Category: Uncategorized

Intercropping

 

Intercropping allows you to use your space efficiently, utilizing multiple layers, and planting optimal crops between rows. These techniques could maximize the yields per area grown. Some strategies include planting deep-rooted crops with shallow-rooted crops, or planting a tall crop with a shorter crop that requires partial shade. Plants that have large structures or leaves, such as corn and squash, can provide a shelter and filtered sun for lower, larger leaved plants such as lettuce. Corn stalks also provide support for vegetable vines. Lettuce can handle the light sun of spring and fall, but requires protection during the heat of summer. When lettuce receives too much heat they tend to bolt (go to seed).

Many narrow leafed plants such as onions, leeks, shallots, and garlic can easily fit between many leafy vegetables. Plants that are prone to tip over in the wind or rain, may be given structural support by their companion crop. Alley cropping involves crops grown in between rows of trees, and strip cropping, where multiple rows of one crop are alternated with multiple rows of another crop.

Another benefit of intercropping strategies include increased insect pest and disease resistance. Repellant intercrops mask the smell of production crops in order to keep pests away from it. Push-pull cropping is a mixture of trap cropping and repellant intercropping. One type of crop attracts the pest and the alternative crop repels the pest away. Monocropping has a tendency to attract similar pests, that are susceptible to similar diseases. Also, if you intercrop with plants from the same family, your soil may experience nutrient depletion since plants within the same family require similar nutrients. The depletion of nutrients will promote troublesome insects and illnesses in your crops.

Intercropping can increase weed suppression based on the use of crop sequences that create varying patterns of resource competition, allelopathic interference, soil disturbance and mechanical damage to provide an unstable and frequently inhospitable environment that prevents the proliferation of a particular weed species. Greater crop yield and less weed growth may be achieved if intercrops are more effective than sole crops in taking resources from weeds. Alternatively, intercrops may provide yield advantages without suppressing weed growth below levels observed in component sole crops if intercrops use resources that are not exploitable by weeds or convert resources to harvestable material more efficiently than sole crops.

Practical Mycorrhiza techniques

 

Mycorrhizal fungi increase the surface absorbing area of roots as much as 50 times, thereby greatly improving the ability of the plant to access soil resources. Several miles of fungal filaments can be present in less than a pinch of soil. Mycorrhizal fungi increase nutrient uptake not only by increasing the surface absorbing area of the roots, but also release powerful organic compounds into the soil that help to solubilize hard to access nutrients, such as organic nitrogen, phosphorus, iron and other tightly bound soil nutrients.

Since the relationship between plant and fungi evolved to help the plants access low levels of phosphorus in the soil, mycorrhizae do not grow and colonize roots when the phosphorus level is high. Phosphorus levels above 10 ppm in the soil solution will impact the growth and establishment of mycorrhizae. This does not kill the mycorrhizae, but creates an environment in which the mycorrhizae do not germinate and grow effectively.

Mycorrhizal associations DO form in.. (Refer to the bottom of the page for a comprehensive list)

Most green leafy plants, unless they are commercially produced.

Shrubs and foliage except for Rhododendron, Azalea, and Heath.

Berries, except for Blueberries, Cranberries and Lingonberries.

Nut trees, except Pecan, Hazelnuts and Filberts.

Most flowers

Vegetables except Brassica, and Beets.

Grasses, except weedy grasses

Fruit trees including tropical fruits,

Wetland/aquatic species, except rushes and horsetails

There are a few plant types that do not form any mycorrhizal association:

Brassica family (Broccoli, Brussel Sprouts, Cabbage, Cauliflower, Collards, Kale), Beets, Carnations/Dianthus, Mustard, Orchids, Protea, Rush, Sedge and Spinach.

Non-mycorrhizal plants require high levels of fertilization to maintain their health. Mycorrhizal fungi form an intricate web that captures and assimilates nutrients, conserving the nutrient capital in soils.

The mycorrhizal spores germinate in response to the release of sugars and hormones from the plant roots. This trigger allows the spores to stay dormant in a mix until plants are actively growing. Therefore, the shelf life of mycorrhizae is typically longer (up to two years) than other biological additives.

Typical lime rates and medium pH levels of professional growing medium products do not have a significant positive or negative effect on the growth and colonization of mycorrhizae.

Rootshield and Actino-Iron have been shown in independent research to be fully compatible with mycorrhizae in soilless mixes, so these are recommended. There are other helper bacteria or fungi that are often added to a mycorrhizal blend. They can stimulate and support the growth of the mycorrhizal colonies.

Most growing mixes contain inorganic-based fertilizers. Research has shown low levels of mycorrhizal colonies when a standard inorganic nutrient charge is used in the mix, which releases nutrients in a short time frame.

Excellent colonization occurs when mycorrhizae are added to mixes containing organic or controlled release fertilizers. Organic fertilizers release their nutrients slowly over time so the levels of phosphorus remain within a tolerable range for good mycorrhizal growth and colonization.

