NTT has been updated and re-released as a national-level tool. NTT can now be used to estimate nutrient and sediment losses from crop and pasture operations across the contiguous United States. NTT is constantly being improved, so please visit this page for the latest updates.

December 1, 2019:
1. Tier 1 Validation has been completed for all of the lower 48 states. Parameter files have been updated in NTT. Ohio and Minnesota have been validated using field-scale data (Tier 2 Validation). Where we have field scale data we will continue to improve parameters in NTT. Please review the validation information available by clicking on validation on the bottom of the home page. Stay tuned for more updates.
2. Currently, the soil surface slope is calculated based on one centroid pixel (30-m or less) representing each soil type within the area of interest (AOI). Now, the modified slope routine in NTT will calculate the average slope for all existing pixels for each soil type within the AOI. This improve the value of calculated slope for AOI in most cases.

February 2020 (version 20-2):
An official version of NTT (Version 20-2) released with following modifications
1. The weather data period was expanded to Dec. 30 2018. NTT simulation period now spans between 1981 and Dec. of 2018.
2. The mapping system was upgraded to make it faster and more reliable.
3. The crop database planting/harvest dates was updated for different regions of country.
4. The conservation practices page now includes fencing. Fencing has the effect of eliminating direct manure deposits into the stream and creating a de-facto buffer between the fence and the stream that reduces erosion and surface runoff.

September 2021 (version 21-9):
Science and Technical
1. Farm Economic model (FEM) added to evaluate the economic impact of conservation practices.
2. Modification of APEX tile drainage routine to simulate soil profile water content.
3. Modification of tile bioreactors routine to tile drain system.
4. Modification of drainage water management practice to tile drain system.
5. Addition of saturated buffer practice to tile drain system.
6. Addition of start and end date for auto-irrigation practice.
7. Reservoir routine was added to the list of conservation practices.
8. An optional length input was added for grass waterways.
9. Modified soil-P so that it is refreshed at the start of each crop rotation to the user-supplied soil-P value.
10. Soil maximum depth was set to 2.0 m (6 feet) for all soils.
Databases
1. PRISM weather information extended to year 2019 (as always NTT is simulated using the last 30-years of updated weather)
2. Soils data was updated using USDA-NRCS 2019 soil survey data.
3. Economic databases were included for FEM simulations.
Help/Manuals
1. Help, user manual, and page instructions were updated and made available on the site.
2. A forum page was added to the site.
3. An email system was added to submit any posted user’s question in the forum in developers’ desk for possible assistance.
4. An FAQ page was added to organize and post the most common questions asked in the forum to assist other users.
Operational
1. Function allowing users to copy scenarios from other project or field in “Management Scenario” page was added.
2. Combined harvest and end of season operations in one in “Operation”
3. Functionality added to allow user to select “initial year” and “final year” for the tabular report.
4. Updated “tabular results” page to allow users to compare any number of simulated scenarios instead of limiting to just 3.
5. Added an automated function to route runoff, sediment, and nutrient between fields (subbasins) based on the slope order of simulated field (sub-basins) slope.
6. The APEX download button was moved to the actions columns, so the user does not need to simulate a scenario in order to download the APEX folder before running other one (available in NTT-RE version).