Carbon and Nitrogen Stocks in Agricultural Soils under Different Natural Conditions and Management in Slovakia

Abstract

Soil is a natural capital which supplies valuable ecosystem services including carbon and nitrogen storage. Agroecosystems play an important role in soil organic carbon (SOC) and soil total nitrogen (NT) accumulation. The aim of this study was to analyse SOC stock (SOCS) and NT stock (NTS) in relation to land use (arable land-AL, permanent grasslands-PG), management, soil depth, and selected soil properties of six soil subtypes (Rendzic Leptosol—LPrz, Dystric Cambisol—CMdy, Stagnic Cambisol—CMst, Haplic Fluvisol—FLha, Gleyic Fluvisol—FLgl, Haplic Chernozem—CHha) which are the most widespread in Slovakia. SOCS for a 50 cm deep soil profile ranged from 161 t.ha−1 in CHha to 59 t.ha−1 in FLgl in grasslands, and in arable lands from 111 t.ha−1 in CHha to 38 t.ha−1 in CMst. In grasslands, FLs and CMst showed the significantly lowest SOCS and NTS in comparison to CMdy, LPrz, and CHha. The mean soil NT content in arable land and grasslands was 2.21 g.kg−1 and 2.82 g.kg−1, respectively. ANOVA showed that soil subtype, land use, and site have significantly affected SOCS but not NTS. The correlation analysis revealed correlations between SOCS and NTS. SOCS was also correlated with C:N, pH, P, and K. This study should help to encourage practices to maintain soil C and soil properties and to ensure the sustainability of the functions of many soil types in Slovakia.

Inversion Tillage Combined with Organic Fertilizer Application Increased Maize Yield via Improving Soil Pore Structure and Enzymatic Activity in Haplic Chernozem

“…Four methods were used to assess microbial resource limitation, as described previously [19][20][21]. In the first method, microbial resource limitation was judged based on the scatter plot between the (LAP + NAG)/AP and BG/(LAP + NAG) activity ratios, with the four parts of the plot representing N limitation, P limitation, C and N limitation, and C and P limitation.…”

“…In the third method, a vector analysis of extracellular enzymatic stoichiometry was used to assess microbial resource limitation. Vector length and vector angle ( • ) were calculated and described as per Luo and Zhang et al [20,21]. The fourth method used differences between the threshold element ratio (TER) for C:N (TER C:N ) and the DOC:AVN ratio (R C:N ) and between the TER for C:P (TER C:P ) and the DOC:AVP ratio (R C:P ).…”

“…However, a change in the activity of only one enzyme cannot fully represent microbial resource limitation, which needs integral evaluation via the relative availabilities of multiple soil nutrients [19][20][21]. Studying microbial resource limitation thus also needs an analysis of extracellular enzymatic stoichiometry.…”

“…Soil microorganisms play a crucial role in the formation and cycling of soil organic carbon and the release of soil nutrients [18]. Most microbially controlled processes strongly depend on microbial biomass and activity, which are mostly limited by soil nutrient resources, including C, N, and P [19,20]. Therefore, it is important to adopt effective soil management practices to alleviate microbial resource limitations and increase the growth of microorganisms.…”

“…The effects of inversion tillage and organic fertilizer application on soil physical properties and available nutrients have been widely studied, but the functional and metabolic responses of microorganisms to these practices remain unknown. Extracellular enzymatic stoichiometry based on enzymatic activities can indicate the rate of which soil microorganisms obtain organic C, N, and P [22], representing the ability of microorganisms to absorb soil nutrients, which can be an important indicator by which to assess the flow of energy in an agroecosystem [20,21]. However, few studies have adopted extracellular enzymatic stoichiometry to identify the effects of inversion tillage and organic fertilizer application on the metabolic characteristics of microorganisms in agroecosystems in a Haplic Chernozem region in Northeastern China.…”