When using a mix supplemented with mycorrhizae, a fertility program with low levels of inorganic phosphorus should be employed. Any water soluble or controlled release fertilizer formulations should be low in phosphorus and delivered at a concentration or rate that result in 10-ppm phosphorus or less.

Tillage, removal of topsoil, erosion, site preparation, compaction, fumigation, invasion of weeds, and leaving soils fallow are some of the activities that can reduce or eliminate these beneficial soil fungi. Studies show that mycorrhizal populations are slow to recolonize naturally, therefore, reintroducing mycorrhizal fungi in areas where they have been lost or in artificial growing media can dramatically improve plant performance with less water and fertilizer and at a reduced cost.

Ectomycorrhizas

UWL Website bioweb.uwlax.edu

The main structural features are the Hartig net, mantle and extraradical mycelium.

The Hartig net is seen to be a structure with the properties of transfer cells, in which effective exchange of solutes occurs between symbionts.

Extraradical mycelium are the structure primarily involved in exploration and exploitation of soil.

Ectomycorrhizae forms relationships with birch, oak, myrtle, beech, willow, spruce, pine and fir. It forms an extensive hyphal network, which is frequently visible to the eye and is characteristic of this organism

Some of the species found in ectomycorrhizal product blends include Rhizopogon villosulus, R. luteolus, R. amylopogon, R. fulvigleba, Pisolithus tinctorius, Schleorderma cepa, and S. citrinum.

Ectomycorrhizal fungi do not penetrate their host’s cell walls. Instead, they form an entirely intercellular interface, consisting of highly branched hyphae forming a network between epidermal and cortical root cells, known as the Hartig Net.

Ectomycorrhizas are further differentiated from other mycorrhizas by the formation of a dense hyphal sheath, known as the mantle, surrounding the root surface. This sheathing mantle can be up to 40 mm thick, with hyphae extending up to several centimeters into the surrounding soil. This hyphal network aids in water and nutrient uptake often helping the host plant to survive adverse conditions, and in exchange, the fungal symbiont is provided with access to carbohydrates.

The extramatrical mycelia of ectomycorrhizas function as transport structures. They are often able to spread great distances to maintain a large contact area with the soil. Some studies have even shown a relationship between nutrient transport rates and the degree of rhizomorph organization.

The hyphae extending outward into the soil from one ectomycorrhiza can serve as a source of EcM inoculation to other nearby plants. This can lead to the formation of common mycorrhizal networks (CMNs), which experiments have shown to culminate in the sharing of carbon and nutrients among the connected host plants.

Many ectomycorrhizal fungi are known to rely upon mammals for the dispersal of spores, particularly those fungi with hypogeous fruiting bodies. These mammals are often drawn to hypogeous fruiting bodies because they are rich in nutrients such as nitrogen, phosphorus, minerals and vitamins.

Agriculture indirectly affects nearby ectomycorrhizal species and habitats, such as increased fertilization decreasing sporocarp production

In commercial forestry, the transplanting of crop trees in new locales often requires an accompanying ectomycorrhizal partner. This is especially true of trees that have a high degree of specificity for their mycobiont, or trees that are being planted far from their native habitat among fungal species. This has been shown time and again in plantings involving ectomycorrhizal trees. Mass planting of these species often require human addition of inoculum from native EcM fungi in order for the trees to prosper.

After being added to various soil mixtures, the mutualism can begin as seedlings are grown in nurseries or plantations. This is already becoming common, and there are many companies that are beginning to sell a variety of mycorrhizal inoculum. Pisolithus tinctorius is widespread among the EcM fungi.

Ectomycorrhizal fungi are susceptible to heavy metal contamination. However, there seems to be widespread heavy metal tolerance in these fungi, with many species having the ability to colonize soils both with and without high heavy metal content.

Another problem faced by many plants is high soil salinity. One study shows that some EcM fungi are capable of improving salt tolerance in a species of poplar by altering leaf physiology. Though the symbiotic contact takes place at the root interface, the fungus was able to alter such leaf traits as concentration of nutrients and phytohormones.

EcM communities are affected by increased temperatures, which can either slow respiration, or alternatively improve colonization of host plants. They are also affected by drought, but do provide protection, and improve water uptake ability of the roots.

It is apparent that Ectomycorrhizal communities influence forest productivity and recovery. In europe there has been a concerning decline in many species of Ecm fungi, gaining attention of conservation communities. This loss is attributed to the conversion of forests to other uses, pollution, and the acidification of forest soils.

 

Vesicular Arbuscular mycorrhizae

 

Vesicular Arbuscular mycorrhizae are a category of fungus the penetrate the cortical cells of the roots of a vascular plant. These mycorrhiza are characterized by the formation of unique structures, arbuscules and vesicles by fungi of the phylum Glomeromycota. The fungi help plants to capture nutrients such as phosphorus, sulfur, nitrogen, and micronutrients.

VA mycorrhiza form associations with plants in the Angiosperm, Gymnosperm, and Pteridophyte categories.

