Irrigation Flashcards
What is irrigation?
The science of applying water to the land or soil.
How much water do vegetables generally require per week?
As a general rule, vegetables grown on a loam soil require approximately 2.5 cm (1 in) of water per week
What are techniques for measuring soil moisture?
Lack of cracking, hand feel, the “gravimetric” method where soil-moisture content is determined by weighing the soil before and after oven drying, a tensiometer (to determine the tension of water in soil), Time-Domain Reflectometry (TDR) (measuring soil moisture at different depths through access tubes), monitoring plant-water status rather than soil.
What is the CWSI?
The Crop Water Stress Index which measures the canopy temperature with an infrared thermometer using the relationship between leaf temperature and transpiration, which is reduced by drought stress, leaf temperature increases.
What is leaf water potential?
Direct measurement of water in single representative plants using a pressure chamber (LWP) can be measured by quickly placing detached leaves into a portable pressure chamber whereby xylem sap is under tension and sucked back into the leaf. The xylem tension is roughly equal to LWP.
What is the “pan” method for estimating evapotranspiration?
A sunken pan is placed in the field so the top of the pan is near the soil surface. The rate of water loss from the pan is taken as an approximation of evapotranspiration.
Pan evaporation is related to evapotranspiration by a crop coefficient that has been determined experimentally for many vegetables Crop coefficients change with crop development, so the amount of water needed for irrigation changes during the season.
List types of irrigation systems?
Overhead (sprinklers and guns), surface delivery, furrow irrigation, seepage, spate water, trickle or drip
What is fertigation?
The application of fertilizer through irrigation water, commonly used with drip irrigation and permitting fertigation allows fertility inputs to change during the season to match the changing needs of a developing crop.
