Introduction

North Carolina Nutrient Assessment Tool, Version 2.0 contains two field-scale assessment tools: Nitrogen Loss Estimation Worksheet (NLEW) and Phosphorus Loss Assessment Tool (PLAT).

NLEW was developed in response to the Neuse Rules. In August of 1998, the Neuse Rules became law. These rules represented a series of regulations that control point and nonpoint source discharges of nitrogen into the Neuse. As a result of the Local Option that was added to the agricultural best management practice (BMP) rules, producers can join a local strategy rather than implementing mandatory BMPs. The local strategy allows a county to determine where the approved BMPs can be installed to obtain the 30% nitrogen reduction. In addition, the local option provides a few more alternatives to the list of BMPs, such as unfertilized cereal cover crops and no-till corn in the Piedmont, than the standard BMPs. In exchange for this flexibility, however, the rules mandated accountability. The accounting and tracking tool that has been developed to meet the requirements of the Neuse Rules is the Nitrogen Loss Estimation Worksheet (NLEW). In addition, NLEW was adopted by the NC Division of Soil and Water Conservation in 1996 as the method to estimate BMP effects on relative nutrient dynamics for projects funded with Agriculture Cost- Share Program funds. It is also being used in the Tar-Pamlico River Basin.

PLAT was developed in response to the new USDA-Natural Resource Conservation Service (NRCS) nutrient management standard (590). The charge was given that each state must assess phosphorus (P) status during nutrient management planning if animal waste is involved or the field is within an impaired watershed. Three selection strategies were allowed (soil test, environmental test and P index). The North Carolina Phosphorus Loss Assessment Committee chose to use a modified P index assessment method; a unique P assessment method was designed for North Carolina conditions. This P assessment is known as the NC Phosphorus Loss Assessment Tool or PLAT.

How to Use NCANAT

The program allows users to run NLEW alone, PLAT alone or both NLEW and PLAT simultaneously. In the center of the program, toward the top, there are three buttons:

1. NLEW
2. PLAT, and
3. NLEW And PLAT

Simply click the button that corresponds to the program(s) you want to run and the necessary input boxes will be displayed.

Identification

Calendar Year

• The current calendar year will automatically display in the calendar year box. Should you want another year, use the pull-down menu to enter the calendar year. For crops that span two calendar years, such as wheat, count the crop in the calendar year during which it is harvest. For example, if your wheat crop is planted during the fall of 1999 but harvested the spring of 2000, you would count your wheat crop for the 2000 calendar year.

Tract number

• Enter the appropriate tract.

Producer ID

• User can be identified numerically or alphabetically.

Field number

• Enter the field number.

Location

County

• Use the pull-down menu to select the county.

Soil mapping unit

• Enter the predominant soil mapping unit of the field. Only soil mapping units found in your county will be listed.

Cropping System

Current Crop (NLEW only)

• Use the pull-down menu to enter the crop for the current year.

Most Erosive Crop (PLAT only)

• Use the pull-down menu to enter the crop in the rotation that is the most erosive.

Field Slope (NLEW only)

• Enter the average field slope. RYEs are determined for a 0-2% slope. Slopes greater than 2% are assumed to have lower yields due to water relations. The relationship between slope and yield reduction is not linear, but rather curvilinear with much greater yield loss at higher slopes (>15% slope) than a moderate slope (3 to 8%).

Field Acres (NLEW only)

• Enter the number of acres in the field

Cover Crop (NLEW only)

• Select the cover crop type that was used. (Cover crop must be seeded by November 30 and killed no sooner than April 1 in the Coastal Plain and April 10 in the Piedmont to receive credit as a cover crop.)

BMP

• Select the BMP and then click the arrow pointing to the right. If the BMP is a buffer, a new input box will popup. Use the pull-down menu to select the minimum buffer width (in increments of 5 feet). When NLEW is being used you will also be asked for the number of acres affected by the buffer. Please enter this number. Continue to add as many BMPs as appropriate. Press “OK” when all the appropriate information has been added.

Nutrient Application

RYE (Producer Derived – NLEW only)

If the producer knows the crop RYE (average best 3 out of 5 years) for the soil series of the soil mapping unit, enter the value in units/acre.

Application Source and Rate (for PLAT)

• Enter the amount of the material that you are applying into the “Yearly_App_Amount” column, unless you are applying a fertilizer and you know the actual amount of P205 that you are applying. The application units of the material are in the next column (Application_units).
• The amount of P205 is listed in the column “lb_ P205”. If the material is animal waste, this column represents the pounds of P205 per unit applied. The column to the right, “Content_Unit”, lists the units of the material. If you have your own waste analysis, change the value in the “lb_ P205” to reflect your value. If you are working with fertilizers, you have two choices:1) if you know the amount of P205 that you are applying, simply enter this value in the column that reads “lb_ P205”. 2) Otherwise enter the amount of fertilizer that you are apply in the “Yearly_App_Amount” column and then enter the phosphorus analysis of the fertilizer in the “%_P205” column.
• Double click on the line “AppMethod”. Then use the pull down menu to select the application method of the nutrients.

