How to lower pH
Using peat moss is a common way to lower the aquarium’s pH. Simply put the peat moss into a mesh bag and add it to the filter. Peat moss will gradually lower the pH. With peat moss, it is likely however that your water will temporarily discolor. It should clear up over time and you can also use activated carbon to help it along.
Other methods of lowering the pH include:
- Increase aeration of the aquarium
- Driftwood will soften the water and lower the pH
- Increase CO2 levels (planted aquariums)
What influences the pH in the aquarium?
- The pH level can be different before and after water changes, especially if the pH of the aquarium water and the aquarium itself vary
- Increased aeration will lower the pH
- driftwood will soften the water and therefore lower the pH
- adding CO2 will lower the pH
- high nitrates can cause the pH to drop
- pollutants and waste in the water will lower the pH
- crushed coral (substrate or ornaments) will increase the pH
- hard water will cause higher pH levels
- using a water purifier can lower pH levels (good with hard water)
- soft water is generally low in pH
- overstocked aquariums can be low in pH
submitted 1 year ago by LEDwizard1600W LED | Organic
I get a lot of questions about “is this LED light good?” or “what is the best ratio of color1/color2?” and I see a lot of posts where people still vehemently believe IR and UV are necessary, or that you can grow using nothing but color X, or they flat out dismiss a whole chunk of the color spectrum as “wasted energy.” So for what it’s worth, here’s my primer on the entire spectrum of light from UV all the way down to deep IR. The reason I feel this is worth the time is that people need to know, either as they build DIY LED setups or buy pre-fabricated setups, exactly what is valuable light and what isn’t.
UV (200~430nm): One of the most virulent examples of perpetuated hearsay in the grow world is the claim that THC-laden trichomes exist, or that they increase in number/density, as a plant defense mechanism against UV light. The claim follows that hitting a plant with UV during flower or near harvest will boost production. I always ask “why would the plant only protect itself during late flower? Further, there aren’t really any examples of other Rosales or even Eudicots with a UV-flower-defense mechanism, but if anyone knows of one I will stand both corrected and amazed. People often say “well it might help, so why not do use some UV-B anyway?” Well the answer is Thermodynamics. When a plant absorbs a high energy UV photon, it has to burn off a lot of energy as waste heat to convert it down to a usable PAR photon. Not only are UV LEDs inefficient to begin with, but the UV photon itself is wasteful. This is why CFLs cannot compete with LEDs: they start with a mercury-vapor UV photon of 254ish nanometers and the phosphor burns 50% of that energy immediately converting it into a visible light photon.
Blue (430~485nm): Blue LEDs are really efficient at producing photons. In fact virtually all “white” LEDs are simply a blue LED with a phosphor coating. However just like with UV photons, plants have to down-convert blue photons to a lower (red) energy level to use them in photosynthesis – wasted heat energy. Blue photons do have one very important feature though, and that is they inhibit auxin synthesis. Auxin is a plant hormone that causes elongation, so if you don’t want stretchy plants, some blue wavelength light is a must. An important caveat is that auxin and its blue-wavelength-reactive buddies are important for flowering, which is why it makes sense for people switch to a “warmer” color spectrum during flower. The increase in auxin and the decrease in light from switching to 12/12 both explain why a plant grows 2X to 3X in height during the first few weeks of flower.
Green (500~565nm): There’s this HUGE misconception, based on chlorophyll absorption charts, that somehow plants only need red and blue photons to grow. There are two problems with this. The first problem is that it assumes the only light-dependent activity in a plant is photosynthesis, which is flat out false. The second problem is that those charts of chlorophyll absorption assume you’ve isolated a choloroplast out of a leaf, or even isolated cholorophyll molecules in solution. What happens in a leaf – a complex, three dimensional structure – is much more interesting. Here’s a fantastic article that explains that green photons are actually MORE efficient than red at driving photosynthesis. It’s well worth the read. The problem with green LEDs is they are very inefficient at producing photons. A typical well-designed green LED will produce 50 lumens/watt, while a red from the same manufacturer with similar specs will produce the same lumens for 75% the power. In fact, some white LEDs produce more green photons per watt than green LEDs. Go figure.
