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Transcript of Soil Fertility
The elements in fertilizer, what they do
Fertility and Fertilizer,
Organic vs. Synthetic
Plants absorb nutrition through the cell walls in their roots. Root hairs give plants more surface area to absorb nutrients.
Foliar sprays aren't the main way to nourish plants- they are best for correcting obvious nutrient deficiencies, or helping young plants get a boost, like a multi-vitamin.
We know what compound plants use for photosynthesis.
Nitrogen is a key element in chlorophyll.
Phosphorous helps the plant make proteins- to be hardier, to grow roots and produce flowers.
Potassium - involved with 50 different enzyme reactions in plants. Potassium helps plants resist drought (by keeping water pressure high) and resist disease.
Deficiencies in any of the essential nutrients can stunt plant growth, cause deformed leaves and fruits, or even cause plants to die.
Less fertile soil
More fertile soil
The most "nutrients" plants get are from air and water...
While there are plenty of air and water right now- we do have to protect these fragile resources.
Plants get Hydrogen from water (H20) and use it for making sugars and building the plant.
Plants use the Oxygen from water and air the same way human cells do- to burn fuel for energy.
Plants get all of the rest of their nutrients from the soil solution. "Soil solution" means the elements that can be brought to the roots by water.
Phosphorus is what makes matches light.
Efficient fertilizer use
All of Earth's water
All of Earth's air
The basic elements plants need are like building blocks that can be combined thousands of ways to make amino acids, proteins, carbohydrates, and medicinal compounds.
"Organic" fertilizer means that it comes from organic matter.
That means dead plants,
poop from animals that ate plants,or parts of dead animals.
For thousands of years, compost, manure, and field rotation were the only ways people had to keep their lands fertile. It was "organic."
Another drawback for some people is that different organic fertilizers have different amounts of nutrients. It's hard to be precise.
If not used carefully, plants could get too much of some nutrients and not enough of others.
Most organic fertilizer plans will improve the biological, chemical and physical properties of soils over time.
When a lot of manure is applied there is a tendency for too much Phosphorus to accumulate. This can cause nutrient absorption problems for the plant, or runoff as pollution.
Organic matter feeds and provides a home for soil life, and promotes healthy soil biota.
Because nutrients in organic matter need to be broken down by soil life, they are not immediately available in the soil solution.
This means organic fertilizers need to be added well ahead of time in order to provide for the plant's needs at the right time in the growing process.
However pollution from manures and compost is less likely than from synthetics, because the nutrients get bound up in the bodies of micro-organisms, and stay in the soil longer.
Used improperly, manure will cause pollution. However because the Nitrogen is locked up in the soil and needs to be released by bacteria, typically it causes less pollution.
Fish emulsion, fish bone meal etc.
Won't burn plants
might burn plants
can burn plants
Won't be absorbed with high ph
dangerous to breathe
Toxins in organic matter
If the animal had diseases or ate antibiotics, that will end up in the manure. If a fish has heavy metals in its body from living in toxic water, that will end up in the garden.
That's right, the "greenhouse gas" everyone is worried about- plants make into a yummy and nourishing meal.
pH is a measurement of Hydrogen and hydroxide ions in the soil.
Almost 80% of the air we breathe is Nitrogen.
The micro-nutrients have specific functions in plant health.
Nitrogen is always important, but especially when a plant is growing tall, leafy structures.
Symptoms typically appear in either old leaves or new leaves.
If symptoms appear on new leaves, the nutrients are mobile.
Deficiencies could be Sulfur, Calicium, Iron, Manganese, or Copper.
If symptoms appear on old leaves, the nutrients are non-mobile.
Deficient nutrients could include Nitrogen, Phosphorus, Potassium, Magnesium.
-Plants have stunted growth
-Leaves develop a yellow color, called chlorosis.
-Plants may have stunted growth throughout the whole plant, especially when young
-In older plants, older leaves may develop a dark green t blue color. In corn, purple.
-Deficiencies can cause poor fruit and seed development as well as delay crop maturity.
-Plants often have stunted growth
-Older leaves may develop chlorosis along the margin, or edge of leaves
-Some crops may have weakened stalks
-Plants may show uniform chlorosis (yellowing) of leaves.
-Growth may be stunted with weak leaves and stems.
-New buds, leaves and root tips fail to develop, turn brown and die.
-Leaf tips are often chlorotic or colorless
-Sticky substances may be excreted from the growing points causing leaf tips to stick together as new leaves emerge.
-Young leaves may be cupped or crinkled
-Buds, blossoms and fruit may rot and fail to reach maturity.
-Plants may develop intervenal chlorosis - leaf tissue becomes yellow while veins remain green
-Intervental tissue in some crops may turn reddish, purplish and bronze
-The entire leaf may become chlorotic
-Leaves may be thickened, curled and brittle. Stems may become cracked
-May have rotting and discoloration of fruits and roots
-Plant may have stunted growth
-Plants have chlorosis, stunted growth, curling of young leaves
-Leaf tips and leaf edges may die
-Leaves may turn dark bluish-green
-Deficiency symptoms include intervenal chlorosis, leaf may turn white and die in severe cases
-Chlorosis appears as yellow dots
-In monocot plants black spots may appear at the base of the leaves
-Plant may have stunted growth
-May resemble Nitrogen deficiency since molybdenum is involved in the major nitrogen processes that occur in plants
-Margins of leaves may develop spots of dead leaf tissue
-Intervenal chlorosis may form in younger leaves, bands may form between midrib and edges of leaves
-In some crops chlorosis develops on older leaves, eventually killing the leaf
-Leaf margins may develop red or yellow color
-Plant may have stunted growth
-The plant may have stunted growth
-Root growth may be severly restricted
-Older leaves may develop small, dark brown spots
-Leaf edges and tips may also become chlorotic, which leads to the death of the leaf
-Young leaves may become cupped and crinkled
-Plants develop thickened, rolled leaves
-The plant appears to be wilting due to reduced water uptake
Of the 118 elements on the periodic table, plants use just 17 to make all of their foods, enzymes, vitamins and compounds.
Plants make so many compounds and substances, including medicines, how could they do all that from just 17 elements?
Plants breathe Carbon Dioxide-
These three macronutrients are always going to be the main focus of fertilization because they are so hard for plants to get enough of.
Green stuff called Chlorophyll
As much as half of nitrogen fertilizer can be lost if applied at a time when the plant isn't actively absorbing it. It's lost by runoff and de-nitrification by bacteria.
That pollutes- and wastes a lot of money!
Both Nitrogen and Phosphorus can runoff and pollute waterways.
Blue baby syndrome
Killing off soil life
The high cost of fertilizer pollution
Plants use chlorophyll to make their food
Function- Healthy roots and blossoms or fruits.
