Straw-Derived Synthetic Humic Acid Improves Soil Structure, Nutrient Availability, Humification, and Crop Productivity in a Compacted Alkaline Farmland of the Yellow River Floodplain
Sustainable crop residue management in alkaline agroecosystems is challenging due to trade-offs among carbon stabilization, nutrient availability, and microbial activity. To identify an optimal upcycling strategy for compacted alkaline farmland, a two-year wheat–maize rotation experiment in the Yellow River floodplain compared four treatments: no organic amendment (CK), direct straw return (CS), straw-derived biochar (CB), and straw-derived synthetic humic acid (CH). Results showed that CH produced the most balanced improvements across all dimensions. Compared to CK (pH 8.62) and CB (pH 9.16), CH significantly reduced soil pH to 8.03, enhancing alkaline buffering. CH achieved the highest available phosphorus (2.36 mg kg−1), macroaggregate proportion (19.40%), and microbial biomass carbon (91.77 mg kg−1). Enhanced humification was evidenced by superior HA content (5.82 mg kg−1) and an HA/FA ratio of 1.90 in the 0–20 cm layer. Agronomically, CH achieved the highest annual grain production (ATGP, 12.11 × 103 kg ha−1, comprising 5.65 × 103 kg ha−1 for wheat and 6.46 × 103 kg ha−1 for maize) and maximum Integrated Sustainability Score (ISS = 1.000). These findings suggest that converting straw into synthetic humic acid effectively bridges the gap between unstable raw residues and inert biochar, serving as a promising alternative pathway for improving soil structure, nutrient availability, and productivity in compacted, alkaline floodplain farmland.
A field experiment evaluated the effects of tillage, rice residue management, and microbial decomposers on soil biological properties, carbon dynamics, and wheat productivity. Seven treatments were tested in a randomized block design. The treatment T7 (zero tillage + 70% residue retention + fungal–bacterial consortia @ 250 ml ha-1) significantly (p<0.05) outperformed the residue burning treatment T2. Soil pH decreased from 7.87 (T2) to 7.57 (T7), while oxidizable organic carbon increased from 0.49% to 0.59%. Microbial biomass carbon under T7 reached 297.50 and 288.53 µg g-1 soil at flowering and harvest, showing a 22.0–24.1% increase over T,. Dehydrogenase activity also improved markedly (46.57 and 41.67 µg TPF g-1 soil h-1 at flowering and harvest) compared to T2. Populations of bacteria, fungi, and actinomycetes increased by 86.1, 71.0 and 72.9%, respectively. Carbon fractions, including very labile, non-labile, active, and passive pools, were significantly higher under T7. Consequently, grain and straw yields were maximized (41.03 and 51.09 q ha-1), with increases of 18.8% and 15.1% over T2. Overall, residue-retained zero tillage combined with microbial consortia enhances soil health, carbon sequestration, and wheat productivity sustainably.
