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162 Cards in this Set
- Front
- Back
NH4 |
Ammonium, solid |
|
NH3 |
Anhydrous Ammonia (gas at reduced pressure, liquid under pressure) not plant available, 82-0-0, |
|
NO2 |
Nitrite (unavailable to plant) |
|
NO3 |
Nitrate (leached out or denitrified) |
|
NH2(2CO) |
Urea, 46-0-0, solid |
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UAN |
Urea plus ammonium Nitrate solution- 28-0-0 to 32-0-0, liquid |
|
NH4NO3 |
Ammonium Nitrate, 33.5-0-0 or 34.0-0-0 solid |
|
(NH4)2SO4 |
Ammonium Sulfate, 21-0-0, solid |
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Which Phosphorus form is a liquid? |
Ammonium Polyphosphate, 10-34-0 to 11-37-0 |
|
%P = _ x %P2O5 |
0.44 reverse is 2.29 |
|
%K= _ x %K2O |
.83 reverse is 1.21 |
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Potassium Forms are all Solid or Liquid? |
Solid |
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T or F A fertile soil is always a productive soil? |
False |
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What are 6 external factors that control plant growth? |
Air, temperature, light, water, mechanical support, & nutrients |
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How many essential plant chemical elements are there and how many are found in the soil? |
17 total and 14 in the Soil |
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When is a nutrient considered to be essential? |
If it is necessary for the plant to complete its life cycle & no other element can substitute for it completely. |
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What essential nutrients are non mineral? |
Carbon, hydrogen, Oxygen. Found in the atmosphere and water. |
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How many micronutrients are there? |
6 N,P,K,Ca,Mg,S |
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How many micronutrients are there? |
8 B,Cl,Cu,Fe,Mn,Mo,Ni,Zn |
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What are the four additional nutrients that are almost never deficient in Soils? |
Sodium Na, Cobalt Co, Vanadium V, Silicon Si |
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T or F, Nitrogen, P & S are all micronutrients? |
True |
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T or F, Macronutrients are more essential than micronutrients? |
False |
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When is a soil texture classified as loamy sand or sandy loam? |
When small amounts of silt or clay are present |
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How many soil textural classes are there? |
12 |
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When is soil classified as a clay loam? |
When sand, silt, and clay are all present in similar proportions. |
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What are the structural types of soil? |
Blocky, granular, and prismatic |
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Which particle size has a higher surface area, large or small? |
Smaller particle sizes. As surface area increases water absorbed (held) increases |
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What soil texture holds the largest amount of plant avaliable water? |
Silt loam |
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What is the best structure soil for ease of crop management? |
Blocky or granular |
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What is the most difficult soil structure? |
Soils high in silt, easily compacted |
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T or F, sandy Soils have finer textures than clay Soils? |
False |
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Which soil has larger pore spaces, clay or sand? |
Sand |
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The water a plant uses for its growth is called? |
Available water |
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What is the ideal soil for crop production? |
Medium textured (loamy), adequate clay content to retain sufficient soil moisture, deep permeable sub soil, suitable environment for roots to go deep, minimal compaction, acidity, or salinity |
|
Colloids |
Very small particles not seen by the naked eye. Most mineral clay colloids are plate like in structure. Most Soils contain more clay colloids than organic colloids. |
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What is a colloid primarily responsible for? |
The chemical reactivity in soils |
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What charge is a clay colloid? |
Net negative charge. Organic colloids are also net negative but their negative charge decreases as the soil ph declines (variable charge). |
|
% of clay in loamy sand |
5 |
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% of clay in sandy loam |
10 |
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% of clay in silt loam |
20 |
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% of clay in silt clay loam |
30 |
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% of clay in clay loam |
35 |
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% of clay in clay |
>40 |