Function- Overall plant strength and vigor
These and the micronutrients are equally important but easier to get than NPK.
K stands for Kalium, the Latin and German name for Potassium
Potassium regulates opening and closing of a plant's stomata and many other processes.
Chemical fertilizers provide just one nutrient at a time.
They can be blended to provide more than one element in the same bag.
The advantage is adding high quantities of needed nutrients at the precise time and dose that your crop can use.
Pound-for-pound chemical fertilizers pack the most NPK.
The three numbers are percentages. 16-8-0 means the bag is 16% N, 0% P, and 8% K. You can see the same size bag of chicken manure has a lot less NPK in it.
Chemical fertilizers are available immediately because they don't need micro-organisms to break them down.
Getting the most out of fertilizer
Test your soil to see what you need- You might be able to save a lot of time, fertilizer, and money.
Check pH - your plants aren't going to get any of that expensive nutrition if pH is off
Adding fertilizer when your plants will need it reduces waste. Also make sure not to fertilizer directly before very heavy rain is expected.
Improve the soil's ability to hold nutrients with organic matter.
Fresh manure will burn plants, and can have dangerous pathogens. Manure needs to be composted to be safe, or can be mixed in the ground at least 120 days before planting.
Nutrients available in manure
Cow/ Steer .6-0.2-0.5
Guano (bat) varies
Why so different?
Chicken Manure is considered the best because chickens excrete their liquid and solid wastes together. The liquid waste for all animals is what has Nitrogen in it.
Use animal bedding
The straw used on the floor in animal stalls may have a lot of nitrogen from their pee.
Yes, your pee has a lot of nitrogen too- but if you want to fertilize the garden yourself- careful, too much on a young plant can burn it!
Humanure - if you really have to
Some places in the world there is such a need for fertilizer, there isn't enough animal waste to feed the plants. In China for example, human waste is often composted and used in rural areas.
There are a few commercial fertilizers made from processed sewage.
...Maybe don't buy those.
It's called "nightsoil"
It's called "bio-solids"
Last but not least is compost
Greens are for nitrogen, old leaves are great.
You can get a lot of nutrients out of compost, but over time it won't be enough to keep your garden going without animal manure or other animal-based fertilizers.
Organic fertilizer breaks down slowly over time- so what you add this year will also provide some benefit in the following years.
Keeping track of what you added this year helps you save time and money next year.
-Dead animals (except fish)
-Poop from carnivorous animals like dogs, cats, lions and tigers- these can have parasites and all kinds of nasty stuff.
With and without fertilizer
The "law of the minimum"...
Nitrogen for green leafy growth
Phosphorus for strong roots and blooms
Potassium for overall hardiness and strength
Chemical fertilizer make sense- because they can quickly replace the nutrients that plants use the most.
Some elements plants need come from inorganic sources, from rock that has broken down and become part of the soil.
Some of these rocks contain plant micro-nutrients.
What was planted here? Some crops are "heavy feeders" on certain nutrients, and will deplete the soil.
Plan for your crop
What crop are you planting? What are it's specific needs?
Test your soil- structure.
Soil texture and structure are really important for good drainage and holding on to nutrients- see the soil prezi for more information.
Bacteria and fungi in the soil help make more nutrients available to plants. If growing organically soil life is essential for plant health.
Look how much this plant extends the range of it's roots with mycorrhizal fungi.
Healthy soil is an eco-system, teeming with life. It can regenerate itself and maintain fertility over time.
Soil fertility needs to be cared for with the management of physical soil properties- texture and structure, with nutrients, and with soil life.
This plant can get so many more nutrients!
See more in the pH unit
That will work for a few seasons...
Until the nutrients in the soil run out..
1. Know your soil history.
Some scientists say our soil is already very depleted.
16% of this bag is N 4% of this bag is N
-You'll need 4 more bags of the organic fertilizer to get the same weight of Nitrogen.
Organic matter makes soil healthier because it's not just adding nutrients, it's creating healthy soil
Everything changed in the late 1940's with the "Green Revolution"
Is this really the case? Are chemical fertilizers toxic? Are organic ones all good?
Both organic and chemical fertilizers have a place in the world today,
Chemical fertilizers boost production, allowing more to be grown on less land.
Pound-for-pound chemical fertilizer have WAY more of the macro-nutrients than organic fertilizers.
With a chemical fertilizer, a farmer or gardener can apply exactly the dose of a specific nutrient he or she needs
Organic fertilizers help improve soil health and soil structure, keeping soil fertile in the long-run.
Organic fertilizers will have more trace minerals and micro-nutrients, chemical fertilizers only have the macro-nutrients.
Soil micro-organisms and the soil eco-system benefit from proper organic maintenance.
Organic fertilizers need to be broken down by micro-organisms and are less likely to pollute if used properly.
a molecule of chlorophyll
The idea behind organic growing is to create a healthy ecosystem and soil that is fertile season after season.
Creating soil fertility organically means building soil organic matter, feeding soil life, and using organic sources of fertilizer. (And no toxic pesticides.)
Cover crops alternate with other crops, and are planted in the off-season.
Seaweed is also really nutritious, and can be ground up and put directly on the soil, even right next to crops.
*Some fertilizers have a coating so they are released more slowly over time.
Because inorganic fertilizers are available immediately in the soil, you can fertilize for a crop at the time it needs it most.
Plants, and the people and animals who eat them, need more than just NPK. Some studies show US farmland is severely depleted in minerals.
Healthy soil structure has pores for air, water, and micro-organisms. It has a balanced pH, and can hold lots of nutrients in the soil.
If only chemical fertilizers are used for many years and organic matter isn't replenished, the soil will become hard and crusted.
Because most chemical fertilizers are immediately available in the soil- they are also more likely to runoff and cause pollution.
When Nitrogen and Phosphorus run off they can damage waterways, and the health of humans and animals.
It is important to continue to add organic matter when using chemical fertilizer. This helps build soil, ensuring long-term fertility.
Fertilizer application methods
If using solid fertilizers- there are a few different ways to feed your plants.
De-nitrification is when bacteria break down Nitrite back into Nitrogen and Oxygen gas.
In other words, Nitrogen that's available to a plant (because it's fixed to another element in the soil) returns to the atmosphere.
The "dead zone"
Fish and creatures that can swim away do- the ones that can't move far enough, fast enough, die.
Fertilizer runoff rom farmland to the Mississippi river into the Gulf of Mexico causes a permanent "dead zone"
When nitrates leach into groundwater, and are drank by babies, they can cause hemoglobin in blood to be unable to carry oxygen- causing death.
Nitrogen pollution can cause damage to fisheries, natural wildlife habitats, coral reefs, and to human health. Billions of dollars each year are spent to remediate fertilizer pollution.
