Liquid Organic Fertilizer from Rice-Washing Water and Shallot Skin Waste Improves Growth and Fresh Yield of Pakchong Grass (Pennisetum purpureum cv. Thailand)

Abstract

Feed is the highest recurring cost in ruminant production, and a continuous supply of low-cost, good-quality forage is a persistent constraint for smallholder farmers. This study evaluated the effect of a liquid organic fertilizer (POC) formulated from two abundant household waste streams, rice-washing water and shallot-skin waste, on the growth and fresh yield of pakchong grass (Pennisetum purpureum cv. Thailand). We conducted a 42-day field experiment in Langgongsari Village, Cilongok District, Banyumas Regency, Central Java, Indonesia, using 60 three-node stem cuttings. A completely randomized design with four POC doses (0, 200, 400, and 600 mL m⁻², coded P0–P3) and five replications gave 20 experimental units of three cuttings each; POC was diluted to a constant 2,000 mL m⁻² and applied twice, in the first and second weeks after planting. Plant height, leaf length, tiller number, and fresh yield were recorded and analyzed by analysis of variance followed by the least significant difference test. Increasing POC dose significantly (P<0.01) increased plant height (from 101.99 cm at P0 to 116.76 cm at P3), leaf length (from 58.56 to 64.02 cm), and fresh yield (from 7.2 to 8.9 ton ha⁻¹). Tiller number did not differ among treatments (P>0.05), ranging from 0 to 0.2 tillers per clump; this near-absence of tillering is attributed to the single-defoliation regime rather than fertilizer and is treated here as a design limitation. Overall, POC formulated from rice-washing water and shallot-skin waste, applied at 600 mL m⁻², is a promising low-cost organic input for improving pakchong grass productivity. Because this study did not establish the POC's nutrient concentration or compare it with an inorganic-fertilizer standard, future work should quantify the magnitude of the substitution benefit.