Amber/Orange (580~610nm): Pretty much the exact same thing as green. Plants can and do use these wavelengths of light. One of the reasons HPS is still the gold standard for indoor growing is because it very efficiently produces a lot of green/amber/orange photons, which plants are quite excellent at using. Amber (not warm white, mind you, but true amber) is an extremely inefficient LED, and not worth the trouble, especially considering reds are cheaper and more efficient for the LED and for the plant.
Red (620-660nm): It’s your main photosynthesis driver, duh. PSI and PSII photosynthesis pathways require two photons, one 680nm and one 700nm. Red LEDs typically come in a nanometer peak around 620-630, which means you don’t have to waste much photon energy as heat in order to get usable photosynthesis energy. The only downside of red LEDs is they cost more (than whites) if you are building a DIY setup. Red LEDs are pretty rad because they run at a much lower voltage than white/blue/green/odd color, so for ~12V and 1 amp, you can often run 5 red 3W LEDs in series where you’d only be able to wire 3 white 3W LEDs in series. You can grow monster plants with setups that utilize only red LEDs with a little white thrown in to cover the rest of the spectrum.
Deep Red (660nm peak): It would be so freakin’ handy if deep red LEDs were efficient. The photons are already very close to the peak photosynthetic efficiency wavelengths. Unfortunately, far red LEDs aren’t as efficient as normal reds, and the trade-off in photosynthetic efficiency doesn’t match the trade in chip emission efficiency, so its cheaper per watt (unless far red LED efficiency improves) to feed plants with cheap-and-easy 620nm reds.
Far Red (740nm) Don’t waste your time. Like I mentioned twice before, photosynthesis needs one 680nm and one 700nm photon. Plants cannot convert a photon upwards in energy. To do so would violate the law of conservation of energy. There are no known instances in biology of a mechanism to fluoresce to a higher energy state. So all of these photons are wasted as heat.
Infrared (800+nm): Another horrible misconception is that plants somehow use this level of energy for growth purposes. Come on folks, IR is just heat. If a planted is heated, it respirates to stay cool. Like all other things on this planet, IR can be absorbed and re-radiated. What a plant cannot do is absorb an IR photon and somehow convert that photon to useful energy. To do so, a plant would actually be converting heat to something else and would rapidly freeze and die. Any LED fixture that features Infrared LEDs is literally pouring your money (via your electric bill) into the ground. Or to put it another way, the IR chips on an LED array are simply helping keep your grow tent warm.
White (100% PAR): I’m not going to bore you with explaining the in’s and out’s of color temperature or that cool white = veg, warm white = flower. You can read all about that in a million posts in this sub. A white LED is just a blue chip with a phosphor coating. The coating converts blues into a chemically-controlled spectrum of photons across the entire visible spectrum. “Warm white” LEDs have a short 460 blue peak and a broad slope from green to red. “Cool white” LEDs have a tall 460nm blue peak and a very similar slope from green to red.
Full Spectrum (typically advertised as a series of 6-12 peak wavelengths): UV is a waste, IR is a waste. Blue is okay, white is better, Red is best. If it had 3 reds for every 1 white/blue, in my opinion this is ideal.
That’s about it. If you have science that disproves what I’ve said above, let me know! I also welcome any questions or disagreements…flame wars are what makes reddit great!
50% H20 change-weekly
1/2 Tsp-KN03 3x a week
1/8 Tsp-KH2P04 3x a week
3/4 Tsp-GH booster once a week
1/8Tsp-Trace 3x a weekFollow that schedule and you have a well fertilized planted tank. You can buy the dry chemicals from: http://www.aquariumfertilizer.com/ or Greenleaf Aquariums.
Why is iron important?
By mass, iron is one of the most plentiful element on the planet, and one of the oldest metals known to and used by humanity. It is also an important plant and animal nutrient and thus, very crucial to your aquaponics system.
Iron is very reactive- that is, it exists in a variety of ionic states (from +6 to -2) but exists primarily as Iron++(II; Ferrous Iron) or Iron+++(III; Ferric Iron) and transitions readily between them depending on environmental variables.
For this reason, oxygen is an important component in many organic molecules that fix oxygen, or moderate REDOX reactions.
Animals & iron
In animals, the most common iron containing substance is heme complexes. We’re most familiar with hemoglobin. In hemoglobin, iron helps bind oxygen for transport throughout the body.
