Reduce Soil Salinity Research Articles

The Optimal Layout Strategy for Subsurface Pipes to Improve Soil Desalination and Increase Crop Yield: A Meta‐Analysis

ABSTRACTSubsurface drainage systems are now used in various fields to control soil salinity, manage the water table, and increase crop yields by discharging groundwater and excess water from the soil. However, few studies have compared the effects of subsurface drainage systems on soil salinity and crop yield of different soil and climatic environments. Therefore, this study synthesized 891 experiments from 57 screened papers spanning 1979 to 2024. The results showed that fields with subsurface drainage system significantly reduced soil salinity by 25.56% and increased crop yield by 20.28% (p < 0.05) compared to fields without such systems. Other physicochemical properties of the soil showed a significant decrease (p < 0.05) in the ionic content of CO32−, HCO3−, Na+, etc., and a significant increase (p < 0.05) in soil permeability. This study found that subsurface drainage systems had a significant (p < 0.05) effect on soil desalination and yield increase in most soils and climates. Comparatively better desalination was achieved in weakly alkaline saline soils with medium sand content and high salt content than in areas without such systems. Subsurface drainage significantly reduced soil salinity and increased yield in both dryland and paddy fields (p < 0.05), while the effects on soil desalination and yield improvement were more significant in paddy fields. Additionally, this study suggests that in humid climates, the subsurface drainage system layout should have more than 30 m spacing and a drain depth of over 1.2 m. In arid climates, if the groundwater table depth is less than or equal to 1 m, the drain depth should be over 1.2 m with a spacing of 10–20 m. However, when the groundwater table depth exceeds 1 m, the drain depth should be between 1 and 1.2 m. In summary, subsurface drainage has good application prospects for saline and alkaline soils.

Film mulching can alleviate soil quality decrease and produce high maize yield under different irrigation strategies

Plastic film mulching (PM) combined with irrigation is widely adopted to improve crop yields, water and nitrogen efficiency, especially in arid farming areas. Despite its benefits, the effects of this method on soil quality and its subsequent impact on crop productivity and resource efficiency have not been thoroughly investigated. In this study, we formulated a soil quality indicator (SQI) from five years of field experiments in the Hetao Irrigation District (HID) of Northwestern China. The treatments included border irrigation as the control treatment (CK), CK combined with PM (BI_PM), and three water level drip irrigation treatments combined with PM. Three threshold values of soil matric potential for drip irrigation were −10 kPa (HDI_PM), −30 kPa (MDI_PM), and −50 kPa (LDI_PM). We then examined the SQI changes based on measured multiple soil properties and assessed their implications for maize yield, irrigation water productivity (IWP), and partial factor productivity of nitrogen (PFPN). We found: (1) from 2016 to 2020, HDI_PM achieved the highest average yield (15.77 t ha–1), IWP (3.73 kg m–3), and PFPN (63.18 kg kg–1), showing increases of 54.77 %, 84.90 %, and 96.93 % over the control treatment, respectively; (2) no significant variations in the SQI were observed for HDI_PM in 2020 in the topsoil (0–30 cm) and subsoil (30–60 cm) compared to the initial condition. However, CK, BI_PM, MDI_PM, and LDI_PM showed reductions in SQI in both soil layers, primarily due to decreased soil organic carbon (SOC) and structural stability, along with increased sand content and soil salinity; (3) according to the linear mixed-effects model, a low SQI (< 0.43), elevated temperatures, and drought indices negatively impact yield. Hence, we advocate for HDI_PM to maximize yield and PFPN. To enhance soil quality, identifying agronomic practices that increase SOC and reduce soil salinity in the HID is crucial.

