Seed trench depth detection systems

1. A method of controlling a depth of a closing wheel of an agricultural row unit, the agricultural row unit configured to open a furrow in a soil surface and to deposit seeds in the open furrow, the open furrow having sidewalls defining a bottom of the open furrow, the closing wheel configured to press into the soil surface adjacent to at least one of the sidewalls of the open furrow after the seeds are deposited so as to close the open furrow with soil to cover the deposited seeds, the method comprising:

determining a depth of penetration of the closing wheel into the soil surface; and

adjusting a downward pressure on the closing wheel based on the depth of penetration of the closing wheel into the soil surface.

2. The method of claim 1 , wherein the agricultural row unit includes a firming device configured to press the seeds into the bottom of the open furrow, and wherein the depth of the closing wheel is a difference between an elevations of the firming device and an elevation of the closing wheel.

3. The method of claim 1 , wherein the closing wheel is a pair of closing wheels, each of the pair of closing wheels pressing into the soil surface adjacent to the sidewalls of the furrow on opposite sides of the open furrow.

4. The method of claim 1 , wherein the depth of the closing wheel into the soil surface is determined relative to the bottom of the furrow.

5. The method of claim 1 , wherein said step of determining the depth of the closing wheel in the furrow comprises:

determining a distance to the bottom of the furrow with a first sensor disposed on the agricultural row unit forward of the closing wheel in a direction of travel of the agricultural row unit;

determining a distance to the soil surface with a second sensor disposed on the agricultural row unit rearward of the first sensor; and

subtracting the distance determined by the second sensor from the distance determined by the first sensor.