Kumar Ashish, Mahendra Singh, A. K. Pradhan et al.· Journal of the Indian Societ...· 0 citations
Climate change is steadily eroding agricultural productivity through soil degradation, water and salinity stress, and declining nutrient-use efficiency, while the heavy reliance on conventional mineral fertilizers contributes to greenhouse-gas emissions, nutrient losses, and, in some contexts, reduced soil biological activity. Biochar from lignocellulosic agro-residues can convert low-value waste into a carbon-rich material that has been reported to carry and slowly release mineral and organic nutrients, aligning with the goals of organo-mineral fertilization. This study evaluated the feasibility of coconut (
Cocos nucifera
L.) husk, a major underutilized by-product of the coconut industry-as a feedstock for such an amendment by optimizing two production variables: pyrolysis temperature and feedstock cut size. A laboratory experiment combined four cut sizes (1/8, 1/4, 1/2, and chips) with five temperatures (275 °C, 325 °C, 375 °C, 425 °C, and 475 °C) in a completely randomized design (60 samples), followed by a field-scale trial using a double-chamber pyrolyzer comparing compacted versus loosely packed loading densities. Conversion efficiency and proximate composition (moisture, volatile matter, ash, and fixed carbon) were determined and analyzed by two-way factorial ANOVA to test the temperature × cut-size interaction, followed by one-way ANOVA to characterize the main effects once the interaction proved non-significant. Conversion efficiency ranged from 36.6% to 68.3% and declined with increasing temperature, whereas volatile matter decreased, and both ash (3.6%–12.3%) and fixed carbon (0.27%–5.54%) increased significantly with temperature (
p
< 0.05); fixed carbon is an operationally defined proximate fraction and was not corroborated by elemental (H/C, O/C) ratios, aromaticity or stability indices, or mineralization assays. The 1/4 cut size offered the best balance of yield, carbonization, and operability and was selected for field trials, where compacted loading achieved a significantly higher conversion efficiency (46.95%) than loose packing (40.90%;
p
= 0.03). A resource-utilization analysis over a 60-year plantation lifespan indicated that biochar amendment could reduce husk demand by approximately 94% relative to direct mulching and 81% relative to husk burial. Moderate pyrolysis (325 °C–375 °C) with a 1/4 cut size produced a carbon-rich biochar with potential use as a component or carrier of an organo-mineral soil amendment, suggesting a practical route to valorize coconut husk waste for resilient tropical cropping systems. Agronomic performance, nutrient release, and carbon persistence were not assessed in the present study.
T. M. Thennakoon, M. Awanthi, Nuwandhya S. Dissanayaka et al.· Frontiers in Sustainable Foo...· 0 citations
Arid sandy soils are characterized by poor water retention, low nutrient availability, and limited productivity, posing major constraints to sustainable date palm cultivation under increasing water scarcity. A three-year field experiment was conducted to evaluate the combined effects of bentonite (BN), humic substances (HS), and Bacillus polymyxa (BP) under three irrigation regimes (70, 85, and 100% of crop evapotranspiration (ETc)) on soil hydro-physical properties, nutrient uptake, and fruit quality of ‘Siwi’ date palm (Phoenix dactylifera L.). Twelve treatment combinations (3 irrigation regimes × 4 soil amendment treatments) were evaluated over three consecutive growing seasons. The integrated application of BN, HS, and BP significantly improved soil hydro-physical properties by increasing field capacity and plant-available water while reducing bulk density. These improvements were associated with enhanced leaf N, P, and K concentrations and greater accumulation of total soluble solids, total and reducing sugars, phenolic compounds, flavonoids, and β-carotene compared with the untreated control. The combined application of BN (12 kg palm−1) + HS (1 L palm−1) + BP (28 mL palm−1) produced the most favorable overall responses. Moderate deficit irrigation (85% ETc) provided the best balance between fruit quality and water conservation, maintaining superior fruit biochemical quality while reducing irrigation water use by approximately 15% compared with full irrigation. Multivariate analyses further supported these findings by revealing strong positive associations among soil water availability, nutrient status, sugars, and antioxidant-related compounds, while climatic variables were closely associated with seasonal variation in fruit biochemical characteristics. Overall, the integrated application of bentonite, humic substances, and B. polymyxa under 85% ETc irrigation represents an effective management strategy for improving soil performance, enhancing fruit nutritional quality, and increasing water-use irrigation efficiency in sandy soils under arid conditions.
Nahed M. Rashed, Khairy H. Abd-El-Rahman, D. A. Elyazid et al.· Horticulturae· 0 citations
Soil nutrient depletion severely constrains crop productivity in degraded and saline environments. Strategies such as biochar–compost integration could be useful for sustainable agriculture and land restoration on a global scale. This study evaluated the effects of biochar (1% Bc), compost (1% Co), and their blends (0.5% Bc + 0.5% Co and 1% Bc + 1% Co) on soil properties, growth, physiology and nutrient balance of the halophytic fodder crop
P. antidotale
under controlled greenhouse conditions. The 0.5% Bc + 0.5% Co treatment increased total plant biomass by 68%, net photosynthesis by 68% and stomatal conductance by 90% compared to the control while soil water holding capacity and CO
2
flux were also significantly enhanced. Sole biochar improved leaf water‐use efficiency (18%) and maximized K
+
/Na
+
ratios across plant organs, indicating improved ionic balance under nutrient‐poor soil conditions. Biochar–compost blends significantly increased leaf nitrogen (25%) and carbon (4%) concentrations relative to untreated plants with the lower mixture ratio consistently outperforming higher amendment levels. These responses are likely mediated through improved soil water retention, nutrient availability and rhizosphere functioning. Overall, integrating moderate biochar–compost amendments offers an effective and scalable strategy for enhancing halophyte productivity and soil quality in degraded agroecosystems.
