Soil salinization poses a persistent challenge to crop production worldwide, particularly in arid and semi-arid regions where high salt concentrations and elevated pH levels degrade soil structure, limit water availability, and restrict nutrient uptake. In China's Xinjiang region, salinized farmland represents a substantial portion of irrigated agricultural areas, contributing to notable yield reductions in key crops such as maize. Researchers have long explored biological amendments to address these issues, and a recent study published in Soil and Tillage Research demonstrates the potential of combining deep straw burial with microbial inoculation.
Overview of the Research Publication
The study, titled "Deep straw burial combined with Bacillus subtilis enhances maize growth via soil properties and fertility improvement under saline-alkaline stress," appears in the December 2026 issue of Soil and Tillage Research (Volume 264, Article 107347). It is available at https://www.sciencedirect.com/science/article/abs/pii/S0167198726002928. The authors—Changkun Ma, Ping Wang, Qi Xu, Jiayi Lu, Xiaoxu Jia, Quanjiu Wang, Yan Xu, and Mingjiang Deng—conducted a multi-year field experiment evaluating integrated soil management strategies in saline-alkaline conditions.
This work builds on established practices of straw return while introducing deep burial at 40–50 cm depths paired with Bacillus subtilis, a bacterium known for its cellulolytic activity and plant growth-promoting properties. The research was performed in Alar City, Xinjiang, an oasis agricultural area managed by the Xinjiang Production and Construction Corps, under a warm-temperate continental arid desert climate.
Context of Saline-Alkaline Stress in Agriculture
Saline-alkaline soils feature excessive soluble salts and high pH, which compact soil particles, reduce permeability, create nutrient imbalances, and inhibit root and microbial activity. Maize, a staple cereal crop valued for its high yield potential, shows moderate sensitivity to these conditions, with potential yield losses of 20 to 46 percent in affected areas. Traditional remediation approaches, including gypsum application or intensive leaching, often prove costly and carry risks such as groundwater contamination or localized soil acidification.
Biological methods offer more sustainable alternatives. Straw incorporation typically boosts soil organic matter and microbial diversity, yet shallow applications in saline environments can sometimes promote upward salt migration. Deep burial addresses this by creating a subsoil isolation layer that interrupts capillary salt movement while enhancing porosity and water retention.
Experimental Design and Methodology
The field trial ran from 2021 through 2023, comparing treatments involving deeply buried maize straw and alfalfa stover, applied with or without Bacillus subtilis inoculation. Control plots received no amendments. Researchers monitored soil physical properties such as bulk density, aggregate stability, field capacity, and saturated hydraulic conductivity, alongside chemical indicators including electrical conductivity, pH, organic matter content, and nutrient availability across multiple soil layers.
Maize performance metrics encompassed emergence rates, plant height, leaf area, biomass accumulation, grain yield, water use efficiency, and nitrogen partial factor productivity. The alfalfa straw plus Bacillus subtilis combination (denoted AS+B) emerged as the standout treatment across the three seasons.
Key Improvements in Soil Physical Properties
Deep burial of alfalfa straw with the bacterial inoculant significantly enhanced soil structure. Bulk density decreased to 1.43 g/cm³ in the first year, while the percentage of aggregate destruction dropped substantially relative to untreated controls. Soil organic matter rose by more than half compared with baseline levels, supporting better aggregation and water-holding capacity.
The buried straw layer modified capillary continuity, curbing the upward movement of salts from deeper horizons. This physical barrier, combined with microbial activity that accelerates organic matter decomposition, fostered a more porous and stable soil matrix conducive to root development.
Reductions in Soil Salinity and Enhancements in Fertility
Salinity levels in the root zone declined markedly under the combined treatment. At the maize milking stage, electrical conductivity fell by approximately 55.8 percent in the upper 20 cm and 64.3 percent in the 20–40 cm layer. Nutrient availability, particularly nitrogen and other essentials, increased notably throughout the 0–60 cm profile when compared with straw-only or inoculant-only applications.
Bacillus subtilis contributed by secreting enzymes that break down straw cellulose, releasing nutrients more efficiently and stimulating beneficial microbial communities. These changes collectively improved the soil's capacity to retain moisture and supply resources during critical growth periods.
Impacts on Maize Growth and Resource Use Efficiency
Maize plants responded positively across multiple parameters. Emergence increased by 8.4 percent, plant height by 33.7 percent, leaf area by 47.6 percent, and overall biomass by 46.3 percent under the optimal treatment. Grain yield and associated traits remained consistently higher over the three-year period.
Resource efficiencies showed pronounced gains. Water use efficiency rose by up to 53.4 percent, while nitrogen partial factor productivity improved by as much as 84.9 percent relative to controls. These outcomes highlight how restored soil conditions translate into more resilient crop performance under stress.
Mechanisms Driving the Synergistic Effects
The combination works through complementary pathways. Deep straw placement physically disrupts salt capillary rise and builds long-term organic reserves. Bacillus subtilis accelerates decomposition, mobilizes nutrients, and may produce growth-promoting compounds that aid plant establishment. Together, they address both the structural limitations and biological deficiencies common in saline-alkaline profiles.
Multi-season data confirm that benefits compound over time, with sustained improvements in aggregate stability and reduced salt accumulation supporting repeated cropping cycles without additional inputs.
Implications for Sustainable Agriculture and Marginal Land Reclamation
This approach represents a practical, nature-based strategy for reclaiming marginal saline soils, especially in arid zones where water resources are limited. By improving soil health without heavy reliance on chemical amendments, it supports higher productivity while potentially lowering long-term management costs.
For regions facing similar challenges, such as parts of Central Asia or other dryland agricultural systems, the findings suggest scalable options that integrate readily available crop residues with targeted microbial inoculants. Further adoption could contribute to food security goals by expanding viable acreage for maize and other staples.
Future Research Directions and Broader Applications
While the Xinjiang trial provides robust field validation, additional studies could explore variations in straw types, inoculation rates, and integration with precision irrigation or other amendments. Long-term monitoring across different climatic zones would clarify scalability and interactions with local soil microbiomes.
The work also underscores opportunities for interdisciplinary collaboration between soil scientists, agronomists, and microbiologists in developing region-specific solutions. Academic institutions with strong programs in environmental science and agricultural engineering are well positioned to advance related inquiries and train the next generation of researchers in these integrated techniques.
Photo by Bruno Brikmanis-Jurjans on Unsplash
Conclusion
The publication by Changkun Ma and colleagues offers compelling evidence that deep alfalfa straw burial combined with Bacillus subtilis can restore soil functionality and elevate maize performance in saline-alkaline environments. Detailed results appear in the full article at the ScienceDirect link provided. This research contributes valuable insights for practitioners and scholars seeking effective, environmentally sound methods to enhance productivity on challenging lands.