Narrower Rows Could Improve Industrial Hemp Yields

Hemp Variety Choice Can Create Tenfold Yield Differences

Industrial hemp is often discussed as if it were one crop with one basic production formula. In practice, hemp grown for grain can behave very differently from hemp grown for fibre, and two cultivars planted in the same field can produce dramatically different results.

A multiyear field study¹ in Missouri shows just how important those differences can be. Researchers tested row spacing, nitrogen rates, and numerous industrial hemp cultivars at University of Missouri sites near Novelty and Rock Port between 2019 and 2022. Their results suggest that growers may gain more by choosing the right cultivar and field arrangement than by automatically increasing fertilizer inputs.

The most striking finding came from the 2022 cultivar trial. Biomass production ranged from 1,343 to 13,696 kilograms per hectare, a difference of more than tenfold. Grain yields also varied widely, from 255 to 1,965 kilograms per hectare. Those gaps show why cultivar selection is not a minor purchasing decision. It can determine whether a hemp crop is suited to its market at all.

Why Industrial Hemp Requires A Market-First Plan

Industrial hemp can supply grain, fibre, and other forms of biomass, but a cultivar that excels in one category may not perform well in another. Grain production depends on successful flowering and seed development within the local growing season. Fibre production places more emphasis on vigorous vegetative growth and stem biomass.

This means the production plan should begin with the intended buyer. A grower targeting hemp grain needs a cultivar that can mature seed under local conditions. A grower supplying fibre or another biomass market may prioritize tall plants and heavy dry-matter production instead.

The Missouri trials exposed the cost of getting this choice wrong. Several fibre-oriented cultivars produced no seed because they flowered too late for the region. They could still generate biomass, but they were not dependable grain options in that environment. The result was not necessarily a defect in the cultivars. It was a mismatch between their biological timing, the local photoperiod, and the length of the Missouri growing season.

For growers, the practical sequence is straightforward:

• Choose the target market before selecting seed.
• Confirm that the cultivar can mature under local conditions.
• Match row spacing and equipment to the intended crop.
• Test soil fertility before adding more nitrogen.
• Avoid fields with a meaningful risk of waterlogging.

Narrow Rows Generally Improved Hemp Production

At the Novelty site, the researchers compared rows spaced 19 centimetres apart with rows spaced 76 centimetres apart. The narrow configuration generally supported greater plant populations, grain yields, and biomass yields.

In 2019, grain yields in 19-centimetre rows ranged from 429 to 628 kilograms per hectare, depending on cultivar. The 76-centimetre rows produced between 175 and 475 kilograms per hectare. In 2020, the difference was less consistent, with narrow rows producing 1,289 to 1,598 kilograms per hectare and wide rows producing 1,345 to 1,553 kilograms per hectare. Even so, the broader study supported narrow rows as the stronger general approach for grain and biomass production.

Narrow spacing can help a hemp stand occupy the field sooner. Faster canopy closure limits sunlight reaching competing weeds and lets the crop capture available resources more efficiently. This is especially useful because weed control remains a major production challenge for industrial hemp.

That does not make narrow spacing universally correct. Equipment, cultivation methods, seed cost, stand establishment, and the intended harvest system still matter. The useful lesson is that row spacing should be treated as a production tool, not simply as a fixed habit borrowed from another crop.

What The Missouri Hemp Trials Found

More Nitrogen Did Not Produce More Hemp

The nitrogen findings challenge the assumption that a larger fertilizer application will automatically produce a larger hemp crop. Across the relevant experiments, treatments included rates from zero to 224 kilograms of nitrogen per hectare. At the highly fertile river-bottom site in northwest Missouri, the researchers found no statistically significant yield improvement from increasing the nitrogen rate.

For producers, that result carries an immediate economic message. Fertilizer is a material input cost, and applying nitrogen that does not increase harvestable output reduces margins. Excess application can also create environmental costs if nutrients move beyond the crop root zone.

However, the finding should not be interpreted as proof that hemp never responds to nitrogen. The trial took place on naturally fertile soil, so the crop may already have had adequate access to nutrients. Heavy rainfall could also have contributed to nitrogen loss or made treatment differences harder to detect.

The safer conclusion is that fertilizer decisions should follow soil testing and local evidence. A fixed nitrogen program copied from another region, soil type, or crop can waste money. Hemp recommendations will need to account for existing fertility, expected yield, weather, drainage, and the production goal.

Drainage Can Matter More Than Soil Fertility

One of the study’s clearest lessons did not come from a successful harvest. Saturated conditions destroyed a 2021 trial before researchers could collect harvest data. That failure reinforces hemp’s sensitivity to poorly drained ground.

A field can be nutrient-rich and still be a poor location for hemp. Waterlogged soil limits oxygen around the roots, interferes with establishment, and can prevent the crop from developing a productive stand. If drainage is unreliable, high fertility alone may not compensate for the risk.

This insight changes how a grower might evaluate land. The question is not only whether a field contains enough nutrients. It is also whether the soil structure and landscape can move excess water away during wet periods. In regions exposed to intense rainfall, drainage history may deserve as much attention as a soil test.

Cultivar Performance Defines The Business Case

The 2022 results demonstrate the scale of cultivar-related risk. Vega was among the stronger grain performers, while MS-77, Jinma, Puma, and Yuma led biomass production. The difference between the lowest and highest biomass results exceeded 12,000 kilograms per hectare.

That spread can affect nearly every part of a hemp business. Yield influences revenue per hectare, harvesting efficiency, transportation requirements, storage, processing capacity, and the grower’s ability to fulfill a contract. Selecting a cultivar without local performance data can leave expensive equipment and downstream capacity underused.

At the same time, the highest-yielding cultivar in one trial should not automatically become a universal recommendation. Weather varied from year to year, and cultivar performance interacted with the environment. Missouri results are most useful to growers operating under similar conditions. Producers elsewhere should look for regional trials that reflect their own latitude, soil, rainfall, and season length.

A More Precise Model For Hemp Production

The study points toward a more disciplined way to expand industrial hemp. Instead of treating the crop as a single opportunity and then maximizing inputs, growers can work backward from the desired product.

For grain, that means identifying cultivars with reliable seed maturity and competitive grain yields in the region. For fibre and biomass, it means evaluating dry-matter production, harvest timing, stand density, and compatibility with available processing infrastructure. In both cases, narrower rows may improve field performance, but the system must still suit the farm’s equipment and weed-management strategy.

The absence of a significant nitrogen response is equally important because it shows that optimization does not always mean adding more. In a fertile field, better seed selection and spatial arrangement may provide more value than another fertilizer pass.

Industrial hemp still needs more region-specific research, particularly because weather can transform results from one season to the next. Yet the Missouri trials already provide a useful foundation. Hemp profitability begins with biological and market compatibility. The right cultivar, planted in a suitable configuration on well-drained ground, can matter far more than treating every hectare with the same input-heavy formula.

References:

^{1. Anjeeta, Kaur, G., Nelson, K. A., Crawford, J., & Singh, G. (2026). Effect of row spacing, nitrogen, and varieties on industrial hemp production in Missouri. Industrial Crops and Products, 251, 123946. https://doi.org/10.1016/j.indcrop.2026.123946}