ph level of soil
my soil has tested at 4.2 for ph. I was advised that it would require 180 lbs per 1000 sq. ft.. How often can I apply lime to help boost the ph level?
There is no risk of burning plant roots when liming; however, it is most effective if worked into the top 7 inches of soil where most of the plant roots are. Lime is slow to act and will take up to a year for full effect. If dug in this fall, there will be a substantial difference by spring. Get a soil test a year after application. I suggest you submit samples to your state's extension service. Results include recommendations to correct pH and nutrient problems specific to the plants you will be growing. https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/adding-lime-to-soil.htm
Clay soils need significantly more lime to affect pH than sandy soils. I hope the recommendation you were given takes this into consideration. 180 pounds sounds like a lot but I don't know what pH you are aiming for.