Investigation of the Use of Cow Dung as Mulching Material in Northeast Thailand

Abstract

We investigated the use of cow dung as a mulching material which is commonly applied in Northeast Thailand. Air-dried cow dung (5.0 g) was added to 50 mL of water, mixed for 1 h, and the water-soluble nutrient contents of the samples were determined. A correlation was found between the water-soluble potassium concentration and EC. The amount of leached nutrients was determined by the filtration test performed with various amounts of water and at different intervals. The results showed that the leaching of PO₄-P was related to the amount of water added. The amounts of leached NO₃-N and K varied with the watering interval and the amount of water used. Plastic buckets (3.8 L; diameter, 0.16 m) were buried under the field, and other buckets filled with 2000 g of air-dried soil were set into the former buckets. The soil surface was mulched with cow dung in layers with varying thickness (0~40 mm), and 200 or 300 mL of water were added. The evaporation speed was determined by measuring the weight of the inner buckets. A correlation was found between mulch thickness (x cm) and the ratio of potential evaporation to actual evaporation (y) as follows: y = 0.20x^-0.5 (R² = 0.99). Typically, farmers use both hands to apply cow dung (approximately 400 mL) to the depression (diameter, 20 cm) and add water using a ladle (approximately 500 mL of water). Based on the results of our study, a larger quantity of water (approximately 1600 mL) should be supplied to avoid salt injury. The water supplied will be retained for approximately 1 month because of the effect of the mulch. The effect of the mulch is sufficient to retain moisture because transpiration of the young plants is limited. In terms of nutrient contents, K is expectable but N and P are not expectable.