Composting firms visit trials with compost on location of Delphy

15 July 2021 - Published by Hanne Lakkenborg Kristensen
Written by Esther Hessel. In June 3 compost firms, Orgapower, Van Iersel Compost and Wagro, and a representative of the Dutch Association of Biowaste processors (BVOR) visited the trials at the Trial location of Delphy in Boskoop. Last year Delphy started three trials in the context of SOILCOM. Different bio waste streams and composts were used in these trials.


Compost treatments in cultivation of Boxwood

In the fields of Boxwood, biowaste compost and green compost were applied on top of the soils. In the other treatments greencompost was combined with different organic materials: composted bark, chopped wheat straw, cocoa shells, wood vinegar and iron lime sludge.  In the trial Delphy is researching the effect of the treatments on nutrient availability, growth and soil life.  In 2020 the first measurements were carried out.  The Soilcheck (analysis for nutrients) showed less nitrogen availability in the green compost treatments and more potassium and calcium. Application of green compost leads also to more biological activity of fungi. Addition of organic fertilization increases the activity of bacteria in the soil. It seems that the boxwood treated with compost has a better growth than the untreated plants. In 2021 Delphy will monitor again, were they also look at the effects on the existence of the fungal disease Cylindrocladium.


Tailor made compost application in Picea and Laurus

In Picea glauca ‘conica’  and Prunus a tailor made compost, matching with the soil and crop, was mixed in the top layer with the original peat soil. Soil analyses are made in the USA using the Albrecht method. Based on the analyses, Smeets Agro Consultancy developed two compost mixtures.

In these cases green compost was mixed with different products, based on the soil analysis and the characteristics of the soil.  For this demo leonardite (lignite), vulcanic stonemeal, zeolite, magnesite and lime and trace elements like copper, manganese and zinc were added.

Also in these demo’s a soil analysis and soil life analyse were taken. First observations show that in the field of Prunus with compost there was a increase in availability of nutrients. And also an increase in fungi and bacteria. Interesting to see and to know is how compost is working out on the peat soils of Boskoop. Soils with already a high organic matter content of more as 20%

The first crop observations in the Picea and Prunus showed in Picea no difference and in the first year of the Prunus cultivation, there was a more steady growth in the compost treatment. While a more abundantly growth could be seen in the not treated Prunus.

There was a lively discussion about the first soil analyses. Which differences can we already see in the soils between the treatments? Interesting part of the discussion was about the effects on organic matter. In the peat soils on the trial location the organic matter content is already quite high. Adding and mixing with compost will lead to the same or lower organic matter contents. Next months the effects on the crops are measured.