30/01/2025
Agribusiness talk . Driplines performance.
Let's demystify something about driplines.
The emitter spacings do not dictate the plant spacings and planting should be done as per the particular crop spacing along the line of the driplines either as single or two rows .
The water emitted by each emitter forms a ball like wetting which overlaps with the next emitter provided the pressure is right and the soil texture is right .
In onions planting, for example, 4 driplines of either 30 cm or 20 cm emitter spacings are ideal and will wet the entire 1m width and one should not feel restricted to plant 8 rows eg 2 rows per dripline and may plant upto 10 lines or 12 if applicable.
I deliberately omitted 15cm emitter spacings because, it may not be ideal on onions because of pressure distribution.
Eg ..Generally at ideal pressure most drip emitters for normal soils are calibrated to give 1lt per hour .
A 20cm dripline stretching over 50m bed will have 250 emitters and will emit 250 litres of water per hour . 4 driplines will therefore emit 1000 litres per hr or 1m cubic . A 15cm dripline will have 333 emitters and will emit 333lts p*e hrs x 4 = 1332 litres per hr.
Let's assume the flow rate from the water source is 10m cubic , how many beds can be irrigated at ago ?
In 20cm spacings, the hydrants will be designed to serve 10 beds whileas in 15cm spacings 1 hydrant will serve 7 beds . If 15cm driplines are used in a design for 20cm , pressures will be compromised and one may observe irregular crop growth eg a healthy crop at the lower side and stunted or shorter crop on the upper side .
Nowadays, every Tom, Dick and Harry is a driplines expert and what I would like to enlighten the investors is that , don't just accept anyone simply because he installed drips in your friend's farm . Always question the design.
It is very important to know the output of the borehole or the source of water. The bed length,number of beds per hydrant , crop spacings , the number of driplines per bed , emitter spacings and the calibrated emitter flow rate. During irrigation, the driplines must bulge to maximum and shouldn't be flaccid. Irrigating with poor pressure will always compromise the yields because water will tend to flow more vertically than horizontally which, apart from poor irrigation, will also result in leaching of soluble nutrients.
NB.
Poor driplines installation may cost you ,your yields.
Incase of sandy soils , always go for high emission driplines eg 2 to 3 litres per hour .
I thought you should know ..
Courtesy - David Ndegwa.
