Livestock Manure-Based Organic Fertilizer: Farmer Knowledge, Product Quality, and Spinach Growth Response

Livestock manure from poultry, sheep, and cattle in rural Indonesia is often left unprocessed and pollutes the environment, although it is a potential nutrient source for horticultural crops. This study aimed to examine the effect of participatory training on farmers’ knowledge of manure processing, to evaluate the maturity of the fermented organic fertilizer produced, and to observe the growth response of spinach to its application. A quantitative descriptive study with a one-group pretest–posttest design was conducted in Sukanagalih Village, Tasikmalaya Regency, involving 28 livestock keepers and farmers. Data were collected using a knowledge test, a skill observation checklist, organoleptic and pH–temperature measurements of the fertilizer, observations of spinach growth up to 21 days after planting, and a questionnaire, and were analyzed using descriptive statistics and the normalized gain (N-gain) score. The mean knowledge score increased from 53.75% to 87.75%, with an N-gain of 0.74 (high category), and the greatest gain was in fertilizer production techniques. After training, 80% of respondents were able to produce the fertilizer independently. The 14-day fermentation produced a mature fertilizer that was blackish brown, crumbly, free of pungent odor, and had a pH of 6.5–7.2. Its application made the soil more friable and supported spinach growth compared with the control, and 70% of respondents intended to continue production. Participatory training effectively improves farmers’ knowledge of manure processing, and on-farm fermentation of mixed livestock manure produces a mature organic fertilizer suitable for spinach, supporting integrated crop–livestock farming.