Also, because they are so acidic, N and P fertilizers bond to bases in the soil, and form salt- which makes soil even less fertile and more inhospitable to micro-organisms.
Over fertilization will kill off soil life- making it hard for soil to regain natural fertility, and destroying soil structure over time.
Nitrogen fertilizers are acidifying- over time they cause the soil to become highly acidic and inhospitable for soil life.
As you may have seen in the pH prezi- H+ ions are what determines how acidic a substance is...
Fertilizer is expensive and gets more expensive every year.
More isn't always better..
At some point, more fertilizer won't help, and you'll just be pouring money (and pollution) into the ground!
Use precise applications
Once you know what your soil has- you can add just the amount of fertilizer you need.
Use the right equipment
Modern GPS and computer controlled tractors can deliver precise amounts of fertilizer. That can reduce fertilizer use up to 25%
Plan based on previous and future crops
Each crop has different needs- if using chemical fertilizer, fertilize for the crop.
Timing is everything
Support soil life- bacteria make more nutrients available from the soil. Mycorrhizae fungi help the plant reach nutrients in parts of the soil it couldn't alone.
Areas of severe fertilizer pollution
Does organic fertilizer pollute?
Yes- it can, and does.
But it rarely causes damage on the scale of chemical fertilizer pollution.
In most organic fertilizers, the nutrients are locked up in the dead organic matter, or the bodies of micro-organisms feeding on it.
With chemical fertilizers, the nutrients are available immediately, and can easily wash away.
Most organic fertilizers also improve soil structure, and improve the soil's ability to hold nutrients.
Soils with more organic matter have a charge that helps hold nutrients in the soil, causing less runoff.
Different plants take different amounts of nutrients from the soil. switching up crops gives the soil a chance to recover.
Organic fertilizers almost always contain multiple nutrients, including micro-nutrients
For green growth
For roots and blooms
For overall health and vigour
Want awesome produce?
Of course you do...
You need fertilizer, and fertile soil
Adding a missing nutrient has a dramatic effect on crop yield
Corn deficient in Phosphorus
Fertilizers add missing nutrients to soil
When we talk about
, we are talking about
in the soil
that affect plants being strong and healthy.
Soil texture and structure
The needs of the crop you are planting
All of these things affect fertility
When we talk about
, we mean
just the nutrients
plants need- not all the other factors.
Both organic and synthetic fertilizers can provide plants with the nutrients they need.
Why is Potassium "K?"
K stands for Kalium- which means "Potassium" in Latin and German- the languages used when inventing the periodic table.
Plants need just 17 elements to grow well. They need to get 14 of those from the soil.
As much as 5% of a plant is Nitrogen
1-2% may be Phosphorus
Only a tiny amount is Potassium, but it's so hard for plants to get naturally and so important that it's included as one of the big three.
From air and water
The hardest to get, needed in the largest quantity
These are just as important but only needed in small amounts.
These are only important for some plants.
Calcium, Magnesium and Sulfur
These three micro-nutrients (or "secondary macro-nutrients) are needed in relatively large amounts.
The micro-nutrients are needed just as much as macro-nutrients, they are only needed in teeny tiny amounts, measured in PPM - Parts-Per-Million.
That's like a drop in a bathtub.
So why do plants need Nitrogen to be green and grow?
So why can't plants get enough?
Plants can only absorb Nitrogen when it's been "Fixed" (taken out of the air by attaching it to another element) and is available to a plant's roots.
Bacteria do it in the soil.
Nitrogen deficiency causes a characteristic yellowing of the leaves.
Severe deficiencies will cause purple leaves.
Potassium deficiency may show up as damage to the leaves, or as overall lack of health in the plant.
Plants need calcium for cell wall development and growth.
Magnesium- another important part of chlorophyll
Sulfur helps plants take in the nutrients they need.
Lucky for plants these days there is a lot of sulfur pollution.
These are all just as essential to plant health as the macro-nutrients.
Chemical fertilizers "fix" nitrogen in a high - temperature, high-pressure process, using petroleum.
Nitrogen for green growth, leaves and stalks.
Plants make carbohydrates, proteins, vitamins, enzymes, and thousands of other compounds for disease and pest control.
They can do this from just
The nutrients plants need most are NPK, and compared to chemical fertilizers, a lot more organic fertilizer is necessary to get the same amount of these three.
Plants also need the secondary macro-nutrients and micro-nutrients.
You're more likely to find these in Organic fertilizer.
The downside of that..
Organic fertilizers need to be broken down, so they release slowly over time. What you add one season will still be providing fertility the next.
Chemical fertilizers don't have a slow process of decomposition, so they don't last as much from year to year.
To ensure your Nutrient Management Plan works:
-Know your crop's nutrient needs
-Keep track of what was used to fertilize in previous years and how much is still available to plants
-Test your soil
-Use soil management practices that boost soil fertility
So- on the downside of Organic, you need more organic fertilizer than chemical fertilizer to get the same NPK values, and it's hard to be precise with your dose.
On the upside, you get lots of micro-nutrients, fertile living soil, you need less fertilizer the next year, and there is less pollution.
Over-use of chemical fertilizers can damage soil structure over time.
Those soil bacteria, fungi, bugs and worms all contribute to good soil structure, to making nutrients available in the soil, and to helping plants get more of the nutrients that are there.
-Not as immediately available
-Not as precise
-Need larger quantity
-Potentially more expensive.
-Improve soil structure
-Holds nutrients in the soil
-Feed soil bacteria
-Provides fertility in the future
-Less likely to pollute
Using organic fertilizers
Deficiencies have particular symptoms.
You'll need to use some kind of fertilizer to grow healthy plants.
Fertilizer in the soil can break down or leach out of the soil when it rains, or with irrigation.
Choosing Organic or Synthetic fertilizers
As the algae dies, it decomposes, a process that uses oxygen. This makes the water so low in oxygen nothing else can live there.
It's called "eutrophication"
Soil health and fertility will be different over time depending on organic matter use vs chemical fertilizers.
This is where "sustainability" comes in.
Chemical fertilizers can increase crop yields in the short term- but over time, soil can become infertile if that's all that's used.
Most chemical fertilizers provide the NPK- and maybe some Ca or Mg... but not the micro-nutrents
This doesn't build soil health
Pound for pound, you get way more NPK from chemical fertilizer.
It's not always easy getting enough N or K with organic sources.
Organic fertilizer can cost more, and take more work to apply.
What's wrong with chemical fertilizer?
Cover cropping makes a comeback.
