soil composition new community garden plot

Asked February 26, 2018, 2:09 PM EST

Hello Master Gardener, I have a community garden plot in montgomery county and we are doing raised beds but are not sure what the soil composition should be. We did not grow on this plot last season, but there are weeds and some plants left over from last seasons growers. Our beds will be 12in deep, 8 ftx 4 ft and we are growing mostly vegetables, a few flowers. Can we mix compost with the existing soil? Do we need to test the existing soil for nutrients? additionally, any tips you have for keeping the soil cost effective, i.e. cheap, would be great! Thank you so much

Montgomery County Maryland soil soil testing soil for raised beds raised bed soil soil and fertility issues

2 Responses

Test the existing soil where the raised bed will be located even if you plan to add purchased topsoil. Pay for a basic soil test from a certified soil lab (more accurate and complete and usually less costly than diy testers. The pH level should be in the 6.2-6.8 range.) Here is help with soil testing--how, what an where: https://extension.umd.edu/hgic/soils/soil-testing

If the soil is in good shape (not compacted, drains well) add 4 inches of compost and mix it with the top 4-inches of existing soil using a tiller, spade, or garden fork. You can also help loosen soils with high clay content by pushing in your garden fork and rocking it back and forth. Move the fork 6-8 inches and repeat across the entire bed.

How much should you add? Fresh organic materials lose more than half their volume by the time they are fully decomposed. The best option, if available, is to add compost to the soil. You need 3 cu. yds. of OM to add a 1 in. layer to 1,000 sq. ft. (8 cu. ft. to cover 100 sq. ft.). 7.5 gallons = 1 cu. ft.; so 12, 5-gallon buckets of compost would cover 100 sq. ft. to a depth of 1-inch.

Types of organic matter-- composted yard waste (home-made, purchased from your landfill, Leafgro). Mushroom compost is a good garden compost. Well-rotted farm manure added and turned under in the fall is good but can introduce weed seeds. You can increase soil organic matter levels with buried kitchen scraps, cover crops, and yearly additions of compost.

You can increase your raised bed volume (more rooting area for plants) by adding purchased soilless growing media. These typically contain ingredients such as peat moss, composted bark, perlite, vermiculite, compost, coconut coir. They improve drainage and water holding capacity but are costly and not generally recommended unless the raised bed is set on an impervious surface.


ECN


Test the existing soil where the raised bed will be located even if you plan to add purchased topsoil. Pay for a basic soil test from a certified soil lab (more accurate and complete and usually less costly than diy testers. The pH level should be in the 6.2-6.8 range.) Here is help with soil testing--how, what an where: https://extension.umd.edu/hgic/soils/soil-testing

If the soil is in good shape (not compacted, drains well) add 4 inches of compost and mix it with the top 4-inches of existing soil using a tiller, spade, or garden fork. You can also help loosen soils with high clay content by pushing in your garden fork and rocking it back and forth. Move the fork 6-8 inches and repeat across the entire bed.

How much should you add? Fresh organic materials lose more than half their volume by the time they are fully decomposed. The best option, if available, is to add compost to the soil. You need 3 cu. yds. of OM to add a 1 in. layer to 1,000 sq. ft. (8 cu. ft. to cover 100 sq. ft.). 7.5 gallons = 1 cu. ft.; so 12, 5-gallon buckets of compost would cover 100 sq. ft. to a depth of 1-inch.

Types of organic matter-- composted yard waste (home-made, purchased from your landfill, Leafgro). Mushroom compost is a good garden compost. Well-rotted farm manure added and turned under in the fall is good but can introduce weed seeds. You can increase soil organic matter levels with buried kitchen scraps, cover crops, and yearly additions of compost.

You can increase your raised bed volume (more rooting area for plants) by adding purchased soilless growing media. These typically contain ingredients such as peat moss, composted bark, perlite, vermiculite, compost, coconut coir. They improve drainage and water holding capacity but are costly and not generally recommended unless the raised bed is set on an impervious surface.


ECN