Evaluation of Environmental Parameters and Economic Efficiency of Integrated Farming System on Acidic Soil and Saltwater Intrusion in The Coastal Area: A Case Study of Mekong Delta, Vietnam

The shift to growing sedge plants, combining raising snails and tilapia in coastal areas could improve the soil nutritional environment, income, and land use efficiency compared to rice monoculture. This study aims to evaluate soil and water environmental factors and to compare the financial efficiency of integrated farming with rice monoculture farming. These experiments were arranged on field land affected by drought and saltwater intrusion in two ecological regions of Kien Giang province. The research found the adaptation of crops (rice, sedge) and aquatic species (snails, tilapia) to the characteristics of acidic and saline soils in coastal areas. The results showed that an integrated farming system reduced soil salinity, but increased soil pH, nitrogen, phosphorus, potassium, and organic matter content more than rice monoculture farming. In addition, this system improved pH, reducing salinity, temperature, and TDS of water more than rice monoculture farming. Acidity and salinity factors affect the rice yield of Winter-Spring crops. The sedge grass (Cyperus malaccensis) grew well under the pH and salinity conditions, but the sedge yield in the dry season was higher than in the rainy season. The weight gain of tilapia (Oreochromis niloticus) was from 0.45 to 0.96 g/day, but fish yield was still low (226 - 541 kg/ha); due to low survival rate (30-36%). Snails (Pila gracilis) adapted well to experimental conditions and the survival rate reached 53-79%. The data analysis of financial efficiency showed that the profit of integrated farming was higher than rice monoculture farming (10,905 to 11,146 USD compared to 904-1,672 USD/ha/year). Therefore, diversified land use in coastal areas to grow sedge grass combined with snails and tilapia increased household income in these study sites.

Effects of Long-Term Reed Plantation on Saline Habitat

In recent years, the improvement and utilization of saline-alkaline soil has gradually shifted from engineering measures to biological measures. As a salt-tolerant plant, the reed has been preliminarily proven to have a role in improving saline-alkaline land. In order to explore the long-term effect of planting unharvested reeds on the improvement of saline-alkaline land, a pilot plot was set up in Fuping Pilot Test Base (34° 42'180"E; 109°11'49" N) near Lubo Beach, Fuping, Shaanxi, in 2012 to ascertain the improvement effect of long-term reed cultivation on saline–alkaline land. The objective was to study the long-term changes in soil pH, electrical conductivity, Ca2+, Mg2+, Cl-, SO42-, HCO3-, and CO32- contents, soil particle size and soil fertility. Results showed that (i) reed cultivation could effectively reduce soil salinization in the long term. From 2012 to 2022, the average pH of saline soil decreased from 9.42 to 8.86, and the electrical conductivity decreased from 1.20 μS/cm to 0.70 μS/cm. (ii) Reed cultivation considerably reduced the contents of Ca2+, Mg2+, Cl-, SO42-, HCO3-, and CO32- in the soil in the long term, and the reduction in each index was 5.9, 41.7, 63.5, 90.6, 81.7, 90.6, 77.9and 90.3%, respectively. (iii) Reed cultivation changed the soil structure. The soil texture of the 0–60 cm soil layer changed from silty sandy loam to silty loam from 2018 to 2022. (iv) Long-term reed planting without harvesting effectively improved soil fertility. In 2012, the content of soil organic matter was only 2.74 g/kg, but in 2022, the value reached 12.8 g/kg. Reed planting improved the physical and chemical properties of saline soil. Therefore, biological restoration of reed can be considered in low-lying saline–alkaline areas with high water volumes. Bangladesh J. Bot. 53(3): 665-672, 2024 (September) Special

Salinity challenges and adaptive strategies in salinization-affected coastal Bangladesh: Implications for agricultural sustainability and water resource management