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What does the CEC depend on? |
Amounts and kinds of clay and the amount of organic matter present. |
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What is the CEC expressed as? |
Centimoles of charge per kilogram of soil (cmol/kg) also milliequivalents per 100 grams soil (meq/100g). Both are equal |
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What is the CEC of clay minerals? |
200-400 cmol/kg |
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What is the CEC of organic matter? |
200-400 cmol/kg |
|
Cations |
Potassium, sodium, hydrogen, calcium, magnesium |
|
Potassium ionic form |
K+ |
|
Sodium ionic form |
Na+ |
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Hydrogen ionic form |
H+ |
|
Calcium ionic form |
Ca2+ |
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Magnesium ionic form |
Mg2+ |
|
Anions |
Chloride, Nitrate, sulfate, phosphate |
|
Chloride ionic form |
Cl- |
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Nitrate ionic form |
NO3- |
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Sulfate ionic form |
SO2- |
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Phosphate ionic form |
HPO42 ; H2PO4- |
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What does cation exchange capacity depend on? |
Amounts and kinds of clay and the amount of organic matter present. The total number of exchangeable cations a soil can hold (the amount of its negative charge) |
|
How does the cec increase? |
As the OM content increases |
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What is cec expressed in? |
Centimoles of charge per kilogram of soil (cmol/kg) and also milliequivalents per 100 grams of soil (meq/100 g). Both are equal! |
|
What is the cec of clay minerals usually? |
10- 150 cmol/kg |
|
What is the cec of organic matter? |
200-400 cmol/kg |
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What helps reduce the potential of Nitrate NO3- leaching? |
Splitting N applications using nitrification inhibitors and timing applications to meet peak crop demands. |
|
What has been used to develop fertilizer programs? |
Base saturation- the percent of the total CEC occupied by the exchangeable basic cations (calcium, magnesium, potassium, sodium) The concept is that a certain ideal cation ratio or balance is needed to assure optimum yields. |
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Is Nitrate mobile in the soil? |
Nitrate is highly mobile and moves freely with soil mositure. Under high rainfall it moves downward. Under extremely dry weather it may move upward with soul mositure causing NO3- to accumulate on the surface. |
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Can sulfate attract to OM at low PH? |
Yes organic matter sometimes develops a positive charge at low ph and sulfate SO42- can be attracted to it. |
|
Is phosphate mobile in soil? |
Immobile in the soil because of adsorption and precipitation reactions with the soil minerals. Held strongly by the soil through various chemical reactions. |
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What charge is sand? |
Carry little or no charge and do not react with CEC. |
|
50 cec is classified as? |
Heavy clay! 0= sand |
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Does a higher or lower CEC soil require more lime? |
Higher cec requires more lime because it contains more acidity, more anions then the lower cec soil |
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How much nitrogen does OM contain |
5%. Serves as a storehouse for plant avaliable N. Not immediately avaiable to the plant, must decompose completely |
|
How many tons per acre of residues in high yielding corn is left after harvest? |
8 tons per acre |
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Are soil OM levels usually higher is warmer climates with higher rainfall? |
False |
|
What is soil aggregation? |
The resistance of soil particles being able to break apart. |
|
What is an acid? |
A substance that releases hydrogen ions (H+), saturated with H+ the soil behaves as a weak acidic, the more H+ held in the cec the greater the Soils acidity. |
|
Hydrogen ion + in soil/cec |
Cation exchange can increase alkalinity whenever hydrogen ions in solution exchange on surfaces for base cations. The effect is generally reversible, and thus the process may not contribute to long-term increases in alkalinity once the cation exchange sites are depleted. In fact, cation exchange can act in reverse if base cations are added from sea spray or road salt to a soil solution, causing temporary acidification and loss of alkalinity. Nevertheless, soils with large cation exchange capacities can act as a large buffering reserve against relatively short-term acidification events. |
|
How does decomposition affect soil ph? |
Soil OM is continuously being decomposed by microorganisms into acids. |
|
How does rainfall affect PH? |
Rainfall passes through the soil, basic nutrients like Ca and Mg are leached below the root zone. They are replaced by acidic elements like Al, H, and Mnthat are more acidic. |
|
How does nitrogen fertilization affect PH |
Speeds up the rate of which acidity develops unless the nitrogen is supplied in the form of Nitrate (NO3). |
