Dolomite Fertilizer

Effects of Dolomite Source, Dolomite Rate and Fertilizer Rate on Change in pH of Growing Medium Leachate

Return to: MREC Home Page

Return to: MREC Research Index

C.A. Conover, Ph.D.(1), R.J. Steinkamp(2) and K. Steinkamp(3)

University of Florida
Institute of Food and Agricultural Sciences
Central Florida Research and Education Center
CFREC-Apopka Research Report RH-95-4

A basic ingredient of most potting mixes used in foliage plant production is peat, which tends to be acidic. Dolomite is added to growing medium to raise pH to the range of 5.5 to 6.5 and to supply plants with calcium and magnesium needed for healthy growth. Dolomite also slowly dissolves in the growing medium over time, helping to counteract the acidifying effects some fertilizers and/or irrigation water can have on growing medium pH. The need for new research on pH has been identified by industry as important due to observation of low pH in many soil and water samples.

Nursery supply companies offer several different dolomitic limestone products which vary in particle size (grade). In a previous test, finer grades of limestone were more effective than coarser grades in raising pH of container medium of boxwood (Buxus sempervirens), grown in 2-gal plastic containers over a two year production period (Leda and Wright, 1991).

The following two experiments were performed to explore the short-term effects of different dolomite products having different grades on pH of growing medium in 6-inch (15-cm) pots during production of Dieffenbachia maculata 'Camille'. Whether low pH influences foliage crop quality and whether different dolomite sources could influence pH were the main questions prompting this research. A secondary purpose was to demonstrate effects of using recommended versus excess fertilizer rates on crop quality as well as pH.

For both experiments Dieffenbachia maculata 'Camille' (Camille dieffenbachia, Agristarts II, Inc., Kelly Park Road, Apopka FL 32712) in 72-pack trays were transplanted into 6-inch (15cm) plastic tub pots on June 6, 1994. A customized form of Farard #4 growing medium (Fafard of Florida Inc., 3723 Hogshead Road, Apopka, FL 32703) containing no lime was used. The four different dolomite products incorporated into growing medium at transplanting time were Soil Doctor Dolomite, James River Dolomite, Asgrow Dolomite and James River Camadil Dolomite. The particle size distribution of each of the four products is given in Table 1. 'Camille' dieffenbachia were grown to salable size in a greenhouse where maximum light intensity was about 2000 ft-c (266 µmol•m-2•s -1) and air temperatures ranged from 65°F to 90°F (18°C to 35°C). Plants were watered overhead one to three times per week as necessary.

Electrical conductivity (µmhos/cm) and pH of leachate collected from growing medium of Camille dieffenbachia were measured when experiments were initiated in June, five days before fertilizer treatments started, then monthly until research was terminated in September, 1994. Plant size index was determined by the formula; (height + width) ÷ 2. Growth was determined by the formula; final plant size index - initial plant size index. Plants were graded at termination of research based on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 = excellent quality.

In experiment 1, growing medium was amended at transplanting time with 1 lb/yd3 (0.59 kg/m3) Micromax (The Scotts Company, 6656 Grantway, Allentown, PA 18106) and 7.5 lb/yd3 (4.45 kg/m3) of one of the four dolomite products tested. This was a 4 fertilizer rate x 4 dolomite product factorial test with 5 replications per treatment. Starting on June 13, 1994, plants were fertilized once a week. Liquid fertilizer made from concentrated stock solutions was used, with NH4 and NO3 each providing 50% of the nitrogen source. When fertilized each pot received 100 ml fertilizer solution made up of NH4NO3, K2SO4 and H3PO4 so that fertilizer formulation was 6N-2P-5K. Fertilizer rates tested were 1222, 1833, 2444 or 3666 lb N/A/Yr, (1369, 2053, 2737 or 4106 kg/ha/yr) with 1833 lbs being the recommended level.

Electrical conductivity (µmhos/cm) and pH of the growing medium leachate were determined on June 9, July 7, August 9 and finally on September 7, 1994. Initial plant height and width (cm) were measured on June 8, 1994 and final height and width were determined on September 21, 1994. Plants were graded on September 26, 1994, when research was terminated.