Abstract Salinization has become a rising global concern due to its notable effects on agriculture and freshwater resources. Coastal region of Bangladesh has been struggling with elevated levels of soil and water salinity, exacerbated by storm surges and rising sea levels. We assessed nutrient and salinity contents in agricultural and homestead lands, and the level of salinity in pond and canal water in six sub-districts in coastal Bangladesh. Finally, using household (HH) survey, focus group discussion (FGD) and key informant interview (KII), we explored the adaptive practices and challenges of salinity issues in agriculture and drinking water management. Soil nitrogen, phosphorus, and potassium contents exhibited significant variations across the sub-districts, which reflect the diversity of agricultural practices and soil management strategies. However, there was no notable difference in soil salinity across the sub-districts, which underscores the commonality of soil salinity as a pressing concern. Shyamnagar (13.99 dS m−1) recorded the highest level of pond water salinity, followed by Assasuni (13.96 dS m−1), Dacope (13.91 dS m−1), Koyra (13.58 dS m−1), Morrelganj (13.33 dS m−1), and Mongla (13.19 dS m−1) sub-districts, which highlights that water salinity decreased from exposed coast to the landward areas. Respondents in HH surveys, FGDs and KIIs identified salinity as a major challenge in agriculture and drinking water. Furthermore, climate-related stresses were recognized as significant challenges impacting crop productivity. The research highlights the feasibility of rainwater harvesting, with 89%–100% of HHs harvest rainwater in HH tanks, as an effective adaptive practice for managing drinking water. The study emphasizes the positive impact of vermicompost in reducing soil salinity levels, which is demonstrated by the 43%–88% of HHs using this practice, indicating its potential as a nature-based solution to address soil salinization. The findings underscore the need for resilient agricultural systems and sustainable water management approaches to tackle these challenges.

Phytoremediation of saline soils using Glycyrrhiza glabra for enhanced soil fertility in arid regions of South Kazakhstan

This study investigates the potential of Glycyrrhiza glabra (licorice) as a biological tool for reclaiming saline soils in the arid regions of South Kazakhstan. Licorice was cultivated over three growing seasons in weakly, moderately, and highly saline soils to evaluate its effectiveness in reducing soil salinity and improving soil fertility. The results show that licorice cultivation significantly reduced total salt concentrations and improved organic matter content in weakly saline soils. For instance, in some areas, total salts decreased by 50%, and humus content increased from 1.55% to 1.70%, indicating enhanced soil fertility. In moderately saline soils, the reduction in salt levels was less significant, and the plant's biomass yield dropped to 40 t/ha, compared to 50 t/ha in weakly saline soils. However, licorice still demonstrated its ability to moderately improve soil structure and nutrient availability. In strongly saline soils, licorice's effectiveness was considerably limited, with only minor reductions in salinity and a significant decrease in biomass yield to 20-30 t/ha. The study concludes that while Glycyrrhiza glabra is highly effective in reclaiming weakly saline soils, its impact in moderately and highly saline soils requires supplemental interventions, such as leaching, to optimize its phytoremediation potential. These findings suggest that integrating biological and traditional soil reclamation methods can offer a sustainable solution for managing saline soils in arid regions.

Effect of Magnetized Irrigation Water and Seeds on the Production of OKRA (Hibiscus esculentus)

Very recently special magnetic devices have been developed and used to magnetize irrigation water and plant seeds. Such magnetic treatments were reported to play a great role in increasing the germination rate of seeds, reducing soil salinity and consequently resulting in increasing yield. The objectives of the study to improve crop productivity by using magnetic technologies. A split plot experimental design was used for growing two varieties of okra (Hibiscus esculentus). The treatments included: non-magnetized water + non magnetized seeds (NMW+NMS), non-magnetized water + magnetized seeds (NMW+MS), magnetized water + non magnetized seeds (MW+NMS), magnetized water + magnetized seeds (MW+MS). Each treatment was replicated three times. The parameters considered included: number of leaves per plant, leaf length, plant height, plants density and yield. There was a significant difference (p &lt;0.05) between treatments, the combination of (MW) and (MS) gave higher of leaves per plant, plant density, and plant height and leaf length. There was a significant difference (p &lt;0.05) in yield between treatments (MW) recorded increasing in yield by 50% as compared to (NMW); (MW) + (MS) recorded increase in yield by 24% as compared to (NMW); (MS) record increasing in yield by 18% as compared to (NMS) when both were irrigated by (NMW), the combination of (MW) and (MS) gave higher yields for both okra varieties (25.5 and 35.5 Kg/ha). It was concluded that magnetizing water may lead to better crop establishment and further improvement could be achieved by magnetizing the seeds.

