Could you please explain more details about your work? what is the object of your study?

Please explain about your question

Summer maize crop generally needs 500-700 mm of irrigation water depending upon soil texture and structure, organic matter and water-holding capacity of a soil and climatic conditions of the growing zone.

It needs a lot of calculations. Go through the literatures related to calculations of PET and Crop water requirement through several equations and computer models available on line.

Hello everybody

I suggest that you apply to the farmers that grow maize. They must have the figures.

Ask them how often they irrigate, how much water per portion and what is the irrigation method they use.

Some crops like more water but with longer intervals, some like constant humid soil. The farmers are not necessarily using the type of irrigation that will suite your needs, especially if your aim is, also, to save water cost and labor and time and, and, and.

In addition, maybe that you will find the right irrigation method and this way your crop be much higher than theirs.

We irrigate our crops with different quantity of water, in order to save, if we irrigate @ day time we look for not windy hours, but it takes more time (and water and cost) if it is @ night (which is most recommended, presently, after many years it was not recommended) we use much less water.

Also, what is your soil look like: Is it sand, tine, clay, what is the ploughing depth, what sole you have underneath etc.

The best irrigation, generally is drip irrigation as then you control every drop of water. It cost money, but its performance is the best.

Wish you success

In friendship

Amir

Please look for irrigation design manuals (Modules 1 - 14) by FAO. For your purpose search for Module 4: Crop water requirements and irrigation scheduling. The manuals were written with Zimbabwe in mind, but you can use the formulas and replace data with your country's data to get what you are looking for.

There is also a free program by FAO called CROPWAT 8.0, a Windows computer program for the calculation of crop water requirements and irrigation requirements based on soil, climate and crop data.

http://www.fao.org/nr/water/infores_databases_cropwat.html

Thanks sir

We at central eastern coast of Mexico, sub-humid climate, control irrigation time and therefor amount of water monitoring tensiometers. We irrigate when the tensiometer gauge reches 35 cbars during growth stage and 20 - 24 cb during grain formation in sandy solis during rain season or during dry season which lasts for 7 - 8 months

Pressure needed to ferti-irrigate is achived by management of topográfic levels. A tecnified siphon is used to extract water from a reservoir in which runoff water is catched durin rain season. .

IW/CPE or IW/Epan is the ratio of net depth of irrigation water (IW) to cumulative pan evaporation (CPE) excluding effective rainfall. IW is decided by the available water holding capacity of the soil and the probable deficit before irrigation (Note that gross depth of irrigation would vary depending on the irrigation efficiency that can be achieved). For maize, optimum IW/CPE ratio would be around 1.0. IW/CPE ratio is similar to crop factor, Cf (Hargreaves, 1968), and their relationships are explained below:

In crop evapotranspiration (ETc) based irrigation scheduling, irrigation is scheduled depending on ETc values so that ET losses are replaced in the root zone to meet crop water use. In general, crop water use is determined from a balance of water inputs and outputs from the root zone:

ETc= ER+ IW+ C+ S – D (1)

Where ETc–crop evapotranspiration; ER-effective rainfall, IW-net irrigation; C-capillary contributions; S- original soil profile contribution of water; and D- deep percolation losses (all are in units of depth per time, mm/day).

The above equation(1) can be reduced to the following for upland soils where water table is deep and where irrigation is applied to make good the deficit in soil moisture only (without causing percolation or surface runoff).

ETc = ER + IW (2)

IW = ETc –ER (3)

In other words, the net irrigation requirement is simply based on ETc and ER. However, in dry periods, if no rainfall is received, then:

IW= ETc (4)

ETc values can be estimated with the help of pan evaporation (Epan) correlated with crop factor (Cf ). The relationship between them can be expressed as (Hargreaves, 1968):

ETc= Cf X Epan (5)

Cf= ETc/ Epan (6)

Where ETc = crop evapotranspiration (mm/day); Cf = crop factor ; and Epan= pan evaporation (mm/day).

As IW= ETc as seen equation (4), we can substitute IW for ETc in equation (6), and we get

Cf= IW/ Epan or = IW/ CPE

The net depth of irrigation (IW) is either equal to Epan or CPE or a fraction of it. If the IW/CPE ratio of a crop is 1.0, the net depth of irrigation is equal to Epan (CPE).

Reference

Hargreaves, G.H. 1968. Consumptive use derived from evaporation pan data. J. Irrig. Drain. Div., Amer. Soc Civil Eng. 94(1): 97-104