Plants & iron
In plants, iron serves many functions but is an essential component in the production of chlorophyll, the site of photosynthesis.
Without enough iron, plants cannot produce enough chlorophyll, leading to retarded plant growth characterized by interveinal chlorosis. Iron is also a key component of cytochrome- a hemeprotein that plays a key role in ATP generation- the currency of cellular metabolism.
In this capacity it is irreplaceable to both plants and animals. Iron is also plays a major role in many other proteins and reactions.
Unfortunately, because it is highly reactive, iron is typically unavailable.
It flits between soluble and insoluble forms, forms compounds with other minerals and (in aerobic environments generally) plays hard to get.
The issues with iron in aquaponics
This poses a problem for aquaponic producers. Because systems are generally aerobic (and certainly aerobic in the root zone), iron deficiencies can often arise- even when there is technically plenty of (ferric) iron within the system.
In the aquaponic solution, iron is commonly available in one of two forms- reduced, soluble ferrous iron (2+) and insoluble, oxidized ferric iron (3+).
Ferrous iron is available to plants (soluble!). Ferric iron is not (insoluble).
This is important to understand, because ferric iron is the more oxidized form, whereas ferrous iron is not.
In short, as soon as ferrous iron becomes soluble in aerobic envrionments it is often oxidized, becoming ferric iron or reacts with other compounds to become biologically unavailable (especially at high pH values when different hydroxides are formed).
Now, this relationship between oxygen and iron isn’t a full time thing. In reality iron is flitting between ferrous and ferric states, but the dominant state in high pH and oxidized environments is ferric- and this means that your plants cannot take it up.
These details important because they dictate how we examine the solutions.
Many practitioners throw rusty iron items into their systems falsely assuming that this will supplement system iron.
In a sense it does add to the reservoir of system iron, but not in a constructive or meaningful way. All this does is introduce more ferric iron to the system- a form of iron that was most likely already in plentiful supply.
Other practitioners intentionally develop dedicated anaerobic zones, where ferric iron will be reduced by the oxygen free, anaerobic environment to produce ferric iron. This is a more compelling approach, especially in low pH systems, but still does not entirely address the problem of getting the reduced iron ion (Fe++) through the oxygenated aerobic zone surrounding the plant roots (especially in high pH systems where hydroxyl ions are plentiful!).
In low pH systems, ferrous iron has a much better chance of reaching the root zone, simply because there are fewer hydroxyl (OH–) groups to react with along the way, however even in the absence of hydroxyl groups, there are many other chemical obstacles to reaching the plant root zone in adequate quantities.
Plants have adapted to this issue.
This is a problem, but one that has not been overlooked by nature.
You see, plants have been contending for these nutrients for eons, and as a result have developed some amazing chemical means of hijacking ferric iron ions, tying them up, bundling them into the soluble, biochemical equivalent of the panel van, and delivering them, bound and gagged, to the root surface for plant use.
Plants also use a few other techniques to make iron available, including acidifying the root surface by excreting hydronium ions, and secreting iron reducing compounds. But for the sake of aquaponic system management, this first biochemical iron fixing technique is what we will focus on.
Chelation – an aquaponic iron-fixing technique
This process is called chelation- that is, tying insoluble ferric iron ions and compounds to organic molecules to make them soluble.
Chelation is accomplished by special organic molecules called chelatins or chelating agents. These are organic molecules that are specially designed to capture, or “dissolve” metals, of which iron is one.
In the plant world, chelatins are produced by the plant roots and leaked into the soil capture and deliver insoluble iron ions.
The most effective of these compounds are phytosiderophores which bind ferric iron very strongly, pulling them from the various insoluble precipitates and substances in which they most commonly occur. These are special compounds produced by certain plants (phytosiderophores) and bacteria (siderophores) that are incredibly effective at binding iron. The grasses (Poaceae), and especially barley are particularly effective at producing phytosiderophores for capturing iron.
(As a side note: a great deal of research is being done on using barley to produce siderophores for iron sequestration, and holds some interesting implications for aquaponic system where practitioners are willing to grow barley.)
Other chelating agents
Other common chelating agents are amino acids, organic acids (especially humic acids), and polyphenols.
These are compounds that help keep the iron soluble and biologically available to the plants and algae in the system. While these compounds can be introduced, and humic or “tea-water” solutions can be fostered and managed, they aren’t always enough to keep iron available to the plants- especially in systems with a pH or 7 or above. In these systems, an artificial chelatin is often required.