VA mycorrhiza have three main components

The root

The fungal structures within the cells of the root

The Extraradical mycelium in the soil

Members of the mycorrhiza family are common soil fungi and spores or sporocarps can be collected from almost any soil. Long term compatible interactions are based on bidirectional nutrient transfer between the symbiotic plants and fungi. Some species form sporocarps with limited amounts of sterile mycelium

Classification of VA mycorrhizal fungi are based on the structure and development of the walls of the spores. Taxonomic descriptions and classifications are based on Murographs.

Characteristics of the vegetative stages, such as form of the entry points and branching of hyphae within the root, are variable between fungal species and can be used for recognition purposes by experienced observers.

VA mycorrhizal fungus isolated from one species of host plant will colonize any other species that has been shown to be capable of forming VA mycorrhizae, thus combining wide host range with permanence of association.

Mycorrhizal colonization of roots can be blocked at a number of stages in typical host plants, failure of colonization in non-mycorrhizal plants are due to a number of different mechanisms.

VA mycorrhizal are more frequent on plants growing on mineral soils

Ectomycorrhizas and some cricoid mycorrhizal are characteristic of plants growing on soils with relatively large deposits of organic matter.

High occurrence of VA mycorrhizal in plant communities with high species diversity.

Low incidence of Vesicular Arbuscular mycorrhiza occurs in extreme environments, such as very moist or arid areas, highly disturbed soils, very nutrient rich soils, or tundra and high alpine habitats.

The lack of specificity means that a single plant species can be colonized by many different fungi and individual plants can be linked below ground by common mycorrhizal mycelium

Spores, Root fragments and hyphae are the propagules that can initiate VA mycorrhizal colonization.

Hyphae form a complex network which link plants of the same and different species.  The networks are able to survive both dry and cold conditions, which helps the colonization of roots early in the following season.

Outside the root, an extensive mycelium develops and appears to undergo differentiation, so that different types of hyphae perform different functions in colonization, nutrient acquisition, and survival.

The development of mycorrhizas are under the control of plant and fungal genes, which act in a coordinated manner to produce the characteristic, biotrophic and compatible interaction in mycorrhizal host species.

In low input agriculture where high efficiency of nutrient uptake is required, a cultivar that is both highly susceptible and highly responsive to mycorrhizas would be appropriate.

In highly fertilized situations a non-susceptible and non-responsive cultivar might be more suitable, assuming that mycorrhizal effects on interactions with pathogens or soil structural stability has been adequately considered.

VA mycorrhizal fungi are dependent on an organic C supply from a photosynthetic partner. Between 4-20% of net photosynthate is transferred to the fungus and used in production of both vegetative and reproductive structures, and in respiration to support growth and maintenance, including nutrient uptake.

Glucose can be absorbed by the fungus and transfer from plant to fungus occur across the interface between intercellular hyphae and cortical cells of the root.

External hyphae of VA mycorrhizal fungi absorb non-mobile nutrients from soil and translocate them rapidly to the plants, overcoming problems of depletion in the rhizosphere. Transfer across the symbiotic interface results in increased nutrient acquisition by the plant.

Hyphae are able to penetrate soil pores inaccessible to roots and may also be able to compete effectively with soil-inhabiting microorganisms for recently mineralized nutrients.

The ins and outs of Composting!

Compost is decomposing carbon-based organic matter going through a series of complex chemical and biological processes. Carbon-rich organic matter interacts chemically with nitrogen in a moist, aerated environment and is further broken down with the help of biological agents like fungi, worms, bacteria and other micro-organisms. If we want to re-create the kind of soft, fertile soil we find under the leaf carpet of a forest rather than the gooey muck of a marsh, we need to think of a compost heap as a living thing that requires the essentials of all living things: air, food, and water in a balanced combination when maintaining a healthy compost pile.

Quality compost is a big part of healthy soils. Compost contributes to sufficient organic matter, and healthy bacteria. If your a home gardener, turning your compost will reduce the time it takes for the mixture to become usable.

If you have livestock, you need machinery to turn compost. Another option is having an area where chicken and pigs can mix compost by scratching for insects, foods scraps, and earthworms.

One recommended addition to your compost is Clay. It absorbs excess moisture and volatile gases, has a buffering effect for proper pH, and provides surface area and habitat for microbes.  Clay will scavenge ammonia, accelerating the production of calcium humates, which are a prerequisite of a stable humus formation.

Another is adding Biochar, as it enhances the habitat for compost microbe populations.

Adding Gypsum and humates will cause a reaction between ammonia and sulfate creating ammonium sulfate, a stable form of nitrogen, available for plants.

When composting on large scale landscapes it is recommended to integrate cover cropping and tight rotations to achieve sheet composting.

Sheet composting is the practice of using plant residues or fresh vegetative portions of a crop and shallowly mixing them in your topsoil so they rapidly break down as a food source prior to planting a successive crop.

Mineralization is the process of liberating minerals from organic carbon compounds. Minerals are either complexed in stable humus (humified) or in a free form (mineralized).

Good compost requires a balance of mineralization and humification, which requires a buffet of feedstocks. Ultimately those raw materials have to be acted upon by microorganisms, especially fungi and actinomycetes.

Red-brown humic acids are more mobile, readily complex minerals.

