Intensity and Duration of Nitrogen Addition Jointly Alter Soil Nutrient Availability in a Temperate Grassland

Abstract

Increasing N input can alter soil nutrient availability and influence plant growth. Previous studies focused on N addition effects on N and P availability, while less on other mineral nutrients. Besides, how N addition duration affects nutrient availability has remained unclear. Based on a simulative N deposition experiment in a typical steppe with four N addition levels (0, 2, 10, and 50 g m−2 yr−1) under three N addition duration (2, 5, and 10 years), we determined contents of 10 mineral nutrients in surface soils. In the 0–10 cm soil, short‐term N addition (2‐year) significantly increased exchangeable Ca (+7.2%) and decreased exchangeable Mg (−22.5%) as compared with the control, while decreased available Fe, Cu, and Zn, but increased Mn remarkably (+80.4%). Medium‐term N addition (5‐year) significantly raised soil total N and available Fe, Mn and Cu, while decreased total P and exchangeable Ca, Na and Mg. The response patterns of these nutrients were largely similar in the 10–20 cm soil, but were weaker and significant only at high N inputs (50 g m−2 yr−1). Long‐term N addition (10‐year) significantly decreased contents of total base cations (K, Ca, Na, Mg) and micronutrients (Fe, Mn, Cu, Zn) by an average of 32.1% and 20.4%, respectively, across the two soil depths. Influences of pH and plant growth on micronutrients showed remarkable differences among different duration of N addition. These findings indicate that intensity and duration of N addition jointly alter soil nutrient availability and this should be considered in soil nutrient‐cycling modeling.

Soil acidification drives the negative effects of nitrogen enrichment on soil microbial biomass at the global scale

“…However, excessive N inputs can increase the leaching of base cations from the soil. When N is added in excess, it can cause imbalances in nutrient availability and uptake by plants (Niu et al 2022). Such imbalances can result in decreased uptake of base cations, leading to their leaching out of the soil profile with percolating water (Sverdrup and Rosen 1998).…”

Ideas and perspectives: Beyond model evaluation – combining experiments and models to advance terrestrial ecosystem science

“…In the case of edaphic factors, such as nutrient availability, spatial factors, such as underlying fertility and history of deposition interact with future loading. Ecosystem responses have also been shown to vary with the intensity and duration of the treatment (Niu et al, 2022). This means that it is often difficult to (explicitly) generate hypotheses that reflect multiple known individual processes and their (unknown) interactive effects.…”

Effects of nitrogen and water addition on soil carbon, nitrogen, phosphorus, sulfur, and their stoichiometry along soil profile in a semi-arid steppe

“…As a result, we observed significant interaction effects of N and water addition in most soil layers (Table S2). Second, soil N availability for plants and microbial communities would be altered with increasing intensity and duration of N addition (Elser et al 2010;Niu et al 2022a). In the long run, plant growth processes and plant residue inputs into the soil varied significantly under low-and high-N addition rates (Bai et al 2010), which may further affect soil C and nutrient cycling.…”

“…An increasing number of research demonstrated that soil total C, N, P, and S contents declined as soil depth increased, but fewer studies have examined changes in their ratios along the soil profile (Manzoni et al 2010;Khan et al 2016;Chen et al 2016;Niu et al 2022a). Based on the decreasing trends of soil C:N and C:P ratios with soil depth and the increasing trends of soil N:P, N:S, and P:S ratios regardless of N and water addition, it may be inferred that C and N are the key factors limiting the microbial activity in deep soil.…”