Winter Wheat Growth Issue

[Isaac Kraenbring]

1. Primary Issue Location

• Component:  Model Functionality
• Area of impact: Model Output

2. Software Versions

• 4.0.2 GIS Interface:  4.0.1 SWAT+ Editor:  rev 62 SWAT+ Revision:

3. Project Characteristics

• Watershed Details: (Size, discretization settings/HRU thresholds, and location)

I am currently working on a Pennsylvanian watershed is about 35000 ha larger with 30% of the land being for agriculture. Currently there are 956 HRUs (a bit high for this size, but the model runs smoothly).

• Modeling Aim: (e.g., Water balance, ET, crop growth, water quality, etc.)

The goal is to model the watershed with correct crop growth and use data to calibrate nutrient loads. 

4. Description of Issue

• The Problem: I was having some issues getting the automatic crop rotation cycles to function correctly in the model. This lead me to develop my own scheduled operations to simulate a 2 year rotation with corn, winter wheat, and soy beans. After a bit of effort, the corn and soybean can function correctly, however, the winter wheat struggles. The main issue is that during the switch between rotation year 1 and rotation year 2 the phubas0 value flat lines rather than maintaining the low winter wheat value. Because of the reset, the crop is underdeveloped when the grain harvest action is implemented meaning the yield is low. 

• SWAT+ Check Issue

SWAT+ Check does not seem to reflect the values for yield, biomass, or nutrient uptake seen in the database table hru_pw_day. 

• Step to Reproduce: 

Try to simulate winter wheat in a two year crop rotation cycle. In the hru_pw_day.txt file look at the biomass and yield during projected harvest. Look at the phubas0 column when the year turns over and see the value rest to 0. 

5. Supporting Data (Optional)

• Link to TxtInOut folder: 

https://drive.google.com/drive/folders/1bQgXa7UthxzGccd6JH7Gt85sHEEVDpVv?usp=sharing 

[Isaac Kraenbring]

Here is an update on this ticket. After taking out the winter wheat and working on the model for a while, I identified that SWAT+ Check is not reading the output files correctly when it is filtered for agricultural land use and is showing 0.000 for plant uptake, wrong biomass numbers, and NA for N and P removed in yield. After looking at the nutrient balance and yield files, there is uptake, there is N and P in the yield, and the biomass looks correct. 

As far as the winter wheat goes, the phubas0 value does still flatline, but there is still biomass present leading to yield. Not sure what to do about that, but as long as you are not harvesting for grain, it should be okay. 

If anyone has suggestions on how to reset SWAT+ Check or fix it somehow, please let me know!