Compost and mulch are always assumed to improve a soil, but stable (well digested) OM is colloidal, which means it is made up mostly of very fine particles, like an organic clay. For years, I have been sounding a warning about mulching fruit trees year after year in the humid region because, except on drought years, it gradually turns the soil too rich with too much available water holding capacity,. eventually causing most common fruit species besides plums to produce fruit with reduced sugar. I cannot explain why it doesnāt seem to have the same affect on plums.
This year I think Iāve discovered that it can also be a problem in my vegetable garden where my pepper plants never achieved typical vigor, which is very vigorous indeed. Early in summer we had a long stretch of wet weather including a single night when over 8" fell. My vegetable garden is built with very high mounds in the French Intensive Gardening method, in other words the mounds are not held up with planks. I rebuild them every spring and allow some soil to slip away which I will return the following spring. The FIG method concept is to recreate the conditions of a landslide.
In spite of all the mulch and compost Iāve added over the years, mine is not yet muck soil- it isnāt black and probably still very far from the 30% OM found in that perfect soil for onions. Commercial growers around here also use it for lettuce and members of the cabbage family after digging ditches to provide it drainage, these did fine in my garden this year.
However, I just did some digging in it to plant some cilantro seeds I had been priming in my fridge, and it was quite compacted and heavy, although the soil is essentially a silt loam. It was also surprisingly cool, I think because of all the water it holds. And we havenāt had a meaningful rainstorm for over 2 weeks.
About 30 years ago we had an August with almost 30" of rain, and all my plants on those raised beds, including tomatoes, did fine while neighborās plants were drowned. It appears that with the soil Iāve created with all the mulch and compost Iāve added even very tall and steep mounds do not adequately drain for species that donāt like cool wet soil.
Hi Allan,
In What region are you living? I too have experienced some affects I did not expect with OM, mainly my garden soil tends to repell water absorption initially when I water. Each year I have added mostly horse manure compost. Where I mulch this affect is not as noticeable. But I had expected over time that my soil would become more water retentive. So in my case of mostly sandy loam and volcanic soils I need to mulch to keep moisture within the top 3ā. Each winter I plant green manure cover crops that get tilled in before the garden is replanted.
We do not use commercial fertilizers on the garden, thinking that our practice is best, but often I have to question conventional wisdom.
Dennis
Kent, wa
This pretty much goes under the imbalances are bad column. The thing is; what is too much for your conditions could be just perfect on mine.
Iām a big fan of using the native sand on my compost based mixes (my soil is pretty much rocks/gravel/sand) and it gives me the sort of heavy soil I need. That heavy soil (where the substrate is perfectly draining sand/gravel on sloping ground) would probably be horrendous somewhere else but ideal here.
Alternative explanation, high water levels both create anaerobic conditions in the soil and speed up breakdown of OM which absorbs available nitrogen. While temporary, these conditions are very bad for growing solanums. A combination of anaerobic low nitrate cool soil will knock a lot of plants for a loop. Suggestion: use black plastic mulch on your raised mounds both to warm up the soil and reduce moisture absorption from excess rain.
Iām not sure you meant to communicate what this sentence seems to say. High water is what creates muck soil and peat bogs because anaerobic conditions delay the mineralization of OM and gradually creates a build up of it far beyond what can naturally be created in a well drained soil. Itās also why clay soils tend to have more OM than sandy ones, but I assume you know all this.
I would rather just add a whole lot of sand to the beds I grow peppers on than resort to sheets of plastic. My nursery operation is already ādirtyā enough, but it is a very good suggestion.
I just donāt understand why in a previous year we had more precip over a month period and I didnāt experience a similar problemā¦ until 30 years of adding mulch and compost, the soil drained adequately after very abundant rainfall.
This puzzles me as well. Composted manure creates a medium that absorbs water and holds a lot of it in my experience so I cannot understand how it would make soil repellent to water, especially if you added it in the way the provides the most bang for the buck, only to the surface. Worms should come from lower to grab a meal and create the honeycomb affect that allows a lot of water to enter the soil in a hurry. Mulch does this to a greater degree, probably, just because there is relatively more food in it for worms.
My garden soil has so many worms in it that it would be a very easy protein source for a family. My veg garden is also a worm farm and not the ones that thrive in relatively anaerobic soil.
I grow my vegetables in raised beds about 14" deep and [filled] with (G&B Organics Raised Bed Potting Mix | Kellogg Garden Organicsā¢) which mainly contains organic matter (wood based raised bed mix) it has some perlite thrown around. I throw a bag of compost beginning of the growing season and get good harvest. Pepper plants need a lots of nitrogen, how do you fertilize them?
