New Substrates Derived from Anaerobic Sludge Promote High Plant Yields

New types of artificial soil substrates for green houses have been developed at the Basque Institute for Agricultural Research and Development, Neiker-Tecnalia. These Technosols were developed using sewage sludge, barley straw, metallurgical waste, and ash generated from biomass combustion.

Technosols contribute to the betterment of the environment. They reuse mineral and organic materials. These technosols can also be used for rehabilitating areas that have been degraded due to public works or for extraction of minerals.

The substrates possessed organic matter stability, high acid buffering capacity, and high nutrients levels, including potassium, phosphorus and nitrogen, which are ideal for growth of plants.

Container grown plants have demonstrated advantages over field crop and direct sowing cultivation. Due to this property, peat and other crop growing media have a total consumption of around 20 to 30 million m3 per annum in the European Union. Peat is a non-renewable and valuable organic material and forms 85%-90% of the total consumption. A substitute for peat from waste products will also help in the utilization of these resources.

The University of Santiago de Compostela and researchers at Neiker-Tecnalia used a mixture of green foundry sand, biomass combustion ash, barley straw, Linz-Donawitz slag and sewage sludge of three types – aerobic, anaerobic and lime-treated aerobic sludge to develop new Technosols types.

Technosols from anaerobic sludge contained more organic carbon and high levels of nitrogen and phosphorus. Technosols formulated from aerobic sludge possessed low levels of macro nutrients and organic carbon. Technosols derived from lime-treated aerobic sludge had the lowest levels of phosphorus. The study revealed that Technosols derived from anaerobic sludge delivered the highest yields.

Dr. Fenxia Yao performed this research and submitted it as a PhD thesis. It was defended at the University of Santiago de Compostela.