Start by sending A&L Labs a irrigation water sample from each well. Wells that may have high sodium, bicarbonate, sodium absorption ratios can all have a huge negative impact on your soil & nutrient availability. I have had customers who drilled deep wells for irrigation, send in a water sample & find out that the quality of the water could / should not be used for irrigation! Doing so would cause the soils applied to & crops grown to be ruined / die. Some of the negative qualities of a well water can be adjusted / fixed by injecting a strong acid. If the water has high sodium it just can't be used without toxifying your soil with salt. If you go to A&L's website you can find a fact sheet "Interpreting irrigation water analysis". https://cdn.shopify.com/s/files/1/0979/5626/files/FS20_-_Interpretin...
It will explain the parameters your test results show. I do know that some wells in your Ottawa / Pandora area have very poor irrigation qualities. We have sampled some for customers & have seen the results. As for irrigation water not getting the response that you see with a natural rain, you are spot on with that observation! Every customer I have worked with who irrigates, has told me that at one time or another! I can't exactly tell you why either, except there is huge differences in pH, nutrient content, salts, temperature etc...  If you need further help we are close by & glad to help. [email protected]  Good Luck!