U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Main content area

High rates of gasified rice hull biochar affect geranium and tomato growth in a soilless substrate

James E. Altland, James C. Locke
Journal of plant nutrition 2017 v.40 no.13 pp. 1816-1828
Geranium, Pelargonium hortorum, Solanum lycopersicum, Sphagnum, biochar, byproducts, crop production, energy, floriculture crops, gasification, nutrition, phosphorus, physical properties, potassium, rice, rice hulls, root growth, roots, shoots, soilless media, tomatoes
Gasified rice hull biochar (GRHB) is a byproduct of rice production, where rice hulls are gasified to generate energy for other aspects of rice processing. Other research has shown that GRHB up to 10% (v/v) in a soilless substrate can provide much, but not all, of a potted floriculture crops’ phosphorus and potassium needs. The objective of this research was to determine the effect of higher GRHB rates on floriculture crop nutrition and growth. Two experiments were conducted with GRHB rates ranging from 0% to 30% (v/v) of a soilless peatmoss-based substrate. Geranium (Pelargonium ×hortorum ‘Maverick Red’) and tomato (Solanum lycopersicum ‘Megabite’) were grown in 10-cm diameter pots with amended substrates. Addition of GRHB up to 30% affected the physical properties of the peatmoss-based substrate by increasing container capacity (CC) and decreasing unavailable water (UAW). Summarizing across the two experiments, amending a peatmoss substrate with 15% and 20% GRHB provided sufficient P and K for production of geranium and tomato in soilless substrates over a 5 to 6 week production cycle. However, GRHB did not provide a sufficient source of micronutrients to support acceptable crop growth. Geranium responded negatively to high rates (>10%) with reduced shoot and root growth, while tomato responded positively to higher rates with increased shoot growth. Higher rates of GRHB (>10%) can be recommended for some crops, but not all.