Because I use peat potting mixes for all of my seedling germination and transplants, my systems typically maintain high levels of humic substances. However: I still supplement chelated iron regularly.
Iron is one of the plant nutrients that must be supplemented in almost all aquaponic systems.
To supplement iron, chelated iron must be added to systems.
Admissible under USDA Organic standards, chelated iron is an artificially chelated iron ion- essentially, iron attached to an organic molecule to make it soluble.
By adding chelated iron, iron deficiencies in your plants can be avoided.
Forms of chelated iron
The most common forms of chelated iron are:
FeEDTA: This is a slightly toxic form that aquaponic practitioners should not use. This type of chelated iron is commonly used as an herbicide to kill broadleaf weeds. It should not be used just because of it’s toxicity, but also because it typically only effectively chelates iron up to the pH range of 6.3 or 6.4. Above this range it is not a stable chelate. So, using FeEDTA in your consistently pH 7.0 system represents a significant amount of money wasted in comparison to other forms of chelated iron. For this reason I recommend that AP practioners do not use FeEDTA. It is ironic that this is the most commonly sold and used form of chelated iron in aquaponic systems as it is fairly ineffective- the equivalent of modern “aquaponic snake oil.”
Fe DTPA: This is what I recommend for most systems at pH values between 6 and 7.5. It is commonly available at lawn and garden stores.
FeEDDHA: This is what I recommend for systems above pH values up to 9.0 (let’s hope your pH never gets that high!), and the best all-round form of iron chelate- especially for starting systems. Effective at a broad pH range, FeEDDHA maintains iron solublility in almost all of the water conditions encountered by startup aquaponic systems
Chelated iron fertilizer is available from many different suppliers. I typically get mine from the local hardware store.
Common thinking about adding chelated iron
There are two schools of thought on chelated iron addition.
Some say that chelated iron should be applied any time you see deficiency. This is a reasonable and reactionary dosing method, but ultimately means that your plants must first suffer from iron depletion and deficiency before the problem is addressed. In this scenario plant production can be negatively impacted. The other (and better) school of thought is to apply iron at the standard UVI system rate of 2mg/L every three weeks.
Iron can also be applied through foliar application- using either chelated iron or ferrous sulfate mixed at low concentrations. Foliar application is great for fast response, but because iron isn’t a mobile nutrient inside plant tissues, iron will have to be supplemented regularly using this method- a time consuming, and ultimately less effective iron supplementation method.
Using this method, iron can be regularly dosed so that iron deficiencies do not arise in your system.
Cost of Chelated Iron
While many practitioners complain about cost, when bought in the 5-10 pound bag, chelated iron is really not very expensive, and often even in large commercial systems, will last for many months.
At the dosing rate above, a 10 pound, $15 bag of chelated FeDTPA will last well over a year, or less than $1 per month. At higher iron concentrations it will last much longer.
Chelated iron products
We’ve had several folks ask about where they can get good iron supplements and how much they cost. Here is that info:
- “Miller DP”- DTPA (On the shelf or ordered through Ace hardware)
- “Sequestrene”- DTPA (5 lbs bag on Amazon for $57)
- “Miller FerriPlus”- EDDHA (SunshineGardensFl.com; 1 lb for $20, or 20 lbs for $300)
- “Sequestar Iron 6% Chelate” – EDDHA (RoseCare.com; 5 lbs for $73)
All of these products will work great in your system!
Quick tip: red dye in Miller’s FeEDDHA!
A friend and blog reader let us know about this product that seemed to have turned his entire system water red after adding 3 ounces. It appears the Miller’s product contain red dye! A dye probably won’t hurt your fish, but double check to be sure.
We hope that this blog post is helping you keep your system healthy. To learn more about aquaponics and ZipGrow systems, check out our Youtube channel.
Understanding Aquarium Filtration
‘Aquarium filtration is a bit of a mystery to most people. There is a common misconception that the filter should take care of overfeeding and keep the water perfectly suitable for fish. Manufacturers make a big deal out of it. Most of the new filters coming to market are large, complex and expensive. The companies making them, lead you to believe that if you are having problems with your fish, then it’s probably due to the lack of filtration. You may be surprised to learn that the amount of filtration is the least likely cause of most problems. In this article, I hope to clear up the mystery and make this an easy concept to understand. Keeping your aquariums clean and suitable for fish is quite easy as you’ll see.
