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Agronomic Crops Network

Ohio State University Extension


Evaluating the Effects of NZone Max on Corn Nitrogen Efficiency in Ohio

Corn field

NZone MaxTM is a commercial product by AgExplore International, LLC® (Parma, MO) designed to improve N efficiency by maintaining N in the ammonium form (NH4), slowing the conversion to nitrate (NO3). NZone Max is not a traditional nitrification inhibitor, but rather uses unique calcium-based chemistry to slow the conversion of NH4 into NO3.

From 2016-2018, we evaluating the effects of NZone Max on corn N efficiency in Wooster, Ohio. Urea ammonium nitrate (UAN, 28%) with and without NZone Max were tested at two N rates: a full rate of 195 lbs N/acre (100%) and a reduced rate of 147 lbs N/acre (75%). Continuous corn was planted each year in the same field over three years.

Soil was sampled for NO3 and NH4 at 0-12 inch and 12-24 inch depths at the following corn stages: preplant, V5 (early vegetative), V10 (mid vegetative), R1 (silking), and R6 (physiological maturity). Measured crop properties included: aboveground biomass N at V5, ear leaf N at R1, stalk nitrate at black layer and corn grain N and yield at harvest.

NZone Max had minimal effects on the retention of NH4 in the soil. Out of the 60 total comparisons (3 years, 5 stages, 2 depths, 2 N rates), both soil NO3 and NH4 were equally likely to increase or decrease with NZone Max treated fertilizer (Table 1).

Table 1. Cumulative counts of the effect of NZone Max on soil nitrate (NO3) and ammonium (NH4) from 0-12” and 12-24”.

N Pool


NZone Increased

NZone Decreased

No Significant Difference



















NZone Max did influence the corn crop, by increasing N content in the plant at two growth stages. However, there was no effect on corn grain yields in any year (Figure 1).

Figure 1. Corn grain yield with and without NZone Max (NZM) at the full rate (100%) and reduced rate (75%) over three years. NS = Not significant (no difference found between NZone Max and Control).

Over three years in Wooster Ohio, we did not observe a net benefit with using NZone Max in corn. The full summary report can be found here:

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.