What's Happening

SafeLawns Responds to the NY Times

HERE’S THE SHORT VERSION FOR PEOPLE LIKE US

To the Editor

April 12, 2007

Overall a good overview of the growing organic turf and grounds maintenance movement, but I must take issue with two statements by Dr. Rossi of Cornell.

First, the compost teas of the 1990’s were nothing like the compost extracts of today. Those early concoctions were made by simply soaking a mish-mash of raw materials in water for some unspecified time and then applied willy-nilly to lawns and gardens. Today’s professional compost extracts, by contrast, are produced with very specific ingredients under controlled conditions, and batch tested to assure consistent nutrient levels and microbial populations tailored to specific sites and conditions.

Second, the available phosphorus in compost (including that made with animal manures) is on average only a tenth to a sixtieth that of soluble consumer fertilizers, and considerably less prone to leaching into our surface waters and aquifers, even at higher application rates, and there is plenty of peer reviewed research showing its advantage over both soluble fertilizers and manure in this respect.

Shepherd Ogden, Executive Director, SafeLawns Foundation

References:

1. I have observed the process of making extracts first hand and questioned the technicians in detail on the procedure. Most use no avian or mammal manure.

2. The phosphorus content comparison was taken from the Lowe’s website this morning comparing Scotts starter fertilizer versus a composted cow manure product.

3. I previously worked at The Rodale Institute where some of this research was done. You may contact Dr, Paul Hepperly the Research Director for confirmation of this assertion.

AND HERE’S THE LONGER VERSION FOR YOU SOIL SCIENCE GEEKS

To the Editor:
While an excellent overview of the growing market for organic lawn care, I must point out a few misperceptions that the article leaves undisturbed, especially in relation to the comments of Dr Frank Rossi of Cornell.

First, concerning efficacy, is the necessary distinction between compost tea, and compost extract, a distinction that highlights the differences between the organic technology of the 1990s – when the first wave of today’s organic boom crested according to PLN’s Mr. Delaney – and today, when the demand for organic treatments has spurred private sector research and development of new methods and equipment. Compost teas of the 1990 could be haphazardly concocted brews, where a mish-mosh of nutrient sources like compost and manure were soaked in water and the water used for soil treatment. Not only was the nutrient composition rarely assayed, but the microbial populations that are so important to the efficacy of extracts were not monitored or maintained.

No more. Today professional compost extracts are rigorously controlled at every step of the production process. Very specific feedstocks, in combinations tailored for specific properties and conditions, are combined to create consistent nutrient and microbial contents, and batch tested to assure consistency from application to application. Further, the batches are time dated, as the microbial populations rise and fall based on the nutrient content of the extract, giving them a set shelf life. (Work is going on to produce dried extracts with a long shelf life but results so far results have been mixed.)

That there has been insufficient peer reviewed work with these technologies is a shame, the same shame that applies in the farm sector, where all things “organic” were widely ignored until consumer demand drew private sector players. The sad truth is that over the past 30-40 years less than one tenth of one percent of the USDA research budget was applied to exploring and improving organic technologies. Had those monies been more evenly distributed we would be much farther along the path to a sustainable food system than we are. At the SafeLawns Foundation we hope to help avoid repeating this oversight, and find efficacious methods of grounds maintenance that improve on the environmental performance of current, conventional methods.

A similar problem arises in the discussion of compost as a soil amendment applied directly to lawns. There is no question that animal manures contain phosphorus and that phosphorus is damaging aquatic systems nationwide due to overuse. However the content of most composted manures is in the range of 0.5-0.5-0.5 NPK (the analysis on every bag of fertilizer, while synthetic blends range all the way from, say, 29-2-5 NPK to a whopping 20-27-5 NPK for a turf “starter fertilizer.” And not all composts are animal composts, nor are all composted materials applied as compost; many are further processed and formulated into slow release, organic granular fertilizers.

Reading Mr. Rossi’s comment,  one would get the impression phosphorus runoff is the fault of backyard composters, and not the millions of bags of these synthetic fertlizers applied annually to our lawns and parks, which is hardly a defensible position. He would rightly note that to match the NPK application of a synthetic fertilizer, the compost would have to be applied at a rate that might lead to runoff and other problems. But this ignores one key point, and lets another slip by un-noticed.

Composted materials do not need to be applied at the same rate as synthetic fertilizers. The NPK rating on a bag of fertilizer is a measure of readily available nutrients, and since the organic materials break down more slowly they must, by law, show a lower NPK rating that is not truly indicative of their fertilizer value over the longer term. Second, the solubility of the quick release fertilizers is precisely the problem, and it is a problem that composting largely avoids. Most farmers are now environmentally aware enough not to stack manure in locations where the pile will seep nutrients into waterways, and that is all to the good. But research at The Rodale Institute has shown conclusively that composting will reduce the leaching potential of manure by 75% due to a firmer binding of nutrients to the humus created by the composting process. So even if one were to over apply compost, the rate at which any phosphorus in the material would affect water quality is hardly on the scale of the synthetic fertilizers whose very design emphasizes the solubility necessary for the quick green up their manufacturers have convinced consumers is the ultimate goal of lawn care.

