile during the validation at five sampling sites. The NO3−-N predictions revealed that in the long-term, the ongoing fertilizer-N management practices in the riparian wetlands will not significantly change the average NO3−-N concentration in the groundwater. The modeling approach was satisfactory for an efficient quantitative assessment of NO3−-N pollution in groundwater while accounting for the spatial and temporal variability.

Emerging Issues and Potential Opportunities in the Rice–Wheat Cropping System of North-Western India

“…The decline in the groundwater table also resulted large investments into tube wells, which increased operational costs and led to more power consumption in northwest India ( GoI, 2017 ), and the deterioration of groundwater quality ( Farmaha et al, 2021 ). The management of groundwater is one of the major priorities to combat the challenging issue of water scarcity in India.…”

Elevated Fe and Mn Concentrations in Groundwater in the Songnen Plain, Northeast China, and the Factors and Mechanisms Involved

“…Groundwater containing a high NO 3 − concentration will usually remain sufficiently oxidative to prevent reductive dissolution of Fe and Mn oxides [61]. Agricultural activities in the study area have caused large amounts of NO 3 − to enter groundwater [25,62]. NO 3 − can act as a strong oxidant in a relatively reductive environment.…”

Predicting Regional-Scale Elevated Groundwater Nitrate Contamination Risk Using Machine Learning on Natural and Human-Induced Factors

“…Nitrate is often described as the most pervasive chemical contaminant in groundwater. , Nitrate concentrations up to 45 mg/L are permissible in drinking water. − Beyond this value, nitrate is known to pose fatal health risks, e.g., methemoglobinemia, chronic birth defects, and other diseases . Although nitrate can occur in groundwater from numerous sources, e.g., atmospheric deposition, unmanaged urban sewage, , poorly maintained wastewater treatment plants, and septic systems, the major contributor of nitrate in the environment is considered to be agriculture in the form of chemical fertilizers, , animal manure, , and crop fixation. − The highly agrarian parts of north and northwestern China, − the Mekong-deltaic region of Vietnam, several parts of Africa, southwest Germany, and California, Pennsylvania, central valley plains, and east coast of the United States − are reported with elevated groundwater nitrate. In the Indian context, nitrate concentrations above the permissible value are reported from several areas of both the peninsular ,,, and upper parts of the country. − …”