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Oxidation and reduction are important to understand due to their relation to disease enhancement or suppression.
Disease enhancing soils tend towards oxidizing, alkalinity, nitrogen as nitrates, with poor biology.
Disease suppressive soils tend towards reducing, acidifying, nitrogen as ammonium, with aggressive biology
pH: Proton transfer potential – Scale from 0 to 14
Redox potential, Eh: Electron transfer potential – Scale from 0 (reduction) to 48 (oxidation)
“It is worth reviewing that the main constituents of living organisms, especially proteins, are just six elements: (i) oxygen; the strongest oxidizing agent; (ii) hydrogen; the strongest reducing agent; and (iii) the four elements that have the largest amplitude in redox numbers: carbon (−IV in CH4 to + IV in CO2), nitrogen (−III in NH 4 + to + V in NO 3 – ), phosphorus (−III in PH3 to + V in PO 4 3- ), and sulfur (−II in H2S to + VI in SO 4 2- ).” https://link.springer.com/article/10.1007/s11104-012-1429-7
Redox reactions describe the movement of electrons from one ion to another. The term RedOx comes from the two processes that occur during a reaction: REDuction and OXidation. These reactions occur together, they cannot occur separately.
eH determines anion availability.
eH is not stable like pH. It moves all the time, for example with soil saturation
Oxidized soils are electron hungry. If you put a reduced substance into them, the electrons will be stripped.
Rainy periods are a reducing environment / dry periods are an oxidizing environment
Mn, Fe, Cu, Co (but not Zn) are absorbed and active in the reduced form
Cultivation causes a CO2 release due to oxidation. Also strong bacterial digestion will cause a CO2 release.
Reduced environments: anaerobic fermentation, blueberry or cranberry bogs, bokashi
Reduced and acidic systems usually correlate in biological systems. This is not necessarily true in chemistry.
Blueberries need very reduced environments because they need Mn, Fe, P.
It’s important to know the biological state.
N, P, S have large redux swings
Ammonium is the reduced form of N. Oxidized forms are No3 and nitrate.
Dry soil becomes oxidized.
Salt fertilizers such as KSO4 are oxidizing. We need to include reducing effects.
We need to move the system from oxidizing to reducing.
Disease suppressive soils are slightly reducing in eH. Neither aerobic nor anaerobic dominant. Facultative microbes are defined as those who can produce ATP using an oxygen pathway when present or anaerobically when not. These include human diseases such as strep, staff, e coli, salmonella. Another, Shewanella oneidensis, is able to strip electrons from metals and convert them to a reduced form.
Plants with reducing roots include non-GMO corn, alfalfa, forage legumes, oats, buckwheat, brassicas.
Plants with oxidizing roots include wheat, GM corn, soybeans
High glucosomate mustard or mustard seed are highly reducing.
A diverse ecosystem moves things towards a healthy, reducing environment.
Healthy manure is reducing
Milk house waste in manure is related to disease.
Soil type will help you estimate water holding capacity (inches of water available to plants). Soil texture influences the water holding capacity of soils. The proportion and absolute amount of water available to the plant in coarse-textured, sandy soils is less than in fine-textured, clay soils, therefore clay holds the most water.
Each foot of soil depth holds:
|Sands||1.0–1.5 inches of water|
|Loam||1.5–2.0 inches of water|
|Clays||2.0–2.5 inches of water|
Citrus Growth Stages
• Flowering, Fruit Set and New Flush Development:
This growth stage must have optimum soil moisture. Even a slight water deficiency means that leaves are smaller, and the plant is not in its prime. Severe water deficiency results in poor leaf development, incomplete flowering, poor fruit set and a high rate of fruit drop (Food and Fertilizer Technology Center, 2003). The soil water tension reading should be 30 – 60 cBar.
• Fruit Development:
The remaining fruits now begin to develop, and it is during the late fruit development stage that citrus trees need their greatest amount of water because of the high transpiration rate. Not having enough water at this stage would inhibit photosynthesis. The water tension reading at this time should be between 60 and 90 cBar.
• Fruit Maturing Stage:
At this stage of fruit development the quality of the fruit is the concern. A high soil moisture content promotes vegetative growth which does not help the already existing fruit. In order to slow vegetative growth and improve reproductive growth, soil should be kept fairly dry, without any irrigation, roughly 80 to 95 cBar.
