Effects of zeolite application on nitrate and ammonium retention of a loamy soil under saturated conditions

Abstract

Nitrogen (N) loss from irrigated cropland, especially in rice paddies, results in low N-use efficiency and groundwater contamination. Soil conditions that increase ammonium and nitrate ion retention alleviate these problems. Clinoptilolite, a naturally occurring zeolite with high-exchange capacity, may be used to absorb ammonium and retard excess leaching of nitrate. The objectives of this research were to determine the effects of different rates of Ca–K-zeolite application (0, 2, 4, and 8 g/kg soil) on pore water velocity and leaching of ammonium and nitrate applied as ammonium nitrate fertiliser to a loam soil at a rate of 350 kg N/ha under saturated conditions similar to that of a rice paddy. The results indicate that Ca–K-zeolite applications of 4 and 8 g/kg soil increase the pore water velocity by 35% and 74%, respectively. The maximum relative concentration (c/co) for the nitrate breakthrough curve occurring at pore volume of about 0.5 was reduced by 15% with a zeolite application rate of 8 g/kg soil. When applying 40 cm of leaching water, leached nitrate was 75% and 63% of total applied nitrate at the soil surface with zeolite applications of 4 and 8 g/kg soil, respectively. Due to the high ion exchange capacity of zeolite, the application of zeolite at 2 g/kg soil is enough to increase the exchange sites in the soil in order to absorb the applied ammonium and prevent its leaching by the inflow water. The maximum ammonium concentration in the breakthrough curve for the zeolite application rate of 2 g/kg soil was reduced by 43% compared with the control treatment. The relationship between the hydrodynamic dispersion coefficient (D) for nitrate and pore water velocity (v) was not linear and it was correlated with squared pore water velocity. The coefficient of the relationship between D and v2 was dependent on the zeolite application rate and linearly increased with this rate.

Transport of nitrate and ammonium ions in a sandy loam soil treated with potassium zeolite – Evaluating equilibrium and non-equilibrium equations

“…According to the CDE model, application of 2, 4 and 8 g zeolite per kilogram soil increases 145.38, 172. 14 …”

“…Two holes were built at 31 cm height; one of them was for input and other was for output of water. This way was made for steady state water flow on soil columns [14]. Before re-packing the soil in the columns, it has been passed through a 2-mm stainless steel screen.…”

Two-dimensional modeling of nitrogen and water dynamics for various N-managed water-saving irrigation strategies using HYDRUS

“…While denitrification occurs at high soil temperatures, nitrification is reported to take place mainly in the temperature range of 30-40 • C. Our previous research demonstrated that both DI and PRD strategies control soil temperatures at lower values and within the considered range (Karandish and Shahnazari, 2016). NO 3 − -N concentrations tend to be significantly higher than NH 4 + -N concentrations under favorable conditions for the nitrification process (Sepaskhah and Yousefi, 2007). Marschner (1995) reported that average annual NH 4 + -N concentrations are often 10-1000 times lower than NO 3 − -N concentrations in well-aerated agricultural soils.…”

Laboratory Evaluation of Zero Valent Iron and Sulfur‐Modified Iron for Agricultural Drainage Water Treatment

“…(Note: Gas bubbles were observed exiting the permeameter outlet during column test 5.) Low‐cost, abundant, natural zeolite has been proven effective for removing NH 4 + from water via cation exchange processes (Booker et al 1996; Demir et al 2002; Sepaskhah and Yousefi 2007). Therefore, a two‐stage filter treatment system in which drainage water first flows through SMI (to convert NO 3 – to NH 4 + ) and then flows through zeolite (to remove the NH 4 + ) could be a feasible way for taking out inorganic nitrogen originally present in subsurface drainage waters.…”