{"id":45081,"date":"2026-11-11T11:00:48","date_gmt":"2026-11-11T10:00:48","guid":{"rendered":"https:\/\/resoilfoundation.org\/?p=45081"},"modified":"2026-11-11T14:26:32","modified_gmt":"2026-11-11T13:26:32","slug":"compost-organic-matter-climate","status":"publish","type":"post","link":"https:\/\/resoilfoundation.org\/en\/circular-bioeconomy\/compost-organic-matter-climate\/","title":{"rendered":"Compost protects soil carbon. But climate change is rewriting the rules"},"content":{"rendered":"

A German study examines 29 years of agricultural trials: compost application increases soil organic carbon by up to 33% compared with untreated soils. However, rising temperatures and drought may be contributing to declining carbon stocks, even where organic matter continues to be added<\/h2>\n

by Emanuele Isonio<\/p>\n

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Compost helps agricultural soils accumulate carbon, but global warming could gradually undermine some of these benefits. This is suggested by a study published in the scientific journal Geoderma, which examined changes in soil organic carbon over 29 years of agricultural experimentation in Germany. The findings show that applying organic soil amendments can significantly increase soil carbon stocks<\/strong>, but also that these stocks may decline even when fertilization practices are maintained.<\/p>\n

The research, led by David I. Schubert and conducted by a team including scientists from the Technical University of Munich<\/a>, the Bavarian State Research Center for Agriculture and the Th\u00fcnen Institute, examined a long-term field experiment carried out between 1994 and 2023<\/strong> in Puch, Bavaria. The aim was to understand how different agricultural management strategies affect the soil’s ability to store carbon over time and what role climatic conditions may play.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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Twenty-nine years of compost application and fertilization<\/h4>\n

The researchers compared agricultural plots<\/strong> subjected to different treatments<\/strong>: green manure, three types of compost, and varying levels of mineral nitrogen fertilization. The findings confirmed the importance of organic inputs in maintaining soil organic matter.<\/p>\n

Even the highest level of mineral nitrogen fertilization produced an increase of between 7% and 9%, but its effect was considerably smaller than that of organic amendments.<\/p>\n

One significant finding concerns crop productivity<\/strong>. Although nitrogen fertilization substantially increased yields and, consequently, the amount of crop residues returned to the soil, this greater input of biomass did not translate into a comparable increase in carbon stocks.<\/p>\n

The amount of organic material entering the soil is therefore not the only determining factor. The properties of soil amendments<\/strong> and the processes governing the decomposition and stabilization of organic matter also play a crucial role.<\/p>\n

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Compost can be an alternative to chemical fertilisers in urban agriculture<\/a><\/p><\/blockquote>\n