Application Source and Rate (for NLEW)

• NLEW was only designed to work with commercial fertilizers. At the bottom of the table is the fertilizer information. Enter the amount of fertilizer that you are applying into the “Yearly_App_Amount” column. The application units of the material are in the next column (Application_units).
• Then enter the nitrogen analysis of the fertilizer in the “%N” column.
• Double click on the line “AppMethod”. Then use the pull down menu to select the application method of the nutrients.

Soil (PLAT only)

Soil Loss (t/ac/yr)

• Enter the amount of erosion in t/ac/yr, calculated from RUSLE.

Receiving Slope Distance (feet)

• Enter the receiving slope distance. The receiving slope is the concave slope extending from the base of the RSLE slope to the field edge or to a source of concentrated runoff flow in a defined channel.

Soil Test (P-I)

• Enter your agronomic soil test value.
• A second soil test box may be visible for the 28-32” depth. If the box is visible, you will need to take a deep soil sample at the 28-32” depth. Enter the P soil test value for this sample.

Weight:Volume (W/V) Ratio

• Enter the weight:volume ratio from your soil sample for the agronomic soil depth sample. If you do not have this value, a default ratio will be provided based on your soil mapping unit.
• Enter the weight:volume ratio from your soil sample for the deep soil depth sample (28-32”). If you do not have this value, a default ratio will be provided based on your soil mapping unit.

Drainage (PLAT only)

Artificial Drainage

• This box will only be viewable if the soil is a poorly drained soil, otherwise this box will not be viewable, but you will have the option to enter information in the Hydrologic Condition box. If the field is drained, even if the drainage is irregular, this should be considered a drained soil. Click “yes” to denote a drained field.
• For regularly spaced drainage ditches or tile drainage, simply enter the required spacing and depth information. To compute the drainage spacing for irregularly drained soils, calculate the area drained and divide by the total length of the drainage (which may include streams, ditches, or tiled drainage). Enter this number as your drain spacing. Determine the average depth of the drainage devises and enter this as your drain depth.
• If the field is not drained, and you click “NO”, then proceed to Hydrologic Condition.

Hydrologic Condition (PLAT only)

• If there is artificial drainage, the drainage input box is not viewable.
• If there is only one hydrologic condition, that condition will already be checked. If there is more than one hydrologic condition, you will need to check the appropriate condition. Hydrologic condition is based on factors that affect infiltration and runoff, including density and percent canopy of vegetation, amount of year round cover, amount of grass or close seeded legumes in rotation, percent of surface residue cover, and surface roughness.
• Cropland choices are Good or Poor. A poor condition is a finely prepared seedbed, not drilled, with a low plant population, and not in rotation with a sod. A good condition is rough seedbed, high plant population, and in rotation with sod, high residue-producing crop, or conservation tillage.
• Pasture choices are Good, Fair, or Poor. A poor condition is over-stocked, under fertilized, low year-round plant population and poor plant condition. A good condition is properly stocked, adequate nutrient management, and a full plant population (nearly 100% cover). A fair condition is represented by factors less than “Good” and better than “Poor”, and is determined at the planner ’s discretion.

Calculate

• Press the "Calculate" button at the bottom of the screen. The output will be calculated and the value will be displayed next to the calculate button.
• If PLAT has been run, each P loss pathway is expressed in terms of an index and the total assessment is stated both verbally (low, medium, high, or very high) and numerically.
• If NLEW is run, the total N loss is stated.

View/Print Results

• Press the "Print Results" button to look at a detail of the inputs and outputs. Inputs for the current run can be viewed on this page as well as the outputs. For a listing of the inputs and outputs see Appendix 1.
• Click "Print" to obtain a printed copy or click "Print to file" in order to save the output as a text file.
• Comments can be appended to the output by pressing the “Add Comments” button.

Record Buttons

Save Button

• Press the "Save Record" button to save the file. You will need to name the file. All files will be saved consecutively. The files are saved under the name you gave the file and are saved in the following path: Program Files/USI/NCANAT/UserTables/UserInputs.DBF. Once you have saved the record, it can then be imported into data bases or spreadsheets.

Importing Save Records into Access

• Open Access. A box will come up for you to choose: Blank Database, Database Wizard, or Open an Existing Database. Choose 'Blank Database' and click OK.
• Once you click OK another box will come up titled, 'File New Database'. In the 'File name' box at the bottom will be a file called 'db1.mdb.' This is the default file that you can change to any name you want (the extension still has to be .mdb though). Once you are satisfied with the name click the 'Create' Button to the right.
• A window will come up with multi-tabs on it. The first tab is 'Tables' which is what you want. Click the 'New' button to the right.
• In the next window that appears, choose 'Import Table' and click 'OK'.
• In the next window that appears, go to 'Files of type' on the bottom and choose 'dBase IV (*.dbf)'. There are many different dbase tables so make sure you select the right one.
• Then browse through your directories and select whatever DBF File you want to view and click the 'Import' button.
• Any table or tables that you selected will be put into the .mdb file that you named earlier.

