Journal
EUROPEAN JOURNAL OF AGRONOMY
Volume 77, Issue -, Pages 138-145Publisher
ELSEVIER
DOI: 10.1016/j.eja.2016.03.005
Keywords
Soil organic carbon; Humification coefficient; Long-term field experiment; Roots; Crop residues; Organic amendments
Categories
Funding
- Italian Ministry for University and Education - PRIN Project IC-FAR [2010FRE7J4]
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Annual C input to soil is a major factor affecting soil organic carbon (SOC) dynamics. However different types of C-sources can have different behaviour, in relation to their chemical characteristics and how they interact with soil. Root-derived C, in particular, should be more efficient than other organic materials as a result of the physicochemical and biological characteristics of the surrounding environment, leading to a reduction in the C decomposition rate. To test this hypothesis, we considered a long-term experiment underway in Northern Italy since 1962, comparing permanent meadow and 6 different crop rotations over a wide range of nutrient inputs, in both organic and inorganic forms. C inputs from amendments were measured and those from crops were calculated using allometric functions and crop and residues yields. The time evolution of SOC was studied through a single-pool, first-order kinetic model, allowing the estimation of humification coefficients for residues, roots, farmyard manure and cattle slurries. The highest value of the humification coefficient was estimated for farmyard manure, which confirmed its high efficiency in stabilising SOC content. Root C presented a humification coefficient 1.9 times higher than above-ground plant materials while slurries were intermediate, with a humification coefficient roughly half that of farmyard manure and even lower that of roots. The quality of C input thus seems of fundamental importance for evaluating the sustainability of different cropping systems in terms of SOC dynamics. (C) 2016 Elsevier B.V. All rights reserved.
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