Impact of N fertilization on subsoil properties - Soil organic matter and aggregate stability
Year: 2011
Type: dissertation
Abstract: During the last century mankind has been able to boost food production with fertilization \nand improved cultivation techniques. Crop biomass production has been increased both, \nabove and below ground. Due to this fact it is expected that highly yielding crops may also \ninfluence the soil organic carbon pool in the subsoil through increasing root production. \nThe goal of this thesis was to investigate the impact of low and high yields (no N vs high N \nfertilization) on (1) the soil organic matter pool (2) soil stability and (3) related chemical and \nphysical interactions. \n \nSoils of three Swedish long-term field experiments (Fors, Kungsängen and Örja) were \nsampled to a depth of 0.40 m and analyzed. The organic carbon content decreased with \ndepth at all three sites. Nitrogen addition through organic manure and inorganic fertilizer \nslightly increased the soil organic carbon content (SOC) in the topsoil, but in the subsoil \n(0.30-0.40 m) only the soil from Fors showed higher SOC contents in N fertilized \ntreatments. Nitrogen fertilization (organic and inorganic) resulted in lower pH values \ncompared to control without fertilization at all three experimental sites. Manure had an \nimportant influence on aggregate stability at the site Fors. The soil treated with manure \nshowed a higher soil aggregate stability (SAS) and a lower amount of readily dispersible clay \n(RDC) than no manure treatment. At Kungsängen, the soil stability was governed by the \nhigh clay content of 56%. No stabilizing effect of fertilization was detected. The acidifying \neffect of biological N fixation was observed in Örja soil. Samples with lower pH showed \nlower stability. Inorganic N fertilizer significantly stabilized the Örja surface soil layer (0- \n0.20 m). Multiple regressions revealed that the factor clay seems to have the most impact \non soil stability. \n \nIn conclusion, it has been shown that small differences in soil management practices \n(organic and/or inorganic fertilization, cultivation of N fixing plants) have an impact on soil \nproperties in the long-term with a much greater degree in the topsoil than in the subsoil.
Author: Martina Schön
Language: English
Subfield: Soil Science
Domain: Life Sciences
SDGs: Zero hunger, Life on land
Open Access status: green
OpenAlex ID: W2329140511