Biochar and spent mushroom compost on tomato production in Puerto Rico

Abstract

Tomatoes are a globally important vegetable crop with a high nutrient requirement. Vegetable growers in Puerto Rico show interest in alternative nutrient sources to chemical fertilizer use. The aim of this two-year trial is to evaluate the use of two locally produced organic soil amendments: spent mushroom compost (SMC) and pine wood biochar (PWB), on growth and yield of field produced tomatoes and the soil’s chemical composition compared to use of the commercial organic fertilizer BioFlora crumble (BF). Trials took place in the Agricultural Experimental Station of Juana Diaz, in the southern region of Puerto Rico in 2022/23 and 2023/24. The study on both years was arranged as a randomized complete block design (RCBD) with four replicates. Treatments were incorporated into the soil series Jacaguas (Fluventic Haplustolls). SMC and BF were applied based on 150 pounds of N/acre, PWB was applied as 0.5% of soil’s volume. Combined treatments: SMC+BF, PWB+BF, and SMC+PWB were applied as half the weight of each material applied alone. Lower number of flower clusters and plant height were observed in PWB treatment. PWB-treated plants also showed higher disease incidence of Target spot (2022/23) and severity of Orthotospovirus (2023/24). Use of SMC resulted in higher yields compared to: PWB (138%), PWB+BF (127%), SMC+PWB (121%), SMC+BF (115%), and BF (103%). After 5 months, SMC-amended plots had a significantly greater change of soil P (112%), S (1,575%) and Zn (102%). Differences in plant tissue nutrient components were found for B, S, and Ca, but all plants were within or above the normal range. Soil amended with SMC sustained competitive yields and fewer diseases; however, crop rotation or use of other nutrient sources may need to be implemented to avoid nutrient imbalance in the soil.

Los tomates son hortalizas de importancia mundial con alto requisito de nutrientes. Productores de hortalizas en Puerto Rico muestran interés en fuentes de nutrientes alternas a los fertilizantes químicos. El objetivo de este ensayo de dos años es evaluar el uso de dos enmiendas de suelo orgánicas producidas localmente: composta agotada de zetas (SMC) y biocarbón de pino (PWB), en el crecimiento y rendimiento de tomates producidos en campo y la composición química del suelo comparado al uso del fertilizante orgánico comercial BioFlora Crumble (BF). Los ensayos se llevaron a cabo en la Estación Experimental Agrícola de Juana Díaz, en la región sur de Puerto Rico en 2022/23 y 2023/24. Se utilizo un diseño en bloques completos aleatorizados (DBCA) con cuatro réplicas. Los tratamientos se incorporaron a suelo de serie Jacaguas (Fluventic Haplustolls). SMC y BF se aplicaron en base a 150 libras de N/acre, PWB se aplicó como 0.5% del volumen del suelo. Tratamientos combinados: SMC+BF, PWB+BF y SMC+PWB se aplicaron con la mitad del peso de cada material aplicado solo. Se observo menor número de racimos florales y altura de plantas con el uso de PWB. Las plantas tratadas con PWB también tuvieron mayor incidencia de la mancha foliar (2022/23), y severidad de Orthotospovirus (2023/24). El uso de SMC resulto en mayores rendimientos comparado con: PWB (138%), PWB+BF (127%), SMC+PWB (121%), SMC+BF (115%) y BF (103%). Después de 5 meses, las parcelas enmendadas con SMC tuvieron un cambio significativamente mayor de P (112%), S (1,575%) y Zn (102%) en el suelo. Se encontraron diferencias en la muestra de tejido vegetal para B, S y Ca, pero todas las plantas estaban entre o por encima del rango normal. El suelo enmendado con SMC mantuvo rendimientos competitivos con menos enfermedades; sin embargo, será necesario implementar rotación de cultivos o uso de otras fuentes de nutrientes para evitar acumulación de nutrientes en el suelo.