Effect of Mulching Materials on Yield and Water Productivity of Drip-Irrigated Tomato

Abstract

Mulching is promoted alongside drip irrigation as a way of getting more tomato from less water, yet the claim is usually made for all mulches at once, as if straw, black polyethylene and a biodegradable film behaved alike. This narrative review asks what published work can and cannot say about how organic and plastic mulches affect yield and water productivity of drip-irrigated tomato. It draws on research into soil evaporation, root-zone temperature, weed suppression, irrigation scheduling, and the performance and fate of mulch films, and it reports no new data. Mulches act mainly by reducing evaporation from the soil surface and by altering soil temperature, so their benefit depends on climate, soil, season and crop cover, and it tends to be largest early in the season and in dry, warm conditions. Organic and plastic materials trade different advantages: residues add organic matter but compete with other uses and may harbour pests, whereas films are effective and cheap but leave a disposal problem and, increasingly, a microplastic concern. Reported comparisons are also hard to line up because water productivity is defined in several ways and is often measured against applied water, not water actually consumed. The review concludes that a mulch benefit is plausible but conditional, and it sets out the measurements that would make future comparisons fair.