Ammonium Sulfate (NH4) 2 SO4
21% N 11% S lowers soil pH if used a long time
Ammonium Phosphates MAP
Nh4H2P03 supplies N and P 11-13% N and 48-62%P205
completely water soluble
placement must be done with caution because NH3 can be produced, causing seedling injury... causes alkaline reaction
or Diammonium phosphate DAP (NH4)2HPO2 causes soil pH acidic
KNO3 Contains N 13% and K2O 44% causes soil pH to increase slightly
Calcium Nitrate Ca(NO3)2 contains 15% N and 34% CaO. Can liquify if not stored properly and kept dry
(CO(NH2)2 45-46% N. Less tendency to cake and less corrosive than other N fertilizers. High concentration is convenient. Soluble and can leach easily as nitrate.
Once converted to NH4- and HCO3- in the soil the NH4+ can be held on exchange sites and is less subject to leaching. can raise soil pH initially but over time soil pH can decrease due to nitrification of nH4+ to NO3-
Urea can contain biuret, a phototoxic impurity. citrus and pineapple can not tolerate these.
Sulfur-coated urea (SCU) is a controlled-release fertilizer that has a sulfur shell around each urea particle. The shell breakind down depends on micro-organisms. 36-38%N. useful in porus soils or where NO3- can leach easily.
27-41% P2O5, which is slowly available to plants but persists in the soil for many years.
broadcast and mixed thoroughly so it can dissolve more rapidly. Effective on pastuers and perennials.
Single Superphaosphate SSP 16%-22% P2O5 and triple superphosphate TSP or CSP 44%-52% P2O5.
These are made by treating rock phosphate with acids. These are neutral and don't affect soil pH
NH4H2PO4 11-13%N 48-62%P2O5 and 0-2% S
di-ammonium phosphate (NH4) 2HPO4
18-21%N 46-53%P2O5 and 0-2% S
completely water soluble.
potassium chloride KCl. Murate of potash 60-63% K2O, completely water soluble. the most popular
Potassium sulfate K2SO4 sulfate of potash 50-53% K2O 17%S. used on crops sensitive to Chloride (Cl) completely water soluble
Potassium nitrate KNO3 44% K2O and 13% N. readily soluble, increases soil pH
Potassium-Magnesium sulfate K2SO4-2MgSO4 sul-po=mag 22%k 11%Mg and 22%S. widely used in dry fertilizer formulas.
Lime (CaCO3) and Dolomite CaMg(CO3)2 are used as liming materials to adjust pH and also supply calcium. Lime contains 38% Ca and dolomite 22%Ca and 12%Mg.
Calcium sulfate- gypsum CaSO4-2H2O supplies Calcium while stabilizing pH. 23%Ca and 19%S
Calicum nitrate Ca(NO3)2 highly soluble and supplies 15%N and 20% Ca. Useful for rapid apvailability and minimal pH change.
superphosphates SSP 12-21% Ca TSP 12-14%.
Colomite CaMg(CO3)2 is used as a liming material, supplies Ca dn Mg. 22%-38% Ca and .6-12% Mg
Magnesium sulfate, Epsom salts MgSO4-7H2O
Mg 9.8% and S 13% without changing soil pH - readily soluble.
Magnesium Oxide MGO 55% Mg and will increase soil pH
apply nutrients in a way that maximizes profitability and minimizes environmental harm.
N and P are the greatest environmental threats.
evaluate site for concerns- such as runoff
evaluate nutrient status
nutrient application methods
there is more and more legislation
Maximum yield + most crop you can get with fertilizer and no more
To supply 200 lbs of Nitrogen to an acre, you would need 8000lbs of chicken manure to compared to 435lbs of Urea.
Water will run off, and plant roots will have trouble growing in this kind of soil.
You have to plan ahead and know your crop for any kind of fertilizer you use.
When you think of Nitrogen, think of grass, or a giant grass like Corn.
Same soil, better structure.
Organic matter also creates pore space for a healthy balance of air and water, with good moisture retention and good drainage.
Because of it's slight electrical charge, organic matter holds nutrients in the soil.
Great soil structure,
Cover cropping and "Biological Nitrogen Fixation"
Cover crops are plants that attract bacteria to fix nitrogen into their roots. As the plant dies or is tilled under, the nitrogen becomes available for the next crop.
Clover, oats, winter wheat, beans and other legumes are crops that invite Rhizobia- nitrogen fixing bacteria to live in their roots.
Cover crops can fix 100 to 200 pounds of Nitogen per acre.
All farmers used to use cover crops. After the invention of synthetic fertilizers in the 1950's many stopped. But it's making a comeback because it's cheap, benefits the environment, and improves soil structure.
Dutch white clover
Brown or black mustard
Most cover crops can be eaten by people or are good forage for animals. Above is some winter Rye.
In summary, organic fertilizers come from food scraps, poo, or cover crops.
The benefits are healthier and more fertile soil in the long-term, more micro-nutrients for plants and people who eat them, and less pollution.
The drawbacks are more planning, and more volume of fertilizer.
Plants absorb the majority of their nutrients through their roots.
Foliar sprays can give a boost of nutrition, but can not replace feeding the plant in the soil.
A great choice for helping plants with severe deficiencies.
Also used for pesticide applications.
To incorporate fertilizer is to mix it in evenly with the soil.
Compost and manure are typically incorporated.
Chemical fertilizers can be too, although because so much fertilizer ends up not being used by the plant, there can be a lot of waste.
-Top Dress/ Side dress
Broadcasting is to spread fertilizer out over a wide area. In some cases fertilizer is broadcast and then incorporated or plowed in.
Top dressing and side dressing are putting fertilizer near the plant on the surface, and letting dew or rainwater carry it into the soil.
A banded application when planting in rows gets fertilizer only in the areas where plants are growing- it can save farmers a lot of money and reduce pollution.
Soil drenches are most often used for liquid fertilizers like fish emulsion, or adding beneficial bacteria or fungi. They take a while to take effect.
Soil drenches are most often used for large plants like trees.
They are also often used in pest control applications, as herbicides or fungicides.
Injecting fertilizer gets it deeper into the soil, and in some cases closer to the roots of the target plant.
For anhydrous ammonia- (a nitrogen fertilizer) it's injecting a gas (which is liquid under high pressure) into the soil.
Please fertilize responsibly!
Time and the right amount is important.
The "dead zone" in the Gulf of Mexico -from fertilizer pollution.
Top dressing and side dressing are often used in the middle of a growing season.
Use solid or liquid fertilizer around the "dripline" or where the edges of the tree would keep the ground dry if it were raining. - That's where the roots are.
Only use the fertilizer your crops need.
Make a nutrient management plan
Especially if using organic fertilizer- where one year's application will be available the following year as well, keeping track of fertilizer applications ensures you don't use more than you need.
To save money and pollution, fertilizers should never be applied on the surface right before a big rain.
...Where they will end up right in the nearest body of water.
Broadcasting is one of the most common application methods for organic and synthetic fertilizer.
In short, you can put it on top of the soil, in the soil, put it in your irrigation, or spray it on the leaves.