|
What are the base cations. |
Ammonium, magnesium, potassium, calcium, sodium |
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What are the acidic cations? |
Hydrogen & aluminum |
|
Do legumes usually contain more Ca & Mg than non legumes. |
Yes |
|
Some nitrogen fertilizers can produce acidity in the soil? |
True |
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Lime requirement is related to both? |
PH and Cation Exchange capacity |
|
Buffer capacity |
The measure of a Soils resistance to PH change. |
|
Buffering capacities are higher for sands than clays? |
False, buffering is higher when clay and OM are present. |
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A general lime requirement can be determined properly only if what is measured? |
Potential acidity |
|
For best results, when is lime applied? |
Several months before planting to allow sufficient time to neutralize soil acidity. Or after harvest if already planted. |
|
Solubilitied of ion such as Al and Mn increase as soil PH increases to potentially toxic levels. |
True |
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Low soil PH does not affect symbiotic nitrogen fixation by legumes? |
False, greatly reduced |
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Which crop grows best in ph range above 6.5, corn, alfalfa, wheat, soybeans, watermelon? |
Alfalfa |
|
What should be considered in a soil ph maintenance and lime program? |
Lime cost, specific soil, micronutrient levels. Soil mineralogy, the potential for Al toxicity. Soil phosphorus levels. Whether sub soil PH is higher or lower than in the surface soil. Soil tillage system, specific disease risks |
|
What do liming materials remove from the soil? |
H+ and aluminum (Al3+) |
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Liming increases soil ph but converting H+ into....? |
Water and Soluble aluminum (Al3+) into insoluble Al(OH)3 |
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Which soil needs to be limed more Sandy or Clay? |
Sandy Soils |
|
Basic slack has a higher neutralizing value than CaCO3 (calcitic lime)? |
False |
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Do oxides or carbonates react more rapidly? |
Oxides |
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Calcium lime (CaO) is also called? |
Unslacked lime, burned lime, or quicklime |
|
What do the neutralizing values of lime usually range from? |
65-70% to more than 100% |
|
Can acidic soil cut fertilizer efficiency as much as 50%? |
Yes by damaging roots and stunting growth. |
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Which soil contains free calcium carbonate? CaCO3 |
Calcareous |
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How is the degree of salinity measured on the soil testing lab? |
As electrical conductivity |
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What crops are salt tolerant? |
Barley, cotton, sugar beets, canola, bermudagrass, sweet clover |
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Sodium (alkali) contain higher amounts of? |
Sodium |
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Is gypsum used to reclaim sodic Soils? |
True |
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Sodic Alkali soil |
Excessive amounts of salts and ph above 8.5 |
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Saline Soils |
Excessive sodium and ph less then 8.4 or less |
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Is Sulfur need closely related to the amount of Nitrogen available to crop plants? |
True |
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Is sulfur mobile in plants? |
No |
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Most plants contain about the same amount of Mg to S & S to P? |
True |
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Is Sulfur considered the 4th most needed fertilizer after NPK? |
Yes |
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How is Sulfur absorbed in plants? |
As the sulfate (SO42-) anion. It can also enter plant leaves from the air as Sulfur dioxide (SO2) gas, and so crops are rarely deficient in S in areas of industrial air pollution |
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Is Sulfur required for Protein Synthesis? |
Yes, it aids in seed production and producing the chlorophyll necessary for plants to carry out photosynthesis. |
|
What are the three S containing amino acids? |
Cysteine, methionine, and cystine |
|
What is S required for in legume crops? |
Nodule formation on root hairs |
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What happens if you have a shortage of S? |
Reduces crop yield & quality. Bread baked with low S wheat will not rise properly and has dense loves because certain proteins are missing in the grain. |
|
Are N & S both needed for protein formation? |
Yes, S availability can't be ignored when evaluating N fertilizer use efficiency. |
|
Is sulfate an Anion or cation? |
Anion |
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Most S found in Soils is contained in? |
OM |
|
Why does Sulfur remain in soil soultion and move with soil water? |
