Rice husk mat: organic Mulch for inhibition of weed seedling emergence and growth in nursery polybag

Abundantly available rice husk residues in Malaysia may be used as mulch that can result in reduced environmental pollution. Hence, this study was undertaken to determine the suitable thickness of rice husk mulch mat against selected weeds i.e., Eleusine indica (L.) Gaertn., Ageratum conyzoides (L.) L. and Cyperus distans L.f. These are highly invasive and abundant weeds found in oil palm nursery polybags. The experimental treatments consisted of 2-factors; (i) three levels of mulch mat thickness i.e., 2, 4 and 8 mm and two rice husk varieties i.e., MR 220 and MR 297. The results showed that increasing the mat thickness from 2 to 8 mm reduced the emergence, coverage, and biomass of weed seedlings at 6 weeks after treatment regardless of the rice variety used to produce the mat which was either MR 220 or MR 297. Punching tests were used to assess the mechanical properties of mats, while micrographs of the mats were captured to investigate the relationship between mat thickness and mechanical properties. Agglomerating agent was highly hydrated and nucleated on the rough surface of rice husk under 8 mm thick mats which led to the highest stress resistance and associated energy. However, intra-spaces of powdered rice husk were visible under 2 and 4-mm thick mats, resulted in decreased stress resistance and associated energy, thereby reducing the physical barrier of mats on test weeds. These findings imply that 8 mm thick rice husk mulch mat could be employed to control weeds in nursery polybags.