Planting halophytes increases the rhizosphere ecosystem multifunctionality via reducing soil salinity

Soil salinization poses a significant global challenge, exerting adverse effects on both agriculture and ecosystems. Planting halophytes has the potential ability to improve saline-alkali land and enhance ecosystem multifunctionality (EMF). However, it remains unclear which halophytes are effective in improving saline-alkali land and what impact they have on the rhizosphere microbial communities and EMF. In this study, we evaluated the Na+ absorption capability of five halophytes (Grubovia dasyphylla, Halogeton glomeratus, Suaeda salsa, Bassia scoparia, and Reaumuria songarica) and assessed their rhizosphere microbial communities and EMF. The results showed that S. salsa possessed the highest shoot (3.13 mmol g−1) and root (0.92 mmol g−1) Na+ content, and its soil Na+ absorption, along with B. scoparia, was significantly higher than that of other plants. The soil pH, salinity, and Na+ content of the halophyte rhizospheres decreased by 6.21%, 23.49%, and 64.29%, respectively, when compared to the bulk soil. Extracellular enzymes in the halophyte rhizosphere soil, including α-glucosidase, β-glucosidase, β-1,4-N-acetyl-glucosaminidase, neutral phosphatase, and alkaline phosphatase, increased by 70.1%, 78.4%, 38.5%, 79.1%, and 64.9%, respectively. Furthermore, the halophyte rhizosphere exhibited higher network complexity of bacteria and fungi and EMF than bulk soil. The relative abundance of the dominant phyla Proteobacteria, Firmicutes, and Ascomycota in the halophyte rhizosphere soil increased by 9.4%, 8.3%, and 22.25%, respectively, and showed higher microbial network complexity compared to the bulk soil. Additionally, keystone taxa, including Muricauda, Nocardioides, and Pontibacter, were identified with notable effects on EMF. This study confirmed that euhalophytes are the best choice for saline-alkali land restoration. These findings provided a theoretical basis for the sustainable use of saline-alkali cultivated land.

Coastal Salinity Management and Cropping System Intensification through Conservation Agriculture in the Ganges Delta

Soil salinity is the major constraint for cropping system intensification in the coastal region of the Ganges Delta. Salts build up on the soil surface, as well as in the crop root zone, due to the capillary rise in underground brackish water, hampering the growth and development of crops and resulting in mortality and low yields. We studied, for three years (2020–2021 to 2022–2023), the effect of conservation agricultural practices (zero tillage planting, crop residue recycling, and crop rotations) on the major soil properties (soil salinity and organic carbon status), crop performance (yield and economics), and water footprint. Conservation agricultural practices significantly reduce soil salinity, build soil organic carbon, reduce water footprint, and increase the profitability of cropping systems compared to tillage-intensive conventional practices. Under conventional agriculture, the sole cropping of rice is more profitable than double and triple cropping systems.

Combining Desulfurisation Gypsum and Polyacrylamide to Reduce Soil Salinity and Promote Buckwheat Photosynthesis

ABSTRACTSoil salinisation poses a significant threat to global agricultural production and food security. China is among the countries most severely impacted by soil salinisation. To investigate the improvement technology for saline–alkali stress in buckwheat, a typical multigrain crop in northwest China, a coupling regulation study using desulfurisation gypsum and polyacrylamide (PAM) was conducted in 2019 and 2020. Desulfurisation gypsum was applied at 0, 5.5, 11, 16.5 and 22 kg·ha−1, while PAM was applied at 0, 15, 30, 45 and 60 kg·ha−1. The results demonstrated that applying 11 t·ha−1 desulfurisation gypsum and 30 kg·ha−1 PAM effectively reduces soil salinity and pH, averaging 81.79% and 6.07%, respectively. Furthermore, it did not cause soil heavy metal pollution and created the best soil environment for buckwheat growth. Among the models tested, the nonrectangular hyperbolic model was the most accurate in describing buckwheat's photosynthetic light response. The optimal treatment for achieving the best photosynthetic performance—measured by apparent quantum efficiency, maximum net photosynthetic rate, light compensation point, light saturation point, dark respiration rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, leaf water use efficiency and yield—was achieved through applying 11 t·ha−1 desulfurisation gypsum and 30 kg·ha−1 PAM. Therefore, desulfurised gypsum and PAM should be applied at 11 t·ha−1 and 30 kg·ha−1, respectively, to improve buckwheat's adaptability to different light intensities while promoting its photosynthetic response in saline–alkali soils. This study provides an effective technical scheme for reducing salt and promoting the growth of crops under salinity stress, which is of great significance for improving salinity land in arid areas.

