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From: George Foster <FOSTERG@ars.usda.gov>

To: asaleh@ag.gov, flanagan@ecn.purdue.edu, dyoder@utk.edu, jlown@utk.edu,

wagner@weru.ksu.edu

Cc: meyerc@ecn.purdue.edu

Subject: variables for operation processes

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Management Subgroup

At our meeting in Indianapolis, I had the assignment of developing a list =

of variables for each process that we will use to describe operations.

One reason for this information was to help Daniel and Joel to develop a =

modified proposal on how we can represent operations.

Another reason is to help each of us more clearly understand what each =

process represents.

Give me and the group comments on this information.

Thanks.

George

August 12, 1997

List of processes associated with operations

Soil:

Create/modify ridges

Create/modify furrow dikes

Create.modify random roughness

Incorporate material into soil

Mix material within soil

Move material laterally between rill and interrill areas

Compact soil

Biomass:

Begin growth

Kill

Cut

Flatten

Remove

Shred

Add Outside Material

Add materials like mulch, manure, and fertilizer

Irrigation

Controlled drainage

General Note

The idea is to define processes independent of each other and independent =

of the plants or residue that is present. For example, the processes for =

mowing of an annual crop like oats for hay would could involve cut and =

kill, whereas mowing for a perennial crop would only involving cut. =

However, from the machine perspective, the machine actions are independent =

of the crop, and thus kill should not be a process used to represent =

mowing. Therefore, we will have to find another way to represent the kill =

effect. One way is to include parameters in the plant file such that if =

certain processes occur, like cut, certain plant processes occur.

This idea also relates to assigning parameter values, which are expected =

to be independently assigned among the processes. However, some operations=

(implements) will involve multiple processes that have common variables.

In developing the information for an operation involving multiple =

processes that have common variables, the interface would allow the user =

to identify the operation variables that will be changed at the operation =

level. Two examples are speed and depth.

For those variables identified as operation level variables such as speed =

and depth, my expectation is that both speed and depth would already be =

assigned variables in the processes. The interface would ask for the =

operation speed and would assign that to each of the processes having a =

speed variable. Regarding depth, the interface would ask for a depth =

value at the operation level and then assign depth values for the =

processes and would adjust the depths for each process while maintaining =

their relative relationship already specified based on the depths given =

for individual processes.

SOIL

Create/modify ridges

Variables:=20

Geometry of ridges including as a minimum spacing and height,

In some cases, a sinusoidal shape can be assumed, but in other cases, the =

capability is needed to describe an elevated flat bed. Width and height =

of the bed and steepness of the bed side slope are key variables.

Create/modify furrow dikes

Variables: Height of the dike. The interface will need to ensure that =

ridges with a height greater than the dike are specified when furrow =

diking is assumed.

Create/modify random roughness:

Variables:

The roughness index that will be used is standard deviation of the =

roughness height. The chain measurement will not be used. =20

The two important variables are the roughness immediately left by the =

operation and a long term roughness that persists indefinitely. Long term =

roughness does not decay to a smooth surface on pasture, range, and =

perhaps other conditions.

Incorporate surface material into soil or pull materials from the soil to =

surface:

Variables:=20

Fraction by percent or mass that is incorporated or pulled to the surface,

Curve that gives the distribution of the material as it is incorporated in =

the soi,.=20

Depth,

Speed.=20

As a note, most likely the relationship for amount incorporated will =

change from a simple coefficient to a relationship where the amount =

incorporated will depend on the amount of residue on the surface and =

perhaps the type of residue. Randy Raper is analyzing that issue for us =

and hopefully will have recommendations for us in six months.

Mixes material within soilVariables:=20

Distribution curve for type of tillag,. =20

May also have to develop a mixing efficiency variable in conjunction with =

the distribution curve,

Depth,

Speed.

Moves material between rill-interrill areas (ridge-furrow areas)

Variables:=20

A coefficient, probably based on mass, that divides the total residue left =

on the surface between that on the interrill (ridge) and that in the rill =

(furrow) areas,=20

Speed.

Compacts soil

Variables:=20

??????? (Larry, give us help)

BIOMASS

Note:

Two types of biomass pools are anticipated, which are live and dead. =

Within these pools, the types of biomass are expected to be stems, leaves, =

pods, and roots. In those cases where stems, leaves, and pods can be =

separated, the model would use a composite for those biomass types.

Begin growth

A signal that vegetation is to start to *grow.* The interface at the =

management screen level would ask for the vegetation that is beginning to =

grow.

There are some model specific issues that we need to deal with such as how =

to handle intercropping like a legume being planted in an already growing =

small grain. RUSLE handles this effect, but the approach with RUSLE may =

not be applicable to WEPS and WEPP.

Kill plant

This process converts live biomass to dead biomass and nothing else.

Killing can be a selective process such that only part of the growing =

vegetation would be killed. An example is banding a herbicide. Another =

example that is not banding but only a portion of the plant growth is =

harvesting small grain where a legume has been inter-seeded. How will we =

deal with these effects in MOSES? These are also some model specific =

issues. RUSLE handles the latter effect, but the approach with RUSLE may =

not be applicable to WEPS and WEPP. If the kill process is used, perhaps =

the interface will needed to ask some questions.

Cut standing biomass

This process converts biomass at a height above the cutting height to dead =

biomass and leaves the dead biomass on the soil surface. To describe a =

silage harvester, one would need cut and remove processes.

Variables:=20

Height either above the ground or below the canopy top.

Issue: Cutting should involve a change of canopy. How will that be =

related to canopy information associated with the vegetation? This will =

be model specific. How is canopy changes related to cutting handled in =

WEPP and WEPS?

Flatten biomass to soil surface or raise biomass from surface to be erect

The effect is that standing biomass is converted to biomass on the soil =

surface or conversely biomass that is on the surface is converted to =

standing biomass. It says nothing about conversion between live and dead =

biomass pools.

Variables:

A coefficient based on mass that converts standing to flat biomass.

Issue: How will a concurrent change in canopy be handled?=20

Remove biomass

A mechanical process that removes biomass from the system without regard =

to live or dead pool.

Variables:=20

Fraction of present amount based on mass that is removed.

Note: The models will most likely track residue based on mass, but the =

user should have the option of inputing a removal fraction based on mass =

or on percent cover in the case of surface cover (flat residue).

Shred biomass

Changes the geometric properties of the biomass pieces. Implicit is the =

assumption that shredding also cuts.

Variables:=20

Height of cut

Variables indicating how shredding changes residue properties.

Note: A simple way is to specify another residue type from the data base =

rather than trying to model how shredding changes the geometry of the =

residue.

Adding Materials:

Add materials like mulch, manure, and fertilizers

Adds outside materials to the system.

Variables:

Type material,Amount,

Location of placement (on the surface or injected),

Width if banded,

Height of band if injected.

Notes:

If injected, a soil disturbance process would be used in conjunction with =

this process.

A list of materials would be available in the data base. Properties of =

the materials would have already been entered

Irrigation

Active addition of water

(Dennis, please add a variable list.)

Controlled drainage

Active removal of water from system.

(Dennis, please add a variable list.)

Notes:

This controlled drainage is where an *operator* has control over how much =

and when subsurface water is removed is removed in contrast to *passive* =

drainage where no control is possible.