Effect of Cutting Interval and Cutting Height on Yield and Chemical Composition of King Napier Grass (Pennisetum Purpureum x Pennisetum Americanum)

The experiment was conducted to determine the effects of cutting interval and cutting height on the yield and nutrient composition of King Napier grass (Pennisetum purpureum x Pennisetum americanum) when grown on a sandy soil in the Northeast of Thailand. The cutting intervals were 30, 45 and 60 days between harvests and the cutting heights were 5, 10 and 15 cm above ground level. The experiment was a 3×3 factorial layout in a randomized complete block design with 4 replications-giving a total of 36 plots each 3×3 m2. Harvested plant material was weighed, dried and the ground subsamples taken for analyses of crude protein (CP), crude fiber (CF), ash, ether extract (EE), acid detergent fiber (ADF), neutral detergent fiber (NDF), acid detergent lignin (ADL), Hemicellulose and Cellulose. Results showed that increasing the cutting interval (i.e. advancing age of maturity) increased dry matter and nutrient yields significantly. In terms of nutrient content, it also increased the crude fiber, acid detergent fiber (ADF), neutral detergent fiber (NDF) and acid detergent lignin (ADL) percent in the plant. However, crude protein and ash percent was markedly decreased as the cutting interval increased. Increasing cutting height had no effect on dry matter yield and yields of nutrients, but in terms of nutrient content, it decreased crude fiber content. The percent EE, NDF, ADF, Hemicellulose and Cellulose in the plant was unaffected by cutting height. From the results presented it is clear that cutting a stand of King Napier grass every 45 to 60 days will achieve greater dry matter and nutrient yields than cutting more frequently, at 30 days. The cutting height at harvest, whether 5, 10 or 15 cm above ground level had no effect on dry matter or nutrient yields of King Napier grass.