Unable to get soil data for coordinates using Soilgrids REST API

Question

I am trying to extract soil data from https://soilgrids.org/ using their very new Soilgrids REST API. They have a special website (http://rest.isric.org/soilgrids/v2.0/docs) where I am able to enter the coordinates and get the soil data that I require.

But for some reason, I am not able to get data for many coordinates that I tried. For example, I can get data for (lat=39.1813855,lon=-77.1827295) but not for (lat=39.1825835,lon=-77.1828465).

Why can't I get data for the last point (lat=39.1825835,lon=-77.1828465)??

Answer 1

Checking the two points for soil property silt at depth of 0-5cm with the following script:

#!/usr/bin/env python3.8

import requests

p1={"lat":39.1813855,"lon":-77.1827295}
p2={"lat":39.1825835,"lon":-77.1828465}

rest_url = "https://rest.isric.org"
prop_query_url = f"{rest_url}/soilgrids/v2.0/properties/query"

props = {"property":"silt","depth":"0-5cm","value":"mean"}

res1=requests.get(prop_query_url,params={**p1 , **props})
print(res1.json()['properties']["layers"][0]["depths"][0]["values"])
#p1 --> {'mean': 462} 

res2=requests.get(prop_query_url,params={**p2 , **props})
print(res2.json()['properties']["layers"][0]["depths"][0]["values"])
#p2 --> {'mean': None}

The REST returns a valid GeoJSON with content for both cases, but the second point has null/None value instead of a numerical value.

Checking the soilgrids FAQ, there is a mask being applied on the soil estimations and no estimations have been done for urban areas. Your second point is returning null because it falls on an urban area.