Inhibition of nitrate accumulation in vegetable by Chroococcus sp. and related mechanisms

Vegetable nitrate accumulation is a major threat to food security and human health. The application of a non-toxic and non-nitrogen-fixing cyanobacterium, Chroococcus sp., was found to reduce soil nitrate content; however, the influence of Chroococcus sp. on vegetable growth and nitrate accumulation remains unclear. In this study, Chroococcus sp. was introduced to soil fertilized with NaNO3, (NH4)2SO4, and CO(NH2)2. Variations in growth performance and nitrate content of pakchoi (Brassica chinensis L.), coupled with changes in soil fertility, were investigated through pot experiments. The varied abundance of rhizosphere bacteria and differential expression of bacterial functional genes were studied using 16S rRNA and meta-transcriptomic sequencing analyses, respectively. Chroococcus sp. reduced vegetable nitrate content by 42.29%, 21.34%, and 27.10% in pakchoi planted in soil fertilized with NaNO3, (NH4)2SO4, and CO(NH2)2, respectively. This reduction was mainly attributed to regulation of the rhizosphere bacterial community by Chroococcus sp. First, Chroococcus sp. stimulated denitrifying bacteria (such as Methylotenera, Gemmatimonas, Nitrosomonas, Nocardioides, Gaiella, Lysobacter and Sphingomonas) that contributed to a reduction in soil nitrate content. Second, Chroococcus sp. stimulated several rhizosphere bacteria such as Methylibium, Micromonospora, Bacillus, Pedomicrobium, Hyphomicrobium, Steroidobacter, Pseudolabrys, Streptomyces, Methylobacillus and Pseudomonas that directly participated in the reduction of vegetable nitrate accumulation, according to their negative correlation with vegetable nitrate content. Chroococcus sp. increased soil fertility and consequently promoted the growth of pakchoi by reducing soil salinity and increasing soil polysaccharide content, available phosphorus, and functional enzyme activity. The increased abundances of various rhizosphere bacteria genera also contributed to an increase in soil fertility and the promotion of vegetable growth. In general, this study demonstrated the effectiveness of Chroococcus sp. in reducing vegetable nitrate accumulation and explored the related mechanisms.

Biochar effects on salt-affected soil properties and plant productivity: A global meta-analysis

Biochar has been recognized as a promising practice for ameliorating degraded soils, yet the consensus on its effects remains largely unknown due to the variability among biochar, soil and plant. This study therefore presents a meta-analysis synthesizing 92 publications containing 987 paired data to scrutinize biochar effects on salt-affected soil properties and plant productivity. Additionally, a random meta-forest approach was employed to identify the key factors of biochar on salt-affected soil and plant productivity. Results showed that biochar led to significant reductions in electrical conductivity (EC), bulk density (BD) and pH by 7.4%, 4.7% and 1.2% compared to the unamended soil, respectively. Soil organic carbon (by 55.1%) and total nitrogen (by 31.3%) increased significantly with biochar addition. Moreover, biochar overall enhanced plant productivity by 31.5%, and more pronounced increases in forage/medicinal with higher salt tolerance than others. The results also identified that the soil salinity and biochar application rate were the most important co-regulators for EC and PP changes. The structural equation model further showed that soil salinity (P < 0.001), biochar pH (P < 0.001) and biochar specific surface area (P < 0.01) had a significant negative effect on soil EC, but it was positively impacted by biochar pyrolysis temperature (P < 0.05). Furthermore, plant productivity was positively affected by biochar pH (P < 0.001) and biochar feedstock (P < 0.01), while negatively influenced by biochar pyrolysis temperature (P < 0.01). This study highlights that woody biochar with 7.6 < pH < 9.0 and pyrolyzed at 400–600 °C under 30–70 t ha−1 application rate in moderately saline coarse soils is a recommendable pattern to enhance forage/medicinal productivity while reducing soil salinity. In conclusion, biochar offers promising avenues for ameliorating degradable soils, but it is imperative to explore largescale applications and field performance across different biochar, soil, and plant types.