Importing Save Records into Excel of Dbase

• To import the contents of the table into a data base or spreadsheet program, such as Excel or DBase, start the pr2.
• Open the program you want to use. Then use "open a file" option and find the following path: Program Files\USI\NCANAT\UserTables\UserInputs.DBF. When you get to user tables, select "all files". (Selecting "all files" will allow all the data base files to be visible.) This brings all stored records into your data base.

New Record Button

• Click the "New Record" button to start a new run. All records will clear.

Find Record Button

• To find a record, click “Find Record” button. You will be asked for the name under which the record is save. Type in the name of the record information will appear in the input boxes.

Tabs

Record View

• This table allows you to see each input you have made to a record. To move through the records, either use the scroll bar on the far right-hand side or the scroll bar on the bottom. You can select a record by clicking on the gray box on the far left-hand side next to the record you are interested in.
• Once you have clicked on a record, the information for the record you have indicated will be in the input boxes when you return to the input table.

View Tables

• To view any of the tables used in NLEW or PLAT, click "View Tables" button and then select the data table you want to view. You will be able to scroll through the data tables and view the information. You cannot, however, change any of the values. The button, “Process List” allows large data sets to be calculated automatically. If you have a large data set, simply bring it into the program and then click the “Process List” button.

About NLEW_PLAT

• To read about NLEW or PLAT, click on this tab.
  

Credits

• Information on persons responsible for the conceptual development and the programming is listed.

Symbols at the Top

Arrows

• Allows you to move between records. Left facing arrow moves you back – Right facing arrow moves you front. Click the arrows to move forward and backward.
  

Negative

• Allows you to delete a record. Click the negative sign to delete a record.

Binoculars

• Allows you to search the data base to find a stored record. Use the pull-down menu to find the column name under which the information is stored. Then enter the specific information you are looking for when you are asked to enter "record item of the information you are looking for". For example, if you are trying to find an entry that had a Lenoir soil type, select the "Map Unit" from the pull-down menu and then enter Lenoir.The record will automatically be entered.

Exit

• This button will exit the program. Simply click to exit.

INPUTS and OUTPUTS for NCANAT

Inputs for NLEW consist of

• Calendar Year
• Producer Identifier
• Tract Number
• Field Number
• County
• Mapping Unit (Soil Series)
• Crop (Current Crop) & Tillage
• Field Slope
• Field Acres
• Cover Crop
• Crop NUE (nitrogen use efficiency which is pulled from a data table)
• RYE (either producer supplied or determined from the data base table using the appropriate RYE based on soil mapping unit, field slope and crop)
• NFactor (N factor taken from the data base and used to determine total N needs)
• N Application Rate. This information is derived from the Application Source And Rate table. In NLEW, this is the amount of N fertilizer supplied to the crop.
• Recommended N Application Rate. This nitrogen recommendation is based on the RYE and N factor.
• BMPs (best management practices that reduce N losses)
• BMP Acres Affected (the number of acres that are affected by the BMP)

The outputs for NLEW are as defined below:

1. N_Applied = the amount of N applied by the producer.
2. N_Needed = the appropriate N fertilization rate as determined by RYEs and N factors.
3. Excess_N (Field acres) = if the total amount of nitrogen applied to a field is greater than the recommended application amount, then there will be excess N.
4. Excess_N_Surface = of the excess nitrogen that is applied, this is the amount that is lost through surface processes.
5. Excess_N_Subsurface = of the excess nitrogen that is applied, this is the amount that is lost through subsurface processes.
6. N_Needed_Field = amount of N recommended on a field-basis. This amount is determined either from the user-supplied RYE or the database supplied RYE and multiplied by the size of the field.
7. Utilized_N_Crop = the amount of nitrogen used by the crop. This is determined by the recommended N amount multiplied by the nitrogen use efficiency factor (NUE).
8. N_Lost After Crop = the amount of nitrogen not used by the crop. It is the N_Needed – Utilized_N_Crop.
9. N_Lost Before BMPs = the amount of nitrogen not absorbed by the crop + the excess N in the subsurface due to excess N application. This N can be lost to the shallow ground water. To obtain N_Lost Before BMPs, N_Lost After Crop and Excess_N_Subsurface are added.
10. N_Lost_After_Cover_Crops = the amount of nitrogen remaining in the soil that can be lost to the shallow ground water after a cover crop has been utilized.
11. N_Lost_After_BMP = the amount of nitrogen remaining in the soil that can be lost to the shallow ground water after a BMP has been utilized.
12. Total_N_Lost = both the N lost through surface and subsurface processes.

Some of the inputs for PLAT are identical to NLEW:

• Calendar Year
• Producer Identifier
• Tract Number
• Field Number
• County
• Soil Mapping Unit
• Crop and Tillage
• BMPs.

Some of the inputs, however, are different. These unique inputs may include:

• Soil Loss
• Receiving Slope Distance
• Soil Test (agronomic depth)
• Soil Test (at the 28" - 32" depth), if it is used
• Weight:Volume (optional)
• Hydrologic Condition or Drainage Spacing and Depth.

The outputs for PLAT are simply the indexed ratings for each of the four loss pathways and the total rating.

Written by Dr. D.L. Osmond,
North Carolina State University,
Department of Soil Science, Raleigh, NC.
June 2003