Solid manure crucial for soil OS content

By making use of 7 decades of data, research agency Eurofins Agro has been able to analyze the development of the organic matter contents on plots in Zeeland. One of the conclusions is that the OS content can be increased by being economical with the soil and using a lot of organic fertilizer.

Several studies have been conducted in recent years on the course of organic matter (OS) in the soil. Practice and policy have commented on the conclusions. For example, there are questions about the differences at plot level, the period and the effect of measures taken for soil fertility.

Eurofins therefore had Aeres University of Applied Sciences student Christiaan Maljaars conduct research into soil investigations from 1950 to the present. In addition, 9 arable farmers were interviewed about their working method and its effect on the OS content in the soil. In all cases, this concerns plots of clay soil in Zeeland.

More scaffolding than descenders
Eurofins has data on 160 Zeeland plots, which in some cases go back to 1950. Maljaars' analysis shows that the differences in the OS content are sometimes large. The content has increased significantly on 29 plots. The content decreased on 44 plots. Because the increase is on average greater than the decrease, an average level is noticeable across the board.

Data indicate that, since 1950, some plots in OS content have fallen from 1,8% to 1,4%. There are also plots that increased from 1,6% to 2,3%. The average OS content is 2,2%. In a majority of 87 plots, the content remained approximately the same.

Solid manure has the greatest value
The interviews show that arable farmers, who consciously deal with OS, can relate this back to the studies. The supply of effective organic matter, in the form of solid manure and compost, is the decisive factor. The construction plan and the tillage have less effect on the development management balance, concludes Eurofins.

Arable farmers dealing with declining OS levels are generally aware of this, but present the current manure policy as the argument that they cannot turn the tide with organic fertilisers.

Supply necessary
In the study, Maljaars concludes that working with an OS balance forms the basis for maintaining soil fertility. If the supply is equal to the output, the balance is maintained. Solid manure and compost in particular have a positive effect on this. It is therefore of great importance to be able to continue to realize this supply.

Eurofins wants to conduct follow-up studies in other provinces in order to be able to form a picture of the development of the OS levels in the soil throughout the Netherlands.

Niels van der Boom

Niels van der Boom is a senior market specialist for arable crops at DCA Market Intelligence. He mainly makes analyses and market updates about the potato market. In columns he shares his sharp view on the arable sector and technology.

n.vanderboom@boerenbusiness. Nl

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