More than you ever wanted to know about fertilizer
Relative to the micro-nutrients plants need a huge amount of N, P and K, that's why most "all purpose" chemical fertilizers just have these three.
Of course plants need trace amounts of other nutrients- which can be added individually.
If only chemical fertilizers are used, over time the other minerals will be depleted.
For heavy N-feeding crops, such as corn, it can be hard to get enough Nitrogen.
Any deficiency can be devastating to a farmer's harvest.
With any huge need or huge deficit, chemical fertilizers are the fastest and easiest way to get crops the nutrition they need.
Even if it's"organic" a plant that has a deficiency isn't going to be nutritious for humans or animals.
Remember- the nutrients are the same to the plant, there is nothing "unhealthy" about eating food that has been grown with a synthetic fertilizer.
That's great for timing nutrients precisely when you need them, and not having to wait for organic fertilizer to break down.
If soil organisms die, the soil won't be fertile by itself again, and the dependence on chemical fertilizer will grow.
Any fertilizer can cause pollution if not managed properly near waterways.
Proper applications of fertilizer use just the amount the particular crop is able to uptake at it's stage of development.
High organic matter
Low organic matter
Why doesnt N stay in the soil?
N fertilizers that acidify soil
Fertilizers will provide "lime equivalent on the bag- gives the info on how much limestone (calcium carbonate) to neutralize the acidifying effects of using one ton of a particular fertilizer.
N fertilizers that alkalize soil
Low in ammonium, high in nitrate. Sometime contain calcium. Lime equivalent for these indicates the equivalent effect, not the lime needed to offset acidity
Lime equivalent is an estimate.
For example, by the time corn is half grown, it has already accumulated 100% of the K it will need for the season, and 55% of P. Corn needs these nutrients early in the season and won't benefit from them in the middle.
However late in the growing season when nutrients are accumulating in the seed or the grain, adding fertilizer may improve yield and quality.
You can have tons of nutrients (literally) in the soil- and your plants might not be making much of the nutrition.
SOIL nutrient mobility N is quite mobilte in the soil, but P fertilizer is generally banded or applied with seed because it is immobile in most soils.
N can be nitrate NO3- or ammonium NH4+ but NO3= moves freely through the soil due partly to its negative charge, but NH4+ is held by cation exchange sites, and therefore, is mobile
fertilizing with the mobile utrients needs to be done more frequently than the immoble elements
immobile utrients can be banked- meaning its okay to apply more of the then will be used in this crop cycle. also called a "build" program"
Roots will only touch 2.5% of NPK
water has to move nutrients towards the plant
especially for the mobile nutrients
that accounts for 80% of N movement into the root system but only 5% of P
Diffusion moves chemicals from high concentration to love
N from an Inorganic source
N from an Organic source
The difference in chemical vs organic lies in the impact of the fertilizer on future soil fertility, micro-organism health, and the mineral content of food.
Organic fertilizers have low nutrient content compared to chemical- but the rest of the weight of the fertilizer is building soil structure, adding micro-nutrients, carbon, and making a healthy loam.
Some inorganic fertilizers lower the pH of the soil, causing it to become acidic over time.
Remember how we measured pH by how many Hydrogen ions were present?
NH4 means one nitrogen and 4 hydrogens atoms.
If NH4 converts to NO3 - you see 4 Hydrogen ions enter the soil solution.
Remember our awesome friends that live in the soil? The ones that fix Nitrogen, plow the soil, make micropores, make nutrients available, and improve soil texture? They can't survive if the pH gets too low or too high.
Soil pH can be corrected with lime or wood ash, if acidic, or sulfur if too alkaline.
Does that mean inorganic fertilizers are evil and should never be used?
It means we have to remember the soil is a living organism, and we have to keep it in balance to be healthy.
A plant might get enough NPK to grow large and look healthy, but it might not be very nourishing to eat if there were few micronutrients in the soil.
Ever cut into a delicious looking vegetable only to find it tastes like cardboard?
The more minerals in the soil, the more the plant can not only grow large, but resist pests and disease. Minerals are also what gives fruits and vegetables a rich flavor and make them nutritious.
Some studies have shown that organically fertilized crops have more nutrients, some other studies show there are more anti-oxidants.
In the end, it's important that plants get all the NPK they need AND that the soil is nourished so it stays fertile and full of minerals and micro organisms.
Fertilizers and pollution
Most "Inorganic" or "Chemical" fertilizers are man-made. Or mined and refined.
The Haber-Bosch process for making Nitrogen
Fertility is the soil's ability to produce healthy plants over time.
As rock erodes over thousands and hundreds of thousands of years, minerals are released into the soil.
Rock being eroded by water.
Also, since animal waste is pollution if not composed and disposed of, using it to feed plants is the best place for it to go.
N from Manure lost
fungi and bacteria
When Nitrogen and Phosphorus run off they feed algea in lakes and rivers the same way they feed plants. This causes an "algea bloom."
Over time, the algea choke out sunlight, leave sediment when they die, and change the ecosystem.
Fertilizer pollution/ eutrophication.
It's important to use only the amount of fertilizer needed, and to use it carefully in regard to plant needs, location and weather.
If the plants and manure aren't composted, the soil will lose fertility over time- the cycle is broken.
"Organic" fertilizers use compost, manure, and parts of dead animals to get nutrients- the same way ecosystems do by themselves.
If a plant is deficient in any nutrient- it will be less able to synthesize the vitamins and foods it needs, and will be less resistant to pests and disease.
If you only ate candy and hamburgers, your immune system would be weaker. If plants don't get good nutrition- they will be weaker too!
Nitrogen might be as much as
of a plant's body by weight.
Nitrogen is also a key component in making amino acids- the building blocks of protein.
Manure and compost can also be used with synthetic fertilizers to add Soil Organic Matter to help buffer the pH, improve soil structure and provide a home for micro organisms.
When purchasing and using Nitrogen fertilizer, the only considerations are which form the fertilizer is in, and if it has a coating that slows the release over time.
Most nutrients are the same, and come from the same place.
Nitrogen fertilizer comes in a few different forms.
The difference is what is bonded to the nitrogen.
Friendly soil bacteria can fix nitrogen too.
A common problem with fertilizers- only adding NPK.
While getting big produce, after enough years planting in the same soil, it might be empty of nutrition unless farmers and gardeners are adding micro nutrients as well as NPK.
Other studies show there is no difference in nutrient content between organic and non-organic vegetables.
It probably depends on the specific farm- just a few years of farming organic or conventional might not make a big difference.
You may prefer this for some crops, or for your ability to fertilize during the growing season.
Fertilizing at the wrong time is costly in terms of money, and in pollution.
Farmers strive to use as little fertilizer as possible and still get the maximum of crop yield.
