soil fertility and essential nutrients

Question 1

what is the definition of soil fertility

Answer 1

the ability of the soil to supply essential nutrients to support plant growth and reproduction

Question 2

what is the criteria of plant nutrient essentiality

Answer 2

1) element is necessary for the plant to complete the vegetative or reproductive stage of its life cycle
2) deficiencies of the element are specific to that element; the element is not replaceable by another
3) element is directly involved in growth or metabolism

Question 3

where do elements come from

Answer 3

most essential elements are derived from the mineral and organic fractions of the soil

exceptions are C,H,O which are supplied as CO2 and H2O

Question 4

what are macronutrients

Answer 4

elements required in relatively large quantities—make up the bulk of structural and protoplasmic tissue

Question 5

what are micronutrients and what do they help with

Answer 5

elements required in small amounts— for enzymatic, oxidation, reduction, and other reactions

Question 6

how are macronutrients measured

Answer 6

in percent dry weight

Question 7

how are micronutrients measured

Answer 7

parts per million dry weight

Question 8

why are macronutrients and micronutrients equally important to plant growth

Answer 8

nutrients are assimilated and become components of cell constituents in defined proportions.

ex. think of it as building a house without nails. they are small but you can’t build a house without them you cant

Question 9

what is Liebig’s Law of the minimum

Answer 9

crop yield is proportional to the amount of the most limiting growth factor (e.g., nutrients) and that additions of resources to alleviate the limiting growth factor will increase yield until the point that some other growth factor is needed in greater quantity than the soil or environment can provide

Question 10

what forms do plants take up nitrogen

Answer 10

NO3-, NH4+

Question 11

what are the functions of nitrogen in plants

Answer 11

combines with carbohydrates to form amino acids and proteins involved in enzymatic processes; components of DNA and RNA

Question 12

what forms do plants take up phosphorus

Answer 12

PO4^3-, H2PO4-, HPO42-

Question 13

what is the function of phosphorous in plants

Answer 13

energy transfer-constituent of ATP

Question 14

how do plants take up potassium

Answer 14

K+

Question 15

what is the function of potassium in plants

Answer 15

activates cellular enzymes; regulates osmotic potentials

Question 16

how do plants take up sulfur

Answer 16

SO4-2

Question 17

what if the function of sulfur in plants

Answer 17

an essential component of some amino acids; important for the synthesis of oils, especially in oil crops like canola

Question 18

what are the ways roots take up nutrients from the soil

Answer 18

diffusion, mass flow, root interception

Question 19

how does diffusion work for root nutrient uptake and what nutrients get taken up this way

Answer 19

dominant for K & P, concentration gradient drives diffusion

Question 20

how does mass flow work for root nutrient uptake and what nutrients get taken up this way

Answer 20

dominant for Ca & Mg and anions like NO3-, mass movement of nutrients with water driven by transportation

Question 21

haw does root interception work for nutrient uptake and what nutrients get taken up this way

Answer 21

a very small contribution to overall uptake. as the root grows the root moves toward the nutrients and intercepts the nutrients in the soil

Question 22

what are symptoms of N deficiency in plants

Answer 22

yellowing of the leaves and stems–older leaves yellow first.

stunted growth

less tillering in cereals

Question 23

what are some symptoms of P deficiency

Answer 23

stunted growth, limited root development

purplish coloration of stems and leaves

Question 24

what are some symptoms of K deficiencies

Answer 24

dull green leaves

yellowing leaves (you can distinguish the difference between N because it will be yellowing on the edges although a test can be done to determine)

Question 25

if you do suspect a deficiency whats the best way to confirm

Answer 25

identifying by doing a chemical analysis of plant tissue is especially helpful for micronutrient diffecencies.

Question 26

nutrient deficiencies can be hard to diagnose. what can deficiencies be confused with

Answer 26

diseases, herbicide damage, heat?cold damage, drought damage, insect damage