QLK5-2000-70015 A New, Environmentally Friendly Substrate From Compost and Agricultural Waste, For Glasshouse Horticulture and Reforestation

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Summary Information



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Agriculture : Biological Conversion : Composts/Fertilisers : Forestry : Horizontal Actions - INCO2, INNOVATION/SMEs and IMPROVING (Human Potential)

Contract No:	QLK5-CT-2000-70015
Source:	Final Report - 2003

Final Report - 2003

Summary

A large amount of various substrates are used in glasshouse-based horticulture. Most of the substrates are not durable. In the present project a substrate has been developed from a durabe source - compost ,made from agricultural waste. To test the performance of this 'New Substrate' various trials were carried out. In a trial with kohlrabi the 'New Substrate' with and without a thin layer of peat on top was compared with a peat-based subssrate. In addition two different nutrient solutions, with high or low electrical conductivity (EC), were supplied to the crop.

The extent of germination was determined and plant weight measurements were made one and two weeks after sowing. The level of germination was poor. Measurements of the characteristics of the 'New Substrate' showed that the pH remained too high whle the EC at the start was high. Using a nutrient solution of low EC was not beneficial. The weight of plants grown on the New Substrate was not as high as for those grown on the peat substrate. However, the addition of a thin layer of peat on the ' surface of the 'New Substrate' improved the situation, resulting in growth almost as good as for the peat substrate.

Based on these results a trial was set up with cucumber. In total six different substrates were tested:

• Peat-based substrate
• Perlite
• New Substrate
• Mixtures - New Substrate/Peat substrate 75/25 and 60/40 (volume/volume)
• New Substrate' supplemented with sulphur.

The substrates were placed in ten litre containers. The EC of the 'New Substrate' remained higher even after the initial flushing of more then 3 times the substrate volume. The pH of the 'New Substrate' remained high also during the cultivation. There was no positive influence of mixing peat on the behaviour of the pH. The pH was lowered a little bit by adding sulphur but the mixing procedure had a negative influence on the physical structure. Due to this high pH the leaves showed some chlorosis caused by low levels of iron since plants have some difficulty in absorbing this element at high pH's. The differences in plant growth were only minor. The difference in total plant weight of plants grown on perlite and those grown on 'New Substrate' was around 8% but this was not significant.

Although there are still some technical problems to overcome (high EC and pH), it seems that there is a possibility of producing an environmentally friendly new substrate, based on composted agricultural waste, for growing plants in glasshouse horticulture.