can you use too much compost?

Hermanator · February 12, 2015

Hi!
I'm new to serious gardening but quite enthusiastic. I recently rototilled a 20' x30' garden bed which was previously lawn. This lawn hasn't seen commercial fertilizers or weed killers to my knowledge ever. My question is even though the soil is a very rich brown color I plan to add compost. I have access to an unlimited supply of compost that the county offers free. (Even though I'm sure some of it is from grass clippings that have seen fertilizers and weed killers in the past, I'm thinking it is negligible in the end product) Can I use too much? Does compost burn like some fertilizers? If you were starting out what would you do here to build the soil? Thanks for any help!
Jack

Redbaron · February 12, 2015

Quote:

Originally Posted by Hermanator

Hi!
I'm new to serious gardening but quite enthusiastic. I recently rototilled a 20' x30' garden bed which was previously lawn. This lawn hasn't seen commercial fertilizers or weed killers to my knowledge ever. My question is even though the soil is a very rich brown color I plan to add compost. I have access to an unlimited supply of compost that the county offers free. (Even though I'm sure some of it is from grass clippings that have seen fertilizers and weed killers in the past, I'm thinking it is negligible in the end product) Can I use too much? Does compost burn like some fertilizers? If you were starting out what would you do here to build the soil? Thanks for any help!
Jack

Start with a small amount in a cup and plant a bean seed in it. See if it is affected by residues. If it is good, then 3-6 inches over the whole garden should be good.

swamper · February 13, 2015

The short answer is if you're just starting out with a new garden you shouldn't have to worry about using too much compost. If it's mostly leaves from trees you shouldn't have to worry much about toxicity. Incorporate lots of that County compost and get your soil tested at least every other year. Maintain soil organic content and structure by mulching and not tilling more than necessary and you'll be rewarded. Adjust pH gradually and as needed to 6.5 to 7. Uncomposted organic matter that is low in nitrogen can deplete N during the breakdown process, so nitrogen fertilizers may be needed when plants are growing rapidly, especially in rainy seasons, as nitrogen is susceptible to leaching.

Compost derived from manure from animal feedlots or from crop residuals that have had lots of herbicides applied to them might be risky. Long term application of composted manures can boost soil phosphorus levels above optimum. The adverse consequence of too much phosphorus in your soil can be a loss of connection between plants and mycorrhiza. And no, mycorhiza is not something you buy in a store and apply. It exists in healthy soils with plenty of organic material. When you lose that connection you are essentially growing in a system where most of the measurable nutrients might not be plant available.

snugglekitten · February 25, 2015

The utility of it will run into diminishing returns at a certain point. Like everything else. And like Swamper says, if you are getting it from places with questionable amounts of inorganic compounds, that will accumulate, which is not a good thing.

bughunter99 · March 1, 2015

Hi Jack,

If it is old and done, it would be hard to do any damage with it so long as it doesn't contain manure.

If it is fresher/greener and still hot and active your plants could suffer some nutrient deficiency. Not really a problem, but you will probably have to supplement with fertilizer.

As Swamper said I would definitely skip any and all compost that includes manure by products from cows or horses. There is just too much herbicide in their food these days and some of them can destroy your soil for years. There are multiple lawsuits out about this but it is still not very common knowledge.

PaulF · March 1, 2015

Too much of anything can be detrimental to growing conditions. Soil needs to be balanced and too much organic matter could throw things out of balance. That is a rare condition but I remember our state extension people saying something like 18-20% organics and you will get diminishing returns.

Redbaron · March 1, 2015

Quote:

Originally Posted by PaulF

Too much of anything can be detrimental to growing conditions. Soil needs to be balanced and too much organic matter could throw things out of balance. That is a rare condition but I remember our state extension people saying something like 18-20% organics and you will get diminishing returns.

Considering my soil is 1.2 and 2.6 % SOM respectively. That's not an issue. I am not alone. Most soils are very low until people add that compost. Now sure there is a point of diminishing returns. But I suspect 99% of people reaching 18% have been adding a WHOLE LOT of compost every year for years and years. Composting causes a lot of shrinkage. It would be quite difficult to get numbers like that in a normal bed. Maybe a container, or a raised bed with sides.