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

The Hetao irrigation region is located in Inner Mongolia, China, within a dry and semi-dry region. This region suffers from poor agricultural productivity and environmental damage due to the presence of saline soil. To explore the growth of salty lands using a more environmentally friendly method, this research employed three eco-conscious amendments to improve the soil. These include flue gas desulfurization gypsum (S), humic acid (H), and biochar (C). During a two-year study, the amendments were utilized to enhance the soil quality for planting sunflowers. Humic acid was used prior to every seedling season, whereas the remaining two substances were only used once. These additions increased the soil’s water-holding capacity, reduced soil salinity during sunflower growth, and improved the macroaggregate proportion. The most effective treatment for decreasing the soil’s salt content after the seedling stage was the application of humic acid (0.6 t ha−1). Biochar (15 t ha−1) decreased the soil’s bulk density (from 1.49 to 1.34 g cm−3) and mostly increased the sunflower seed yield up to 3133−3964 kg ha−1. Humic acid addition significantly increased the aggregate (&gt;0.25 mm) content up to 27.88% after the experiment, but it led to a lower seed yield (2607−3686 kg ha−1). In 2019, the temperature was lower compared to 2018, which may have led to a reduction in the yield. However, these three amendments could potentially increase yields by more than conventional methods. These three environmentally friendly amendments are useful for improving saline soil and increasing yields. More studies are required to understand their impacts on larger areas and over extended periods.

Evaluation of slow-release fertilizers derived from hydrogel beads: Sodium alginate-poly (acrylic acid) and humic acid-encapsulated struvite for soil salinity amelioration

Soil salinity, a severe environmental factor, significantly reduces the productivity of crop plants by increasing salt and mineral fertilizer concentrations in the soil. As a result, the development of sustainable slow-release mineral fertilizers (SRFs) is critical for addressing salt-affected soils. This study aimed to synthesize struvite (MgNH4PO4·6H2O) into hydrogel beads made from sodium alginate-poly (acrylic acid) in the absence (Sa@S) and presence (Sa@SHa) of humic acid (HA). The optimal conditions for struvite formation were at pH 9.0, resulting in a remarkable 73.21 %, 98.74 %, and 99.20 % for Mg, NH4-N and P removal, respectively. The SRFs study demonstrated that struvite had a significant release of Mg, P, and NH4-N, notably higher (P ≤ 0.05) than Sa@S and Sa@SHa. Experiments on swelling and soil water loss demonstrated that Sa@S yielded higher results in comparison to Sa@SHa. Furthermore, an experiment was conducted to study the impact of Sa@S and Sa@SHa on saline soil parameters over 20 days of incubation. The results showed both encapsulated struvite hydrogel beads reduced soil salinity, as indicated by the sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP). Additionally, a significant reduction (P ≤ 0.05) in soil electrical conductivity (EC) and sodium (Na) was observed for both hydrogel bead encapsulation treatments compared to the control soil. However, no apparent variance was observed in pH and soil organic carbon (SOC). Moreover, the levels of available phosphorus (P), ammonium-nitrogen (NH4-N), nitrate-nitrogen (NO3-N), cation exchange capacity (CEC), and exchangeable cations (Ca, Mg, K) in the soil were observed to be increased (P ≤ 0.05).

Deep vertical rotary tillage reduced soil salinity and improved seed cotton yield and water productivity under limited irrigation in saline-alkaline fields

