gSSURGO: Fix spatial sampling and improve data aggregation accuracy

CHANGELOG.md

@@ -40,6 +40,11 @@ For more information about this file see also [Keep a Changelog](http://keepacha
 - Fixed a bugs and BADM now process both single-site and multi-site settings, detecting the input structure and processing each site independently to generate the correct number of ensemble members per site.
 - Fixed "external pointer is not valid" error and addressed key bugs in `soilgrids_soilC_extract()` function (#3506)
 - Fixed a bug within the `model2netcdf.SIPNET` function where we assumed the constant calculations of `pecan_start_doy` across years (the calculations should vary depending on the last date from the last loop and the start date of the current loop), which will lead to incorrect calculations of the start `sub_dates` and `sub_dates_cf` if we are jumping between years (e.g., from 2012-12-31 to 2013-01-01). The `sipnet2datetime` function is no longer used anywhere and therefore has been removed.
+- `extract_soil_gssurgo()` (#3643)
+  - Replaced point-based WFS queries with raster-based WCS approach using `soilDB::mukey.wcs()`.
+  - Replaced `grid_size`/`grid_spacing` parameters with `radius` (meters) for simpler buffer-based AOI creation.
+  - Switched to single `soilDB::fetchSDA()` call for component-level soil data retrieval, enabling better ensemble uncertainty quantification through within-map-unit variability. Added support for custom AOI polygons. 
+  - This eliminates spatial coverage gaps and reduces network requests while maintaining backward compatibility.
 
 ### Changed
 

modules/data.land/DESCRIPTION

@@ -25,6 +25,7 @@ URL: https://pecanproject.github.io
 BugReports: https://github.com/PecanProject/pecan/issues
 Depends: R (>= 4.1.0)
 Imports:
+    aqp,
     coda,
     curl,
     doSNOW,
@@ -53,6 +54,7 @@ Imports:
     rlang,
     sf,
     sirt,
+    soilDB,
     sp,
     stringr,
     terra,

modules/data.land/NEWS.md

@@ -4,8 +4,14 @@
 * New utility script `IC_SOILGRID_Utilities.R` for processing SoilGrids data to generate soil carbon initial condition (IC) files. This includes (#3508):
   - **`soilgrids_ic_process`**: A function to extract, process, and generate ensemble members from SoilGrids250m data.
   - **`preprocess_soilgrids_data`**: A helper function to handle missing values and ensure data integrity during preprocessing. 
-  - **`generate_soilgrids_ensemble`**: A function to create ensemble members for a site based on processed soil carbon data. 
+  - **`generate_soilgrids_ensemble`**: A function to create ensemble members for a site based on processed soil carbon data.
 - Add events schema and validate_events() function to validate events.json files against the schema (#3623, #3521).
+* `extract_soil_gssurgo()` (#3643)
+  - Replaced point-based WFS queries with raster-based WCS approach using `soilDB::mukey.wcs()`.
+  - Replaced `grid_size`/`grid_spacing` parameters with `radius` (meters) for simpler buffer-based AOI creation.
+  - Switched to single `soilDB::fetchSDA()` call for component-level soil data retrieval, enabling better ensemble uncertainty quantification through within-map-unit variability. Added support for custom AOI polygons. 
+  - This eliminates spatial coverage gaps and reduces network requests while maintaining backward compatibility.
+
 
 # PEcAn.data.land 1.8.2
 - Removed unused parameter `machine` from put_veg_module()