Let’s get down to basics. You can filter water with three basic methods. There is chemical, mechanical and biological filtration. Most filter systems involve a combination of at least two of these and some use all three. We are often led to believe that all are necessary, yet in my opinion only one is really important, and effective in most filters. Now let’s take a more detailed look at each and how much sense it makes to incorporate them into your filtration methods.
With chemical filtration You use an item like carbon or zeolite to remove an impurity. The chemical reaction that takes place is usually very short lived and its effectiveness lessens rapidly from the very beginning of its use. In my opinion, unless you want to do an extraordinary amount of maintenance on a continual basis, this type of filtration is suitable only as a temporary measure. It’s great for emergencies, removing medications from the water or trying to reduce sudden spikes of toxins. It’s good to have some of these items on hand, but don’t bother to incorporate them into your daily filtration system. In general, doing so would be a waste of time and money.
Mechanical filtration: This involves the trapping and removal of waste particles. In concept, this is a great idea. In reality, most filters cannot do this in a manner that is effective or convenient for the aquarist. Most mechanical filters do a great job of trapping some particulate matter, but unfortunately they don’t get it all. They have a tendency to move the water too fast, thus breaking the particulate matter into smaller pieces. The very small pieces tend to become suspended. These suspended micro particles contain the dangerous heterotrophic bacteria that can potentially cause great harm to our fish. The bacteria should be kept away from our fish, but these suspended particles do the opposite. They are in the water column and can be very harmful.
Filters that move water through the aquarium at higher speeds, cause this problem to become worse. Small waste particles are the enemy. Filters that move water too quickly and those that create a large amount of small bubbles, break these particles into even smaller pieces and will actually cause this bacteria to become an even greater problem. To encourage small waste particles to settle in the filter chamber, water movement must be the slow enough to cause the particles to settle. This is very difficult to achieve with most power filters and canister filters. Very large aquariums or aquaculture systems will generally have large filter systems that contain proportionately large settling chambers, where these fine particles can be eliminated from the water column.
In addition to removing these particles from the water column, they need to be removed from the bottom of the tank. The fins of fish often touch the bottom, and the waste particles that settle here can cause problems when the fish rubs against them. Therefore, a filter needs to draw from the tank bottom and anything it doesn’t get, must be removed through siphoning. After waste has been on the tank bottom for more than a day, it has been largely broken down by the heterotrophic bacteria and turned into an unsightly, but relatively harmless mulm. At this point, it’s only danger is that it will slowly increase the dissolved solids in the water, and will contribute to higher nitrates. However, it will do this whether it’s on the tank bottom or sitting in a filter. Unless you clean your filter a couple time/day, it won’t make much difference.
Biological filtration: This is the process by which nitrifying bacteria break down ammonia and nitrites. I will not cover the basics of biological filtration. That is detailed in many other sources. Just realize that it is easy to have adequate nitrifying bacteria in aquariums containing ornamental fish. In intensive aquaculture, it is common to raise as much as 1 lb of fish per gallon of water, with relatively small biological filters. That would be equivalent to raising somewhere around 100-150 adult angelfish in a 20 gallon tank. In such a system containing angelfish or other ornamentals, problems from dissolved organics and heterotrophic bacteria would destroy the fins or kill the fish long before ammonia or nitrites became a problem. A surprisingly small biological filter can handle the ammonia produced in the average aquarium containing ornamental species. So, although biological filtration is very important, it’s also very easy to provide with a small inexpensive filter. The only requirement is that the filter does not clog so the nitrifying bacteria has constant exposure to oxygenated water, and that the filter does not move the water too fast, producing the dangerous micro-particles of waste that are so harmful.
Tying it all together: As you have probably surmised by this point, chemical filtration is not practical or effective for most aquarists. In addition, mechanical filtration is normally performed in a manner that can actually be detrimental. Unfortunately, most aquarists rely heavily on these and are not aware of the best way to utilize them. In fact, some of the most expensive filters can also be some of the least effective.