Z. Abideen, Maria Hasnain, H. Koyro et al.· Land Degradation & Devel...· 0 citations
Straw incorporation generally improves soil nutrient availability, aggregate stability, microbial activity, as well as carbon dioxide (CO2) emissions. However, the regulatory effects of tillage regimes on soil physicochemical properties, microbial community structure, and CO2 emission rates (CER) remain largely unexplored in rice–rapeseed rotation systems incorporating straw residue in the upper Yangtze River basin. A two-year field experiment in Sichuan’s Xindu District adopted three tillage practices: rotary tillage combined with whole rice straw incorporation (RT), deep plowing combined with whole rice straw incorporation (DP), and no-tillage with whole rice straw mulching (NT). Compared with NT, both RT and DP significantly lowered soil bulk density (BD) and macroaggregate stability, and elevated soil available nitrogen (AN), available phosphorus (AP), and available potassium (AK). On average, the AN, AP, and AK were significantly increased by 7.4%, 9.0%, and 80.3% in RT and by 4.1%, 43.9%, and 42.2% in DP relative to NT, respectively. Compared with the NT, the CER was significantly decreased by 37.1% in RT and by 12.9% in DP. Notably, RT effectively mitigated CER. Microbial α-diversity was significantly higher in the NT relative to other tillage treatments. Proteobacteria dominated the bacterial community, and Ascomycota dominated the fungal community. RT and DP increased the relative abundance of Proteobacteria and suppressed Ascomycota simultaneously. Redundancy analysis revealed positive associations between Proteobacteria and both AN and AK, whereas Ascomycota positively correlated with BD, MWD, and CER. Mantel test confirmed significant correlation between soil microbial community compositions and the soil properties, including BD, AN, AK, and CER. Relative to the other tillage practices, RT is conducive to soil quality improvement and CER reduction, and can be recommended for sustainable rice-rapeseed production locally.
Ben-Chuan Zheng, Jing-Fang Zhang, C. Cui et al.· Agriculture· 0 citations
Although green manure crops are widely recognized for ameliorating alkaline soils, some previous studies have focused mainly on laboratory germination screenings or single yield indicators, and field validation of the synergy between high yield and soil improvement remains comparatively limited. This study evaluated 16 species/accessions with varying salt tolerance in a typical alkaline soil (initial pH 9.01, EC 306 μS·cm−1) in Heilongjiang Province during 2024–2025, based on prior laboratory screening. The experiment was conducted at a single location with three field replicates, and the same plots were monitored across both years. Plant height, fresh/dry grass yield, and soil properties (pH, EC, organic matter, nutrients) were monitored. Glycine max (L.) Merr. and Sesbania Scop. achieved dual synergy, with two-year average fresh yields of 40,733 and 35,750 kg·ha−1, respectively, while reducing soil pH by 0.28–0.29 and electrical conductivity (EC) by 42.2–46.3%. Melilotus officinalis and Vicia villosa Roth exhibited the strongest alkali reduction (pH ↓0.29, EC ↓39.0–39.7%) with moderate yields. Sorghum sudanense showed the highest salt reduction (EC ↓49.0%). Principal component analysis classified the 16 species into four functional types, revealing preliminary ecological patterns for functional differentiation. This study proposes a “laboratory screening–field validation–functional classification” evaluation framework, which requires further validation across different regions and longer time scales for the biological amelioration of alkaline soils.
Ruonan Du, Qiang Gao, Xue Yang et al.· Agronomy· 0 citations
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