Beyond the colour of mulch

One of the most relevant technological innovations of mulch over time has been the multilayer extrusion to develop two-colour films. Surely the most common bicolour within this range is the white/black combination whose white face reflects solar IR radiation while its black face guarantees maximum opacity to control or fight weeds.

We performed a comparative experience in a field of strawberries on the coast of Peru which provided very interesting conclusions. Our objective was to measure the soil temperature difference between the ridges covered with White/Black mulch and those covered with Black mulch. The test was conducted between the months of March and June of this year (2018), collecting close to 100,000 soil temperature records which we summarize below:

	Environment	Black	White/ Black
Medium T	21.4 ºC	26.8 ºC	25.0 ºC
Max T	32.0 ºC	42.7 ºC	36.8 ºC

Analyzing the data above we conclude that the Black mulch is the one that clearly heats the soil the most with a differential of almost +6º C with respect to the White/Black mulch. While the crop withstood peaks of almost 43º C with the Black mulch, the plot with White/Black mulch did not reach 37º C any day of the 3-month cycle analyzed.

But perhaps the most surprising and unexpected test result that we found with this study was a 100% plant mortality with the Black mulch versus 8% with the White/Black mulch, which we were able to verify in one of the follow-up field visits. Next, we show you the proof:

In the foreground we can see all the plants that did not withstand the high temperatures with the Black mulch, while in the background the strawberries with White/Black mulch develop normally.

The choice of color and arrangement of layers of the mulch is a critical choice that can cause a wide range of results on the crops from the most beneficial to the greatest of failures. When implementing new techniques in plasticulture it is important to know well the conditions of climate, soil structure, humidity and crop to design the most suitable plastic for the application. If you need to discuss or research further information on the subject, send us your questions!

We invite you to read our recent posts related to how to prepare the soil for harvest and the use of plastic mulch in berries crops.