If you have Comfrey growing around the garden. Add it to your compost or plot. It is a compost activator, with a massive tuberous root system, that can produce a great deal of biomass. Comfrey leaves are rich in nitrogen and carbon. They grow well on the perimeter of gardens, cropland, hedgerows, and trees.

Vigorous population of microbes in the rhizosphere translates into a balanced soil food web.

Fungal growth is important due to disease suppressive exudates produced by beneficial fungal organisms. These suppressive exudates are essentially antibiotics that eliminate harmful bacteria.

 

What is Compost Tea?

Compost is filled with beneficial microorganisms and nutrients, and you can take composting one step further by steeping it in aerated water. This process, extracts the microorganisms and soluble nutrients into a water “tea” solution. The goal of compost tea is to introduce nutrients, fungal colonies, and beneficial bacteria to either the soil or the foliage of your plants to aid in growth and provide protection from harmful disease.

 

What is Vermicompost?

This form of compost uses vermicastings (worm castings/poop) from native, or compost earthworms. The material has high nitrogen levels. If your looking to brew your own batch, put eight ounces of worm castings to one gallon of water, and soak for one to three days.

 

What is Nature farming?

Obtaining an inoculant from native soil in the forest or grassland and blending it with a substrate like wheat bran on molasses, and the subsequent culture is then inoculated upon rice in order to produce metabolites that can be used for plant growth, plant protection, odor control, and livestock health. It using a similar method as compost tea to inoculate soils with healthy bacteria and fungi.

Biological Life in the Soil

This entry covers some of the biological processes within soil, affected by biological and fungal activity. These processes affect the health of plants, and determine whether the soil hosts biological activity that is beneficial for plant growth.

Bacteria perform many functions within the soil, and help plants access nutrients. Their activity can support plant function, as well as tarnish it due to non-desirable pathogens.

What is Chemotaxis?

It is the movement of an organism in response to a chemical stimulus using cellular communication.

Bacteria emit biochemicals that act as communication molecules to encourage microbes to move away from dangerous environments. This causes an intentional movement of plant roots toward or away from a chemical stimulus.

This includes…

-Hormonal secretions for plant growth, maturity, and reproduction

-Biochemical defense compounds against fungal, bacterial, insect, and nematode enemies

-Compounds solubilizing certain tied-up nutrients like iron, phosphate, manganese etc. -Providing microbial secretion to enhance microbial growth and activity, providing enzymes that can decontaminate miscellaneous toxins.

Microbial systems make up 50 percent of the Earth’s total biomass and 80 percent of all the Earth’s biodiversity is microbial.

Soil hosts 2-3 million species of bacteria, 1.5 million species of fungi

Bacteria have tremendous reproduction potential

These are practices used to encourage healthy bacteria and prevent disease in your soils

-Limiting acid soils

-Compost

-Proper irrigation and water quality (pH, TDS, bicarbonate, alkalinity, salinity)

-Aeration and drainage

-Reduced or zero tillage

-Cover crops -multiple species

-Balanced fertilizer applications

-Tight crop rotations

-Crop residues returned to surface or shallow sheet composting

-Seed inoculation with mycorrhizal and trichodermal fungal spores

 

Carbon and Oxygen in soils

Air vs. Soil – Oxygen/Carbon percentages

Atmosphere-21% oxygen, .025-.035 % carbon

Soil atmosphere- 15% oxygen .2-.4 % carbon

Carbon dioxide is a primary raw material that plants recycle through their stomata to create sugars, which are in turn the building blocks of numerous other carbon complexes, such as starches, cellulose, hemicellulose, lignin, waxes, oils, resins, pectins, fructans, glucans, and numerous plant secondary metabolites like terpenes alkaloids and phenols.

Climate change issue– vast amounts of carbon lost from our soils and the soil ecosystems diminish the ability to rapidly and effectively sequester carbon dioxide. Soil erosion exceeds 24 billion tons per year worldwide.

Increasing the soil organic matter on the planets 4.9 billion hectares of rangeland by 2 percent would sequester 2880 billion tons of co2 compared to 44 billion tons emitted by human activities per year.

Facultative Organisms- those that can adapt to utilizing oxygen either as atmospheric oxygen or as a complex oxygen compound such as no3 or so4.

Manure lagoons are challenged by depleted oxygen. They can be mixed with equipment or clay added to cow food or lagoon.

 

Water and Irrigation

Evaporation of water in the soil is often due to lack of vegetative cover, and organic matter.

Varying soils have different water holding capacities.

 

Example

Sandy soil can hold 8 percent water

Silty loam can hold 28 percent

Cover crops reduce runoff

Clay and organic matter contain more pores and surface area

Water content and evaporation is affected by Soil temperature

Soil temperature is determined by…

-Field slope

-Season

-Rainfall, irrigation

-Wind speed

-Humidity

-Cloudiness

-Ground cover

-Amount of tillage and soil disturbance

-Soil structure and permeability

-Soil density

 

Comprehensive soil testing

Ward Laboratories– Provides in depth biological information called green chemistry. Includes the Solvita 24 hour Co2 Burst test to evaluate the respiration of the soils microbes. Measures carbon dioxide released in a soil sample. Water extract taken to determine the water-extractable organic carbon and water-extractable organic nitrogen. Measures the quality of carbon, and energy source that feeds on soil microbes. Organic pool of carbon is roughly eighty times smaller than the total carbon amount. Water extract of the soil is taken to determine total nitrogen, inorganic nitrogen and organic nitrogen.

