M3M and bare ground?

Agriculture
1

Hi, newb here with a DJI M3M.

Can anything be learned from flying a field pre-planting? Does everything rely on leaves or is there useful information that can be learned for fertilizing or row spacing from flying bare ground?

-Mbahr

2

Anyone?

3

Hi, i think it is not bad idea to fly over a bare ground. We usually do it because we can see the different soil color and see if it is more or less wet and then understand if it tends to be clayey or sandy. Of course, it is not a 100% precise information but it can be very useful. We can suggest you to use the MSAVI index, that is specific for the ground.

1 Like
4

It also helps you to digitise precisise field boundary and you will get a baseline digital surface model of your field without crop cover.

1 Like
5

Hey there Julius - I’m bumping this to keep it alive and to offer another thought about bare ground: I am curious about how to help farmers with planning prior to planting. It seems that between satellite and drone data we could have good imagery about SOIL type and health that would help in planning for soils treatments just prior to planting or during planting?

Can you suggest the indexes we should look at for soil health or soil type?

-Mike

6

Some Ideas:

Soil Organic Carbon (SOC) Indices

Soil organic carbon is a critical indicator of soil health and fertility. Multiple studies have identified specific Sentinel-2 band combinations that correlate strongly with SOC content.

Red-Edge Carbon Index (RE-CI)

  • Formula: (B5 + B6) / 2
  • Bands Used: B5 (705 nm) and B6 (740 nm) - both from the red-edge region
  • Value Range: Typically between 0.10 and 0.15 for agricultural soils
  • Interpretation: Lower values generally indicate higher SOC content due to the principle that soil albedo decreases with increasing organic matter content
    image
    image1340×1121 100 KB

Red-Red-Edge Carbon Index (RRE-CI)

  • Formula: (B4 + B5) / 2
  • Bands Used: B4 (665 nm, red) and B5 (705 nm, red-edge)
  • Value Range: Similar to RE-CI, typically between 0.10 and 0.15
  • Interpretation: Follows the same principle as RE-CI, with lower values correlating with higher SOC content

Soil Moisture Indices

Soil moisture status significantly impacts agricultural productivity. Sentinel-2 offers several indices for assessing soil moisture conditions.

Normalized Burn Ratio 2 (NBR2)

  • Formula: (B11 - B12) / (B11 + B12)
  • Bands Used: B11 (1610 nm, SWIR1) and B12 (2190 nm, SWIR2)
  • Value Range: -1 to +1
  • Interpretation:
    • Values near 0 typically indicate dry bare soil
    • Values above 0.05 may indicate increasing soil moisture or presence of crop residues
    • The difference between reflectance at approximately 1600nm and 2100nm is close to 0 for pure soil, while the presence of straw or crop residues increases this difference

Soil Type and Texture Indices

Soil texture, particularly clay content, influences numerous agricultural and environmental processes. While direct estimation is complex, several indices provide insights into soil texture characteristics.

Topsoil Grain Size Index (TGSI)

  • Formula: (B4 - B2) / (B4 + B2 + B3)
  • Bands Used: B2 (490 nm, blue), B3 (560 nm, green), and B4 (665 nm, red)
  • Value Range: Typically ranges from -0.1 to +0.4
  • Interpretation:
    • Negative values typically indicate vegetation or water bodies
    • Positive values correspond to exposed soil
    • Higher positive values generally indicate coarser soil grain sizes
    • Specifically developed to characterize the texture of soil surfaces based on spectral reflectance properties
7

There is a lot to dig into here… This is an amazing response!

-Mike

8

I don’t see enough difference between RE-CI and RRE-CI. Can you provide guidance about when one would be used over the other?