Seasonal changes in the content of dissolved organic matter in arable soils

Abstract

Purpose The aim of this paper has been to determine the seasonal changes in the content of dissolved organic matter (DOM) in the soils under agricultural use based on assaying changes in dissolved organic carbon (DOC) and dissolved nitrogen (DNt) as well as determining the factors which can define the DOM in soils. Materials and methods The research has involved the soils under agricultural use sampled in the Kujawsko-Pomorskie province (Poland). Phaeozems and Luvisols were sampled from the depth of 0-30, 30-60, and 60-100 cm, November 2011 through September 2013, in November, March, May, July, and September. The soil samples were assayed for the grain size composition, pH, dry weight content, content of total organic carbon, and total nitrogen. Dissolved organic matter was extracted with 0.004 mol dm 3 CaCl 2 ; in the DOM extracts, the content of dissolved organic carbon (DOC) and dissolved nitrogen (DNt) were assayed. The research results were statistically verified. Results and discussion It has been demonstrated that in the first year of research, the content of dissolved organic carbon in the soils was changing throughout the year. The highest differences in the content of that carbon fraction occurred across the soil sampled in autumn and the soil sampled in spring. In the second year of research, an inverse dependence was noted. DOC was migrating to deeper layers of the soil profile; yet, the migration got more intensive in summer. The content of dissolved nitrogen was not changing significantly throughout the year. Higher DNt content in the surface layer, in general, resulted in a higher content of dissolved nitrogen in deeper profile layer, which could have been due to leaching of the nutrient deep down the soil profile. Conclusions The content of dissolved organic carbon was significantly related to the content of total organic carbon and total nitrogen. Significant changes in the content of dissolved forms of nitrogen were reported in the profile of Phaeozems due to mineral fertilization and irrigation. The soils where irrigation and higher nitrogen rates had been applied demonstrated a higher content and share of soluble forms of nitrogen, as compared with the soils non-irrigated and the soils where lower nitrogen rates had been supplied.

Divergent Accumulation of Microbial Residues and Amino Sugars in Loess Soil after Six Years of Different Inorganic Nitrogen Enrichment Scenarios

“…Nitrogen enrichment decreases soil DOC concentration due to the chemical stabilization of organic carbon [56] and the stimulation of the microbial mineralization rate, which increases DOC consumption [57]. Results of the current study, however, revealed that nitrogen enrichment stimulated soil DOC concentration, which is consistent with Shi et al [58] and Wei et al [52]; this could be attributed to the nutrient status of the soil [59,60]. Rosa et al [60] pointed out that soil DOC significantly correlated with SOC and total N. Soil DOC increased with an increasing N rate (Figure 4b), probably due to aboveground plant biomass, which was returned to the soil annually.…”

The Soil Organic Matter in Connection with Soil Properties and Soil Inputs

“…The regression model analysis of the dependences of the soil SOC development in the field conditions clarifies the basic soil properties as the most important factor. The available humus content models refer mainly to the SOC and soil total nitrogen (STN) assessments [86][87][88], and the time of sampling [89]. Malkina-Pykh [90] investigated the behaviour of humus in the Sod-Podzolic soils.…”

The Effect of Organic and Conventional Farming Systems with Different Tillage on Soil Properties and Enzymatic Activity

“…Moreno et al [54] found that long-term conservation tillage increased TOC content and the quality and stability of SOM. The labile fractions of organic carbon are more sensitive to changes in soil management practices [55]. Both tillage treatments and the application of cattle manure as well as the addition of legumes in crop rotation have increased SOC, enzymatic activity and improved soil fertility on the OF.…”