Biomass composite with exogenous organic acid addition supports the growth of sweet sorghum (Sorghum bicolor ‘Dochna’) by reducing salinity and increasing nutrient levels in coastal saline–alkaline soil

Abstract

IntroductionIn coastal saline lands, organic matter is scarce and saline stress is high. Exploring the promotion effect of intervention with organic acid from biological materials on soil improvement and thus forage output and determining the related mechanism are beneficial to the potential cultivation and resourceful, high-value utilization of coastal mudflats as back-up arable land.MethodThree exogenous organic acids [humic acid (H), fulvic acid (F), and citric acid (C)] were combined with four kinds of biomass materials [cottonseed hull (CH), cow manure (CM), grass charcoal (GC), and pine needle (PN)] and applied to about 0.3% of medium-salt mudflat soil. The salinity and nutrient dynamics of the soil and the growth and physiological differences of sweet sorghum at the seedling, elongation, and heading stages were observed under different treatments to screen for efficient combinations and analyze the intrinsic causes and influencing mechanisms.ResultsThe soil salinity, nutrient dynamics, and forage grass biological yield during sweet sorghum cultivation in saline soils differed significantly (p < 0.05) depending on the type of organic acid–biomass composite applied. Citric acid–pine needle composite substantially reduced the soil salinity and increased the soil nutrient content at the seedling stage and improved the root vigor and photosynthesis of sweet sorghum by increasing its stress tolerance, allowing plant morphological restructuring for a high biological yield. The improvement effect of fulvic acid–pine needle or fulvic acid–cow manure composite was manifested at the elongation and heading stages.DiscussionCitric acid–pine needle composite promoted the growth of saline sweet sorghum seedlings, and the effect of fulvic acid–pine needle composite lasted until the middle and late stages.

Effects of Silicon Alone and Combined with Organic Matter and Trichoderma harzianum on Sorghum Yield, Ions Accumulation and Soil Properties under Saline Irrigation

“…Trichoderma are recognized as synthesizers of phytohormones, such as auxin, and hormone-like compounds called harzianolide, substances that, together with auxin, act to expand the cell wall and increase biomass production by plants [97,98]. OM acts as a source of nutrients, soil conditioner, and food for the soil microbiota, and these characteristics improve fertility, soil aggregation, and nutrient cycling, thus promoting better nutrition and more significant biomass accumulation by sorghum [99,100]. The productivity obtained in this study is compatible with that found even when forage sorghum is irrigated with good-quality water [101][102][103].…”

Modifying soil bacterial communities in saline mudflats with organic acids and substrates

“…The specific physicochemical properties are shown in Table 1. The area has a subtropical monsoon maritime climate with an average annual temperature of 16.3°C and an average annual precipitation of 1,024 mm, which mainly occurs in summer (Wang et al, 2023;Yang et al, 2023).…”

“…It was found that exogenously applied organic acids can adjust the acid -base and redox conditions of soil tillage using acidic functional groups, adsorb soil saline ions through chelation, and enhance the solubility and mobility of phosphorus, thus promoting the enhancement of effective nutrients in saline soils (Chatterjee et al, 2015). Consequently, it may be due to the addition of exogenous substances to improve the soil microbial survival of the adverse environmental conditions, such as soil structure, pH, aeration and permeability, and topsoil nutrient composition changes (Yang et al, 2023), the improvement of the adverse environmental conditions makes most of the bacterial community's more easy to grow and reproduce, which adjusts the species and number of various bacterial groups in the soil, resulting in the bacterial community development direction differences, changing the diversity of the community. However, short-term application cannot easily have a significant effect on bacterial community diversity due to the relatively stable structure of organic materials (Wu et al, 2013).…”

Effects of Environmentally Friendly Materials on Saline Soil Improvement and Sunflower Yields in the Hetao Irrigation Region, China

“…Humic acid is derived from plant materials that are comparable to biochar. However, humic acid has more active organic materials that can enhance soil fertility [21], regulate the biological community [22], ameliorate soil aggregate compositions [23], increase fertilizer utilization efficiency [24], and improve seedling growth [25] in saline soils. The abundant functional groups of humic acid allow it to form complexes with ions, thus reducing salt toxicity [26].…”