This fertile layer of topsoil was created by nature's composting. With a few years of using only inorganic fertilizer it will look the same, after many years it will be hard, crusted and depleted.
Manure, for example is relatively high in phosphorus.
Biochar- carbon under the microscope.
Don't drink from this river!
Not very fertile
Fertile soil has plenty of nutrients AND healthy soil structure.
Different elements have different abilities to bond to each other
Most organic fertilizers come from plants, poop, and animal parts.
Most inorganic fertilizers are mined, or created in chemical reactions.
Potassium for example can be mined, or obtained from the bones of animals.
Prior to the green revolution, population was limited by the amount of food that could be produced. In some places, the nutrients in the soil had been exhausted, and starvation was feared.
The Haber-Bosch process, developed in 1913 is an industrial method of "fixing" nitrogen- making it available in a form plants can use.
The German scientist who invented the process was trying to make ammonia for weapons and poison gasses.
Turns out it works as fertilizer, too.
He also invented Zyclon B.
The importance of NPK and other plant nutrients was discovered, and the mining and synthesis of chemical fertilizers made them available on a large scale.
To fertilize this acre with Nitrogen you need...
Manure is cheaper- but you need more of it.
The three numbers are percentages. 16-8-0 means the bag is 16% Nitrogen, 0% Phosphorus, and 8% Potassium. You can see the same size bag of chicken manure has a lot less Nitrogen and Potassium in it.
END OF PART ONE
if we're talking about "organic farming" we're also talking about using fewer pesticides- but for today were just talking about fertilizer.
Food scraps in the trash just cause methane gas
Many animal breeding operations have a huge problem with pollution from manure
Denitrification, runoff and poor soil conservation practices all cause loss of nutrients.
Plants can't use this
But they can use this!
These bonds between Nitrogen and Hydrogen are much weaker, and the plant can break them apart to access the Nitrogen
Nitrogen fertilizer use soared.
With chemical fertilizers, farmers could easily produce more food per acre. Fewer people had to be farmers to get the same volume of food.
Other elements only come from biological sources, such as Nitrogen, and can't be found in rock.
Here bacteria fix Nitrogen into a plant's roots.
"Synthetic" fertilizers are produced in chemical reactions, and/or mined.
Synthetic fertilizers feed the plant directly.
Focusing on getting plants all of the nutrients they need to maximize production, is the focus of synthetic fertilization.
There is a lot of debate on what is healthiest for people and the planet.
Lower crop yields?
The same nutrients as "organic?"
Organic fertilizers feed the soil, synthetic fertilizers feed the plant.
Because an organic fertilization program is adding in a lot of
with nutrients, it is building soil quality-
improving soil texture
, making the soil a better home for
improving soil's capacity to hold air and water.
If ONLY inorganic fertilizers are used over time, soil can get hard and crusted. This is due to a lack of organic matter, the death of the micro-organisms and bugs and worms that improve soil quality, and a change in pH.
With manure and compost you're adding a lot of soil organic matter.
Just a few percent NPK and mostly organic matter
Almost entirely NPK and some fillers
With synthetic fertilizer you're just adding the nutrients directly.
Over time, fertilizers can cause soil to become more acidic. With organic fertilizers, organic matter is added, which acts as a pH buffer.
Both "Chemical" and "Organic Nitrogen fertilizers create H+ ions, which are acidic.
Organic matter neutralizes the pH by sticking to hydrogen ions.
If worms, and the good bacteria and fungi die, the soil can't rebuild.
If there is no plan to maintain soil health, the first few years of using synthetic fertilizer will show large returns. After that a farmer may have to do more and more work to make the soil fertile enough to grow.
Farmers may have to do more intensive plowing to break up crusted soil, or add more amendments to adjust pH and nutrient levels if the soil "dies."
To fertilize a tree
Fertilizer needs to be washed against plant roots- especially the tips, in order to be absorbed.
Plants need nutrients in water solution to absorb them.
However too much irrigation or a rainstorm right after application can wash them away.
Soil tests should show how much of any nutrient is needed.
Fertilizer should be planned for the crop's needs
How much fertilizer is in the soil is only one aspect of soil fertility.
These are factors in soil fertility:
Plants need soil that holds a healthy amount of air and water, and gives their roots room to grow.
Soil that is too compacted won't allow roots to grow, or water and air to circulate.
Plants absorb the most nutrients at their root tips where the root hairs give them more surface area.
Proper watering and soil care make for a larger root system- and more nutrient absorpon
That same organic matter will also help hold nutrients in the soil by sticking to them with it's slightly negative charge.
Those tiny pores are made possible by organic matter in the soil, and the balance of sand, silt and clay. Also by the bugs and microbes that live in the soil.
From worms to microscopic bacteria and fungi- creatures moving through the soil leave sticky substances behind them that hold the soil together. They also make pores
Soil pH also affects how many nutrients in the soil are actually available to plants.
Soil with good buffering capacity can hold both positively charged and negatively charged nutrients in the soil.
Biochar is a type of charcoal that's made when plant material burned very slowly. It adds organic matter to the soil, but not "fertilizer."
Same amount of fertilizer- with and without biochar
Sandy soil, clay soil, and biochar under a microscope. You can see the differences in how they would hold air, water, an make a home for micro-organisms.
A balanced pH, and lots of organic matter make a good home for beneficial micro-organisms.
These 'lil bacteria are fixing Nitrogen, building soil health, and making more nutrients available to plants.
Here you can see the effects of adding Rhizobia (N fixing bacteria) to a crop of soybeans.
Our fungal friends- the Mycorrhizae also add a huge boost in fertility for some plants by extending their root system.
How soil is plowed or tilled can also affect fertility over time.
Over-use of fertilizers, can cause salts to form in the soil, damaging soil structure.
This, combined with over-use of pesticides can kill off beneficial soil life.
Whether growing "organic" or "conventional," caring for the health of the soil will boost fertility, and save money in fertilizer and time spent dealing with damaged soil.
Claiming nature for farmland
Plants take in carbon to make the mass of their bodies- and sweet foods.
It's Carbon with a bunch of Hydrogens. That's right- plants breathe in our waste- CO2 gas, and make sweet sugars out of it!
If your soil has been damaged with heavy chemical use, you may want to add a microbial innoculant. Check to see if it is likely to help your particular crop.
Typically, bacteria and fungi are present in the soil and find their way to plants they are symbiotic with.
Some farming methods, such as Korean Natural Farming promote the cultivation of Indiginous Micro-Organisms (IMO's) or Beneficial Micro-Organisms (BMI's)
In this method, beneficial bacteria and fungi are found under the oldest tree in the area, then cultivated and spread around the farm.
Soil in the forest is different than soil on the prarie.
When new land is cleared, how much fertility it has depends on what was growing there before.