One of the oldest filters is an undergravel filter. Water flows through the gravel, and in the process will create a very effective biological filter. If it is set up to have the flow go down through the gravel and then up a lift tube, the gravel will collect waste, making it an effective mechanical filter. It often gets an undeserved bad rap. When maintained properly, they are very effective. Add in the fact that they are very inexpensive to purchase and operate, and you have one of the better choices for an aquarium that contains a substrate.
When setting one up, place the filter plates on the bare tank bottom. Then cover them with a layer of polyester batting or even better – an inch or two layer of reticulated foam. The foam will prevent the substrate from falling into the filter plates and it will also provide greater surface area for nitrifying bacteria. Cover with a substrate that is fine enough that no food particles can fall beneath the surface of the substrate. This will allow the easy siphoning of uneaten food that cannot be trapped. When doing a water change, use a gravel cleaner to remove particulate matter. Do this to no more than one half of the substrate during any one water change. Vary the location of the substrate cleaning with each water change. Using this technique, I’ve maintained beautiful, healthy aquariums for more than 20 years without ever having to add any additional filters or perform any other maintenance.
For breeding operations or the raising of fry, bare bottom tanks should be used. In these situations, nothing beats a simple sponge filter or whole-tank foam filters for effectiveness and ease of maintenance. However, not all foam filters are equally good. You must choose one with a pore size appropriate for the fish size being kept. The object is to keep the pores from getting clogged with food or fish feces. It should provide adequate surface area for nitrifying bacteria. The sponge type should allow easy rinsing of the filter. Yet, it must also allow space for the settling of organic debris.
If one sponge filter isn’t enough, use more or switch to whole-tank foam filters. Slow to moderate flow rates are essential. The smaller the filter, the slower the flow rate must be. The inside of the sponge becomes the settling chamber. Too much flow, and the settling chamber will not work. It is important that the sponge filter lifts water from the bottom of the tank. It not only makes it easier to get particles off the bottom and into the filter, but it turns the water over in the tank more efficiently for greater gas exchange. Therefore, foam filters should sit flat on the bottom. Those that are on a pedestal, may create dead spots in the aquarium, and are the worst at trapping particles that make it to the tank bottom.
A note about filter size: Filters are not sized for a particular number of gallons of water. They work by consuming ammonia and nitrites produced by a particular bio-load. The bio load consists of the total mass of fish and heterotrophic bacteria in the tank. It matters not if the tank is large or small, filters have to be sized accordingly to the number and size of fish in relation to age, water temperature, pH and a few other factors. It is something you can only figure out for a given situation through experience. As long as the water isn’t moving too fast in the tank, it doesn’t hurt anything to over-filter, which is why we are so partial to whole-tank foam filters.
So far, providing the needed filtration sounds fairly simple, but don’t get too excited. One of the more important aspects of filtration can’t be performed perfectly by any filter and is usually done manually. That is, the aquarist must periodically remove fish waste and detritus with water changes, and they must also occasionally rinse the filters to keep them from clogging. Water changes are what is used to remove harmful dissolved organics and nitrates. Most aquarists worry about ammonia and nitrites. However, they are easily controlled and seldom a problem for anyone other than a beginner with poor husbandry practices. Dissolved organics and heterotrophic bacteria are the real concerns, yet they are almost impossible for an aquarist to detect. It is critically important to keep them at low levels. Water changes are the most effective way to do this.
How to rinse sponge filters: Gently squeeze the sponge into fish-safe water (we use water taken out of the aquarium from a water change). Do not rinse it too thoroughly. You don’t want to wash all the nitrifying bacteria out of it. Never clean them in a washing machine or dishwasher. This will essentially kill all the good nitrifying bacteria and render your filter useless.
Water changes can even be used to remove uneaten food, but hopefully your fish husbandry is good enough that uneaten food doesn’t exist. The frequency needed for water changes will vary greatly with fish density, temperature, amount of food being put into the tank, pH and a few other factors. It’s better to err on the side of more water changes. You can perform too few, but never too many.
It should be a relief to know that through the combination of properly designed foam filters, correct feeding, and adequate water changes, you can filter an aquarium better and at lower cost than any other practical method. Don’t fall prey to the hype surrounding expensive aquarium filters. There exists some very effective, sophisticated and expensive central filtration systems designed for hatcheries, however for practical filtration on individual aquariums, nothing works better than the simple filters recommended here.’
