The Effect of Biochar and Fertilizers Made from Plant Extracts on Crop Growth and Nitrogen Leaching with Containerized Greenhouse Plants

Consumers’ increased awareness of the environment and sustainability has created new markets for the floriculture industry.  Floriculture growers are increasingly adopting sustainable agricultural practices to meet market demands.  Organic fertilizers are considered sustainable because of their low energy consumption and impact on the environment.  Biochar is presumed to be sustainable because of its carbon sequestration properties.  The objective of this investigation was to evaluate fertilizers derived from plant extracts (Bombardier 8–0–0 liquid amino acid and Espartan 2.70–3.03–2.60 humic acid) on the growth of marigold (Tagetes erecta L. ‘First Lady’) and nitrogen (N) leaching and to evaluate the effect of biochar on the fertilizer performance.  Two greenhouse experiments were conducted, and plant extract fertilizers were evaluated against chemical fertilizer (20–2–20) and another organic fertilizer, Sustane (4–4–4), derived from turkey litter and feather meal. In Experiment 1, chemical, Sustane and Bombardier were used with or without biochar.  In Experiment 2, chemical, Sustane and Espartan were used with or without biochar.  Plants received the same amount of N from all treatments.  Leachate was collected at 10-day intervals and analyzed for ammonium (NH₄⁺) and nitrate (NO₃^-). At the end of the experiments (62 d after transplanting), plant growth was measured.  In Experiment 1, Bombardier resulted in highest shoot dry weight after chemical fertilizer, which gave the greatest growth. Sustane produced the lowest dry weight among all treatments.  Bombardier resulted in the highest N leaching, mostly as NO₃-N. Sustane resulted in the lowest N leaching, also mostly as NO₃-N.  Biochar had no effect on the fertilizers’ performance with regard to shoot dry weight.  Biochar also had no effect on N leaching from Sustane but reduced NO₃-N leaching from chemical and Bombardier pots. In Experiment 2, there was no significant difference among treatments with regard to shoot dry weight.  Among all treatments, Sustane resulted in the lowest N leaching, mostly as NO₃-N.  No differences occurred among the other treatments.  In terms of shoot dry weight, biochar had no effect on the performance of fertilizers. In terms of N leaching, biochar had no effect of the performance of chemical but reduced NO₃-N leaching from Sustane pots and increased NH₄-N and NO₃-N leaching from Espartan pots.  Results indicate that both Bombardier and Espartan have performance limitations in terms of plant growth or N leaching.  Biochar did not affect the performance of fertilizers in terms of plant growth and its effect on N leaching depended on the fertilizer used.