Sugarcane Waste Shows Promise for Hemp Growing Media

Could a material left over from sugar production help grow hemp at a lower cost? The question matters because growing media do more than hold plants upright. They influence root conditions, nutrient availability, and the cost of bringing a crop to harvest. Finding a dependable alternative to commercial mixtures could give growers another way to manage those expenses.

A new study accepted by Food and Humanity examined composted sugarcane filter cake as an ingredient in hemp growing media.¹ Researchers in Thailand found that these mixtures supported promising crop performance while costing less than their commercial comparison. They also identified an obstacle that needs addressing: elevated arsenic in the starting substrate.

The opportunity is therefore more specific than turning waste into fertilizer. It is about determining whether a locally available byproduct can become a consistent, tested growing material without sacrificing harvest quality.

What Sugarcane Filter Cake Does in Growing Media

Filter cake is a residue produced during sugar processing. After composting, it can supply organic matter and nutrients to growing mixtures. In this experiment, researchers combined it with soil and cow manure rather than using it alone.

A useful growing medium must balance several jobs. Roots need moisture, but they also need oxygen. Nutrients must remain available without salts accumulating excessively. Acidity affects how easily plants can access those nutrients. Changing one ingredient can alter several conditions simultaneously.

Think of a substrate as both a pantry and a plumbing system. Having nutrients present is useful only if roots can reach them under suitable water and air conditions.

This helps explain why replacing peat is an active research field rather than a simple ingredient swap. A 2025 review of alternatives to peat in container horticulture describes how growing media, irrigation, and fertilization developed together. A substitute may require changes in management even when it supports healthy plants.

How the Hemp Cultivation Experiment Worked

The researchers grew one hemp cultivar, KKU05 plus, across two cropping cycles in Thailand. Their randomized experiment included five treatments, with 20 individual plants per treatment in each cycle. Plants grew in bags with managed irrigation and supplemental lighting.

The baseline treatment combined soil and cow manure. A commercial comparison contained peat moss, vermiculite, perlite, and manure in equal proportions. Three additional treatments combined soil, filter cake compost, and manure at ratios of 1:2:1, 1:3:1, and 1:4:1.

The team measured growth, harvested plant material, cannabinoids, seed fatty acids, and selected contaminants. They also estimated production costs and returns.

This design provides a useful initial comparison, but it represents a particular cultivar and production setting. It cannot establish how every hemp variety would respond, or whether the same mixtures would perform similarly in unrestricted field soil.

Lower Substrate Costs Were the Clearest Practical Finding

The compost treatments produced numerically higher dry flower yields than the commercial mixture, but those differences were not statistically significant. That means the experiment did not establish a reliable flower-yield advantage. It also does not prove that the treatments were equivalent under all conditions.

The cost comparison was clearer. Estimated growing-media costs ranged from $19,527.82 to $22,782.45 per hectare for the compost treatments, compared with $40,682.96 for the commercial mixture. Calculated from those figures, the reduction was approximately 44% to 52%.

However, the soil-and-manure baseline remained cheaper than every compost treatment. Filter cake therefore offered savings against the commercial mixture tested, rather than demonstrating that it was the least expensive option overall.

The cannabinoid findings need additional care. The pre-proof’s abstract describes CBD yield increases as statistically nonsignificant, while Table 8 reports significant differences among treatments. The lowest compost ratio also recorded a lower CBD concentration than the commercial comparison. These inconsistencies make a blanket claim that sugarcane compost boosts CBD inappropriate.

Why Input Testing Matters for Recycled Growing Materials

The elevated arsenic measurements identify where further development should begin. They do not establish that every batch of sugarcane compost carries the same contamination. They show that the tested mixtures needed additional assessment before commercial adoption.

Equally, low cadmium in flowers answers a narrower question than whether all harvested products are safe. Arsenic and cadmium are different contaminants. Testing one cannot substitute for measuring the other, and results from flowers cannot automatically establish conditions in processed oils.

This creates a useful distinction between agricultural performance and suitability for a particular product. A mixture may support vigorous growth while still needing adjustment before it can serve a food or cannabinoid supply chain.

For future trials, three checks would make the evidence more useful:

• Test multiple compost batches before planting to establish consistency.
• Measure relevant contaminants in harvested material and finished products.
• Repeat the comparison across cultivars, locations, and growing cycles.

The researchers discuss possible pretreatment and blending approaches, but they did not experimentally establish a remedy. Those possibilities remain research directions, not validated instructions for making contaminated material suitable.

When Cheaper Growing Media Improve Hemp Economics

A 50% reduction in one input does not mean a 50% reduction in production costs. Labor, harvesting, processing, equipment, and other expenses remain. Additional screening or treatment could also absorb part of the substrate savings.

The study illustrates this distinction. Seed production alone generated negative returns under its assumptions. Flower production looked more favorable, but the estimates excluded fixed infrastructure costs and relied on assumed flower selling prices. They should not be read as forecasts for another farm.

A more useful commercial question is the cost of producing material a buyer will accept. A cheap substrate has limited value if inconsistent batches create rejected harvests. Conversely, a tested alternative could be worthwhile even without increasing yield if it reduces costs while maintaining required quality.

This connects with MyCannabis’s recent examination of industrial hemp supply-chain coordination. Cultivation choices become more useful when growers understand the specifications and processing needs of their intended customers before planting.

Hemp Sustainability Depends on the Whole Production System

Reusing a sugar-industry byproduct offers an appealing circular approach: material from one production process becomes an input for another. The Thai experiment supports investigating that possibility, but it did not measure the complete environmental footprint of the substitution.

Transport, compost preparation, treatment, and irrigation would all matter in a fuller assessment. A nearby source of suitable compost could offer different advantages from material shipped long distances or requiring extensive preparation.

Related work shows that the search extends beyond sugarcane residues. A 2026 review of kenaf core as an alternative growing medium examines another plant-derived material and identifies processing and standardization questions. The broader opportunity is to develop regional alternatives that meet measurable cultivation requirements.

Hemp itself can also supply useful residues. MyCannabis’s coverage of hemp straw for renewable gas explores another potential pathway for agricultural material. Together, these examples encourage evaluating crops as connected flows of inputs and outputs, while checking each proposed use separately.

The Next Test for Sugarcane Compost and Hemp

The strongest follow-up would compare screened, lower-contaminant compost batches against commercial media across several locations. Researchers could track flower performance, cannabinoid production, finished-product quality, and complete production costs together.

That would help answer the question this experiment opens: can growers repeat the savings while meeting the requirements of their chosen market?

Sugarcane compost has earned further investigation as a hemp substrate ingredient. Its promise rests on an achievable goal: turning an available agricultural residue into a dependable input through better characterization, controlled trials, and clear quality standards.

References:

¹ Sungthongwises, K., Lapjit, C., Lomthaisong, K., & Paluka, J. (2026). Enhancing growth and important compounds of Cannabis sativa L. cv. KKU05 plus using filter cake compost-based organic amendments. Food and Humanity. Advance online publication. https://doi.org/10.1016/j.foohum.2026.101602