Exam 2 Flashcards
What are the 3 tools that can be used for diagnosing nutrient deficiencies and toxicities?
Foliar analysis, soil/substrate analysis, visual diagnosis
Describe the procedure for collecting a foliar sample
The youngest fully expanded leaf, 20+ leaves (30 g dry weight)
Why does position of the leaf matter when collecting a foliar sample?
There’s different nutritional zones on a plant
What is a nutritional zone?
The top half of a plant would mean the nutrient problem is immobile, and the bottom would be a mobile element
What information can be gathered from a soil/substrate sample analysis?
Real time and futuristic data
What are the 5 integral set of information that need to be gathered to diagnose a proble?
crop history, water analysis, visual diagnosis, soil testing, foliar analysis
How do you collect a soil sample and a substrate sample?
4-8” soil probe (removed top mulchy bits), dry soil in the sun, ship asap
Soluble ions in irrigation water can be both good and bad for plants in production. For example, Na is a beneficial nutrient for many plants. However, when Na levels in irrigation water are too high, or out of proportion with other nutrients, Na levels can be a problem. What are the possible beneficial and harmful components in irrigation water?
Good-N,P,K,Mg,S,Fe,Mn,Cl,B,Zn,Mo,Cu, good amounts of salt, microbes
Bad-fluoride, too much salt, microbes
Why does poor water quality have a greater impact on the nutrient uptake of plants growing in substrate than plants growing in soil?
Soil has a buffering capacity, where substrates do not, they can work around bad water for the most part
If soil/substrate pH is too high, how will nutrient uptake by the plant be affected?
Certain nutrients just won’t be taken up
If soil/substrate pH is too low, how will nutrient uptake by the plant be affected?
It may over absorb certain nutrients and cause a toxicity
What is hardness? How does hardness affect plant nutrition?
The amount of Ca and Mg in water
Describe salt stress associated with irrigation water with high soluble salts
It will cause nutrient antagonisms
Define primary and secondary macronutrients
Primary are the most limiting to growth and secondary are not limiting to growth
T/F: Liebig’s Law of the minimum states that the capacity for growth is limited by that is in least supply
True
What are specific functions of the essential plant nutrients?
-N+S=integral elements of C compounds
-P=essential in energy acquisition and utilization in the genome
-Ca,B,Si=structurally associated with the cell wall
-Mg,Fe,Mn,Ca=serve to activate or control the activity of enzymes
What are the non-specific functions of the essential plant nutrients?
-K,Na,NO3,Cl,SO4,Ca,Mg=counter ions to positive or negative charges
-K,Na,NO3,Cl=major cellular osmotica
What are the major ionic forms that N can be taken up by plants?
NO3- and NH4+
What are the minor ionic forms that N can be taken up by plants?
N fixation, urea, soluble organic compounds
How do plants differ in their NH4:NO3 preference and uptake? As a rule, how does N rate play into a plant’s NH4:NO3 preference?
Preference is species specific, as a rule mix NH4+ and NO3-
What are the sources of N in the soil? Explain the steps of mineralization, ammonification and nitrification. How does pH affect each of these?
-Ammonification=organic N>NH4
-Nitrification=NH4>NO3
-A lower pH will inhibit nitrification
-A higher pH favors nitrification
What are the major ionic forms that P can be taken up by plants? Which form is the easiest for the plant to take up?
H2PO4- and HPO4(2-), labile P is easiest to take up
How does low (less than 7.22) and high (greater than 7.22) pH affect the P form present in the soil?
Low pH gets its H2PO4 from Al and Fe compounds, high gets it from Ca compounds
What are the sources of P in the soil? Describe the 3 pools of P in the soil (soil solution P, labile P, and non-labile P)
-Solution is available now, labile is available in mins/hours, non-labile is not available
