Effect of anaerobic soil disinfestation amendment type and C:N ratio on Cyperus esculentus tuber sprouting, growth and reproduction

Abstract

Anaerobic soil disinfestation (ASD) is a cultural technique primarily targeted for control of soilborne plant pathogens, but can also impact weed propagules. A repeated pot study was conducted to evaluate ASD treatment impact on sprouting and growth of introduced Cyperus esculentus (yellow nutsedge) tubers using dry molasses-based and wheat bran-based amendment mixtures at four carbon-to-nitrogen (C:N) ratios (from 10:1 to 40:1) and compared with a nonamended control. The mean percentage of sprouted tubers recovered after ASD treatment was lower for wheat bran-based (42%) than dry molasses-based (65%) amendments, and tuber production was 1.6-fold higher in dry molasses-based than wheat bran-based treatments. The highest percentage of sprouted tubers (79%) and the highest mean production of large tubers (threefold higher than wheat bran-based and 1.7-fold higher than molasses-based amendments) were observed for the non-amended control. Tuber sprouting was significantly lower from all ASD treatments (regardless of amendment C:N ratio) compared with the non-amended control at a 15 cm burial depth. New tuber production was lowest at C:N ratios of 10:1 and 20:1 and more than twofold higher in the non-amended control. Wheat bran-based amendments reduced above-ground C. esculentus biomass compared with the non-amended control and ASD treatments with molasses-based amendments, and reduced belowground biomass compared with molasses-based amendments. Above-ground biomass was highest at amendment C:N ratio of 10:1, and below-ground biomass was highest at amendment C:N ratio of 40:1 and the non-amended control. ASD treatment with wheat bran-based amendments at lower C:N ratios reduced tuber sprouting and reproduction compared with the non-amended control, but not at rates high enough to use as a primary weed management tactic.

Amendment Properties Affect Crop Performance, Leaf Tissue Nitrogen, and Soil Nitrogen Availability Following Soil Treatment by Anaerobic Soil Disinfestation

“…To our knowledge, this is the first study to specifically evaluate ASD amendment C:N ratio effects on soil inorganic N, crop N status and crop yield. At the same time, our results are consistent with other reports of high soil inorganic N following soil disinfestation with ASD amendments with relatively low C:N ratios (Butler et al, 2014a;McCarty et al, 2014;Di Gioia et al, 2017;Shrestha et al, 2018b). Soil microbial stoichiometry is fairly constrained within a C:N ratio of ∼5:1 to 7:1, which along with microbial energetic needs causes substrate C:N ratios above ∼20:1 to lead to N limitations on microbial decomposition and reduced available soil inorganic N (Sinsabaugh et al, 2013;Spohn, 2015).…”

Effect of Different Substrates on Soil Microbial Community Structure and the Mechanisms of Reductive Soil Disinfestation

“…The C/N ratio is a key factor in RSD treatment (Liu et al, 2016;Shrestha et al, 2018). The results of NH + 4 -N content analysis showed that higher C/N ratios were associated with lower NH + 4 -N contents when the substrate input amount and treatment time were the same.…”

Temporal Dynamics of the Soil Metabolome and Microbiome During Simulated Anaerobic Soil Disinfestation

“…Significant effort has been targeted toward enhancing ASD efficacy for soil-borne disease control with an emphasis on optimizing implementation variables such as carbon source (Butler et al, 2012; Hewavitharana et al, 2014; Serrano-Pérez et al, 2017; Shrestha et al, 2018), irrigation volume and duration (Daugovish et al, 2015), length of the incubation period, and the effects of soil temperature (Hewavitharana et al, 2015). Concurrent studies have examined the influence of these variables on the proposed mechanisms that yield disease suppression in response to ASD.…”