Question
I purchased a home a year ago and the lawn area is approximately 1 acre.  I went through the four seasons once to see what condition the lawn is in and it's painfully obvious that the lawn has been largely neglected except for mowing.  I divided the lawn into sections and ran soil tests for pH, nitrogen, phosphorous, and potassium on each section, finding very little variation in the different sections but very low amounts of nitrogen, phosphorous, and potassium across the entire yard.  The pH level ran around 7.2 every place except those (2) closest to the location of the field drain line for the septic tank where it ran about 6.8. I've been trying to find information on how much (per 1,000 sq. ft) of what fertilizer mix to put on this yard.  The lawn is also well compacted so I'll be running an areator over it immediately after application of the fertilizer.  Can you give me some direction concerning the fertilizer mix?
Thank you,

Answer
The best time to fertilize depends on where you are located and the type of grass you are growing.

Generally, in the northern half of USA and elevated areas where you grow cool season grass (kentucky bluegrass, fescue, perennial ryegrass, etc) you should fertilize in late spring and early fall. Not too early in spring and not in summer at all. In early fall one application is made (most important) typically followed by another 8-10 weeks later, or after first light night frost.

In warmer areas, such as texas, southern california, the us gulf, nevada, georgia,etc where warm season grass are typically grown (bermuda, st. augustine, bahia, zoysia) lawns should be fertilized in early summer and again mid summer. A last application can be made in early fall. Avoid fertilizing too early in spring in particular.
If you live in an area as outlined above, but grow fescue then fertilize as a cool season lawn outlined above (cool season grass type).

I recommend a single application of 10-10-10 next time you fertilize (also called general purpose or balanced fertilizers) and then switch to a "lawn formular" thereafter. Lawn formulars are characterized by having a higher first number, such as 29-3-4, 10-2-6, 33-3-3, 20-10-10, etc. In general the first number should be 4-5 times larger than the second and thrid numbers. Another option is to use a so-called "turf type" fertilizer, such as 29-3-14, 10-2-6, 20-5-10, etc. E.g. with slightly elevated last numbers. These fertilizers are often sold as socalled "winterizers" (can be used year round despite the name).

Avoid 15-30-15, 5-10-10 fertilizers, etc. They are for flowers and fruits.

You can either choose regular synthetic fertilizers (vigoro, scotts, miracle grow, bayers advanced, etc) or organic alternatives (espoma, milorganite, ringer lawn restorer, etc). It does not matter.

I do recommend a single balanced fertilzer (such as 10-10-10) due to lack of nutrients in your soil, but it is not critical. If you can not find a large bag of 10-10-10 then just go with 29-3-4, or 29-3-14 etc.

The most important part is to fertilize regularily (spring and fall in north, summer in south) and to water the products in (or apply when rain is expected).

I can highly recommend core aerating, but apply fertilizer AFTER aerating as to not destroy the pelleted fertilizers and so that the fertilizer pellets may fall into the holes for faster action.

Your soil pH is ideal for lawn growing (6.5-7.5) and you should have no problem growing grass.

Remember to mow the lawn frequently and mow high (2.5-3.5" tall for most grass types). Recycle clippings to the lawn for extra (free) nutrients. Water infrequently but deeply, such as once per week for 2 hours rather than 15 minutes daily. If you have moderate temperatures it may not be necerssary to water, or water less frequently, (such as springs in the north). If you live in a warm season area (texas/florida, etc) then you may have to water more frequently (every 2nd or 3rd day) but under all circumstances, always water infrequently but deeply rather than frequent shallow applications. This gives best grass growth.

Test your soil again in 2 years, and if soil pH is significantly lower then apply limestone to the soil. There is no reason to do this with your current pH (in fact, do NOT apply lime at this point in time).

Good luck.