Zone Recommendation Statistic Explanation

The Zone Recommendation Statistics is a table within the Adapt-N Recommendation Summary Report. This article will explain the terms used within this table.

Expected N in crop at harvest is the amount of N estimated to be in the corn crop at harvest time.   This is calculated from the "Expected Yield" input combined with the Recommendation Parameter for Pounds of N per Expected Bushel of Yield.   Estimates of N contents of grain, stover and roots are used.

N mineralization so far is plant-available N derived from soil organic matter or organic amendments from simulation start date until the current date.

N loss since planting / since simulation start date reflects all nitrogen losses since the beginning of the simulation or since the planting date. This includes all nitrogen lost from manure applications, overwinter leaching losses, lost nitrogen from organic matter mineralization, as well as losses from all types of N applications (ammonia volatilization, etc.).

Additional N Credits includes credits from previous crops as well as from manure applications. This is supplemental to the simulated effects of N mineralization or immobilization from incorporation of previous-crop residues.

N in crop now is the amount of N that is already in the crop for the day you run the model (or on the season end date you selected if you are running on a prior season). This is determined by simulations using the corn growth routines in the model, and incorporates information from the high resolution weather data and soil N availability for the field location.

Expected Future Fertilizer Loss represents the N loss risk specifically for the recommended fertilizer application. This basically is a time-dependent fertilizer use efficiency factor. Values represent the fraction of the fertilizer to be applied that can be expected to be lost due to weather events following application, based on probabilistic estimates from 30 year simulations. Values are proportional to the recommended fertilizer rate, and they will generally decrease as the growing season progresses and the risk of N losses from weather events is reduced 

Future Net N Credits represents the combined nitrogen credits and debits that are expected for the remainder of the growing season.  Credits include future mineralization from soil organic matter, manure applications, previous crop, etc. They are generally higher with soils with high organic matter contents and when organic amendments have been applied.   Debits include the risks associated with future leaching and denitrification losses, which are mostly based on current nitrate levels in the soil, potential future mineralized N, and the time in the growing season. In general, debits from future losses are greater for simulations done in early spring, as the N loss risk from high rainfall events in the following weeks is higher. Also, debits are higher for cases where high N rates have been applied prior to planting, as this generates greater potential for early-season losses.   As the growing season progresses and weather events are playing out, the recommendations become more precise and the N loss risk is reduced.  Values are probabilistic and based on 30 year simulations.

N in soil now is the amount of mineral N available to the crop from the soil for the day you run the model. This is determined from model simulations based on input information on soil type, rooting depth, slope, organic matter content, tillage system, previous organic and inorganic N applications, rotations (sod, soybean, etc.), and corn variety, maturity class, and population, where mineralization and losses are similarly affected by weather to date.

Rainfall since planting / since simulation start date reflects climate data which is updated several times per day. (estimates may slightly change in following 2 days as more precise precipitation data become available).

Current plant available water / Maximum plant available water represents the plant available water for today's soil moisture status for that soil texture.  The Maximum plant available water is what is available when at field capacity.

Current Nitrate / Virtual PSNT represents simulated nitrate levels in the top 12” and 12"-24" depth of the soil on a daily basis throughout the season. The virtual PSNT is presented as a convenient comparison but is not used directly to make a recommendation. Our field trial data show the virtual PSNT simulated by Adapt-N to generally be within 5 ppm of the measured value.  See this article for further details and recommended sampling protocol.

Current Ammonium N represents simulated ammonium N levels in the top 12" and 12"-24" depth of soil on a daily basis throughout the season.