Nitrate distribution pattern under conventional and trickle irrigation system

Nitrate is a highly mobile ions that moves with water. So that nitrate distribution around the driplines is strongly affected by irrigation and fertigation strategy. Nitrate movement under conventional flood irrigation system was observed 2 to 3.5 times faster as compared with trickle irrigation as well as NO3 "-N concentrations exceeded the threshold limit (i.e. 10 mg l-1) under traditional irrigation method, while stayed below the threshold limit under micro irrigation methods. Nitrate distribution was influenced by hydraulic properties, drip discharge rate, soil layering, timing of nutrient application and irrigation frequency. To maintain larger amounts of nutrient nearby emitter in highly permeable coarse-textured soils, nutrients must be applied at the starting of an irrigation cycle so that it is less susceptible to leaching losses. Study revealed that higher transpiration raised the NO3-N uptake by the plats. The study also revealed that urea moves promptly with irrigation water and urea–ammonium–nitrate fertilizer increased the nitrate concentration, near the drip line immediately after the drip fertigation due to the nitrification, while low concentrations was found near the periphery of the wetting zone.

Biogeochemical zonation reveals three zones of nitrogen turnover in the Ems estuary

<p>Estuaries are nutrient filters for coastal waters and can act as nitrate sink or source depending on predominant microbial processes, environmental conditions and geomorphological characteristics. Such environmental factors can change along the estuary itself. This study aims to identify different zones of nitrogen turnover in the Ems estuary and to determine the main processes.</p><p>Water column properties, dissolved inorganic nitrogen and dual stable isotopes of nitrate were measured along the Ems estuary during two research cruises in August 2014 and June 2020. Based on mixing calculations and stable isotope changes, we found that the estuary in both years is clearly divided into three zones that vary in the predominant nitrate turnover pathways. This was confirmed by principle component analysis.</p><p>The zonation mainly corresponded to changes in the geomorphology of the estuary, but a spatial shift of the zones occurred between 2014 and 2020. In both years, the most upstream zone acted as a clear nitrate sink. A strong fractionation (~30 ‰) of nitrate stable isotopes points towards removal by water column denitrification in this hyperturbid estuarine section.  In the middle reach of the estuary, nitrification gained in importance, turning this section into a net nitrate source during both sampling campaigns. In contrast to the biogeochemical active inner zones, mixing dominates nitrate distribution in the outermost section of the estuary.</p><p>Overall, the Ems estuary acted as a nitrate sink in both years. However, the zonation showed that relative stable zones of nitrification and denitrification existed along the estuary, which can change – and possibly move – when biogeochemical properties vary. </p>

The effect of deep percolation in agricultural lands on contaminant concentration of groundwater

Balance management and the health improvement of the limited groundwater resources are unavoidable to prevent of water scarcity. The irrigation drainable water is the main factors of groundwater contamination that depended on leaching amount, type of surface contaminants and used fertilizer provided the different levels of pollution. In this research, the effect of deep percolation amount on nitrate concentration and salinity in Shahrekord plain is analyzed. The sensitivity of chemical parameters such as Ca, SO4, Cl, Na, K, HCO3 relative to season variation, also nitrate distribution in 80 to 86 years are investigated. For this subject, 10 agricultural areas were identified and estimated their discharge volume and deep percolation. The result show that the groundwater nitrate concentration in the summer season is depended on depletion volume from the effective limitation with R-squared value equal to 0.9, except two cases that NO3 is under the wastewater effect. Na, K and HCO3 in the winter season have a significant difference rather than summer. Also nitrate mapping indicated that the considerable part of groundwater nitrate is happen by leaching in the agricultural lands.