Effect of nitrogen fertilization on central tendency and spatial heterogeneity of soil moisture, pH and dissolved organic carbon and nitrogen in two bioenergy croplands#

Abstract

Background Soil moisture, pH, dissolved organic carbon and nitrogen (DOC, DON) are important soil biogeochemical properties in switchgrass (SG) and gamagrass (GG) croplands. Yet their spatiotemporal patterns under nitrogen (N) fertilization have not been studied. Aims The objective of this study is to investigate the main and interactive effects of N fertilization and bioenergy crop type on central tendencies and spatial heterogeneity of soil moisture, pH, DOC and DON. Methods Based on a 3‐year long fertilization experiment in Middle Tennessee, USA, 288 samples of top horizon soils (0–15 cm) under three fertilization treatments in SG and GG croplands were collected. The fertilization treatments were no N input (NN), low N input (LN: 84 kg N ha−1 in urea) and high N input (HN: 168 kg N ha−1 in urea). Soil moisture, pH, DOC and DON were quantified. And their within‐plot variations and spatial distributions were achieved via descriptive and geostatistical methods. Results Relative to NN, LN significantly increased DOC content in SG cropland. LN also elevated within‐plot spatial heterogeneity of soil moisture, pH, DOC and DON in both croplands though GG showed more evident spatial heterogeneity than SG. Despite the pronounced patterns described above, great plot to plot variations were also revealed in each treatment. Conclusion This study informs the generally low sensitivity of spatiotemporal responses in soil biogeochemical features to fertilizer amendments in bioenergy croplands. However, the significantly positive responses of DOC under low fertilizer input informed the best practice of optimizing agricultural nutrient amendment.

Influence mechanisms of N addition on the concentration of soil dissolved organic matter in China

“…Previous studies reported that soil DOM (including DOC and DON) concentration could be changed by N addition (Jing et al, 2021; Lei et al, 2017; Yuan et al, 2022). However, soil DOM concentration influenced by N addition remained inconsistent, with not only the magnitude but also the direction (Jing et al, 2021; Wang et al, 2022; Yuan et al, 2020). Soil DOC concentration showed increase (Niu et al, 2021; Sun et al, 2015), decrease (Jing et al, 2021; Yuan et al, 2022), and minor change (Chen et al, 2022; Li et al, 2019b) in response to N addition.…”

Simultaneous Measurements of Dissolved Organic Carbon and Soil Respiration Reveal Reduced Soil Carbon Loss Under Nitrogen Addition in a Montane Forest

“…Responses of both soil respiration and DOC leaching have been shown to depend on the level of N addition (Evans et al., 2008; Peng et al., 2017; X. Wang et al., 2022) and the duration of N addition (Zhou et al., 2014). In particular in N‐limited forest ecosystems, the effects of N addition might be diminished gradually under chronic N addition (Janssens et al., 2010) and it is an open question how long the effects would be sustained.…”

“…Responses of both soil respiration and DOC leaching have been shown to depend on the level of N addition (Evans et al, 2008;Peng et al, 2017;X. Wang et al, 2022) and the duration of N addition (Zhou et al, 2014).…”