MODULE 7 Flashcards
Water management
Lack of water causes
- poor crop stand
- reduction in yield
- predisposes the plants to pests and diseases
Water management
An integrated process of timely application of the needed amount of water and the removal of excess water from the field to ensure optimum growth and crop productivity
Blossom end rot of tomato
caused by a Ca deficiency aggravated by lack of water
Excess water causes:
- too much leaching of nutrients from the soil and leads to high acidity
- water-logged condition which leads to reduced root development and death of roots
- predisposes the plant to root-rotting pathogens
Soil factors
affects water holding capacity, water percolation and includes soil structure, texture and depth
Climatic factors
affects the rate of water losses through evaporation & transpiration and includes temperature, length and intensity of sunshine, relative humidity, wind movement and rainfall increases level of soil moisture
Plant factors
includes rooting characteristics, drought tolerance and growth stages
Gravimetry
involves oven drying a sample of soil and compute soil moisture content
Tensiometer
to measure the water potential
which is inversely related to amount of available
water
Threshold level at which water can be depleted
Usually, the threshold level is 50 % of the available water
Measurement of evapotranspiration rates
to determine values of evapo- transpiration rates of the crops over a short time intervals
Observing visual symptoms of plants
- Temporary wilting/leaf rolling
- Color of the foliage (beans turns yellow, eggplant turns bluish green leaves)
Irrigation in sandy soil is needed when
Appears dry but doesn’t form a ball
Irrigation in loam soil is needed when
Somewhat crumbly but particles hold together
Clay
somewhat pliable, forms a ball but does not readily form a ribbon