ScottinAtlanta · March 1, 2015

I made 4000 pounds of oak leaf compost this year, and it is still measured out like black gold. I don't think I will ever have enough for the 3 inches of top dressing on every bed.

tuk50 · March 2, 2015

I practice no till.. so every year we put 12 inch mounds down each row and plant directly into it.
We lay the rows each february and plant into it late march or early april.. we have two mounds of compost going at all times a year old pile that we use each year and a new one that gets all the horse manure, chicken poop, pig poop and any and all spoiled bales of hay, plus kitchen, garden and coffee shop scraps over the year... KEYS, well composted with literally hundreds of worms at ground level working the compost into the soil within a couple of weeks after laying the rows. seeds sprout well in it. my soil grew cactus only 5 years ago and had little or no organic matter so it probably will handle much more compost than your soil.
Each year my garden produces more and healthier veggies, so until this changes and the production levels off, I will continue doing this each year before I back off. Hope this helps some to judge your needs.
I'm like Scott, I don't think I will ever have enough. (my pile starts out 10ft wide 20ft long and 5ft tall and shrinks to about half by the end of the year)

habitat_gardener · March 2, 2015

One year we had free horse manure compost at the community garden, so I piled one or two garden beds with 12-18 inches of it. Then, in the spring, I hollowed out a space big enough to plant each tomato plant with a 5-gallon container of homemade compost. All the tomatoes did well.

On the other hand, there's that book by Steve Solomon where he says the optimal amount is something like one-eighth inch of compost per year, and he rants about the evils of relying solely on compost. Nauta in Building Soils Naturally doesn't include a rant, but he concurs about the amount of compost needed in established gardens.

I've basically added as much as I could produce, which lately has been 1-2 gallons per plant (including top dressing later in the season).

ScottinAtlanta · March 3, 2015

1/8 inch!!!

Jwb4707 · March 3, 2015

I'm a licensed pesticide applicator, the things that break down chemicals and pesticides the most are heat, light, and water, along with time. If it's fully composted, it should be fine, the chemicals used these days are not very toxic to begin with, and are heavily diluted, and all the rain, heat, and sunlight should take care of them. If any doubt, you can always have a soil test done.

zeuspaul · March 3, 2015

The herbicide Clopyralid survives the animal digestive process and composting. It takes years to degrade to a safe level. Dow no longer recommends it for residential lawns. However it is still sold and is found in compost, hay, straw and animal manures. Tomatoes have a high sensitivity to Clopyralid.

drew51 · March 4, 2015

Quote:

Originally Posted by bughunter99

Hi Jack,

If it is old and done, it would be hard to do any damage with it so long as it doesn't contain manure.

If it is fresher/greener and still hot and active your plants could suffer some nutrient deficiency. Not really a problem, but you will probably have to supplement with fertilizer.

As Swamper said I would definitely skip any and all compost that includes manure by products from cows or horses. There is just too much herbicide in their food these days and some of them can destroy your soil for years. There are multiple lawsuits out about this but it is still not very common knowledge.

Well something about this I'm at a loss, if they are being sued to death, what are they still doing it? I have never had a problem with manures, and I have used five or six different sources. The stuff is awesome as far as I'm concerned.

drew51 · March 4, 2015

Quote:

Originally Posted by Redbaron

Considering my soil is 1.2 and 2.6 % SOM respectively. That's not an issue. I am not alone. Most soils are very low until people add that compost. Now sure there is a point of diminishing returns. But I suspect 99% of people reaching 18% have been adding a WHOLE LOT of compost every year for years and years. Composting causes a lot of shrinkage. It would be quite difficult to get numbers like that in a normal bed. Maybe a container, or a raised bed with sides.

I disagree, not with you, the premise is incorrect. I use pine bark, peat, and compost in containers. that's about 95% organic material and I get great results.
Same with my raised beds.

February 12, 2015	#1
Hermanator Tomatovillian™ Join Date: Jan 2015 Location: Atlanta, GA Posts: 6	can you use too much compost? Hi! I'm new to serious gardening but quite enthusiastic. I recently rototilled a 20' x30' garden bed which was previously lawn. This lawn hasn't seen commercial fertilizers or weed killers to my knowledge ever. My question is even though the soil is a very rich brown color I plan to add compost. I have access to an unlimited supply of compost that the county offers free. (Even though I'm sure some of it is from grass clippings that have seen fertilizers and weed killers in the past, I'm thinking it is negligible in the end product) Can I use too much? Does compost burn like some fertilizers? If you were starting out what would you do here to build the soil? Thanks for any help! Jack

March 1, 2015	#6
PaulF Tomatovillian™ Join Date: Jan 2006 Location: Brownville, Ne Posts: 3,296	Too much of anything can be detrimental to growing conditions. Soil needs to be balanced and too much organic matter could throw things out of balance. That is a rare condition but I remember our state extension people saying something like 18-20% organics and you will get diminishing returns. __________________ there's two things money can't buy; true love and home grown tomatoes.

