Soil Particulate and Mineral-Associated Organic Matter Increases in Organic Farming under Cover Cropping and Manure Addition

Karin Kauer, Sandra Pärnpuu, Liina Talgre, Viacheslav Eremeev and Anne Luik
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Karin Kauer: Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, EE51006 Tartu, Estonia
Sandra Pärnpuu: Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, EE51006 Tartu, Estonia
Liina Talgre: Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, EE51006 Tartu, Estonia
Viacheslav Eremeev: Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, EE51006 Tartu, Estonia
Anne Luik: Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, EE51006 Tartu, Estonia

Agriculture, 2021, vol. 11, issue 9, 1-23

Abstract: This study aimed to investigate the soil organic carbon (SOC) sequestration rate and soil organic matter (SOM) composition in conventional rotational cropping with mineral fertilization compared with organic cover cropping with and without composted manure addition during 2008–2018 to specify the SOM stabilization under different farming systems. The SOC proportion in particulate organic matter (POM) (63–2000 µm) and mineral-associated organic matter (MAOM) (<63 µm) fractions were estimated in different treatments, and the SOM composition in the fractions was characterized by FTIR spectroscopy. The SOC sequestration rate was treatment-dependent, with the higher SOC sequestration rate (1.26 Mg ha −1 y −1 ) in the organic treatment with cover crop and composted manure. Across all treatments, 57.3%–77.8% of the SOC stock was in the MAOM fraction. Mineral N fertilization increased POM-C concentration by 19%–52% compared with the unfertilized control. Under the organic treatments, the POM-C concentration was 83%–95% higher than the control. The MAOM-C concentration increased by 8%–20%. The mineral N fertilization and organic treatments (with and without cover crops and composted manure) increased the SOC stock proportion of POM. The highest proportion of SOC stock related to POM was in the cover cropping system, reducing the proportion of C related to the MAOM fraction, but the addition of composted manure with cover cropping also increased the proportion of C in MAOM. Compared with MAOM, the POM had a less resistant organic matter composition, and the POM resistance was higher in organic than conventional treatments. In general, the recalcitrance of SOM increased with SOC concentration. The POM fraction had higher aromaticity (or degree of decomposition) than the MAOM fraction. The aromaticity in POM and MAOM fractions was higher in the organic farming system and depended on mineral N fertilization and cover cropping, but the effect of manure was not significant. Although the SOC sequestration rate was higher under manure addition, resulting in the highest formation of both POM and MAOM in the soil, manure addition had little effect on overall SOM composition compared with cover crops.

Keywords: SOC sequestration rate; organic and conventional farming; N fertilization; cover crop; particulate organic matter; mineral-associated organic matter; FTIR spectroscopy (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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