Neiker-Tecnalia have developed two new types of tecnosoils to be used as cultivation substrates in greenhouses.
Instituto Vasco de Investigación y Desarrollo Agrario has used sludges resulting from waste-water treatment, biomass combustion ashes, metallurgy and syderurgy residues and barley straw to elaborate tecnosoils, artificial soils.
New substrates demonstrated good properties for growing crops, as nutrient levels (nitrogen, phosphorus and potassium), adequate acidity and organic material stability when mixed.
Peat substitute need
Horticultural and forestry production systems, plants production in containers has suffered a great development in the last few years due to its advantages regarding direct seeding or plant production in the field.
Total cropping media used in UE is about 20 and 30 million per year, being peat 85-90% of the market need. As peat is an organic material valued and non returnable, we are interested in searching residual product mixes, coming from urban or industrial processes, which can substitute peat and at the same time, contribute to a more efficient residue use.
Neiker-Tecnalia researches, together with the University of Santiago de Compostela, have developed two new types of tecnosoils to be used as cultivation substrates in greenhouses.
Both are made with EDAR sludges, green sand from foundry ( sand used for the metal foundry industry to create moulds where molten metal is poured)Linz-Donawitz slag ( slag coming from steel refining), barley straw and biomass combustion ashes.
The difference is in the sludge used: anaerobic, aerobic and aerobic lime treated and in the proportions of the organic and inorganic material used on the mixes: 5% of foundry sand,10% of steel slag, 2% of barley straw, 23 or 33% combustion ashes and 60-50% sewage sludge.
Results show tecnosoil made from aerobic sludges have more primary nutrient quantity, nitrogen, phosphorus and potassium, as well as organic carbon, while if they mix with lime there is less phosphorus.
Both tecnosoils have appropriate acidity properties which is interesting for the immobilization of heavy metalsand crop development. Furthermore both promote organic material stabilization, which improve substrate durability.
Regarding plant return, results show highest outputs are obtained in tecnosoils coming from without lime treatment aerobic sludge mixes. This is consistent with the nutrient availability in the mixes.
A way to scientific research
The research was made by the doctor in agriculture Fenxia Yao, with studies in Universidad de Agricultura de Shenyang (China). Fenxia Yao is the first person presenting a doctoral thesis in Spain related to tecnosoils. This thesis has been managed byDr. Marta Camps and Dr. Felipe Macías, and has been defended in Universidad Santiago de Compostela on January the 31. It opens an important way to study tecnooils and their application.
Tecnosoils supposed an important contribution to the environment. Furthermore they can be used as crop substrate, to recover areas degraded by mineral mining activities, public works… At the same time, they are used to reutilize materials, both organic and mineral, that would otherwise be thrown to a landfill.