Posts Tagged 'microbes'

Rhizoboost and Defensor No Longer OMRI Listed

You may have noticed recently that some previously listed products are no longer on the OMRI (Organic Materials Review Institute) Products List. This past year, OMRI has been re-reviewing all products on their list for NOP compliance. The USDA National Organic Program (NOP) has recently revised its requirements for products to be approved for use in organic. The new requirements no longer allow the use of some inert ingredients (see full list below). Consequently, OMRI has withdrawn certification of a lot of products. Listing status is renewed annually, and another reason a product may fail to stay on the list is that some companies decide not to pay the listing fee. For companies with a small volume of sales, it can be a lot of money.

Two Rincon-Vitova products no longer listed as of September 2008 are BioStart Rhizoboost and Defensor. Bio-Cat, the manufacturer, is currently working on finding a preservative that will meet the new NOP standards. They haven’t given us a specific time frame, but testing a new formulation will take a few months and getting the products recertified by OMRI will take a few more months after that. We’ll keep you updated on their progress. We will continue to carry these products, but be aware that they are no longer approved for use in USDA certified organic production. If you need an OMRI listed microbial inoculant, we also carry Natural Resources Group’s Activate line of products. Hopefully a new formulation will be approved for organic soon because we have seen the benefits of these products extend beyond improving and maintaining soil biodiversity and promoting balance in the soil foodweb. Rhizoboost is especially helpful for farms in the first year of transition off of fumigated and chemically treated soils before moving the land towards organic certification.

Cucumber plants with and without Rhizoboost.

Cucumber plants grown with and without Rhizoboost.

Squash plants grown with and without Rhizoboost

Squash plants grown with and without Rhizoboost.

Inert ingredients no longer allowed by NOP standards:

acetylated lanolin alcohol
acrylic acid methyl ester, polymer with acrylonitrile and 1,3-butadiene
coumarone-indene resin
manganous oxide
pentaerythritol monostearate
pentaerythritol tetrastearate
polyglyceryl phthalate ester of coconut oil fatty acid
sodium fluoride


Getting microbes on your team: Soil food web basics

When I started at Rincon-Vitova in July, I saw a book in the break room called Teaming with Microbes: A Gardener’s Guide to the Soil Food Web. I’ve been gardening whenever I have the space since I was eight and plants are so interesting to me that I got a biology degree focused on them, but I’d never heard of a soil food web before. I know mostly about the macroscopic parts of a garden ecosystem: dirt, water, plants, and bugs. Of soil microbiology, all that was usually mentioned in my botany classes was the nitrogen-fixing Rhizobium bacteria and mycorrhizae, the fungi that help plant roots reach farther and absorb more. Books and websites I read to further my hobby talked about the negatives of soil biology – nematodes, wilts, damping off. This looked like an interesting change of pace. So I picked up the book and started reading.

The part of the soil food web that you can see – the bugs and earthworms around a plant’s roots – rely on an entire microscopic world of bacteria, fungi, nematodes, and protozoa. You’ve probably heard about the qualities of good soil: dark, moist, full of organic matter and earthworms. Besides being able to hold water well, this soil supports life. Land that’s been used for intensive farming and land that has recently been developed is missing this key living component. This is part of the reason why home gardeners are seen fertilizing their lawns and battling fungal diseases regularly. Dirt with no life in it doesn’t support life very well.

The microbes in soil can help plants in a few different ways. I mentioned mycorrhizae earlier. They are fungi that evolved a handy symbiosis with plant roots. The roots secrete simple sugars at the root hairs. In exchange for this food, the mycorrhizal fungi pass water and nutrients to the plant. Of course, plants can absorb nutrients and water without the fungi, but the fungi increase the amount and range of stuff the roots can absorb. Besides mycorrhizae, there are microbes that help break down decaying material and unlock the nutrients, microbes that bind soil together into water-holding clumps, microbes that release chemicals that stimulate plant growth, and microbes that protect the plants from other microbes. The last category is one that many gardeners probably notice without realizing it. Without the defense of beneficial microbes, plants are vulnerable to root-knot nematodes and a whole slew of fungal diseases. There are a few ways gardeners can help out these microscopic workers. Incorporating compost, manure, or other organic matter into the soil can give the microorganisms already there a moist and comfy home, as well as a food source. If a lot of the microbes have been killed off, they can be replenished with a well brewed compost tea. Commercial inoculants of specific species are also available. There are many facets of a health soil food web. As I learn more about the soil food web, I’ll share it with you.


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