Organic nitrogen– Protoplasm-it consists of amino acids, peptides, algae, nematodes, and plant cells. Easily digested by living microbes and released to growing plants while not at risk of leaching.

 

Organic carbon to nitrogen ratio

• Determined using the water extracts of each (carbon to nitrogen)Soil ratio above 20:1 indicates that no net nitrogen or phosphorus mineralization will occur, meaning nitrogen and phosphorous are “tied up” within the microbial biomass until the ratio falls below 20:1.

Phospholipid fatty acid test (PLFA) analysis– measures functional groups of microbes and their contribution to the total biomass in the soil, both in weight and percentage. Community composition ratios are evaluated for fungi to bacteria ratios scaled from very poor to excellent. Bacteria are important but fungi populations are indicators of soil health.

 

Parasitic Nematodes –

These are aquatic animals, that need moisture to migrate. They are .5- 4.0 millimeters in length. Parasites can attack all parts of the plant. They utilize an organ called a stylet, which is a spear-like form used to puncture plant tissue and withdraw liquid contents.

Ectoparasites- Remain outside of the plant tissue. Have short stylets and can only feed on epidermal tissue of the roots.

Endoparasites- Dwell inside the root mass and cause more damage to the plant. Incidence of nematode infestation in agriculture soils is directly related to the health and complexity of the soils ecological community.

Anything that compromises the size of the root mass amplifies the negative effects of nematode infestation. Sandy or sandy loam soils low in humus and dosed with salt fertilizers, pesticides, and irrigation water are ideal environments for parasitic nematodes.

Signs of nematode dominance- patches of wilting, dying, clorosis, early senescence, stunted growth, and thinning.

Accurate assessment of nematode problem only determined by a nematode lab assay to provide identification of the species, and the numbers present.

Same symptoms caused by nematodes can be attributed to poor soil health and extremes in moisture content.

 

Addressing nematode infestation

-Crop rotation, not returning a crop to the same plot for at least 3 years.

-Cover crops, cocktails of at least four to six species

-Vegetative fumigants such as plants of the mustard family (crucifers like kale, cabbage, collards, broccoli) note. When using crucifers to fumigate soils, ensure that a non-cruciferous crop is planted afterward and properly inoculated with mycorrhizae as well as rhizobium.

-Quality compost- introduces a plethora of healthy bacterial, fungal, and predatory nematode species into the soil. Pest suppressing metabolites are found in compost.

Using iodine to kill nematodes- alcohol in solution becomes phytotoxic. Tame solutions without alcohol helpful for killing nematodes in root bulbs acting as a bacterial enhancer especially of nitrogen fixing rhizobia, and azotobacter.

 

Trace Elements- Micronutrients

Micronutrients are often overlooked, but are critical to plant vitality. They should be in suitable supply and balance within the soil. Comprehensive soil tests can detect levels, and indicate deficiencies. If you are deficient in micronutrient, you are advised to spread your application over months, or years into the soil in an attempt to avoid a shock in the system which could throw the soil out of balance. Foliar feeding, (direct spray) to plant vegetation can also help apply these nutrients.

Trace elements are vital to enzymes, which are catalysts that govern many thousands of physiological and metabolic functions in plants. Enzymes are able to speed up biological reactions up to one million times. These sped up reactions can increase crop production and performance.

Tissue and forage tests are useful in this regard, and visual observation of leaf, stem, root, tuber, and fruit reveal what’s happening with your crop.

Micronutrient deficiencies are known to increase the likelihood of plant disease.

Plant Immunity

Mineral nutrition supports the synthesis of complete proteins, complete carbohydrates, lipids, and chlorophyll production.

Plant secondary metabolites (PSMs) -Category of Plant Physiology contribution to plant immunity. There are three main categories.

Phenols, Terpenes/Terpendoids, Alkaloids

Phenols include flavonoid compounds, and Isoflavones, also called phytoestrogens (compounds produced in legumes which ward off mildews). Legumes depend on micronutrients as raw materials to build phytoestrogens. Also included within Phenols are the non-flavonoids such as phenolic acids, tannins, hydroxycinnamates, stilbenes, and lignins.

Aspirin is a popular phenolic acid known as salicylic acid, which is essential for a plant’s immune response to attack.

Tannins are effective against internal parasites and bloat. They detoxify bad proteins. Tannins deter insects and excessive grazing by animals, also acting as sunscreens against ultraviolet radiation.

Stillbenes are produced by plants as phytoalexins, compounds released as a SAR response to insect attack.

