Soil bacterial communities play a key role in nutrient cycling and ecosystem functioning. This study aims to reveal how green space type impacts soil quality and the bacterial community, which finally contributes to suggesting strategies for managing sustainable environments in urban areas. For this purpose, urban green space soils in this study are divided into four different types; park green space (PARK), street green space (STREET), attached green space (ATTACH) and residential green space (RESID). Results showed that significant differences were observed for soil physicochemical properties. Soil organic matter, total nitrogen, soil moisture content and available nitrogen in the ATTACH and PARK soils were significantly higher than in the STREET and RESID soils. Across the four green space types, the structure of bacterial communities was dominated by Proteobacteria, Actinobacteria and Chloroflexi at the phylum level. The diversity and richness of bacteria were significantly higher in the PARK and ATTACH soils than in the RESID and STREET soils. Results of principal component analysis (PCoA) showed that soil bacterial communities could be clustered into four different groups according to different green space types. In addition, analysis of similarities (ANOSIM) also implied that soil samples differed significantly from others. Redundancy analysis (RDA) and Spearman correlation analysis both showed that the contents of soil organic matter, total nitrogen, soil moisture and pH had great influence on the structures of bacterial communities. In summary, these results suggest that soil physicochemical properties and bacterial communities can be strongly affected by green space types, and thus, objective assessment of a particular measure can be provided to land managers and policy makers for informed decision-making in urban development and sustainability.

Increasing maize planting density is considered as a potential strategy for enhancing grain yield in Northeast China; however, its yield-enhancing effects and underlying regulatory mechanisms remain inadequately characterized. Based on 508 paired observations from 42 publications, this meta-analysis quantified the effects of increased planting density on yield components and elucidated the regulatory roles of environmental and agronomic factors. Results demonstrated that increased density intensified plant competition, raising grains per ear by 43.7% and 100-kernel weight by 6.7%. The optimal regional planting density was determined to be 89,622.6 plants ha⁻¹, achieving a peak yield of 12,143 kg ha⁻¹—significantly exceeding current conventional densities (49,000–65,000 plants ha⁻¹) and highlighting substantial yield potential. Although nitrogen (N) management did not alter peak yield levels, it significantly increased the optimal density threshold (reaching 99,600 plants ha⁻¹ under high N). Among environmental factors, mean annual precipitation (MAP) was the primary constraint: yield responses to increased density were negligible in arid regions (20 g kg⁻¹) and optimal bulk density (BD) (1.25–1.40 g cm⁻³) synergistically enhanced optimal density and peak yield. This study confirms the substantial, yet context-dependent, yield potential of increasing planting density in Northeast China, providing a science-based framework for region-specific optimization.

Northeast China’s black soil region serves as a critical cornerstone of national food security, yet accelerating soil degradation, characterized by declining soil organic matter (SOM) and rising bulk density (BD), threatens the productive capacity of its farmland. Understanding how soil physicochemical properties regulate crop yields in this ecologically heterogeneous landscape is essential for sustainable agricultural development. Here, 2916 soil samples from 201 counties across six ecological zones were analyzed in conjunction with county-level rice and maize yield records. Our findings revealed that crop yield determinants are fundamentally governed by regional resource endowment characteristics rather than uniform factors. In areas characterized by sandy soil texture, low precipitation (1.34 g cm⁻³) and alkaline soil conditions (pH > 7.0) constitute the primary constraints to productivity through restricting root development. Conversely, in regions with fertile mollisols and high baseline soil organic matter (SOM > 40 g kg⁻¹), nutrient dynamics emerge as the dominant yield-regulating factors. For volcanic soil landscapes with strong phosphorus fixation capacity, available phosphorus deficiency represents the critical bottleneck for maize production. Path analysis further demonstrates that BD and pH operate predominantly through indirect mechanisms, modulating SOM accumulation and nutrient cycling rather than directly constraining yield. Threshold analysis identified that BD exceeding 1.34 g cm⁻³ and SOM below 26 g kg⁻¹ markedly reduce productivity, while SOM levels above 40 g kg⁻¹ yield diminishing marginal returns. These findings advance our mechanistic understanding and provide scientific foundations for spatially differentiated soil conservation and precision nutrient management strategies essential for sustaining grain production capacity in northeast China’s black soil region.

Regional assessment of soil fertility requires separating concentration dispersion from spatial dependence while recognizing the limits imposed by coarse regional surveys. We quantified soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP), and available potassium (AK) in 638 topsoil samples (0–20 cm) from cultivated land in Wuwei, northwestern China. Descriptive statistics, Pearson correlations, distributional diagnostics, isotropic semivariograms, and additional sensitivity analyses of drift, directionality, and spatial validation were used. Pooled coefficients of variation ranged from 57.8% to 97.3%, with AK showing the greatest dispersion. SOM and TN were strongly correlated (r = 0.954, p < 0.01). The strongest in-sample semivariogram fits were exponential for SOM, spherical for TN, and Gaussian for both AP and AK; nugget-to-sill ratios [C₀/(C₀ + C)] were 0.266–0.441. In a separate 373-record georeferenced sensitivity analysis, detrended directional practical-range ratios (larger/smaller) ranged from 1.17 to 1.92, and spatially blocked five-fold R² values were markedly lower than random-fold values, especially for AP. Thus, directional structure and geographic transfer remain uncertain, and the empirical variogram fit does not establish predictive performance. The results provide a regional baseline for sampling prioritization, not field-scale fertilizer prescription.