1. Higher Nitrification rates with AER – aerobic conditions – Hamra (sandy loam)
NH4Cl addition (100 mgN/kg soil)
AER affects both - Nitrification and Mineralization Kinetics – aerobic conditions –
Hamra (organic) without fertilizer addition
Ion Exchange Resins for Improved Prediction of Nitrogen Mineralization and Nitrification Rates in Soils
Oshri Rinot, Raphael Linker, Nomi Kahane and Avi Shaviv
Faculty of Civil and Environmental engineering, Technion – Israel Institute of Technology
Motivation:
Fertilization management should be based on quantitative understanding of processes involved in nitrogen dynamics in soil, and mineralization process, in particular. This should improve N
inputs management, particularly, when organic wastes are supplied (manure, compost, sewage sludge, reclaimed waste water) and thus minimize water resources contamination and air
pollution while sustaining or even improving crop production.
NH3 volatilizationNH4
+
Mineralization
Nitrification
Immobilization
Plantuptake
LeachingNO3
-Nitrification
Denitrification
Immobilization
Plant uptake
Mineralization and Nitrification Gross Rates
Master 2003
Allowing improved quantification, understanding and management of N processes.
Gross mineralization rate was found as a better estimator for N uptake by plants than net
N mineralization.
The ratio between net and gross mineralization rate is considered to be a reliable index to
N loss processes dominance for a specific soil.
Chemical assays measure certain forms of N, so they are likely to be most successful as
indicators of gross N mineralization.
Anion Exchange Resins (AER) for determination of “real” mineralization and
nitrification rate
Nitrate adsorption to AER beads significantly protect it from denitrification losses under
“real” conditions.
Mineralization and Nitrification rates were significantly higher in AER treatments compared
to control treatments in different soils, assumable due to AER protection from N losses.
N mineralization rate may be reduced due to N adsorption to AER thus increasing C/N
ration, particularly under high N loads.
Mineralization rates were higher in Mixed bed IERs treatments, compared to control and
AER treatments due to N adsorptive protection and increasing availability of OM.
 Mixed IERs show potential for improved estimation of “Realistic” Mineralization rates;
AERs appear effective for estimating Nitrification rates; However, More validation needed
AER beads (Cl- loaded) reduce significantly Nitrite and Nitrate losses under severe
anaerobic conditions – Grumosol (Alluvial clay), glucose enriched
Nitrification rate for– NH4Cl addition (100ppm)
mgN/kg soil/day (𝑹2
>0.9)
ControlAER 10%Soil
16.2918.68Grumosol – FW irrigated
23.5226.67Grumosol – RWW irrigated
13.0816.76Hamra - organic
8.7611.05Hamra - RWW irrigated
y = -3.7x + 179.0
R² = 0.95
y = -7.0x + 194.6
R² = 0.96
0
50
100
150
200
250
0 5 10 15 20 25
N(mg/kgsoil)
Time (hours)
NO3+NO2
IE Control
Minimizing diffusion
constrains
“Simulating” plant
roots activity
No “separation”
between IE and soil.
Full Distribution of IER Beads in Soil
Mixed-bed Ion Exchange Resins (IER) for determination of “real” mineralization rate and
evaluation of N uptake by plant roots
NH3 volatilizationNH4
+
Mineralization
Nitrification
Immobilization
Plant uptake
LeachingNO3
-Nitrification
Denitrification
Immobilization
Plant uptake
Anion exchange resin
(AER)
Amberlite® IRN-78
𝑪𝒍− loaded
NH3 volatilizationNH4
+
Mineralization
Nitrification
Immobilization
Plantuptake
LeachingNO3
-Nitrification
Denitrification
Immobilization
Plant uptake
Anion exchange resin
(AER)
Amberlite® IRN-78
𝑶𝑯−
loaded
Cation exchange resin
(CER)
Amberlite® IRN-77
𝑯+ loaded
𝑯+
release
𝑶𝑯−
release
Mixed bed IER affects Mineralization and Nitrification Kinetics – aerobic conditions – Hamra
(organic and RWW irrigated; 30mgN/kg soil added)
Summary and Conclusions
Sensible use of IERs by uniform mixing of IER beads in soil should minimize diffusion constrains and better indicate plant roots activity. This is expected to provide an effective solution for
estimating more realistic, close to gross mineralization and nitrification rates, in soils for acquiring deeper understanding of processes controlling soil N availability and for estimating N
roots uptake.
Research Hypothesis
Treatment AER (Cl-) Control
Mixed IER
(H+/OH-)
Control -2.0 AB -8.0 B 6.8 A
Sludge compost 2.4 A -2.6 A 8.2 A
N-Viro 50kgN+fertilizer 30.7 B 29.7 B 56.2 A
N-Viro 150kgN 12.4 B 1.4 C 27.8 A
Mineralization rates for 14 days aerobic incubation – comparison between different sludge
treatments – Grumosol (Revadim) – Mixed IER (H+/OH-), AER and Control treatments
All values – mgN/kg soil
N mineralization and nitrification rates with IERs are
compared to N balance and uptake by plants in pot
experiments. Special focus on N2O losses.
Under Investigation These Days