Agronomy

describe the soil classifications in the Northern region

Vertosols - clay >35%, cracks, slickensides

Sodosols - strong texture-contrast (2 completely different soil textures on top of one another), sodic (high sodium) B horizon. When it rains, these soils erode fast. Can cause water logging. 

Chromosols - strong texture contrast, pH > 5.5 in B horizon. Not sodic. 

Kandosols - Lacking strong texture contrast, massive B horizon. Low nutrient content. 

Describe the soil classifications in the Southern region

Sodosols - strong texture-contrast (2 completely different soil textures on top of one another), sodic (high sodium) B horizon. When it rains, these soils erode fast. Can cause water logging.

Chromosols - strong texture contrast, pH > 5.5 in B horizon. Not sodic. 

Calcarosols - lacking strong texture-contrast, high in calcium

Describe the soil classifications in the Western region

Tenosols - does not retain moisture well. 

Sodosols - strong texture-contrast (2 completely different soil textures on top of one another), sodic (high sodium) B horizon. When it rains, these soils erode fast. Can cause water logging.

Calcarosols - lacking strong texture-contrast, high in calcium

Kandosols - Lacking strong texture contrast, massive B horizon. Low nutrient content. 

What is PAW? What can it be affected by?

Plant Available Water. Can be affected by rainfall, infiltration, drainage, runoff, evaporation, transpiration, and soil-available water capacity

What is PAWC? What is needed to calculate it?

Plant available water capacity. You need

1. DUL (= Drained Upper Limit - field capacity; amount of water a soil can hold against gravity)

2. CLL (= Crop Lower Limit - permanent wilting point; amount of water remaining in a soil after a specific crop has extracted all available water) OR LL15 (= Lower Limit 15 - Water remaining in soil at 15 bar pressure.)

3. Bulk density (g/cm^3) (the mass of dry soil per unit volume, including both solids and pore space.)

What is fallow efficiency and how can it be affected?

Fallow efficiency is how much water is able to be retained in the soil profile within a fallow. It can be affected by infiltration, runoff, erosion, evaporation. 

Some crops like wheat leave residues that are good for fallow efficiency. Weeds can make a big difference in fallow management. 

How do you calculate fallow efficiency?

2 soil samples, one at start of fallow and one at end. Know water inputs into the system during the fallow (rainfall). 

Fallow efficiency = change in plant-available water during fallow / rainfall during fallow