Efficiency of Biomass Pellets from Rice Straw, Rice Bran, and Rice Husk as Growing Media for Green Oak Lettuce (Lactuca sativa cv. crispa L.)

Abstract

     This study investigated nutritional compositions, characteristics, and effectiveness of biomass pellets from rice straw, rice bran, and rice husk used as planting material for lettuce var. green oak. Three formulae of biomass pellet treatments and a planting medium control were laid out in a completely randomized design with four replications. Formula 1 had rice straw, manure, and water at the ratio of 7 : 2 : 1. Formula 2 consisted of rice straw, manure, rice bran, and water at the ratio of 5 : 2 : 2 : 1. Formula 3 included rice straw, manure, rice husk, and water at the ratio of 5 : 2 : 2 : 1. Formular 4 (control) was a normal planting medium (not pelleted) consisting of peat moss and manure at the ratio of 8 : 2. The nutrition and characters of biomass pellets were evaluated. Plant height, plant canopy, shoot weight, root length, root weight, leaf number, leaf width, leaf length, and leaf color (L*, a* and b*) of lettuce were measured. All biomass pellet formulae had higher total macro nutrients (N, P and K) than formula 4 and could be pelletized without fracture and decay. All growing media were significantly different for all traits of lettuce (p<0.01 and p<0.001). Formula 2 showed the greatest for all characters followed by formula 4, formula 1, and formula 3, respectively. Lettuce planted in formula 2 for 45 days had plant height of 4.8 cm, plant canopy of 16.8 cm, shoot weight of 18.8 g, root weight of 5.2 g, leaf number of 15.1 leaves, leaf width of 8.7 cm, leaf length of 11.3 cm, and greener leaves as indicated by the low hue values (L* = 54.0, a* = -7.1, and b* = 31.5). The formula consisting of rice straw, manure, rice bran, and water at the ratio of 5 : 2 : 2 : 1 was appropriate for making biomass pellet and using as growing media of lettuce var. green oak.