My goal is to make a shapefile with polygons for variable rate fertilizer application within a farm field.
I have a point shapefile with soil sample values (pH, P, K and so on) and a line/polygon file with field borders. IDW is recognizes as a suitable interpolation method for soil samples. I have gotten as far as having the interpolated points as a raster file and I have experimented with the "Contour" function to make a suitable classification.
I'm looking for a solution in QGIS to convert/make/bake the classified raster in to polygons, and clip the results to the field border. Does any one have a suitable solution for this using QGIS?
I don't know if my question is clear enough. To illustrate my goal the attached picture shows how I need my final shapefile to be.
The picture illustrates the final result I'm after. The points are interpolated, clipped to the field border and then (some how) the classified raster is converted to a polygon shapefile.