Anaheim from one of my bed this year, this bed receives 4-5 hrs of sun. I use it for volunteer cherry tomatoes, Amaranth and redundant starts that I plant rather throw away.
I too have noticed certain composts repel water, I canāt tell why since I buy bagged compost, they will need gradual hydration like leaving them out in the rain or use water penetrant and hydrate in stages.
Since you are in PNW, I recommend trying Stutzmanās Chicken Manure Compost itās from Oregon and costs $6 a bag at Concentrates Inc. at Milwaukie, OR. I amend my beds with a bag of Stuzman, 1/4 bag of generic compost and put organic granular 5-5-3 in the planting hole. Feed them weekly water soluble fish fertilizer until mid-july and donāt apply fertilizer unless I see loss of vigor for plants like Pepper or Squash.
Your situation is completely different from those of us in the humid region- your rain season is the inverse of your growing season- you control the water and give your plants precisely what they need while they can take in the warm sun almost every day during the growing season, unless you are right by the coast, of course. But even in coastal Oregon you are not going to get 18 inches in about 3 weeks in the heart of the growing season. My sister lives in the Redwoods less than a mile from the sea in CA near the Oregon border. Her soil is impossible to flood- the redwoods create the most porous soil imaginable.
I usually include the caveat that those living where it gets little rain during the growing season probably donāt have to concern themselves with making their soils excessively rich in OM because you can control vigor and drainage problems with the spigot. Deficit irrigation tends to produce very high brix fruit.
I also prefer high brix peppersā¦ and growing things in more or less natural soil.
What Alan describes isnāt much of a practical issue here in the Rocky Mountain foothills.
Iāve thought that my extra-heavy mulch inhibited springtime soil warmup. If you overdo it with high N ferts you have a problem, but thatās true anywhere, any time.
Excessive moisture retention and excess fertility would be more a theoretical problem for us.
Pretty much. Too much has a big fat ādependsā on it.
On my soil the big holes I dug to plant trees are like an island of good soil in a sea of rocks, gravel, and sand. Iām certain a tree would be fat and happy on 100% well cured manure; on my aforementioned rocks/gravel/sand I have 0 drainage issues so the ability of the soil to retain water has to be enhanced with a big fat cap of mulch.
If you have clay soil, that would be a recipe for disaster. It would soak up water and it could not drain the excess fast enough.
Iām not a soil expert, but saturation of our mine drainage treatment systems at work (primarily mushroom manure compost/probably horse manure + hardwood chips) is necessary for anaerobic sulfate reducing bacteria to live and generate alkalinity/fix heavy metals (mainly iron and aluminum oxide). These guys may or may not be beneficial to nitrogen availability, Iām not sure as itās not something we usually test for or focus on.
There is plenty of focus on achieving the best balance of water and air for plant growth in soil, but Iāve neve seen a single thing in the literature about the possibility of making soil too rich with organic matter to achieve that balance in areas that can get flooding rains during the growing season. Itās not likely to become an issue in commercial production systems because mulch and compost tend to be used relatively modestly because of the expense of application. However, it is telling that in well drained muck soil, the list of species that are grown commercially is somewhat limited- at least in humid regions.
The literature suggests that raised beds and berms (or gravity based ātileā drainage systems) are a panacea for poor drainage, and Iām suggesting here that it isnāt always the case. In an orchard where I had the best success with mounds, I used large quantities of sand against the recs of Cornell and others. The advice was that I would create concrete if I added sand, given that I was starting with a grey, almost pure clay subsoil that had been trucked to the site.
Such advice was probably originally derived for commercial growers unlikely to incorporate sufficient sand to adequately alter soil texture. Stupid, really, because soil texture is based on the ratios of sand, silt and clay, so obviously enough sand will create a different, better draining soil. It may not be commercially profitable to do this, but for someone with a little property that wants a small orchard it is a different matter entirely.
Thatās because amending soil is about adding something, it isnāt feasible to remove something. If your soil is too sandy and doesnāt retain moisture you add material that does. If your soil has too much clay you add material to loosen it up.
Take sand; if your soil condition requires it you wonāt necessarily see in the literature warnings about adding too much. It assumes that once a problem has been identified that the provided solution will be applied as_needed. That is determined by your own conditions.
Heck think about absolutely anything you can put into your soil; all of it has a point of too much and downright counter productive.
