Estimating Nutrient Losses Within Indiana

 

November 21, 2001

 

Bernie Engel and Kyoung Jae Lim

Agricultural and Biological Engineering

Purdue University

 

The NAPRA (National Agricultural Pesticide Risk Analysis) model was enhanced. An overview of the most significant enhancements is provided below. A series of five workshops were held describing the NAPRA model and providing hands on training in its application. The NAPRA model can be accessed on the WWW at http://pasture.ecn.purdue.edu/~napra/.

 

The NAPRA WWW system was run with state average commercial fertilizer and animal waste application for corn-soybean rotations within Indiana. The application rates of fertilizers and animal waste were set at the average application rate within Indiana as determined by the Indiana Agricultural Statistics Service. The STATSGO soil data were used to provide the soil properties for the model runs. The model was run only for areas that are cropped or potentially cropped based on the Indiana GAP land use map. Other model inputs are described in the sections below. The average annual pesticide losses estimated by NAPRA were mapped within GIS using the STATSGO soil layer. The maps for pesticide losses are contained in a section that follows. Electronic copies of the maps are also available at the NAPRA WWW site http://pasture.ecn.purdue.edu/~napra/.

 

 

Enhancement of the NAPRA WWW System

 

In the previous nutrient enabled NAPRA WWW, only one pesticide could be simulated at a time.  Since multiple pesticides are often applied to the field during the cropping season, the NAPRA WWW was modified to enable users to simulate multiple pesticide applications.   For practical purposes, up to 6 pesticide applications to a crop were enabled in the NAPRA WWW system.

 

The National Soil Information System (NASIS) (NRCS, http://nasis.nrcs.usda.gov/) data for 80 counties in Indiana were added to the ORACLE database to provide more specific soil information for the NAPRA WWW system.  It provides more detailed soil information than that of State Soil Geographic (STATSGO) (USDA, NRCS, 1994) soil data.  However, NASIS is not related with spatial location, and thus it is used only in the NAPRA WWW system when estimating pesticide losses for fields.

 

To estimate soil erosion in GLEAMS 3.0, a modified version of the Universal Soil Loss Equation (USLE) is used, and one of the factors is a C factor which accounts for cropping systems such as conservation tillage and crop rotation and gives consideration to prior land use, canopy cover, surface cover, and surface roughness.  To help users with NAPRA WWW input, 15 tillage operations with corresponding C factors were included in the NAPRA WWW, so the users need to select only a tillage system description rather than provide C values. 

 

Grassed waterways/ditches and grassed buffers are important components of a soil and water conservation program aimed at reducing erosion.  Waterways provide a nonerodible outlet for runoff.  Grassed waterways can be an effective practice to improve water quality.  To represent grassed waterways/ditches in Indiana, the “Overland-Channel-Channel” option in the erosion component of GLEAMS was used to represent the field (GLEAMS is the hydrologic/water quality model used within NAPRA).

 

 

NAPRA Input Information for Nutrient Loss Maps

 

- State average fertilizer and animal waste values were estimated based on Indiana Agricultural Statistics Report, 1998-1999.

 

Corn

1)      Day of Planting: May 16

2)      Day of Maturity: Sept. 22

3)      Day of Harvesting: Oct. 22

4)      Fall Chisel

5)      138 lb/ac of N ( = 216 lb/ac of Anhydrous ammonia) on May 15

6)      64 lb/ac of P ( = 336.84 lb/ac of Superphosphate) on May 15.

7)      13.61 lb/ac of N and 9.395 lb/ac of P from manure

( =  415 gal/ac of liquid, swine) on May 6 and Nov. 12

 

Soybeans

1)      Day of Planting: May 25

2)      Day of Maturity: Sept. 18

3)      Day of Harvesting: Oct. 10

4)      No Tillage

5)      31 lb/ac of N ( = 48.6 lb/ac of Anhydrous ammonia) on May 24

6)      45 lb/ac of P ( = (Single) superphosphoate) on May 24

7)      No manure applied for soybean

 

 

 

 

Figure 1.  Crop Land from GAP Land Use. Pesticide Losses Were Estimated for Cropped Areas.


Figure 2.  Eight Digit Hydrologic Unit Boundaries


Figure 3.  Subsurface Drainage System Percentage in 1974. The Subsurface Drainage Percentage Was Used to Estimate the Portion of Pesticides Estimated to Leach Below the Rootzone Delivered to Surface Water.


·     Corn – Soybean Rotations

 

Figure 4.  Annual Average Runoff for Corn-Soybean Rotations in Crop Land

 

Figure 5.  Annual Average Percolation for Corn-Soybean Rotations in Cropped Areas.

 

Figure 6.  Annual Average NO3 Loading in Runoff for Corn-Soybean Rotations in Cropped Areas.

 

Figure 7.  Annual Average NH4 Loading in Runoff for Corn-Soybean Rotations in Cropped Areas.

 

Figure 8.  Annual Average PO4 Loading in Runoff for Corn-Soybean Rotations in Cropped Areas.

 

 

Figure 9.  Annual Average NH4 Loading in Sediment for Corn-Soybean Rotations in Cropped Areas.

 

 

Figure 10.  Annual Average PO4 Loading in Sediment for Corn-Soybean Rotations in Cropped Areas.

 

 

Figure 10.  Annual Average NO3 Loading in Percolation for Corn-Soybean Rotations in Cropped Areas.

 

Figure 11.  Annual Average PO4 Loading in Percolation  for Corn-Soybean Rotations in Cropped Areas.

 

 

Figure 12.  Annual Average NO3 Concentration in Runoff for Corn-Soybean Rotations in Cropped Areas.

 

Figure 13.  Annual Average NH4 Concentration in Runoff for Corn-Soybean Rotations in Cropped Areas.

 

Figure 14.  Annual Average PO4 Concentration in Runoff for Corn-Soybean Rotations in Cropped Areas.

 

 

Figure 15.  Annual Average NO3 Concentration in Percolation for Corn-Soybean Rotations in Cropped Areas.

 

 

 

Figure 16.  Annual Average PO4 Concentration in Percolation  for Corn-Soybean Rotations in Cropped Areas.