Hello,
I am trying to setup Aquacrop for the first time by comparing different irrigation schemes (no calibration) in Sudan just to estimate the amount of irrigated water usage. Can anyone point me in the right direction on how to approach that task. For example, if I have wheat, I know the planting date starts around September 10 and the growing season is around 100-120 days.
The crop phenology data I can obtain from AquaCrop Reference Manual while the growing season would be FAO-56
http://www.fao.org/3/a-br244e.pdf
Hence I am trying to figure out when and how much irrigated water you would need to add when do you stop. Running everyone to field capacity creates results that have excessive water usage.
Secondly, how would this change is you change the type of irrigated water.
Any help you can provide would greatly be appreciated. Thanks.
Shaffiq Somani
Interesting question . Infact , this is the major issue in any crop where you do not have any information about irrigation or water requirement of that crop. First thing is to decide based on which parameter , you are going to schedule irrigation like daily pan evaporation rate , evapo-transpiration rate , IW/CPE ratio , soil available water capacity-based , however , best is to schedule irrigation based on depletion in soil available water capacity . Then , you need to identify the critical growth stages , however i personally feel , in a crop , all stages are critical , it could be a possibility , some stages would require less water while other stages require more water . Initially , its your wisdom and knowledge on crop physiology to move in this direction ..Here are some PDFs enclosed for your information please to give you some initiative about teh crop ...
As pointed out by Dr.AK Srivastava, irrigation scheduling may be done based on any one of these methods viz., daily pan evaporation rate , evapo-transpiration rate , IW/CPE ratio , soil available water capacity, soil moisture etc. I am also enclosing a reference paper, in which we have sued FAO-CROPWAT along with that irrigation interval was determined using the following formula
Irrigation interval refers to the frequency of applying water to a particular crop at a certain stage of growth and is expressed in days.
I = SMra / ETc or I = (AWC x MAD x D ) / ETc
Where:
I = Irrigation interval in days
SMra = Readily available soil moisture = AWC x D x MAD in mm
AWC = Available Water Content in soil = (FC – PWP) in mm/m
MAD = Management Allowable Deficit
D = Depth of effective root zone in m
ETc = Crop evapotranspiration in mm/day
I hope this MAD concept will reduce your wastage of water.
Thanks
Irrigation management is location specific and crop specific. For higher water use efficiency, the SPA system be considered in totality. Hence data of weather data particularly evaporation and rain fall is must. The crop duration depends on thermal energy available at particular location. Secondly the available water capacity of soil will help in deciding irrigation depth and irrigation interval. The simplest method is critical phenological crop stage eg in wheat Crown Root Initiation and anthesis. However, most scientific approach is crop water status which is governed by soil water availability and atmospheric demand for that you can use infra red thermometer.
- Badges
- Science topic
- Similar topics
- Geoscience
- Asia
- India