March 2, 2015	#9
tuk50 Tomatovillian™ Join Date: Oct 2007 Location: Tucson, Arizona (catalina) Posts: 413	I practice no till.. so every year we put 12 inch mounds down each row and plant directly into it. We lay the rows each february and plant into it late march or early april.. we have two mounds of compost going at all times a year old pile that we use each year and a new one that gets all the horse manure, chicken poop, pig poop and any and all spoiled bales of hay, plus kitchen, garden and coffee shop scraps over the year... KEYS, well composted with literally hundreds of worms at ground level working the compost into the soil within a couple of weeks after laying the rows. seeds sprout well in it. my soil grew cactus only 5 years ago and had little or no organic matter so it probably will handle much more compost than your soil. Each year my garden produces more and healthier veggies, so until this changes and the production levels off, I will continue doing this each year before I back off. Hope this helps some to judge your needs. I'm like Scott, I don't think I will ever have enough. (my pile starts out 10ft wide 20ft long and 5ft tall and shrinks to about half by the end of the year) __________________ Hangin on for dear life! Last edited by tuk50; March 2, 2015 at 07:07 PM.

February 13, 2015	#3
swamper Tomatovillian™ Join Date: May 2009 Location: CT Posts: 219	The short answer is if you're just starting out with a new garden you shouldn't have to worry about using too much compost. If it's mostly leaves from trees you shouldn't have to worry much about toxicity. Incorporate lots of that County compost and get your soil tested at least every other year. Maintain soil organic content and structure by mulching and not tilling more than necessary and you'll be rewarded. Adjust pH gradually and as needed to 6.5 to 7. Uncomposted organic matter that is low in nitrogen can deplete N during the breakdown process, so nitrogen fertilizers may be needed when plants are growing rapidly, especially in rainy seasons, as nitrogen is susceptible to leaching. Compost derived from manure from animal feedlots or from crop residuals that have had lots of herbicides applied to them might be risky. Long term application of composted manures can boost soil phosphorus levels above optimum. The adverse consequence of too much phosphorus in your soil can be a loss of connection between plants and mycorrhiza. And no, mycorhiza is not something you buy in a store and apply. It exists in healthy soils with plenty of organic material. When you lose that connection you are essentially growing in a system where most of the measurable nutrients might not be plant available.

February 25, 2015	#4
snugglekitten BANNED Join Date: Jan 2012 Location: Land of the White Eagle Posts: 341	The utility of it will run into diminishing returns at a certain point. Like everything else. And like Swamper says, if you are getting it from places with questionable amounts of inorganic compounds, that will accumulate, which is not a good thing.

March 1, 2015	#5
bughunter99 Tomatovillian™ Join Date: Feb 2010 Location: zone 5 Posts: 821	Hi Jack, If it is old and done, it would be hard to do any damage with it so long as it doesn't contain manure. If it is fresher/greener and still hot and active your plants could suffer some nutrient deficiency. Not really a problem, but you will probably have to supplement with fertilizer. As Swamper said I would definitely skip any and all compost that includes manure by products from cows or horses. There is just too much herbicide in their food these days and some of them can destroy your soil for years. There are multiple lawsuits out about this but it is still not very common knowledge.

March 1, 2015	#8
ScottinAtlanta Tomatovillian™ Join Date: Jul 2011 Location: Atlanta, Georgia Posts: 2,593	I made 4000 pounds of oak leaf compost this year, and it is still measured out like black gold. I don't think I will ever have enough for the 3 inches of top dressing on every bed.

March 2, 2015	#10
habitat_gardener Tomatovillian™ Join Date: Apr 2008 Location: California Central Valley Posts: 2,543	One year we had free horse manure compost at the community garden, so I piled one or two garden beds with 12-18 inches of it. Then, in the spring, I hollowed out a space big enough to plant each tomato plant with a 5-gallon container of homemade compost. All the tomatoes did well. On the other hand, there's that book by Steve Solomon where he says the optimal amount is something like one-eighth inch of compost per year, and he rants about the evils of relying solely on compost. Nauta in Building Soils Naturally doesn't include a rant, but he concurs about the amount of compost needed in established gardens. I've basically added as much as I could produce, which lately has been 1-2 gallons per plant (including top dressing later in the season).

March 3, 2015	#11
ScottinAtlanta Tomatovillian™ Join Date: Jul 2011 Location: Atlanta, Georgia Posts: 2,593	1/8 inch!!!

March 3, 2015	#12
Jwb4707 Tomatovillian™ Join Date: Jan 2015 Location: Western MA Posts: 78	I'm a licensed pesticide applicator, the things that break down chemicals and pesticides the most are heat, light, and water, along with time. If it's fully composted, it should be fine, the chemicals used these days are not very toxic to begin with, and are heavily diluted, and all the rain, heat, and sunlight should take care of them. If any doubt, you can always have a soil test done.

March 3, 2015	#13
zeuspaul Tomatovillian™ Join Date: May 2007 Location: North County, San Diego Posts: 419	The herbicide Clopyralid survives the animal digestive process and composting. It takes years to degrade to a safe level. Dow no longer recommends it for residential lawns. However it is still sold and is found in compost, hay, straw and animal manures. Tomatoes have a high sensitivity to Clopyralid.