In experiment 2, the four dolomite products were incorporated into the same basic growing medium as used in the previous experiment, each product at three different rates. For each product tested, Camille dieffenbachia were also grown using the basic potting mix without dolomite. There were 5 replications per treatment.

Fafard #4 growing medium, containing no lime, was amended with 1 lb/yd3 Micromax. Treatments consisted of each of the four dolomite products incorporated at 0.0, 2.5, 5.0, or 7.5 lb/yd3 (0.0, 1.48, 2.96 or 4.45 kg/m3 ). Plants were fertilized once a week using the same liquid feed as used for experiment 1, applied at the recommended rate of 1833 lb N/A/yr.

Electrical conductivity (µmhos/cm) and pH of the growing medium leachate was determined initially on June 9, 1994. Electrical conductivity and pH were then determined once a month throughout production, on July 6, August 8 and September 6, 1994.

Results

In experiment 1, interaction of dolomite source and fertilizer rate affected pH of growing medium leachate on July 7, August 9 and September 7, 1994 (Figures 1, 2 and 3). From July 7 until termination, growing medium leachate with higher pH, fertilized at any rate, were mainly those with incorporated James River Camadil or Asgrow dolomite, followed by James River and Soil Doctor, in order of decreasing pH. The first two products are made up of more finer particles compared to particle size makeup of Soil Doctor Dolomite and James River Dolomite (Table 1). On June 9, 1994, five days before fertilizer treatments were initiated, pH of leachate collected from growing medium of Camille dieffenbachia averaged 5.4. Over time, the increase in fertilizer rate from 2444 to 3666 lb/A/yr had a much greater acidifying effect on growing medium leachate compared to when rate was increased from 1222 to 1833 or from 1833 to 2444 lb/A/yr.

Although all plant grades were above 4.0 (good quality), plants grown in medium containing Asgrow or James River dolomite were slightly better than plants grown in medium containing James River Camadil dolomite or Soil Doctor dolomite (Table 2). particle size of these two products were more similar, when compared to particle size of the two other products tested (Table 1). Soil Doctor Dolomite had more larger size particles and James River Camadil had more smaller particles.

The recommended fertilizer rate of 1833, the second lowest rate, produced the largest best quality plants (Table 2). Plants grew less and received lower plant grades as fertilizer rate was increased above the 1833 lb/A/yr rate.

When pH was measured soon after incorporation, on June 9, growing medium leachate from products made up of finer dolomite particles had higher electrical conductivity compared to leachate collected from growing medium getting one of the two products having coarser particles (Table 3). On later sampling dates, however, electrical conductivity of the growing medium leachate was not significantly different due to dolomite source. Electrical conductivity of leachate from samples collected from July through September increased as fertilizer rate increased.

In experiment 2, when dolomite sources were compared, no significant differences due to dolomite source were found in plant grade, plant growth and electrical conductivity and pH of the growing medium leachate (data not shown). However, for each dolomite source tested, incorporation rate did affect pH and electrical conductivity of leachate and most plant growth measurements.

Electrical conductivity of leachate was variable in its response to increasing dolomite rate, although it generally increased (Tables 4 through 7). However, over time conductivity decreased, and this probably related to use of nutrients by the plants as well as leaching of calcium and magnesium from dolomite.

When the amounts of Asgrow dolomite in growing medium increased plant growth increased but plant quality was not similarly affected (Table 8). Increasing dolomite incorporation rate from 0 to 5.0 lb/yd3 produced a small but significant increase in plant growth and quality for Camille dieffenbachia getting any of the other three dolomite products (Tables 9 through 11). When the amount of any of these three products in the growing medium was increased from 5.0 to 7.5 lb/yd3 plants grew less compared to plants getting the 5.0 lb/yd3 rate and quality did not further improve.

Quality of all Camille dieffenbachia was better than good when the experiment was terminated, but increasing lime rate did slightly increase plant quality for two of the four products tested, Soil Doctor Dolomite and James River Camadil Dolomite. These two products were on opposite ends of the particle size scale (Table 1). (In experiment 1 use of either of these two products incorporated at 7.5 lb/yd3 the highest rate tested in experiment 2, produced slightly lower quality plants).

