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How much topsoil is lost when producing turfgrass?
Researchers have looked at how much soil is removed when turf is harvested – and what producers can do to reduce this loss.
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Increased use of turfgrass has raised questions about whether production leads to loss of topsoil, which is essential for agriculture.
Researchers at NIBIO have recently documented how much soil is removed during sod harvest – and what producers can do to reduce this loss.
Sod, also called turf, has become an increasingly popular method to establish lawns in gardens, parks, and sports facilities.
Although demand varies with activity in the construction sector, the share of lawns established using sod is higher today than it was 10 to 20 years ago.
When time is short
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“In many housing projects, there's a need for a ready-to-use lawn in a very short time. In such cases, sod is often the only realistic solution,” says Trygve S. Aamlid.
He is a senior researcher at NIBIO.
“Admittedly, the preparatory work involving soil cultivation, precise grading, and irrigation requirements are roughly the same as for direct seeding. But these areas can be put to use much faster – usually after three to four weeks,” he says.
Today, there are around 15 turfgrass producers in Norway, with a combined production area of 500 to 600 hectares.
Annual sales have declined slightly in recent years, from around 200 to approximately 160 hectares. Production takes place mainly in Eastern Norway, but also in Agder, Rogaland, and Nordland.
Concerns about soil conservation
Increased use of turfgrass has also led to greater attention to production methods. One key question is whether sod production leads to soil loss.
In 2022, a question was raised in the Norwegian Parliament as to whether turfgrass production could conflict with Section 9 of the Soil Act, which aims to ensure that cultivated land is preserved for future food production.
“We have received similar questions from local politicians and agricultural authorities in several municipalities and counties,” says Aamlid.
This was the background for the Sustainable Production of Turfgrass project, in which NIBIO collaborated with Norwegian sod producers to document actual soil removal.
How much soil is removed with turfgrass?
In 2023 and 2024, the researchers analysed 240 turf rolls from 12 producers. The analyses showed that an average of 3.6 kilograms of soil mineral matter were removed per square metre of turfgrass.
Soil mineral matter refers to soil of mineral origin. That is, soil derived from the weathering and breakdown of rock and stone. This is different from organic soil, which is formed from the decomposition of plants and animals.
“The results showed considerable variation, ranging from 0.7 to 6.9 kilograms per square metre,” says Aamlid.
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Whether the average of 3.6 kilos per square metre is high or low depends on what you compare it with, the researcher explains.
Less soil is removed in Norway than in other countries
International studies from Europe and the United States show average values of roughly twice this amount.
A German study, for example, found that sod harvest removed an average of seven kilograms of mineral matter per square metre.
According to Aamlid, the main explanation is that Norwegian turfgrass is usually allowed to grow for a longer period before it is harvested.
NIBIO’s surveys showed that the average age of turfgrass at the time of harvesting in Norway was 27 months, compared with 18 months in the German study.
“The extra time allows the turf to build up more organic matter, and less soil is removed during cutting,” Aamlid explains.
Comparison with other agricultural production
Soil removal is not unique to sod production.
When harvesting other crops such as potatoes, carrots or swedes, some soil will always be removed from the field.
In cereal production with conventional autumn ploughing, Norwegian studies show that erosion losses can amount to one to two kilograms per square metre over a two- to three-year period. This is equivalent to a turfgrass production cycle.
Most of this erosion loss is now avoided through reduced tillage.
“In sod production, the soil is usually tilled every second or third year only. This results in very little erosion,” says Aamlid.
What can producers do?
The variation seen in turfgrass rolls shows that sod growers have much to learn from each other when it comes to reducing the amount of soil loss.
“This includes, among other things, choosing the optimal sod harvesters. They should avoid cutting two wide rolls at the same time,” says Aamlid.
The waste management company Lindum participated in the project to investigate whether sod growers could make use of various types of residual organic products such as composts or digestates.
The trials showed that a moderate amount of organic residual products before sowing resulted in slightly better turf quality and slightly less soil removal during cutting.
However, there were also challenges related to nutrient content, impurities, and application.
Found a mobile phone in the compost
“In one of the compost batches, we found both textile rags and an old mobile phone,” says Aamlid.
Another way to compensate for mineral matter removed in sod rolls may be to apply inorganic soil improvers, such as sand, rock flour, or crushed brick.
Together with NIBIO, the turfgrass producer Utomhus Østfoldgress has developed a soil improvement product based on crushed brick.
“The project has provided us with data that show how we can operate sustainably. Crushed brick replaces lost mineral matter, makes our turfgrass rolls lighter, and increases soil fertility,” says managing director Ole Christian Trandem.
“To compensate for the removal of 3.6 kilograms of mineral matter in turfgrass rolls, it is necessary to apply a 2-3 millimetre thick layer before sowing,” he adds.
Grass as a soil builder
Aamlid emphasises that the grass grown for turfgrass sod production is in itself primarily soil-improving.
“Turfgrass produces large amounts of roots and clippings that enhance soil fertility when returned to the soil,” he says.
In this project, the grass produced clippings corresponding to 1.5 kilograms of dry matter per square metre from sowing to cutting.
“This means that soil used for turfgrass sod production largely rebuilds what's removed and does not lose its long-term productive capacity,” Aamlid says.
References:
Borchert et al. Bærekraftig produksjon av ferdigplen: Virkning av jordart, plenalder, skjæreutstyr og forhold under skjæring på tykkelse og innhold av jord i norske ferdigplenruller (Sustainable sod production: Effects of soil type, turf age, cutting equipment, and conditions during cutting on the thickness and soil content of Norwegian sod rolls), Research report NIBIO, 2024.
Borchert et al. Produksjon av ferdigplen i Norge: Tilførsel av organiske og uorganiske jordforbedringsmidler og biokull ved produksjon av ferdigplen (Potteforsøk 2022 - 2024) (Production of sod in Norway: Application of organic and inorganic soil amendments and biochar in sod production (Pot experiment 2022–2024)), Research report NIBIO, 2025.
Haraldsen et al. Produksjon av ferdigplen i Norge: Virkning av tilførsel av organiske jordforbedrings- midler, steinmel og knust tegl på utvikling av grasdekke, plenkvalitet ved skjæring og kjemiske- og fysiske jordegenskaper (Production of sod in Norway: Effects of the application of organic soil amendments, rock dust, and crushed brick on turf development, turf quality at harvest, and chemical and physical soil properties), Research report NIBIO, 2025.
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