Laying a Drip Lateral Under Plastic Mulch

The sheet makes every later decision permanent

Laying a lateral on bare soil is forgiving. If the spacing is wrong or a run comes up short, you lift the pipe, punch it again and move it. Put a mulch sheet over it and that option is gone: the lateral sits under the sheet for the whole crop, and getting at it means disturbing the mulch you have already paid for.

So the order matters. Settle the row spacing, the run lengths and the position of every take-off before the sheet goes down, not after.

Why a flat thin-wall lateral suits mulch

A flat lateral lies low against the soil, which is exactly what you want under a sheet. Our 16 mm flat inline lateral is made to IS 13488:2008 Class 2 with emitters at 30 cm, and the flat profile sits close enough to the bed that the mulch lies flat over it instead of tenting wherever the pipe passes.

Emitters at 30 cm give a wet strip along the row rather than isolated points, and that is what a mulch bed wants: the sheet holds the moisture in and the strip wets the root zone evenly underneath it.

Joints are the part that fails

A joint under a mulch sheet is a leak you cannot see and cannot easily reach. Fewer joints is the most useful thing you can do, which is an argument for taking the lateral down the full row length rather than piecing it together.

It is also an argument for checking run length before you buy rather than after. A run that is too long loses pressure at the far end, and under mulch the crop at that end simply receives less water with no visible sign until it shows in the plants.

Specifications at a glance

Common questions

Can the lateral go on top of the mulch instead?

It can, and it is easier to service, but it stays exposed to sun and to anything that walks or drives over the bed. Under the sheet is the usual arrangement for a seasonal crop; on top is worth considering if you need to reach the emitters often.

Do emitters clog faster under mulch?

The sheet does not clog emitters by itself, but it does hide them, so a blockage is found later. That is an argument for filtration you can inspect, and for checking pressure at the far end of a run rather than waiting for the crop to show it.

Is 30 cm or a wider spacing better under mulch?

Under mulch the sheet is already limiting evaporation, so the wet strip is doing more of the work. A closer spacing such as 30 cm wets a continuous strip, which is usually what a mulched bed is after.