Conclusions

Results from experiment 1 reinforce the importance of following recommended fertilizer guidelines. Higher than needed fertilizer rates, regardless of dolomite product used, adversely affected plant quality, had a more acidifying effect on growing medium pH and produced an unnecessary increase leachate electrical conductivity.

Since plants require calcium and magnesium for healthy growth, it makes sense that potting mixes containing dolomite would produce larger, better quality plants compared to growing medium without a source of those two elements.

When incorporated at the rates used here, dolomite products having more particles in the moderate size range shown in Table 1 may be slightly better for Camille dieffenbachia production compared to dolomite products made up of more large or fine size particles. Even though the two products with finer particles did a slightly better job of raising the pH level, pH of growing medium incorporated with either of the two products having moderate size particles was well within the acceptable limits for healthy foliage plant growth, and produced slightly better quality plants than the growing media containing either of the two dolomite products made up of finer particle sizes.

These results also demonstrate that pH in itself is not an especially good indicator of the potential for production of quality foliage plants as long as a reasonable level of dolomite has been incorporated into the growing medium.

Healthy Food Mall Expands LIne

"Bozeman, MT (PRWEB) April 12, 2009 -- According to an article by the Associated Press, the majority of adults in the United States are overweight and unhealthy. The report - based from a two year study by the Centers for Disease Control and Prevention in Atlanta and the National Center for Health Statistics - addresses a growing trend that Americans are eating worse and exercising less.

Part of the problem is the dietary choices that people make. Fried foods and sugary snacks are consumed on a daily basis for many Americans, thus increasing their chances of Type-2 diabetes and obesity. Luckily, buying healthy food is no more than a few clicks away."

Read the article

Pesticide Lobbyists Interested in the White House Garden

"The pesticide peddlers are not happy with Michelle Obama.

We support organic gardening.
Tell the board members of MACA (virtually all of them big chemical executives) that we don't appreciate their telling Michelle Obama (or any of us) to use pesticides in our gardens.

The Mid America CropLife Association (MACA) represents chemical companies that produce pesticides, and they are angry that — wait for it — Michelle Obama isn't using chemicals in her organic garden at the White House.

We are not making this up."

Organic Honey Crystals Introduced

"Manhattan Beach, California (PRWEB) April 13, 2009 -- Organic everything is hot! What's old is new again and it's organic honey crystals - a new green organic and natural sweetener. Honey has always been a mainstay flavor for many, and a growing number of consumers, who seek alternatives to sugar and artificial sweeteners, are falling in love with honey crystals, not only to use in their beverages and honey recipes, but in their foods as well."

The Soil Association Warns of Difficult Times Ahead

AT LEAST eight organic farmers are leaving the sector every month as consumer demand for premium food stagnates and costs rise, according the industry's two biggest certification bodies.

The Soil Association and the Organic Farmers and Growers has warned the sector faces difficult times and the organic revolution faces stalling in the face of rising food prices and job uncertainty.

The National Farmers' Union has also said that "a small number at breaking point" wanted to leave farming but could not, because they had converted from standard farming less than five years ago and would have to pay back all the subsidies they had received.

Fresh Harvest Products Acquires Organic Chef

"Fresh Harvest Products, a US-based distributor of organic food products and beverages, has signed a letter of intent to acquire the assets, including the intellectual property, of Organic Chef, a supplier of organic and natural beverages in Brooklyn, New York.

The letter of intent, which is subject to completion of due diligence by the parties and their execution of a definitive acquisition agreement, contemplates Fresh Harvest issuing common stock only as consideration for the acquisition."

Recall: Stonyfield Farm 32-ounce Fat Free Plain May Contain Food Grade Sanitizer

"Stonyfield Farm is recalling about 44,000 quarts of fat-free plain organic yogurt in Stonyfield Farm branded containers because the yogurt products might contain sanitizer that's normally used in food plants. The company said it hasn't received any reports of illnesses, but it has received several reports from people noticing an off-taste or off-smell. Stonyfield Farm said the issue resulted from human error in not following the company's standard operating procedures.

The recalled products are limited to Stonyfield Farm 32-ounce Fat Free Plain yogurt with the UPC code 52159 00006. It carries one of these product codes printed along the cup bottom that start with the following date codes:

_ May 06 09: Time stamped 22:17 through 23:59 (limited to these specific time stamps only).

