Amending the soil in your garden on hot July days is not a pleasant prospect, but the rewards of having good-quality dirt for your fall planting will be well worth the sweaty effort.
Ongoing research on how soil quality affects plants’ health and vigor is proving that plants grown in soil that is full of beneficial microorganisms, fungi and bacteria, as well as earthworms, need less water, much less fertilizer and fewer applications of pesticides. The soil in our urban gardens often lacks high numbers of beneficial organisms due to heavy traffic (compaction), high pesticide use and overuse of chemical fertilizers. This explains why even the most conscientious gardeners can have poor results. The sources of the problems may lie below soil level and are invisible to us.
There are three steps to adding beneficial organisms into your soil. The first entails improving the soil’s texture, drainage, aeration, and water retention capability. Heavy clay soil, especially clay soil that is compacted, can be lightened and opened in texture with the addition of gypsum or gypsite, a mineral which prevents clay molecules from binding together. Adding compost or humus to sandy soils helps close the gaps between sand particles, allowing for better water retention. Earthworms, a very important contributor of beneficial fungi and bacteria, readily move into better irrigated, noncompacted soil. Earthworms’ movement through the soil helps with aeration as well.
The next step is to add composts that are full of organic beneficial microorganisms. Many well-known brands are adding organic composts to their product lists. Read labels and look for lists of beneficial bacteria and fungi. Mycorrhizae which are beneficial fungi should be listed on any compost you buy.
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Mycorrhizal fungi attach themselves to the roots of plants and extend long filaments into the soil, increasing the roots’ surface area by 100 to 1,000 times. The fungi also release enzymes into the soil which break down hard to absorb nutrients. Plants grown in soil full of mycorrhizal fungi are able to draw up more water and nutrients through their roots. Because the plants are healthier they attract fewer pest insects and require fewer or no pesticide applications. Mycorrhizal fungi are also available separately as pellets or inoculants and in bio-char products.
The third step is to feed plants with organic fertilizers that also contain high numbers of beneficial micro-organisms. Again, many well-known brands now offer organic/ micro organism rich formulations. Chemical fertilizers, especially liquids, leach out of the soil fairly quickly, often within two to three weeks; the nutrients in organic fertilizers can remain available for well over a month.
Our fall planting/transplanting season begins in mid-September. We need to amend and improve our soils two to three weeks ahead of fall planting. Check out the selection of organic composts, fertilizers and amendments available locally in garden centers and nurseries soon and plan ahead for improving and increasing the content of beneficial organisms in your soil.
Send Elinor Teague plant questions at firstname.lastname@example.org or email@example.com (“plants” in the subject line).