I believe jujubes would be the 2nd exception. No matter how much water they get, the trees just produce more and better fruit. If the water is close to harvest time, it can crack the fruit, but otherwise lots of water hasnāt been a problem.
There is an interesting video about a guy growing them in Australia. His son āhelpedā him while he was away by planting ~200 trees is about 1.5ā of fresh (3-4 months old) manure. He expected them to die, but they grew very well. He tried the same with figs and they all died.
I havenāt tried planting in pure OM, yet, but probably should. In my case it would be leaf mold, not manure, as I thankfully donāt have piles of it sitting around.
I have been adding one to four 5 gallon buckets of leaf mold each time I plant a jujube. Iāve been doing that for a few years now and they seem to establish quicker, though part of it is that I have more trees and am thus a bit less impatient
This summer, most of my tomatoes did very poorly. Low growth and low production. But there is one bed which was the exception- it is at a rental, next to a driveway. The bed is raised about 3 feet above the driveway. I planted tomatoes in ~6 different beds and that was the only one which did well. There was a 2nd one on the same property which also did poorly, so it doesnāt appear to be location specific.
Both beds had plenty of old compost mixed into them. But I suspect the additional drainage from the bed by the driveway made the difference.
TBH, I donāt really give a lot of attention to growing vegetables. FWIW, I plant overwintering veggies in the my beds and containers and donāt care about them throughout our wet winter and spring. If we get 8" of rain overnight, the last thing I will be worrying about is vegetables grow space.
Nothing but plants evolved to live in rainforests will survive that level of saturation, i.e. if they are not already 2ft+ under water.
Edit: These fruit trees I planted in my yard this year are planted on level surface because my yard soil is whatever the builder filed during construction and hard to dig and drainage is an issue due to clay. The mounds you see here are entirely potting soil, compost and sawdust mulch. The tree have established nicely and handling winds without any issues. I have noticed they have fine roots in the mound but also growing roots in the clay that is anchoring them. I think/hope they will survive this winter and all the rain.
Now that you mention it, there are probably many exceptions. I get more blueberries with lots of rain and they seem to be up to the standard I expect, although Iāve never tested them for brix.
Your comment made me realize that my experience of evaluating fruit plant response to excess water is limited, concerning brix. Really, my anecdotal knowledge only extends to some stonefruits and apples.
somewhat generic question. I want to understand why does any home/hobby growers should give importance to BRIX. Iām sure commercial growers walk around with expensive refractometer testing their water swollen fruits to ensure it meets the criteria required for them to successfully market the fruit when their living depends on retaining the customers. If home growers too determine their produce quality using the same metric what is difference and is there any difference at all?
I have no idea if there is any commercial requirement for specific level of brix of fruit sold commercially- if so the bar is way too low and I think it is a testament to the general produce ignorance of U.S. consumers that are willing to even buy fruit that is of little pleasure to eat (that doesnāt include many who go to farm stands or farmerās markets). Low brix fruit is bland. I tend to like high brix- high acid fruit, but do enjoy low acid nects once brix gets will into the '20ās
Where in Oregon are you? If you are far enough from coastal influence to have almost all clear sky days as fruit ripens you wouldnāt understand, although my sister has difficulty getting J. plums to adequate brix to be real fun to eat, or peaches, or tomatoes, or cornā¦but as I wrote earlier, she is completely under coastal influence. You can literally hike from where she is up a mountain to a completely different climate where brix must never be an issue.
We in the east talk about brix because getting up high sugar can be a challenge and it is the primary difference between bland and utterly delicious fruit here. If you are a fruit nerd you like to quality it with a real number so when we discuss varieties with others, we know what they are talking about.
What my neighbors consider the best peach they ever tasted can be so-so to my palate, and my best fruit would probably be so-so to Fruinutās palate, which has been rendered inoperable by the excess sugar of his product
The blueberries with lots of rain probably have good drainage. My experience is that blueberries in a non-draining field do poorly in Western Oregon. Too high of a ratio of compost will hold more water even with 10 to 15% pumice.
Partially composted course bark or aged fir works great as a potting mix at the nursery until it turns to dust and becomes compost and then it holds water like clay. Adding pumice at least keeps the soil medium friable and easier to work after it sheds water.
My conclusion is compost adds organic material to the growing medium which is a plus but you still need drainage via 1-graular surrounding soil 2-sloping ground / berm / ditch 3-drainage pipes.
I am in Portland. Technically part of Willamette Valley. Our weather here is unpredictable at best. Last year we had nothing but cloudy skies and rain until July, and 80F October days. This year rains and cloudy skies for last couple of weeks.
