Question
QUESTION: 1. What is the PURPOSE of turf aeration? Is it to facilitate the entry of rainwater, or of air, or is it something else?

2. The local public is hysterical about outlawing the use of all outdoor "pesticides." Where can I find authoritative information about the safety of legal products used according to directions?

Thank you!



ANSWER: Hi Alan, It does improve water and air movement, but soil often becomes compacted due to foot traffic or filled with roots from trees or just the grass itself.  The mechanical piercing of the soil cuts roots, loosens soil and improves the environment for roots to develop, and for microbes, which in turn will make your turf healthier.
That said, "aeration" is often sold as a service by lawn care companies that may not actually be needed.  It will open up your turf and may increase weed infestation.  If your lawn looks good, it probably doesn't need it.
The best source of information is the product's Material Safety Data Sheet (MSDS) and the product's label.  Homeowner approved pesticides, when used according to the label, have minimal impact on the environment.  Proper use is the key.  If one plant has insects, spray just that plant, not all of them.  Spray each weed, not the entire lawn. Alternate products to prevent resistance.  Choose the right product for the problem.  Look to changing cultural practices that may prevent problems.  Follow label instructions and always use caution even if it's "organic".  Many organic pesticides that are very safe for humans are very toxic to other organisms.  
Last, look for a good independently owned garden center or nursery.  These are the industry experts.  They know what works and what's hype.  Jim


---------- FOLLOW-UP ----------

QUESTION: Thanks for the speedy reply, James, but I have to apologize for misleading you as to the level of my query.

I have seven acres of mostly turf, with 1,000 trees I planted, so compaction is not an issue. I can easily gang my commercial aerator (spike, not core) onto any of my mowers. I was wondering, if a main purpose is to let the rain sink in, should I therefore aerate prior to every downpour?

I know about label reading and proper, cautious use of pesticides, and I know what works, thanks. But I'm a journalist preparing a newspaper article on the pesticide hype. Where can I get scientific background information? The web is full of "experts" who warn against any use. Who can I ask for an evaluation of these claims?

If this is out of your sphere, perhaps you can refer me to someone who can handle it.

Thanks again, and sorry for the trouble.

Answer
Alan,  I would not aerate more than once a year.  The repeated damage to feeder roots may stress the tree.
It's hard to find unbiased information.  Having been in this industry for 35 years, I also know what works and have seen really good products go away mostly because they were not used properly.  I've seen research from manufacturers that contradicts environmental groups, so to "help" the consumer, I just give them all the information I can and let them decide.  Jim