• After Harvest:
After the fruit is harvested, the tree requires a small amount of irrigation water; just enough to meet ET requirements, to restore tree growth back to its normal rate. A minimal amount of irrigation water will maintain photosynthesis in the leaves and help to avoid nutrient stress.
On a scale of 0 to 100 cb soil watertension, how wet is your field?
Our research has allowed us to determine the threshold SWT of various crops growing on silt loam under different irrigation systems. We found that irrigating at these critical values has significant benefits to crops.
Roughly speaking, a GMS reads the following scale of SWT for a medium-texture soil:
The SWT irrigation threshold varies not only by crop but also by soil texture, climatic factors, and irrigation method. The threshold values that maximize marketable yield are known for a wide array of commercial crops growing on different soils under different climatic conditions and irrigation systems (Tables 1–4, pages 7–9).
• > 80 cb indicates dryness.
• 20 to 60 cb is the average field SWT prior to irrigation, varying with the crop, soil texture, weather pattern, and irrigation system.
• 10 to 20 cb indicates that the soil is near field capacity.
• 0 to 10 cb indicates that the soil is saturated with water.
In foliar feeding it is important that the spray droplets remain liquid on the leaf as long as possible so that the plant may take them up. The relative humidity below which a foliar will dry on the leaf and above which it will remain dissolved in water is called the point of deliquescence.
It has been found that the addition of humic acids to the spray will tend to lower the point of deliquescence, and allow the droplets to remain liquid longer.
Blossom end rot is not a calcium deficiency but rather a potassium excess. Manganese is the regulator of potassium. A foliar of chelated manganese along with fulvic acid will regulate potassium, either eliminating the deficiency in the plant or regulating down the excess.
With K or Ca excesses or functional deficiencies (i.e. when there are adequate amounts present in the soil) manage Mn and B. Mn regulates K and B regulates Ca.
Note that Mn triggers reproduction
Plants form a symbiotic relationship with microbes around the growing root tips. They seem to have a way to feed just the biology that will deliver the needed nutrients back to the plant. The broad brusg view of how this works is as follows.
Plants exude sugars out of their roots and feed the biology. The minerals necessary to build the microbes bodies are taken from the surrounding soil. For example, calcium is used for cell wall strength. The microbes die and leave chelated minerals in the soil where the roots need it. Roots take up the chelated minerals or else directly assimilate the microbes. The minerals are then moved through the plants where they are needed, as regulated by hormones.
Grow a rootstock seedling in spring
Graft a bud
Plant it in enriched soil in raised beds if drainage is an issue
Give it microstem irrigation at the proper amount
Give it lots of calcium with gypsum in the foliar feedings and in irrigation
Make sure the soil biology is working with biostimulants in the irrigation every week
Feed with Mn, P, seaweed and Ca for reproductive growth
To combine P and Ca use micronized rock phosphate
Apply Mn in the fall 4-6 weeks before leaf drop and during the spring at green-up. Fulvic acid moves Mn from the leaves (and any applied to the bark) down into the roots.
9-12 days after emergence a corn plant determines the number of ears it will have.
At 14-21 days it determines the number of rows of kernels per ear.
At 42-45 days it determines the number of kernels per row.
Reduce stress at the critical points of influence. Growth cycles between vegetative and reproductive dominance. Critical points of influence occur when the hormone/nutrient balance in the plant shifts from vegetative to reproductive dominance. Lack of nutritional integrity at these points triggers the breakdown of proteins into peptides and amino acids and creates disease/insect susceptibility.
For apples, pears, cherries, spur bearing trees this occurs at
spur bud fill
Cobalt inhibits senescence by inhibiting ethylene production which delays maturity and senescence. The result is uniform maturity. Apply chelated cobalt at 50g / acre.
The most influential CPIs are:
For this sequence to occur properly there must be adequate amounts of micronutrients including cobalt (Co), manganese (Mn), zinc (Zn), copper (Cu) and boron (B) in addition to the macronutrients.
Optimum moisture is required for flowering, fruit set and new leaf development. Any deficiency in water at this time will result in a loss of yield.