Apr. 15, 2019 – Gardeners often rave about the benefits of compost. But can there be too much? The Soil Science Society of America’s (SSSA) Apr. 15 Soils Matter blog takes a look at what compost can do, and where it may have limits.

Jim Friedericks, outreach and education advisor at AgSource Laboratories, explains the three benefits compost provides:

• Soil fertility: “Depending on your compost mix, adding compost may not meet all the nutrient demands of your garden. Crops like corn and tomatoes require more nitrogen than do beans and carrots.  Phosphorus and potassium are also required in large quantities for leafy vegetables…. The thing to keep in mind is that compost is a limited source of nutrients, but it does help retain nutrients in the soil.”
• Soil structure: “This is one attribute of compost where you could, in theory, over-apply….Sandy soil is easy to treat with compost. And adding compost helps this type of soil retain moisture and build up the nutrient supply. But the story is different for soils with a lot of clay. Clay soils are often poorly drained, and adding too much compost can make the problem worse.“
• Soil health: “Active organisms associated with composted organic matter will compete with diseases in a healthy garden soil. To observe this in the garden, evaluate if the soil is easy to dig. If it is and you find plenty of earthworms this is an indication of good soil health.”

“Every plot will have different soil types, nutrient levels–and maybe even different pH,” Friedericks writes. “We always recommend a soil test to determine the appropriate soil amendments for your yard and your gardening goals.”

Read the entire post here: https://soilsmatter.wordpress.com/2019/04/15/how-much-compost-is-enough-for-my-garden.  

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