Q: With all of the rain, then the hot dry spell — I’ve realized I need to amend the soil in my vegetable garden. How should I do this? When should I do this?

• Pat from Youngstown

A: Yes, this season has already been one of great ups and downs and temperatures and rainfall. Clay soil is difficult to work with and slow to drain. Amending is a great idea, but how much depends on your soil test. By completing a soil test, you’ll find out if you need more organic matter. It will tell you the levels of major nutrients and the pH level. The numbers provided by a soil test are the only way to know you are adding the right amount to your vegetable garden.

Compost and manure are some of the best things you can add to the soil in your vegetable garden. Adding them provides both organic matter and nutrients to the soil. Both can help you grow better vegetables as well as flowers.

The organic matter in compost helps improve clay soils. It helps sandy soils improve their water-holding capacity. Topsoil can be added, but a 50 / 50 mix with compost is probably a better idea. The compost or the mix can be added throughout the growing season, and tilled in later in the year. Or, it can be used as a mulch to hold down newspapers — which can serve as a way of reducing summer weed pressure.

Compost contains valuable nutrients, including the major nutrients — nitrogen, phosphorus and potassium. These are the three numbers you see on a purchased bag of fertilizer. Compost also contains micronutrients needed by plants in your vegetable garden. Thus, compost needs treated like a fertilizer. When you add too much compost, it can be similar to adding too much fertilizer, resulting in runoff and other issues.

If you obtain manure this time of year, the best use is to add it to your compost pile. Follow generally accepted practices to compost it correctly. Aged manure is not compost, and should be treated the same as raw manure.

Adding raw manure isn’t the best idea this time of year unless the manure has been fully composted. Making compost involves several weeks of turning and taking temperatures. The process gets the materials hot enough to kill weed seeds and pathogens. Applying fresh manure creates a food safety concern, so wait until fall to apply it and till it into the soil. Details on proper composting are at https://go.osu.edu/homecompost.

To determine the correct amount of compost or manure in your garden, visit http://go.osu.edu/addcompost.

This factsheet provides lots of great information, including the approximate nutrient values of most manures and compost.

Eric Barrett is OSU Extension educator for agriculture and natural resources in Mahoning County. The plant and pest clinic is open Mondays and Thursdays from 9 a.m. to noon at the OSU Extension Office in Canfield. For more details visit http://go.osu.edu/mahoningclinic.