Soils Exam

Question 1

What are characteristics of a good soil>

Answer 1

Water stable aggregates - they can sustain water force
lagers pores for aeration and infiltration (.0.75mm)
Smaller pores for sufficient water holding capacity (0.2-30 microm)
Little resistance to root penetration
good infiltration form water and nutrient movement
Resists erosion (stable)
Easily workable
Absence of surface crusting

Question 2

Describe a poor soil sturcture

Answer 2

High density
poor aeration
low infiltration
low water conductivity
low plant available water
prone to erosion (aggregates non stable)
dispersive soils (particles not held together strongly)

Question 3

What nutrients cause flocculation and dispersion?

Answer 3

Flocculation is the holding together of particles and is done with Ca

Dispersion is the seperation of particles caused by sodicity and Mg

Question 4

What does cultivating do to the soikl?

Answer 4

Breaks down aggregates and OM
Increases aeration and microbial activity
resulting in declining OM
Causes structural decline

Question 5

NO-Tillage system have greater hydraulic conductivity then Tilled systems why>

Answer 5

There is no breeking up of aggregates and strucrture therfore greater pore continuity and larger pore sizes due to bio pores this results in greater amounts of water to flow through the profile compares to a tolled soil where the aggregates have been moved and pores have been broken

Question 6

Soil structire determines what

Answer 6

bulk density
total porosity
pore size distribution
pore continuity

Question 7

Three modes of structural decline?

Answer 7

1- OM delcin
2- vehical traffic or cultivation
3- sodicity /hardsetting soils

Question 8

What questions could you ask the farmer before starting recommendations?

Answer 8

Paddock history- what are the problem areas of the paddock? have you got yeild testing from past years? was the crop successful? how much was produced off the paddock? was it grazed?

Soil test- how many samples were taken where were they taken? was the place accredited? Where samples take in the problem areas (throw results)

What machineray and implimnets have you got access to? for incorporation and sowing? -ability to incorporate or deep band? (see the options you have)

Preferences- what is normally used? Organic farming? no tillage system?

RISK- what is the main aim for this paddock? do you want to have the best yeild in the district? the most protein? OR are we just trying to get over the line? (allows to understand financial constraints without being a dick)

Question 9

When should lime be incorporated into the soil?

Answer 9

It should be done 6-8 weeks prior to sowing… This should be done to allow the Ca CO3 to be broken down and to react to the soil
incorporation as its insoluble pretty much so we need to get it to all areas that need to have the pH altered