Effect of Mulching Materials on Weed Control and New Leaf Flushing of Longan Tree

Abstract

The effects of the application of mulching materials on weed control and new leaf flushing on longan trees was studied using 10 years old trees in the longan orchard at Maejo University, San Sai district, Chiang Mai province, Thailand. The experiment was conducted using a Completely Randomized Design (CRD), consisting of 4 treatments, with 4 replications, using a single tree per replication. The treatments were 1) exposed surface (control), 2) mulching with husk, 3) mulching with straw, and 4) mulching with anti-root plastic. Longan trees were preselected for uniformity, and weeds were removed before the performing the experiment. The mulching material was applied to each experimental unit covering an area of 16 m² (4 meters by 4 meters) per tree. The mulching duration was
7 months. Data collection included dry weight of weed/sampling plot, physical and chemical properties of the soil, and new leaf flushing rate. The results showed that after 7 months of mulching, there was no dry weight of weed found in the anti-root mulching treatment, while other treatments had weed dry weights of between 874.9 and 1,227.0 g/m². On the other hand, mulching with the anti-root treatment produced the highest soil temperature (41.0°C), which was much higher than the temperatures observed for the other treatments, which had a temperature range of 25.4-32.3°C. Organic matter, pH, nutritional quality, and the nitrogen, calcium and magnesium levels of the soil before and after mulching were not significantly different. The values had however increased with mulching time. Nonetheless, mulching with straw improved the soil nutrients with higher phosphorus content (214 mg/kg) observed, while other treatments revealed phosphorus levels of only 39-91 mg/kg. The content of potassium in anti-root mulching soil was lower than that of the control but was not significantly different to soil mulched with husk. Interestingly, mulching treatment had no significant effect on the longan tree’s new leaf flushing as the flushing rate of all treatments were 90-100%, and this typically took about 25-30 days after pruning to occur.