Water scarcity and soil salinization severely limit cotton production in arid areas on the globe. A two-season (2020 and 2021) field experiment was performed on cotton under film-mulched drip irrigation in south Xinjiang of China to explore the responses of soil moisture, soil salinity, root growth, seed cotton yield and water productivity to deep vertical rotary tillage (DVRT) depth (T20: 20 cm, T40: 40 cm, T60: 60 cm, Tck: 20 cm, traditional rotary tillage) in saline-alkaline fields under two irrigation amounts (W1:360 mm, W2: 480 mm, local irrigation amount). It was found that the soil moisture storage (0–120 cm) increased with as irrigation amount increased and decreased with increasing DVRT depth. Soil electrical conductivity in the root zone (0–60 cm) and 0–120 cm soil layer declined as irrigation amount and DVRT depth increased. Irrigation amount and DVRT depth had significant effects on root length density, root mass density, root/shoot ratio, and seed cotton yield, all of which increased with increasing irrigation amount and DVRT depth. Under W2, T20, T40 and T60 increased seed cotton yield by 23.3 %, 45.3 %, 65.6 % in 2020, and by 38.9 %, 62.0 % and 84.1 % in 2021 compared with TCK, respectively. Both water productivity and irrigation water productivity increased with increasing DVRT depth. There were significant positive correlations among seed cotton yield and leaf area index, dry matter accumulation, harvest index, root length density, root mass density, root/shoot ratio, water productivity and irrigation water productivity. W1T60 was suggested for cotton production in the saline regions of southern Xinjiang. The DVRT offset the decrease in seed cotton yield under limited irrigation, which indicates that DVRT is promising to reduce soil salinity and improve seed cotton yield and water productivity in saline-alkaline fields for coping with water scarcity and soil salinization.

Biochar addition can negatively affect plant community performance when altering soil properties in saline-alkali wetlands.

Biochar is a widely proposed solution for improving degraded soil in coastal wetland ecosystems. However, the impacts of biochar addition on the soil and plant communities in the wetland remains largely unknown. In this study, we conducted a greenhouse experiment using soil seed bank from a coastal saline-alkaline wetland. Three types of biochar, including Juglans regia biochar (JBC), Spartina alterniflora biochar (SBC) and Flaveria bidentis biochar (FBC), were added to the saline-alkaline soil at ratios of 1%, 3% and 5% (w/w). Our findings revealed that biochar addition significantly increased soil pH, and increased available potassium (AK) by 3.74% - 170.91%, while reduced soil salinity (expect for 3% SBC and 5%SBC) by 28.08% - 46.93%. Among the different biochar types, the application of 5% FBC was found to be the most effective in increasing nutrients and reducing salinity. Furthermore, biochar addition generally resulted in a decrease of 7.27% - 90.94% in species abundance, 17.26% - 61.21% in community height, 12.28% - 56.42% in stem diameter, 55.34% - 90.11% in total biomass and 29.22% - 78.55% in root tissue density (RTD). In particular, such negative effects was the worst in the SBC samples. However, 3% and 5% SBC increased specific root length (SRL) by 177.89% and 265.65%, and specific root surface area (SRSA) by 477.02% and 286.57%, respectively. The findings suggested that the plant community performance was primarily affected by soil pH, salinity and nutrients levels. Furthermore, biochar addition also influenced species diversity and functional diversity, ultimately affecting ecosystem stability. Therefore, it is important to consider the negative findings indirectly indicate the ecological risks associated with biochar addition in coastal salt-alkaline soils. Furthermore, Spartina alterniflora was needed to desalt before carbonization to prevent soil salinization when using S. alterniflora biochar, as it is a halophyte.

Straw interlayer improves sunflower root growth: Evidence from moisture and salt migration and the microbial community in saline-alkali soil

A straw interlayer added to soil can effectively reduce soil salinity effects on plant growth, however, the effects of soil moisture, salt and microbial community composition on plant growth under a straw interlayer are unclear. A rhizobox study was conducted to investigate the role of straw interlayer thickness on soil moisture, salt migration, microbial community composition, as well as root growth in sunflower. The study included four treatments: Control (no straw interlayer); S3 (straw interlayer of 3.0 cm); S5 (straw interlayer of 5.0 cm); S7 (straw interlayer of 7.0 cm). Straw interlayer treatments increased soil moisture by 8.2–11.0% after irrigation and decreased soil salt content after the bud stage in 0–40 cm soil. Total root length, total root surface area, average root diameter, total root volume and the number of root tips of sunflower plants were higher under straw interlayer treatments than in the control, and were the highest under the S5 treatment. This stimulated root growth was ascribed to the higher abundance of Chloroflexi and Verrucomicrobia bacteria in soil with a straw interlayer, which was increased by 55.7 and 54.7%, respectively, in the S5 treatment. Addition of a straw interlayer of 5 cm thickness is a practical and environmentally feasible approach for improving sunflower root growth in saline-alkali soil.