Lignins are second to cellulose as the most abundant plant carbon compound on earth. Their importance is attributed to strength in the cell wall and a role in water transport. Lignins are a shield against environmental extremes in the fungi, bacteria, insect and root nematode categories. It synthesizes when there are adequate copper and manganese uptake. It also protects the plant against elevated temperatures and drought.

Terpenes are the largest group of Plant secondary metabolites, including carotenes, and carotenoids. Magnesium, copper, manganese, zinc, and iron are required to synthesize carotenes (tetraterpenoids). Terpenoids are volatile, acting to communicate with molecules to repel threats. Terpenoids are also able to attract the predatory insects that feed upon parasitic species. Plant hormones gibberellins and abscicic acid are diterpenes and react as phytoalexins in response to plant adversaries.

Alkaloids are highly present in root systems, and repel pests through their toxicity.

Micronutrient Function

Zinc– a vital element for energy, that partners with phosphorus. The ideal ratio between the two is ten parts of elemental phosphorus to one part of zinc when phosphorus levels do not exceed the norm. Zinc’s role with phosphorus the production of ADP (adenosine diphosphate) and ATP (Adenosine triphosphate) both critical energy components. Mycorrhizae are essential to maximize zinc uptake from soils. Over Fertilizing soils with phosphorus can suppress root colonization of mycorrhizae, lowering zinc uptake.

Copper– Copper acts to increase the uptake of the preferred form of nitrogen (Ammonium (NH4)). Copper is necessary to produce polyphenol oxidase, which is important for the synthesis of lignin and alkaloids to resist pests, as well as flowering and maturation. Copper deficiencies can be found in high-calcium soils, peat soils, high iron soils, high zinc levels, sandy soils, and excessive nitrogen and phosphate application.

Manganese– Manganese is critical for seed germination and early maturity of plants. It has a role in metabolizing nitrogen. It’s necessary for the assimilation of C02 to produce plant carbohydrates. Symbiotic rhizobia and their root nodules are rich in Manganese. Manganese also helps synthesize lignin, the plant protecting against heat, drought, diseases, and insects. Deficiencies can result in silent heats, reproductive failures, abortions, and a predominance of male births. Source of manganese are Manganese sulfate (28 %), and Chelated Manganese (5-15%).

Iron– Iron is widely abundant in soils, however there is often an unavailability due to alkaline soils, cold wet soils, and sulfur deficiencies. Excesses of phosphorus, manganese, and zinc (at low ph) can also interfere with iron availability. Foliar feeding is a good way to address low iron levels. Humic acid can be a contributing factor to make iron more available.

Boron– Boron is an anion, and doesn’t attach to a negatively charged soil colloid. It is found in the soil solution, or complexed with the humus fraction of organic matter. Boron is a potent partner with calcium and is the catalyst that facilitates the release of calcium out of the soil into the plant. Excess calcium in soils will hinder boron solubility, and uptake. Potassium uptake is improved with boron, but excess potash suppresses boron solubility and availability to plants. Boron aids in sugar translocation, the synthesis of nucleic acids, and the activation of cell division. Drought can be a detrimental factor in the uptake of boron. Boron deficiency can cause hollow stems in alfalfa, brassicas, and cause soft pith in apples. Boron also helps with the assimilation of nitrogen in plants, and translocates accumulated carbohydrates from daytime photosynthesis in the leaf down into the root overnight. Boron can be sourced from Borax (11%), Sol-U-Bor (20.5 %), and Boric acid (17%).

Molybdenum– Molybdenum is a trace mineral that increases in availability at a higher pH. It is essential for the production of the enzyme nitrogenase, required for nitrogen-fixing bacteria, especially in the root nodules of legumes. Molybdenum is a core element of the nitrate reductase enzyme necessary to convert nitrate into animes, and then into amino acids and finally protein. To reduce undesirable levels of nitrates in plants, make a soup mix containing about ten pounds of magnesium  sulfate, four to six ozs of sodium molybdenate, two gallons of molasses, one pint of fulvic acid, and one pound of soluble humic acid powder in forty gallons of water per acre. The sources of molybdenum are Sodium molybdenate (47 %), and Ammonium molybdenate (58 %).

Cobalt- Cobalt is essential for nitrogen-fixation microorganisms. Three important enzymes depend on cobalt, Methionine synthatse, for healthy plant protein production, Ribonucleotide reductase, essential for DNA synthesis, and methylmalonyl coenzyme A mutase, required to produce “heme” in root bacteria. Cobalt is associated with yield and nutrient density on a legume. Foliar spratys dusting the seed with cobalt sulfate increase yields. Sources of cobalt are Cobal Sulfate.

 

This week’s focus is taking a look at geological minerals, and how they affect soil health. I’ve been looking at The Farm as Ecosystem, by Jerry Brunetti. In order to get a better understanding, it’s helpful to know whats in our soil, and what we may expect to see from the results. Soil tests can give us an idea of what to anticipate from our soils, giving us information about which soil applications you may add to balance minerals and encourage your plants to flourish with plenty available nutrients. Below is a summary of important minerals, and information regarding their influence on plants and soil.