Forests have little topsoil, and will quickly lose fertility compared to grasslands.
Some farmers believe by reducing tillage or going to a no-till system, they save soil from erosion, and protect the soil scosystem from getting damaged.
A no-till wheat field, recently harvested.
Keeping it healthy helps it do it's job to absorb and provide nutrients.
Synthetic fertilizers were part of the "green revolution." When farmers suddenly started getting much higher crop yields than ever before.
This was due to the discovery of which nutrients plants needed, synthetic fertilizer, and hybrid crops that produced much more than ever before.
Hybrid high-yield wheat
Because of synthetic fertilizers, fewer people have to be farmers, and less land has to be farmed for the same number of people.
With more and more people on the planet, synthetic fertilizers have made it possible to feed more people, without making everything into farmland.
The best method of application depends on the nutrient.
Both crops got the same Phosphorus fertilizer- but applied in different ways.
Nutrient mobility in the soil depends on what type of soil you have, and whether the particular nutrient has a positive or negative charge.
Mobile and immobile
Mobile nutrients can be anywhere near the root zone
Immobile nutrients need to be right next to the roots
Organic matter holds stuff in the soil
"Organic" fertilizers come from natural sources. "Synthetic" ones are man made.
95% of a plant's mass comes from carbon in the air, and hydrogen and oxygen in water.
The other 5% (on average) is from nutrients we can call fertilizer.
Plants, of course, make their own carbohydrates, or energy, from the sun.
Of those nutrients- the ones plants have the hardest time getting enough of are the Nitrogen, Phosphorus, and Potassium.
On average, 2-3% of a plant's mass might consist of Nitrogen.
1% of Potassium and .5% of Phosphorus
After NPK, plants need moderate amounts of Ca Mg and S, and trace amounts of the other nutrients.
Plants need the micro-nutrients as much as the macro-nutrients.
A plant's growth will be limited by ANY missing nutrient.
Because of this, most fertilizers only focus on the macro-nutrients, and sometimes on the secondary nutrients.
With organic fertilizers, micro-nutrients are usually included because they are already part of the plant or animal material that's used to make the fertilizer.
Organic fertilizers are made from plants, animals, or animal wastes.
Synthetic or "chemical" fertilizers are made in chemical reactions, most frequently from petroleum.
Whether "chemical" or "organic," both fertilizers are providing nutrients to the plant at the elemental level- one molecule at a time.
There is actually no difference, at the molecular level, whether a nutrient came from an "organic" or "synthetic" source. With a very few exceptions, the elements are exactly the same.
The difference between chemical and organic fertilizers lies in how they affect the soil, and the ecosystem where they are used.
END OF PART I
In the wild, life feeds off of death, and nutrients are returned to new growth. Everything is recycled.
The plants on the right got the same fertilizer, but more C02
Plants use the elements in fertilizer, "plant food," to make chlorophyll, amino acids, DNA, vitamins and enzymes.
Two amino acids
You can see how much is N(itrogen)
There's no way to separate just the Nitrogen out of that..
Pound-for-pound, synthetic fertilizers have a LOT more NPK than most organic sources. That's because there's just nutrients in the bag- not all the organic matter included that comes from compost, manure, fish meal etc.
-Take a mental stretch break
-Or come back tomorrow
In the wild, plants die and their bodies fertilize new plants. Animal droppings, blood, feathers and bones also decompose and the nutrients are made available again.
Organic farming mimics this system with compost, manure, and specific animal parts.
Secondary and micro-nutrients are added back to the soil.
A lot of organic matter is added to the soil, improving soil structure and increasing soil health.
Great soil structure from organic matter helps plants get the right amount of air and water, and for roots to grow and reach out for more nutrients.
Organic matter also supports a healthy community of microbes- which in turn helps improve soil structure, and helps plants fight off disease and get more nutrients.
Plants actively create a microbial community around their roots.
78% of the air we breathe is Nitrogen gas- but the Nitrogen atoms are stuck together two at a time. Their bond is so strong, plant can't break them apart to make use of them.
Bacteria in the soil can do this- it's called "Nitrogen fixing."
The bacteria break apart the N-N bond, and "fix" the Nitrogen to a different element.
Healthy soil bacteria make it possible for Nitrogen to be produced. Even some synthetic fertilizers rely on bacteria in the soil to make Nitrogen available to plants.
Certain plants in the legume family (beans, peas, and clovers) invite bacteria called rhizobia to come live in their roots and fix Nitrogen directly.
"Cover crops" are crops that can be planted that actually add Nitrogen to the soil. When they die and rot back into the ground they fertilize the next crop.
The Nitrogen cycle
Good soil structure
Poor soil structure
Healthy soil biota is especially important for creating Nitrogen. Until the invention of synthetic fertilizer, the ONLY way plants could get Nitrogen was by through the activity of bacteria in the soil.
Organic fertilization focuses on cycling nutrients back to the soil.
The philosophy behind organic farming is to feed the soil, which then feeds the plant.
As great as that may seem, crop yields are often smaller with organic farming.
While some farmers have demonstrated equal or larger yields with organic methods, synthetic fertilizers typically offer a mega-dose of NPK that organics can't.
Hybrid crops developed in the early 1900's give bigger yields with the same inputs.
Today, better understanding of soil science and adding amendments allows farmers to grow more organically than previous generations.
It's still estimated 30-50% of global food production is a direct result of the invention of synthetic fertilizers.
END PART TWO
-Take a mental stretch break
-Review and answer questions
-Or begin again tomorrow
In a high-heat, high-pressure process, Nitrogen is fixed into ammonia.
Hybrid crops breed two plants with desirable qualities to make a better offspring
More farmers producing less food means people could take other jobs. It also meant people could move to cities.
Synthetic fertilizers are produced from petroleum or are mined and refined in chemical processes.
Synthetic fertilizers may be mixed with fillers- but otherwise you get just the nutrient you are trying to add, or a combination of them.
The benefit of this is you can give your crops exactly what they need, in the ratio they need it, at the time they need it.
So, synthetic fertilizers can save the world- great, let's pour them on!
With synthetic fertilizer- there's rarely a need to worry about a macronutrient deficiency.
Fertilizer over-use can cause acidification of the soil, the build-up of salts, and damage to soil structure.
Due to their immediate availability in the soil, (where they can be washed away) synthetic fertilizers are more likely to cause pollution.
The "dead zone" in the gulf of Mexico
Plants need 17 nutrients, and to the plant, it doesn't matter where they come from
If an "organic" plant isn't getting the nourishment it needs, it's no better.
If a synthetically fertilized plant is growing large but soil fertility is being destroyed for the future, or the environment is polluted, it's not worth a short-term increase in yield.
Growing food in a way that protects the soil for the future is what some call "sustainability" in agriculture.