_ May 07 09: All time stamps."

For more information, please visit

FTC Again Delays Whole Foods Case For More Settlement Talks

"WASHINGTON -(Dow Jones)- The U.S. Federal Trade Commission on Wednesday imposed an additional 30-day delay in its antitrust challenge to Whole Foods Market Inc.'s (WFMI) 2007 acquisition of Wild Oats Markets Inc. so the parties can continue to engage in settlement talks.

Last week, the FTC issued a brief order that withdrew its merger challenge for five business days. That order was due to expire Wednesday night. The commission's challenge is now on hold until March 6.

"We look forward to continuing our discussions with Whole Foods to determine whether we can reach a mutually agreeable settlement that would be in the best interest of consumers," said David Wales, the chief competition enforcer at the FTC."

Read the article

Review of "Amy's Organic Organic Pound Cakes from SouthTownStar

"Amy's Organic Cakes. Orange, and Chocolate. $3.89 to $4.49 per 11-ounce cake.
Bonnie: It's worth hunting down Amy's new cakes in the freezer section of your supermarket - or making a special trip to a natural foods market to get them. They're as moist and delicious as homemade. They're also organic, vegan and contain no dairy.

A hefty slice of either serves up about 175 calories, 6 grams of fat (of which none is saturated) and about 16 grams of sugar, which is quite modest for something so tasty."

Read the article

Anyone else had the opportunity to try these? I've been looking for them at the market every time I go, but with no luck.

RECALL: Nature's Path OrganicOptimum Peanut Butter Energy Bars May Have Been Contaminated with Salmonella

"Washington, D.C. - infoZine - Nature's Path Organic Foods of Richmond, British Columbia, Canada is recalling Optimum Energy Bars Peanut Butter flavor, because it has the potential to be contaminated with Salmonella. The Optimum Energy Bars Peanut Butter flavor were manufactured using peanut butter recalled by Peanut Corporation of American because it has the potential to be contaminated with Salmonella. Salmonella is an organism which can cause serious and sometimes fatal infections in young children, frail or elderly people, and others with weakened immune systems.

The affected products are marked with the BEST BEFORE DATE OF 01OCT09A and sold in 2 oz (56 g) individually wrap bar with UPC code of 0 58449 77715 1."

Read the article

Review of Crispy Cat Candy Bars

Several months ago, I was sent some Crispy Bar candy bars to review, but due to the hustle and bustle of daily life, I haven't had the opportunity to post my thoughts yet. As you can tell, I've been neglecting this blog a bit, but I hope to get back on top of things soon. At any rate, on to the delicious candy bars!

Crispy Bar candy bars are somewhere between 70% and 90% organic, and if you were to look at the ingredient list, you wouldn't find any scientific or foreign sounding names!
Take a look at the ingredients: Organic Brown Rice Syrup, Organic Coconut, Organic Dark Chocolate (Organic Cane Sugar, Organic Cocoa Liquor, Organic Cocoa Butter, Soy Lecithin [Made without GMO], Organic Vanilla), Organic Brown Rice Crisp (Organic Brown Rice Flour, Organic Evaporated Cane Juice, Organic Molasses, Sea Salt), Natural Peppermint Flavor, Natural Vanilla Flavor, Salt.

Totally pure through and through, Crispy Bar candy bars come in three different flavors - roasted peanut, mint coconut and toasted almond. After having the chance to sample all three, I can safely say these are some of the best candy bars around. Sweet without being overpowering, I was thrilled to find such a great product and have it be vegan. I have bought each flavor a number of times since my initial tasting and they have never disappointed me. So the next time you go to see a movie, consider grabbing a Crispy Bar from your local natural food store.

Other Crispy Cat reviews include:
Go Dairy Free's review
Sustainable Coop's review

Wild Flight Farm starts from scratch to build successful organic produce business

"Elena Bruns works the Wild Flight Farm vegetable stand at the Revelstoke Farmers Market this past summer. The Bruns started their business 16 years ago with little capital, equipment or experience and have built it up into a successful enterprise. Photo courtesy of Wild Flight Farms

This week’s Green Business Award goes to Wild Flight Farm. Co-owners Hermann and Louise Bruns supply Revelstoke with produce organically grown on their farm in Mara, located on the Shuswap River. This week I had a chance to ask a few questions that many grateful Revelstokians have been wondering about Wild Flight Farm."

