Expert assessment

Fragment from independent scientific expert assessment of the Scarabaeus project (No. J05-LVPA-K-01-0095) by professor Michael A. Fullen



Careful review of the 2019 and 2020 data and observations led to the following conclusions:

  1. Since the Scarabaeus system uses a relatively small amount of soil conditioner (circa 20% of the usual field application), then transport costs from the source to market (i.e. arid countries) is financially viable.
  2. Since circa 95% of the fresh weight of sapropel is water, dewatering is essential to achieve viable transport costs and to retain the essential properties of the ameliorant. The ‘B3 Snowgun’ (patented by the Project Manager P. Steponavičius) is an effective initial stage in the de-watering process, decreasing overall water content from circa 95% to circa 55%.
  3. Ameliorants produced from sapropel and peat applications improved soil nutrient status, provided soil organic matter, improved soil moisture retention and decreased soil pH to levels suitable for crop production. Thus, the modified soil was a viable substrate for crop production.
  4. Ameliorants produced from sapropel applied via the Scarabaeus system (10.6 t/ha) was equally effective as the field application of traditionally applied 60 t/ha in maintaining the soil fertility necessary for crop production. Furthermore, there is evidence of less nutrient leaching from soil treated with the Scarabaeus system, particularly less leaching of nitrogen.
  5. The insertion of soil ameliorants to targeted depths proved effective in significantly increasing the crop yields of maize, faba beans, common beans, potatoes, cabbages, celery and leeks (in 2019), and lettuce, maize, onions, common beans, cabbage, leeks, faba beans and red beet (in 2020).
  6. The emplacement of ameliorants at 10-15 cm depth protects the material from subsequent shallow cultivation, sowing and harvesting processes for three-four years. Furthermore, the ameliorants are also protected from exposure to the sun and erosion (by both wind and water). Hence, the integrity of the inserted ameliorant remains intact.
  7. In some instances the crop root system did not penetrate to the conditioner-enriched lower topsoil. Therefore, significant crop effects were not evident for carrots in 2019 or radish or potatoes in 2020. Progress requires careful matching of the crop characteristics with the depth of ameliorant.
  8. The Scarabaeus system proved effective on very sandy soils which are generally unsuitable for crop production. This provides evidence that the system may well prove effective on comparable soils (i.e. Arenosols in the World Reference Bureau System; European Commission, 2019). Suitable agro-environmental conditions may include sandy soils in arid zones with associated irrigation and/or fertigation systems.
  9. The soil conditioners used in the field experiments included sapropel mixes with peat. The evidence suggests the system could prove effective in multiple soil treatments, where targeted application to shallow soil depth is required.
  10. Generally, the ‘Scarabeus’ industrial prototype had relatively greater crop responses than the ‘Scarabeus’ laboratory prototype.
  11. Direct soil treatment effects on soil biota were evident from the application of soil ameliorants produced from sapropel. In soil samples taken in 2019, sapropel significantly (P <0.001) increased soil respiration and enzymatic activity. There was also evidence of developing symbiotic activity promoting nitrogen-fixation associated with interactions between sapropel and the legume crops faba beans and common beans. Further soil samples were taken from 0-20 cm on 06/11/20. Effects were statistically significant (P <0.001) for the effects of sapropel-based ameliorant on soil microbial populations (including colonies of both ammonifying and nitrifying bacteria and 10 taxa of soil fungi). Overall, treatment increased the cultivable bacterial population by a factor of 150 and the soil fungal population by a factor of 10. The significant effects (P <0.001) were consistent in the four sampled crops (beans, leeks, potatoes and maize) and was strongest in the topsoil associated with the crop of leeks.
  12. The evidence does support the premise that the Scarabaeus system merits support and further investigations and investment. The system has potential to improve agro-environmental conditions on sandy infertile soils in multiple climatic conditions. Therefore, the Scarabaeus system could prove a practical commodity for sale both in the East European agricultural market and in the wider international agro-technology market.

Full expert assessment