Soil Salt and Water Regulation in Saline Agriculture Based on Physical Measures with Model Analysis

Enhancing crop production in the saline regions of the Yellow River Delta (YRD), where shallow saline groundwater is prevalent, hinges on optimizing water and salt conditions in the root zone. This study explored the effects of various physical methods on soil water and salt dynamics during the cotton growing season in these saline areas. Three approaches were tested: plastic film mulching (FM), plastic film mulching with an added compacted soil layer (FM+CL), and ridge-furrow planting (RF). The HYDRUS-2D model (Version 3.02) was used to analyze changes in soil water and salt content in the root zone over time. The results showed that subsoil compaction significantly lowered salt build-up in the root zone, especially in the top 20 cm. Film mulching was crucial for reducing water loss in the Yellow River Delta. Crop transpiration increased by 7.0% under FM and 10.5% under FM+CL compared to RF planting. Additionally, FM+CL reduced soil salinity in the top 10 cm by 11.5% at cotton harvest time compared to FM alone. The study concludes that combining film mulching with a soil compaction layer is a promising strategy for local farmers, addressing soil water retention, salt management, and boosting cotton yields.

Mulching and drip irrigation to mitigate soil salinity on tomato (Lycoperscon esculentum L.) production in coastal area

Bangladesh’s coastal regions are rich in saline water resources. The majority of these resources are still not being used to their full potential. In the southern Bangladeshi region of Patuakhali, research was conducted to investigate the effects of mulching and drip irrigation on tomato yield, quality, and blossom-end rot (BER) at different soil salinity thresholds. There were four distinct treatments applied: T1= drip irrigation with polythene mulch, T2 = drip irrigation with straw mulch, T3 = drip irrigation without mulch, and T4 = standard procedure. While soil salinity was much greater in treatment T3 (1.19–8.42 dS/m) fallowed by T4 (1.23–8.63 dS/m), T1 treatments had the lowest level of salinity and the highest moisture retention during every development stage of the crops, ranging from 1.28–4.29 dS/m. Treatment T3 exhibited the highest soil salinity levels (ranging from 1.19 to 8.42 dS/m), followed by T4 with a range of 1.23 to 8.63 dS/m. In contrast, T1 treatments consistently maintained the lowest salinity levels (ranging from 1.28 to 4.29 dS/m) and the highest moisture retention throughout all stages of crop development. In terms of yield, drip irrigation with no mulch treatment (T3) provided the lowest output (13.37 t/ha), whereas polyethylene mulching treatment (T1) produced the maximum yield (46.04 t/ha). According to the study, conserving moisture in tomato fields and reducing soil salinity may both be achieved with drip irrigation combined with polythene mulch. The research suggests that employing drip irrigation in conjunction with polythene mulch could effectively preserve moisture in tomato fields and concurrently decrease soil salinity.

Alterations in the composition and metabolite profiles of the saline-alkali soil microbial community through biochar application

Saline-alkali soil poses significant chanllenges to sustainable development of agriculture. Although biochar is commonly used as a soil organic amendment, its microbial remediation mechanism on saline-alkali soil requires further confirmation. To address this, we conducted a pot experiment using cotton seedlings to explore the potential remediation mechanism of rice straw biochar (BC) at three different levels on saline-alkaline soil. The results showed that adding of 2% biochar greatly improved the quality of saline-alkaline soil by reducing pH levels, electrical conductivity (EC), and water-soluble ions. Moreover, biochar increased the soil organic matter (SOM), nutrient availability and extracellular enzyme activity. Interestingly, it also reduced soil salinity and salt content in various cotton plant tissues. Additionally, biochar had a notable impact on the composition of the microbial community, causing changes in soil metabolic pathways. Notably, the addition of biochar promoted the growth and metabolism of dominant salt-tolerant bacteria, such as Proteobacteria, Bacteroidota, Acidobacteriota, and Actinobacteriota. By enhancing the positive correlation between microorganisms and metabolites, biochar alleviated the inhibitory effect of salt ions on microorganisms. In conclusion, the incorporation of biochar significantly improves the soil microenvironment, reduces soil salinity, and shows promise in ameliorating saline-alkaline soil conditions.