Read the article

Organic egg production - For how much longer?

"During 2008, the financial problems that we are and will be facing have led to a reduction in the sales of organic eggs. Fortunately for the free range egg industry, those who have been purchasing organic eggs seem to be deciding that the perceived welfare advantage of free range egg production is one of the key factors in their decision making. I agree with this. In well managed free range units, even large scale ones; the welfare of the hens can be equal to that on organic farms. Therefore any minor alterations in the nutrient quality of the eggs from hens that receive organic feed are likely to be financially forgettable when times are hard. Does this mean that organic egg production is doomed? No, not quite, but the implications are that the share of the market for organic eggs will from now on be lower. Why?

So far, nutritionists and feed compounders have done wonders in sourcing ingredients and formulating feeds that can and do produce good results. However the crunch time is approaching when in 2010, the feed must have a content that rises from 90% to 95% organic. After this, there will be the mandatory final step to 100% organic ingredients in the feed."

Read the article

No Organic Cotton at the Green Ball

"Monday evening’s Green Ball at the National Portrait Gallery in Washington had all of the pomp befitting an industry on the rise. A few hours after walking in on the “green carpet,” Al Gore – to rousing cheers — said that the country would regain its “political will” to help the planet when Barack Obama is sworn in as president.

Denise Bode, chief executive of the American Wind Energy Association, described the event as a “pep rally for green energy.”

Rhone Resch, head of the Solar Energy Industries Association, told Green Inc. that his industry could create 800,000 jobs in the next three years. And the bands – from Maroon 5 to Melissa Etheridge – played on."

Read the article

Shopping for Affordable Organic Foods Has Never Been Easier

"(ARA) - Providing a family with nutritious, well-balanced meals is hard enough for busy consumers, but in today's changing economy, affordability is also a factor. While it may seem like the cost of everything from gas to groceries is on the rise, the good news is that you can feed your entire family organic and natural foods at a lower cost without having to make an extra trip to a specialty health food store. Now you can find a variety of organic and natural products at your local supermarket, for a lot less than you might expect.

Many grocery shoppers are seeking ways to lead healthier lifestyles but also want foods that offer value, selection and convenience. Research shows that they prefer organic and natural foods -- the demand for these foods has grown 10 to 15 percent annually over the past 15 years as shoppers have become more mindful of the ingredients in foods they buy."

Read the article

New Brunswick Organic Farming Conference January 31

"New Brunswick - Excitement is building for the 19th Annual NOFA-NJ Winter Conference -- Greener Fields, Greener Pastures: The Way Forward -- which will take place on Saturday, January 31, 2009 from 8 a.m. to 5 p.m. at the Cook Campus Center at Rutgers University in New Brunswick. NOFA-NJ’s (Northeast Organic Farming Association of New Jersey) Winter Conference is the premier gathering for the organic and sustainable food, farming, and gardening community in the state, and is the only venue which brings together all the stake holders in the local food system. Local and organic food and sustainability in general have captured national attention and this year’s agenda offers an exciting mix of introductory, intermediate, and advanced sessions on a wide range of topics relevant to everyone concerned with the local production of high quality nutritious food and its distribution within the state."

Read the article

People Looking for Green Alternatives to Looking and Feeling Better

"Lisa Agee, owner of New Milford-based Goatboy Soaps, said she sticks to the philosophy of "if you can't pronounce it or spell it, why would you want to put it on your skin?"

Some of those complex ingredients she's talking about include parabens and propylene glycol, which many people looking to live a "greener life" avoid because they aren't natural and could be harmful.

As more and more people are interested in living a greener, more environmentally friendly life, more of us are also turning toward purchasing all natural products from health food or specialty stores. They may cost more than the products with mass appeal, but many believe they have simpler and healthier ingredients."

Read the article

Organic Executives Launch Website to Support Tom Vilsack for USDA

"A group of NGO chiefs, activists, and Big Organic executives have launched a website and petition to support Tom Vilsack, president-elect Barack Obama's choice to lead USDA.