Because it is an anion and is not attracted to most clay soils and OM surfaces. It is readily leached because of this. |
|
Where is much of Sulfur store? |
In soil OM |
|
Leaching of sulfate SO42- Is more likely is what textured soil vs another? |
Coarser textured Soils than finer textured soils |
|
What % of S is contained in fertilizer forms of elemental S? |
85% |
|
What fertilizer material contains the most Sulfur? |
Ammonium polysulfide 40-50% |
|
What is gypsum? |
Calcium Sulfate |
|
Fertilizers that contain insoluble elemental S require a conversion to Sulfate before plants can take it up. |
Yes, S+water+oxygen = sulfuric acid (H2SO4) |
|
Sulfates are water solvable while elemental S is water insoluble. |
True |
|
Extremely small particles of elemental S fertilizer are called? |
Micronized- S converts to SO42 (Sulfate) in the soil quickly. Currently applied as a fungicide. |
|
Plants can utilize elemental S? |
False |
|
Is Sulfur mobile in the plant? |
False |
|
What crops have a high Sulfur requirement? |
Oilseeds like soybean and canola, ans forage crops |
|
How is calcium taken up by plants? |
Ca2+ cation |
|
Roles of calcium in plants? |
Stimulates root and lead development, forms compounds of cell wall to strength plant structure, helps reduce Nitrate- N (NO3-_N) in plant, lowers toxicity of Mn & Al, |
|
Do clay Soils usually contain more calcium than sandy Soils? |
Yes more Cec capabilities in clay |
|
Calcium deficiencies are commonly seen on older plants tissue? |
False- Calcium has low mobility in plants so it will affect the younger tissue first |
|
Does calcium move with the transportation of water? |
Yes, sometimes deficiencies appear on plant parts that have little water loss. |
|
How is Mg taken up by plants? |
As the Mg2+ cation. |
|
Mg & N are the only soil nutrients that are constituents of Chlorophyll? |
True |
|
Mg is not absorbed as tightly by clay and OM so is more susceptible to leaching? |
True |
|
Magnesium is usually most deficient in Coarse textured Soils under high rain fall conditions? |
True |
|
Magnesium deficiency usually appear on younger or older leaves first? |
Older, Mg is mobile in plants and when a deficiency occurs, chlorophyll in the older leaves is broken down and transported to the new plant growth. |
|
What are the 8 essential micronutrients? |
Boron, chloride, copper, Manganese, molybdenum, nickel, zinc, iron |
|
The availability of most micronutrients in the soil increases as soil ph increases? |
False |
|
What is a crops nutrient requirement supplied by? |
Soil and fertilizer |
|
Fertilizer needs can be reliably determined based on crop removal alone? |
False, doesn't take into affect the soil nutrients. |
|
Soil testing is a helpful management tool for immobile nutrients even in areas with wide weather induced variations? |
True |
|
Soil testing is the single best management tool for mobile nutrients even in areas with wide weather induced variations? |
False, nutrient sufficiency & build maintenance |
|
The sufficiency approach is more likely to maximize profits in the year of application and the build maintenance approach is more likely to maximize yields? |
True |
|
The goal of the sufficiency approach is to raise the soil test to a level sufficient for maximum yields? |
False it is to use just enough fertilizer to maximize profitability in the year of application. |
|
The presidedress Nitrate test or late spring Nitrate test has been proposed as an early indicator of yield potential? |
False- it has been correlated with N response in maize. |
|
What does NDVI stand for? |
Normalized difference vegetation index |
|
What are indirect methods for sampling? |
Leaf color chart, chlorophyll meter, optical sensors, drones |
|
Is purchasing nitrogen a long term or short term investment? |
Short term because it does stay in the soil due to leaching or volitalization |
|
Is purchasing P&K fertilizer a short term or long term investment? |
Long term because it stay in the soil for the next crop usually. |
|
Early planting and K fertilization of corn interact positively to increase yield potential? |
True |
|
What does MEY stand for? |
Maximum economic yield |
|
MEY definition |
That yield where unit costs are lowered to the point of highest net return per acre- the most profitable yield. |
|
When does it become unprofitable to increase fertilizer rates? |
At the point of maximum profit (diminishing returns). The key to additional fertilizer increments is whether the return was greater than the cost. You may have a higher yield then last crop but a lower net return overall |
|
The key to deciding whether to use additional fertilizer increments is whether or not the last increment produced a return as high as the previous one? |
True, more input can cause a higher yields but a lower return on $ due to input |
|
What is variable rate fertilizer application? |
Variable rate fertilizer application allows crop producers to apply different rates of fertilizer at each location across fields. |
|
From a crops view there is no difference among the various nutrient sources (organic or inorganic)? |
True because a plant doesn't use nutrients in their original forms. All nutrients must be in a soluble form before they can be taken up by the plant roots. |