Shepherd Ogden, Executive Director, SafeLawns Foundation, www.safelawns.org

Posted by on April 22, 2007 at 6:07 pm, in the category What's Happening.
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8 responses to “SafeLawns Responds to the NY Times”

  1. Eliz says:

    And for those who simply can’t get enough discussion of compost tea, in May, we will be running a pair of commentaries on the subject by Jeff Gilman, author of The Truth About Garden Remedies, and Jeff Lowenfels, co-author of Teaming with Microbes.

  2. Jeff Gillman says:

    I really liked Craig’s answers.

    I’ll be addressing the whole compost tea thing in greater depth in May, but I wanted to mention that, in general, we consider organic fertilizers to have a higher degree of potential for harming the environment with phosphorus runoff because, while we can select a synthetic fertilizer with a lower quantity of phosphorus (this is especially true here in MN), it is difficult to reliably find an organic fertilizer with low phosphorus relative to the amount of N which it contains. Indeed, most organic fertilizers have relatively high P in relation to their N values. Since most fertilizer applications are made based on N and not P, P often gets overapplied, potentially creating a problem.

    By the way, for phosphorus contamination of surface water runoff (water flowing laterally over a soil surface) is often more important than leaching (water flowing through the soil).

    It is true that most of the nutrient runoff problems that we have in this country are due to applications of sythetic fertilizers, but that is because synthetic fertilizers are used more often than organic fertilizers — not because the organic fertilizers are less prone to runoff.

    Having said all of this I have one more thing to say — no matter what type of fertilizer you use – fertilize less — we fertilize our yards way too damn much in this society of ours and it makes me sick — in the last issue of Consumer Reports it recommended adding 5 pounds of N per thousand square feet of turf per year — THIS IS INSANE (The whole article was a mess — I wrote them a long letter…). Only in rare circumstances do you need more than 3 — even if you want to win a green grass competition in your neighborhood. Most people should be at 1 – 2 pounds.

  3. firefly says:

    I’m starting to sound like a broken record, but Linda Chalker-Scott’s mythbusting site also features some research on the subject of organic fertilizers and potential contamination.

    I would like to see some citations for “plenty of peer-reviewed research” — “contact Dr. Paul Hepperly for confirmation” is most assuredly *not* the equivalent.

    Last year I used a soluble organic fertilizer with a high P level around newly planted shrubs. I mixed it for a watering can and intensively watered small amounts around specific plants.

    Hopefully this is a safer practice … ?

    Would it be possible to have some discussion about fertilizing practices at this blog too? Is there a way to minimize the potential for phosphorus runoff with organic fertilizers by using specific application methods? I’ve been trying to read up on ecological gardening practices, but haven’t actually found anything on this subject yet except the general idea that “compost is good.”

  4. Jeff Gillman says:

    yep — soon after I wrote my book I discovered Linda-Chalker Scott’s website — it’s excellent. There are very few areas where we don’t agree (probably the reason I think she’s so great…).

    A discussion on minimizing P lost to the environment — that would be an interesting discussion — it’s tough — but the best way to minimize would probably be to use less fertilizer in the first place and to use some smart gardening techniques — I like lasagnia gardening — see Lee Reich’s book Weedless Gardening. Also — don’t fertilize right before a heavy rain — that’s the best way to get your nutrients washed right into a nearby lake.

  5. Ellis Hollow says:

    What Jeff said.

    I’m working on a lawn care article at work focusing on phosphorus. It should be done sometime this week and I’ll share it then.

  6. John Merrill says:

    I agree with most of the comments on reducing the amount of fertilizer used on our lawns. However, whether it is organic or synthetic is unimportant as both are being absorbed as needed and excess is lost to runoff. What is important is that only what is needed should be applied and this is done through a thorough soil test to determine that need.

    In most lawns, 2 fertilizer applications a year (late spring and early fall) are all that is needed, if you practice grass-cycling instead of bagging lawn clippings, aerate the soil regularly, and add top-dressing to the lawn once every year or two to help improve the soil.

    The importance of a healthy soil can’t be over-emphasized for having a healthy lawn. This means a soil that is not compacted, has lots of bacteria and other microbes living healthy lives, and avoiding pesticides that might kill these little workers.

    The entire disucssion of phosphorus in our water is an important topic, but should not be blantantly blamed on excess lawn fertilization.

    There are many sources of phosphorus contamination. Lawn clippings discharged into the street is a good example as are fall leaves left in the gutter which all gets washed down stream and contributes to excess phosphorus.

    The large Canadian goose population is also a major phosphorus contributor as their droppings decompose and get washed into our waterways.

    Automatic dishwashers are another contributor to phosphorus contamination. In the 1970s, phosphorus was banned from laundry detergents, but in most communities, dishwasher soaps were exempt from this regulation. And very few urban sewage plants are equipped with phosphorus removal systems.

    Finally, many commercial farmers regularly apply fertilizers in the spring before planting. These applications are typically applied to large patches of earth that has no means of retaining these applications should heavy spring rains (which happens frequently)wash over their fields.

    The assumption that because there is phosphorus in the water, that it must be coming from lawn fertilization is simply a conclusion that has not been proven scientifically.

  7. Kathy says:

    Lowenfels vs. Gilman–I am really looking forward to it. I hope they get to respond to each other before they get published.

  8. eliz says:

    Yes, Kathy, that’s the idea–to make it a real exchange.

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