Ensuring healthy soil structure and soil life will ensure there will be enough to eat now, and for future generations.
END PART THREE
Up next- more on organics and synthetics
Then- how nutrients work, factors in fertility, and proper application.
However phosphorus pollution can be a big problem with manure.
... or be a jerk and pollute like this...
Healthy soil tends to have a slightly negative charge. So it will hold positively charged nutrients in the soil better- making them "immobile."
The negatively charged nutrients are more "mobile" in the soil. That also means they are more likely to leach out of the soil.
While some nutrients are more likely to stay in the soil over time, most will wash away if not bound up in organic matter.
When planning for organic fertilization, last year's fertilizer needs to be accounted for- it will still be adding nutrition for 2-3 years to come.
Because of this they can contain just one nutrient.
There are other questions with organics-
The Nitrogen Cycle
These two have equal amounts of fertilizer
Fertilizer doesn't = fertility
Start with good soil structure
Soil needs pores for air and water
Worms, bugs and microbes make pores
Soil needs to be fluffy- not compacted
If roots can't grow- nothing gets absorbed
Creating healthy soil structure
pH makes a big difference
PH measures H+, OH- Ions
Soil has a charge
The best soil sticks holds nutrients with a positive and negative charge.
OH- and H+ ions work just like the soil itself to hold (or not) nutrients.
PH matters for micro-organisms
Bacteria matter a lot!
Fungi make a big difference!
Microbial life in the soil depends on your care
If you don't have them- add them
Cultivating Indiginous Micro Organisms
You can't get fertility with fertilizer alone
Forests make bad farmland
Soil management makes all the difference
How fields are plowed or tilled can greatly affect soil health.
Soil- the stomach of plants
The three main nutrients
Each nutrient is needed most at a different time.
Let's start with Nitrogen
Sweet, sweet sugary plant nectar?
It's made by plants photosynthesizing sunlight.
Without Nitrogen- no Chlorophyll
Without Cholorophyll- plant's can't make energy
Nitrogen is a gas
Plants can't get N from air
There are only two ways plants can get Nitrogen in the soil...
Phosphorous is reeeallly important
Ever heard of a carbo-hydrate?
a plant's #1 food
Plants breathe- a lot like us
Plants have immune systems
Nutrition is about more than growth
What about the thousands of chemicals plants use?
Plants just won't thrive without those nutrients
Doesn't have enough Nitrogen to make Chlorophylll
These Calcium deficient leaves can't form fully.
Different nutrients have different functions, and are needed at different times.
Micro nutrients are often necessary for macro-nutrients to be used
Many of them support the functions of the NPK or Ca, Mg, S. Meaning those nutrients are useless without enough of the micro-nutrient.
This is why some micro nutrient deficiencies look like macro nutrient deficiencies.
Carbon improves soil fertility
Deforestation is really stupid
All these trees are cut down or burned, ecosystems are lost, the globe warms, and meanwhile the soil cleared for farming will only be fertile for 3 or 4 years.
The soil you start with
There are so many factors in soil fertility. Working with all of them is the best way to get healthy soil. Dumping fertilizer on, no matter how good the quality may not even help your crops.
The soil is a living system
Thinking of the soil as a tiny ecosystem that can be supported and balanced in different ways is the most effective strategy for long term fertility.
Every region has different soil, often made from different parent rock and different patterns of erosion.
Soils will naturally be more or less fertile
Depending on the type of soil it will have different texture and structure, (different ability to hold water and nutrients), different pH, different nutrient levels, different biota.
What came before?
Soil is profoundly affected by what grew in it. Some plants add to the soil over time, others can deplete it. What's been growing there before?
Is the nutrient mobile?
Positively charged nutrients are immobile
Water washes things away.
Great for immobile nutrients!
Works great for mobile nutrients
Broadcast vs banded application
Topdressing and sidedressing are typically done with nutrients that are needed in the middle of a season.
Which would be best to side-dress mid-way into the season?
Foliar sprays- like a vitamin shot
Foliar sprays are quicker, not better
Soil drenches, slow and steady
Injecting fertilizer involves some machinery
Just a spot of fertilizer
Especially good for young trees,
Spot fertilizing gets nutrients right to the root.
Remember how the fertilizer gets into the roots
Most root-hairs are at the tip of the root. The more roots- the more tips- the more hairs- the more absorption.
Fertilizer needs water to move it to the plant
Too much is too much
Fertilizer pollution is a BIG problem
Fertilizer doesn't last forever
Nitrogen never lasts
Organic fertilizers last longer
Nitrogen is continuously being fixed in the soil and broken down again back to a gas. Nitrogen fertilizers don't last much year to year.
Loose nutrients floating around can be washed away.
Bound in the soil in dead microbe's bodies-not as much runs off or is lost to the atmosphere.
Whether organic or chemical fertilizer is being used, it's good to make a plan.
An organic plan needs to include previous year's applications.
Because chemical fertilizers are available immediately, they are applied more often.
Only immobile nutrients need to be accounted for from last year's plan.
How much planning?
A good nutrient plan takes into account:
-The nutrients already in the soil (naturally or from previous fertilization)
-What crops were grown before
-What crop is going to be grown
- how much does it need of what?
-when does it need it?
-What nutrients are being applied (mobile/ immobile) (organic source/ inorganic source)
The best method also depends on what form the nutrient is in
In general, more organic matter will hold more nutrients in the soil. Whatever fertilizer you are using- the more organic stuff the better!
Ways to apply fertilizer
Some nutrients can be picked up by water and move in the soil. Some can't.
Factors of Fertility
Fertilizer- organic or synthetic
FYI - air and water are nutrients
"Plant food" allows plants to make their own food.
What plants use fertilizer for
Fertilizers are elements on the periodic table
NPK are the most used nutrients by volume
Secondary nutrients and micro-nutrients
The most "important" nutrients
Organic is more than NPK
Which has the most nutrition?
Nutrients are nutrients
"Organic" and "synthetic" nutrients aren't different
"Organic" and "synthetic" fertilizers are different
Nature uses compost and manure
Organics = animal waste, dead animals, dead plants
What's awesome about organic
Organic matter builds soil structure
Organic matter supports soil life
Soil life is really important for fertility
Fungi - a plant's best friend
Bacteria- a plant's ticket to N
Nitrogen in the air is not available to plants
Nitrogen fixation - only bacteria can do it
These bonds are weak enough for the plant to break
These nodules house N fixing bacteria
Cover cropping- free Nitrogen!
Feed the plant vs feed the soil
Soil Salinizaion is a big problem in some areas where so much fertilizer has been used that the soil can't buffer the pH. The acidic ions in the fertilizer attract bases and turn to salt. The soil literally becomes too salty for plants to grow.
Remember, nutrients are ions and organic matter acts like a buffer for pH. (etc etc)