Participants in the site, known as supportvilsack.com, include Bob Scowcroft, executive director of the Organic Farming Research Foundation; Iowa sustainable-food activist Denise O'Brien (who recently guest-posted on Gristmill); Wayne Pacelle, CEO of the U.S. Humane Society; Gary Hirshberg, CEO of organic-yogurt giant Stonyfield Farm; Steve Demos, founder of soy-food giant White Wave (now owned by industrial-dairy behemoth Dean Foods); and several others.

Institutionally, the Organic Trade Association -- whose members range from tiny producers of hemp products to global agribiz giant Bunge -- signed on."

Read the article

Navita Naturals Introduces Sweet Cacao Nibs

"The cacao bean is a nourishing superfood that has played a fascinating role in the diet, medicine and culture of civilizations for many centuries. Now, Navitas Naturals (www.navitasnaturals.com) is giving this legendary “Food of the Gods” a delicious modern update by blending their popular raw organic cacao nibs with raw organic Cacao Paste (liquor) and organic sugar cane juice. Navitas Naturals’ Sweet Cacao Nibs are a delicious treat right out of the bag and they also add bold flavor and crunchy texture to a wide variety of recipes.

The organic cacao beans used in Navitas Naturals Sweet Cacao Nibs are hand-selected for quality in the rainforests of Peru, and are then partially fermented to alleviate bitterness. The beans are processed at low temperatures to maintain maximum nutrient retention. Once extracted from the pod-like fruit, the beans are cleansed with purified water, peeled and partially ground to form small “nibs.” The crunchy nibs are then rolled in Navitas Naturals raw organic Cacao Paste (liquor) and then lightly mixed with organic sugar cane juice to create the ultimate ‘real’ chocolate treat."

Read the article

The Story Behind Yummy in My Tummy

"Like many parents, Karen and Michael Stanley wanted to give their daughter the best when she was born 17 months ago.

Michael, a partner in Brasserie Las Olas in Fort Lauderdale, Fla., and manager of other restaurants including Tequila Ranch at the Seminole Hard Rock Hotel & Casino in Hollywood, Fla., and Karen, a political consultant, decided to feed Sophia only organic food. They started out buying packaged, but found their choices too limited. When they started cooking it themselves, countless pots of peas, squash and parsnips left them feeling overwhelmed. There had to be an easier way.

What they did was start their own business, Yummy in My Tummy, an all-organic baby food store at in Davie, Fla."

Read the article

Australia Among the Most Innovative Organic Markets

"Being more innovative than most has paid off for three Australian organic companies, whose creative approach to business sees them looking forward to a prosperous 2009 despite the economic turmoil.
The recent opening of Z Mills in SE Queensland was a giant step for organic flour milling. Protection from light, reducing the temperature to 4◦Celsius or lower and using nitrogen to exclude oxygen from the milling process means that the enzyme reactions that cause rancidity in flour are virtually eradicated.
In addition, CEO Thomas Cunliffe reports, the process retains the grain roughage and essential oils, minerals and fibre so that the nutrient value of the flour is maintained.
The mill can be used for hard grains such as brown rice and hemp and trials are planned for milling China, tiny seeds of an ancient South American plant that is rich in anti-oxidants. Even the mill is a local product, a Queensland design in which the grain effectively mills itself through a contained, high-speed impact process that uses no water and 30% less energy than conventional mills.
Australian Harvest’s grape marc produce is also ready for the New Year, after making its mark at a major food expo in Dublin."

Read the article

Malawi Beating Poverty with Organic Methods

"Poverty and penury often push people in Africa into innovation. So it was with Jailos Kanyanga. The story began when government agents arrived at Mr Kanyanga's compound in this central region of Malawi, and demanded that he immediately repay money he owed under a fertiliser credit scheme – with "no further excuses".

The sum involved was 3,750 kwacha (about £17) – an amount that it was unimaginable the poor subsistence farmer would have to hand. If he couldn't pay, the agents said, they would seize his 11 pigs – livestock Mr Kanyanga saw as ensuring the survival of his family of eight. He was lucky. The local pastor lent him the money. But it was then that Mr Kanyanga resolved he could not allow himself to fall into such peril again."

Read the article