Soil categories

Geological- Minerals

Biological- Bacteria, Bacteriophages, Viruses, Fungi, Protozoa, Algae, Arthropods, Insects, Pollinators.

Physical- Clay, Silt, Sand, Loam, and Humus,

When we are determining soil quality, we are taking a look at the relationship and dynamics between geological, biological, and physical characteristics.

 

Nutrients that have been placed at a high importance are Nitrogen, Phosphorus, and Potassium.

Also vital to plant health are trace element levels of Sulfur, Phosphate, Calcium, Magnesium, Potassium, Sodium, Chlorine, Nickel, Iron, Manganese, Zinc, Copper, Molybdenum, and Boron.

Mineral functions in soil and plants

Nitrogen

Most abundant nutrient required for plant growth. Excess Nitrogen in plant tissue attracts insects and disease. Excess nitrogen is unhealthy for human, and animal consumption. Nitrogen mismanagement is a common agriculture mistake, contaminating ground and surface water. Nitrogen produces nitrous oxide, the most potent greenhouse gas, and destroys forests by killing symbiotic fungi in roots.

Three forms of Nitrogen – Ammonium (NH4), Nitrate (NO3), Organic Nitrogen (amino acids)

Conversion of NH4 into amino acids requires an expenditure of energy in the roots, causing the plant to send carbohydrates down to the rhizosphere. Amino acids required to produce complete proteins. This process requires more photosynthesis to occur, creating more energy than is actually needed for amino acid synthesis. Surplus energy is shared with the microbial community surrounding the roots.

As plants take in Nitrogen, they release hydrogen lowering the PH around root hairs. Acid Ph in the rhizosphere is required to inhibit plant pathogens and increase the uptake of minerals, especially trace elements.

Trace elements are required to produce secondary metabolites-Phenols, Terpenes, Alkaloids (plant protection from pests).

-Lighter, sandy soils require repeated additions of nitrogen in small amounts over the growing season.

-Winter cover crops are nitrogen catchers, picking up soluble nitrogen into plant tissue for the next season.

 

Calcium

Recommended to be at 65-77% of base saturation due to its large role in fertility. Calcium helps nutrients travel throughout the plant. It improves soil texture, and makes phosphorus and trace elements bioavailable. It also improves root, stem, and leaf development, affecting the protein quality of plants. Calcium helps plants resist fruit rotting, prevents the formation of mucilage and aging, and helps with freeze resistance. Foliar sprays are more effective than soil applications when these symptoms are experienced. Drought is a major cause of calcium stress more so than low calcium levels within the soil, since calcium precipitates, and can’t move in the soil as it dries out.

-Irrigation water too high in sodium and bicarbonate also contributes to calcium stress symptoms.

-Calcium neutralizes toxic levels of oxalic acid through the creation of calcium oxalate.

Sources of calcium

-High calcium limestone, Dolomitic limestone, Gypsum or calcium sulfate, Cement kiln dust, burnt lime, Sugar beet lime, Calcium silicate, Calcium chloride, Paper mill sludge, Calcium nitrate, Aragonite

 

Phosphorus

Core element of the energy currency of all-life forms, namely ATP. Triple negative charge causes it to lock up with cations like Calcium, Magnesium, Aluminum, Iron, and Potassium. Essential for the synthesis of DNA and RNA. Aids photosynthesis, flowering, fruiting, seed production, nitrogen fixation, root growth, and stalk strength. Perennial crops can utilize more organic and less soluble forms of phosphate than annuals. Recommended to apply soluble form of phosphate as well as slow release phosphate. Bone meal and guano sources perform both fast and sustained-released phosphate.

Sources

-Soft rock phosphate, Hard rock phosphate, Bone meal, Charred bone meal, Bird Guano, Hen manure/compost, Fish Hydrolysate, Super phosphate, Triple super phosphate, Diammonium Phosphate, Monoammonium phosphate, Orthophosphate, Monopotassium phosphate, Biosolids, Dipotassium phosphate

 

Potassium

Major element that doesn’t incorporate into organic compounds. Remains in ionic form in solution within the cell. Activator or many enzyme systems important for starch synthesis, photosynthesis, protein synthesis, and translocation of sugars. Enhances water uptake, drought tolerance, hardiness, and resistance to fungal and insect pests. Locked up volumes of potassium aren’t available to plants, and don’t show up on soil tests since they aren’t located on exchangeable sites of the clay colloids. Increasing organic matter invites bacteria and fungi to produce enzymes and acids to help release potassium. Perennial root systems have an advantage in mobilizing potassium, since they can access the exchangeable and solution sources of potassium, and have enzyme, and organic acid resources to extract hard to access sources of potassium. Higher ph soils don’t readily accept potassium inputs, and when combined calcium and magnesium base saturations exceed 90 percent it is hard to build potassium levels. High sodium levels, often found in arid regions, compromise potassium availability. Excess nitrogen drives potassium down.

Sources of Potassium-

-Potassium sulfate, Potassium chloride, Potassium hydroxide, Dipotassium hydroxide, Monopotassium phosphate, Potassium nitrate, Glauconite, Wood ashes, Manures.

