Sugarcane Bagasse Is an Effective Soilless Substrate Amendment in Quick-turn Osteospermum Production

Abstract

Many greenhouse growers rely on peat-based soilless substrates to produce salable crops in a relatively short period of time. Peat-based substrate suppliers often incorporate additional organic materials such as wood fiber to extend peat supplies. Given the relative success of wood-based substrates, growing interest in other fiber materials such as sugarcane bagasse may provide similar benefits for substrate processers. The objective of this research was to evaluate substrate properties and the productivity of a short-term floriculture crop, Osteospermum ‘Bright Lights Purple’, in a commercially available peat-based substrate (PL) that has been amended with either commercially available wood fiber [Hydrafiber (HF)] or an aged sugarcane bagasse fiber (SCB). Thus, substrates consisting of PL amended with 15% or 30% HF or SCB were developed. Plants were fertigated weekly at rates of 100, 200, or 300 ppm N, respectively. Crop growth and fertility dynamics were assessed. Substrate shrinkage was greatest in the 30% bagasse blend but had minimal impact given the 2-month crop cycle. The incorporation of 15% and 30% SCB and HF produced slight changes in pH over a 9-week growth period, with HF generally raising pH and SCB generally lowering pH compared with the 100% PL, showing promise for bagasse in managing substrate pH where irrigation water has high pH and/or alkalinity. Substrate EC was initially reduced by blending SCB and, to a lesser extent, HF, but differences ceased to exist by the end of the experiment. Chlorophyll and blooms were abundant in all substrates and fertigation rates. Regardless of fertigation rate, 30% HF had the lowest growth index and shoot dry mass, and 30% SCB had the lowest root dry mass, although differences were not visually apparent. Foliar N concentrations were greatest in plants grown in the PL and SCB substrates and lowest in HF blends. Overall, growth and dry mass differences were minimal across substrate treatment and fertigation rate, and all plants were marketable with statistically similar shelf life. In conclusion, this research indicates the potential of using SCB as a substrate amendment for short-term crop systems in a similar manner as wood fiber.

Physical Properties and Crop Performance of Four Substrate Fibers in Greenhouse Petunia Production

“…While the incorporation of SCB at lower percentages (15% and 30%) maintained a pH at or below that of peat in the Thiessen et al [31] study, the results of this study showed that twice as much bagasse usage maintained a pH at similar or lower levels than peat only up to 30 DAP. Similar increases in pH throughout the production process using Hydrafiber were identified when compared to bagasse when blended with a standard bagged substrate by Thiessen et al [31]. Iron deficiency is the most common disorder in petunia production and tends to occur at substrate pH levels greater than 6.4 [47]; therefore, although C and W were limed at a lower rate than P and B in this study, even lower rates may be needed to ensure proper substrate pH ranges during production.…”

“…Similar substrate research [13,20] identified little to no difference in pH in coir substrates over peat. Sugarcane bagasse has an inherently lower pH and has previously shown the capacity to mitigate rising pH in production systems with high pH and alkalinity irrigation water [31]. While the incorporation of SCB at lower percentages (15% and 30%) maintained a pH at or below that of peat in the Thiessen et al [31] study, the results of this study showed that twice as much bagasse usage maintained a pH at similar or lower levels than peat only up to 30 DAP.…”

“…Sugarcane bagasse has an inherently lower pH and has previously shown the capacity to mitigate rising pH in production systems with high pH and alkalinity irrigation water [31]. While the incorporation of SCB at lower percentages (15% and 30%) maintained a pH at or below that of peat in the Thiessen et al [31] study, the results of this study showed that twice as much bagasse usage maintained a pH at similar or lower levels than peat only up to 30 DAP. Similar increases in pH throughout the production process using Hydrafiber were identified when compared to bagasse when blended with a standard bagged substrate by Thiessen et al [31].…”

“…The abundance of SCB and the minimal production and pre-treatment costs of this material provide a valuable opportunity for use as a substrate amendment, particularly in the southeastern United States, where transportation costs can be reduced due to the nearby location of the sugarcane production and refinement industry. Sugarcane bagasse is lightweight, with a lower bulk density, higher air-filled porosity, and similar water-holding capacity as peat [31]. It has a track record of success in improving crop yields in field production [28] as well as in container production [31].…”

“…Sugarcane bagasse is lightweight, with a lower bulk density, higher air-filled porosity, and similar water-holding capacity as peat [31]. It has a track record of success in improving crop yields in field production [28] as well as in container production [31]. Despite demonstrating promise, rigorous evaluation of the physical/chemical properties of SCB and value for use in soilless plant production systems has been limited.…”