PS#4 - Roman Ferro BRAE 331 PS #4 1. A. What is the...

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Roman Ferro BRAE 331 PS #4 1. A. What is the difference between SMD and MAD in units and definition? MAD(Management Allowable Depletion) is the percentage of water that is depleted from the soil between the field capacity point and the permanent wilting point. The units of MAD are in percentage. SMD(Soil Water Depletion) is the depth of moisture depletion at any given time that is required to fill the soil reservoir up to field capacity. This value has units of inches of water. B. Which instrument, if any, provides a direct measurement of MAD or SMD? No instrument provides a direct measurement of MAD or SMD. Each soil is different, and will have different field capacities and permanent wilting points along with other soil properties that will make it harder or easier for plants receive water. There are several instruments that will aid you in calculating how much water is in the soil and how much water is needed, but none will give you a direct measurement of MAD or SMD. 2. If you want absolutely no deep percolation at a point, why should you shut the irrigation off before the wetted front reaches the bottom of the root zone? Use technical terms in your explanation, explaining the initial and final moisture contents. Once the water reaches the bottom of the root zone, it will continue to trickle down further even after the water is shut off. If any point in the root zone has high moisture content or is at saturation, the water will leave by way of gravity until it is at field capacity at this point. Even though the soil at the bottom of the root zone will initially have low moisture content when the water is shut off, the wetted front above it will be at saturation which will allow water to trickle down and fill up past the bottom of the root zone. 3. Should you use a high, or low, MAD if you have saline soil and you want to minimize stress? WHY? How is this different from leaching? You should use a small MAD in order to keep the salty soil water diluted, so that the
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This note was uploaded on 11/14/2011 for the course BRAE 331 taught by Professor Howes during the Winter '11 term at Cal Poly.

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PS#4 - Roman Ferro BRAE 331 PS #4 1. A. What is the...

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