 

Sodium

Part of the cationic mineral balance. Affects soils pH and electrical conductivity. Sodium governs the osmotic pressure in cellular tissues and fluids in plants as well as animals/humans. Excess sodium a common issue, preventing clay from granulating. In C4 plants and warm-season perennials, sodium is needed to bring about a higher utilization of carbon dioxide. Sodium buildup comes from irrigation. Saline waters are an issue, since they will eventually displace other critical cations such as magnesium, calcium, and potassium. Salts will contribute to nutrient deficiency. Adding potassium silicates, humic acids, and soluble gypsum to saline water can counter negative effects. Over tillage can allow sodium and other salts to accumulate.

Sources

-Rock salt, Sodium sulfate

 

Chloride

Secondary element. Affects the opening and closing of the leaf’s stomata. Aids in producing antibiotic and fungicidal compounds. Chloride excesses are a larger concern than deficiencies, especially in arid areas. Overuse of potassium chloride increases the salt index of the soil, dehydrating roots and soil microbes.

Sources

-Rock Salt, Potassium chloride

 

Magnesium

Core element of chlorophyll, and rich in nitrogen. Magnesium acts as an adhesive with soil particles, helping sandier soils improve structure. Excess soil magnesium suppresses the uptake of magnesium by depressing calcium.

Sources

-Dolomitic limestone, Magnesium carbonate, Serpentine, Magnesium sulfate/Epsom salts, Magnesium hydroxide, Magnesium chloride

 

Sulfur

Fourth major nutrient. Sulfur partners with nitrogen to make complete proteins. Necessary for nitrogen fixation, the formation of chlorophyll, and is an essential component of vitamins. Facilitates the translocation of sugars. Sulfur plays an important role in the synthesis of glutathione. It aids in the protection of the cell membrane, and supports glutathione which is a antioxidant, shuttling out toxic metals like lead, cadmium, arsenic, mercury, and metals like copper. Sulfur tends to leach in poorly drained soils, or in greenhouses without rainfall. Soils rich in humus are necessary to hold onto sulfur. Sulfur levels have decreased due to a widespread loss in organic matter. Manure and compost are great sources of non purchased sulfur. Sulfur remediates excesses in the soil, reducing magnesium, calcium, sodium, and potassium.

Sources

-Elemental sulfur, Gypsum or calcium sulfate, Potassium sulfate, Sul-Po-Mag, Ammonium Sulfate, Magnesium Sulfate, Ammonium thiosulfate

 

Silica

Considered nonessential, due to large concentrations in the soil. Plants utilize silica to create armor that discourages fungal and bacterial disease and insect attack. Silica proves useful to increasing plant tolerance to salinity by immobilizing sodium. Supports stalk strength. Foliar silica sprays have been shown to prevent plant diseases. Silica can repel sucking insects.

Sources

-Rock dust, Diatomaceous earth, Potassium, Clay Minerals, Humic and Fulvic acids

 

The mineral makeup and deficiencies of the soil are crucial to understand, and will undoubtedly affect the health of your plants. Next week I will look at the micro nutrients that aren’t mentioned in this list, detailing their interactions and importance.

 

During week two, I looked at some of the biological processes and functions of Mycorrhizae. I have been reading Radical Mycology, written by local mycologist Peter Mccoy. The text explores the uniqueness of fungal biology, and the roles of micro and macro fungi. It includes information for identifying mushrooms and mycorrhizal fungi, and talks about the ways that lichen are indicators of environmental health. It is recently written, and uses language that is helpful, and less wordy than some of the more confusing texts I have read. I also like that there are tools for making fungal medicine, growing fermented fungi, and cheaply cultivating mushrooms.

I focused on the information about Mycorrhizae, and these are some of the points that stood out to me.

Mycorrhizae..

-play a big function in nutrient cycling within the soil and plant roots.

-move carbon, nitrogen, sulfur, phosphorus, and other essential elements throughout the rhizosphere.

-are central to the carbon cycle

-use production of strong acids to release nutrients from rocks into soil webs.

-Are found on the surface, and inside of most rocks

-extract phosphorus and potassium from rocks with the use of Oxalic Acid

 

Mycorrhizae can also play a large role in the remediation of soils

Mycorrhizoremediation

Heavy metals are known to affect soil Ph, and health. Mycorrhizae are known to significantly reduce negative impacts of toxic heavy metals such as mercury, arsenic, and cesium on environment. Current restoration focuses on replacing soils (that are not fungally dominated), and unfortunately chemical fertilizers are often added in the process.

 

Major functions of Mycorrhizae

A large feature of Mycorrhizae is the Hartig Net, a main nutrient exchange interface, that is essentially repeated branching of the inner mantle. It is involved in the bi-directional movement of nutrients. Fungal are capable of absorbing glucose and/or fructose from root cells, converting it into carbohydrates, trehalose, and mannitol, or into insoluble carbohydrate, glycogen. Complex hyphal branching is involved in the absorption of sugars from root cells into the hartig net hyphae and back into the mantle of the Mycorrhizae.

Hartig Net