© 2006 Angels Plus
Using Leaves As Fertilizer: http://www.spectrumanalytic.com/support/library/ff/Plant_Nutrients_in_Municipal_Leaves.htm
Application of collected municipal leaves to agricultural land improves soil quality and pro�vides a solution to a disposal problem. Farmers are permitted (New Jersey Register, NJAC 7:26�1.12. Nov. 7, 1988) to apply up to a 6-inch layer of leaves annually. Application at this rate, which is equivalent to approximately 800 cubic yards/acre or 20 tons/acre of dry matter, will increase soil organic matter content, and im�prove soil tilth and water holding capacity.
A chemical analysis of 100 municipal leaf samples collected from across New Jersey shows that leaves are a valuable source of all crop nutrients (Table 1). Although nutrient con�centration values vary considerably, the applica�tion of 20 ton/acre of leaves would add on average 400 pounds of nitrogen, 40 pounds of phosphorus, and 152 pounds of potassium. As�suming values of $.30/pound N, $.23/pound P, and $.18/pound K, the nutrients from this ex�ample are worth $156.56.
Application of leaves at 20 ton/acre would also add on average 656 pounds of calcium, 96 pounds of magnesium, 44 pounds of sulfur, 1.5 pounds of boron, 58 pounds of iron, 22 pounds of manganese, 50 pounds of chloride, 4 pounds of sodium, 0.3 pounds of copper, and 3 pounds of zinc. The actual amounts of nutrients applied can vary considerably as shown by the concen�tration ranges in Table 1.
Although leaves add agronomically signifi�cant amounts of nutrients, only a portion of the nutrients are available immediately after application for use by the crop. The increase in the soils total nutrient content will, however, con�tribute to the long term fertility of the soil as the nutrients are released over time.
Much of the nutrients in leaves are part of the organic structure of the plant tissue and require microbial decomposition to release them. The carbon-nitrogen ratio of an organic material un�dergoing decomposition is an important indica�tor factor in the rate of release of its nitrogen in available form. The average carbon nitrogen ratio of leaf waste is 50 and it ranges from 27 to 72. For comparison, the carbon-nitrogen ratio of compost is generally about 25.
The abundant carbon (carbohydrates which provide energy) content of leaves leads to exten�sive development of fungi and bacteria in the soil which uses up the supply of available nitro�gen for the production of microbial cell tissue. As decay proceeds, the carbon-nitrogen ratio decreases and some of the nitrogen becomes available to plants. Because of the high carbon content of raw leaves relative to their nitrogen content, there will likely be very little of the organic nitrogen in leaves available to crops for a period of time after application. Observations of crops (including legumes) planted on soil to which leaves have been applied indicate that plants suffer from a temporary N deficiency unless additional N fertilizer is added.
Crops grown on soilsthe year after leaf application likely will need additional N fertil�izer. Legume crops, such as soybean, may benefit from 20 to 30 pounds of starter N banded beside the row at planting. This will supply a readily available N source to be used by the legume until it forms nodules to supply N by fixation. An additional 50 to 100 lbs of N fertil�izer is recommended for corn grown the first year after leaf application. The additional fertil�izer that is required increases the cost of crop production on the soil the first year after an application of leaves.
The amounts of P, K, and other nutrients present in leaves are not easily translated into nutrient credits that may be used to reduce fertil�izer application. These nutrients are relatively stable in soil and can be monitored simply through soil testing. As soil fertility levels in�crease as a result of leaf applications, take credit for these nutrients by fertilizing accord�ingly.
Of the three major nutrients, potassium is the most easily released from leaves and is the most readily available to crops in the first year after leaf waste application. A minimum nutrient credit of 50 lbs K2O per acre may be used for 20 tons of leaves.
Application of collected municipal leaves to soil should not significantly change its agricul�tural limestone requirement. Three years of municipal leaf application caused no decrease in the soil pH compared to unamended soils.
|Table 1 Nutrient concentrations in municipal leaves (dry weight basis).|
|Phosphorous (P2O5)||0.02 (0.05)||0.29 (0.66)||0.1 (0.23)||2.0 (4.6)|
|Potassium (K2O)||0.09 (0.11)||0.88 (1.06)||0.38 (0.46)||7.6 (9.1)|
|Nutrient||Parts per million||Lb/ton|