Water-soluble carbon in roots of rape and barley: impacts on labile soil organic carbon, arylsulphatase activity and sulphur mineralization

Abstract

Investigating the impact of plant species on sulphur (S) availability in the rhizosphere soil is agronomically important to optimize S fertilization. Bulk, rhizosphere soils and the roots of Weld-grown rape and barley were sampled 7 times (every fortnight), from March to June, at plant maturity. Root carbon (C) and nitrogen (N) in water extract, along with soil SO 4 2¡ -S, labile soil organic-C (HWC) and -N (HWN) in hot water extract, as well as soil arylsulphatase activity were then monitored. The average concentrations of both HWC and HWN were observed in the following decreasing order: rape rhizosphere soil >barley rhizosphere soil >bulk soil. In parallel, the average contents of water extractable-C and -N in rape roots were higher than those in barley roots. These results suggest that soil C and N contents in hot water extract (including rhizodeposition) were correlated with C and N released by roots. Great ARS activities found in rape rhizosphere soil were accompanied by great SO 4 2¡ -S mineralization over time. Finally, bulk and rhizosphere soils of rape and barley were pooled from the seven samplings and incubated with the corresponding pooled root water-soluble C of both plant species and glucose-C. After 1 and 9 weeks, a greater net S mineralization (gross mineralization -immobilization) was observed with rape root water-soluble C than with barley root water-soluble C and glucose-C. Conjointly, we found a higher average value of ARS activity in rape rhizosphere than in barley rhizosphere soil. Our Wndings suggest that plant species, via their rhizodeposition, determine the dynamic of S in soil.

Effects of marine biofertilisation on Celtic bean carbon, nitrogen and sulphur isotopes: Implications for reconstructing past diet and farming practices

“…Sulphur isotope analysis of archaeobotanical remains can be undertaken as part of a multi‐isotope approach together with δ 13 C and δ 15 N, and has the potential to provide information on the use of different soils/areas for cultivation as well as crop management practices 51 . The application of sulphur isotope ratios (δ 34 S values) in the investigation of plant metabolism and environmental effects has received minimal attention, 52–54 although there have been numerous reports on the uptake and metabolism of elemental sulphur 55–58 . Although there have been many modern crop studies using seaweed extracts or elemental sulphur, these have primarily focused on the growth response and uptake of sulphur and nitrogen in the plant, 30,55,59–61 rather than tracing the effect of biofertilisation on sulphur isotopes.…”

Early effects of temperate agroforestry practices on soil organic matter and microbial enzyme activity

“…Soil microbial activity is more strongly correlated with labile organic carbon pools than with total SOC (Haney et al 2012), suggesting that these pools can significantly control microbial activity changes on a short-term scale in response to environmental changes due to their accessibility to soil microorganisms (Schimel et al 2007;Blankinship and Schimel 2018). Enzyme activities are considered as potential indicators of soil quality (Dick et al 1996) because they are highly sensitive to land use, cropping systems, and agricultural practices such as tillage and fertilization (Klose et al 1999;Bandick and Dick 1999;Acosta-Martínez et al 2007;Vong et al 2007). As enzyme activities are earlier indicators of the effects of soil management changes than SOC contents (Ndiaye et al 2000), they are commonly monitored in agroforestry systems (Mungai et al 2005;Mao et al 2012;Fang et al 2013;Wang et al 2017;Beuschel et al 2019).…”

Optimizing relative seed frequency of intercropped pea and spring barley

“…Obwohl die Bedeutung des Schwefels für die Ertragsbildung und N2-Fixierung von Körnerleguminosen nachgewiesen ist, fehlt es bislang an detaillierten Daten zur S- (Cazzato et al, 2012;Habtemichial et al, 2007;Robson et al, 1995;Scherer & Lange, 1996;Scherer et al, 2008;Zhao et al, 1999) (Knauff et al, 2003;Vong et al, 2007). Die Mineralisation des an C gebundenen S wird durch den C-Bedarf der Mikroorganismen bestimmt, wobei C als Energiequelle dient und SO4 2als Nebenprodukt dieser Prozesse frei wird (Scherer, 2009).…”