Yulong Yin

Global modeling of soil net nitrogen mineralization rates (Nmin) is challenging due to the absence of an integrated system that accurately quantifies their magnitude and spatial distribution. This study addresses this gap by analyzing the spatial variability of Nmin using a comprehensive dataset of 1347 Nmin measurements from 291 studies, combined with high-resolution climate and soil data. Our global maps reveal average Nmin rates of 1.68, 5.17, and 1.71 mg N kg⁻¹ day⁻¹ for cropland, forest, and grassland soils, respectively. Integrating projected climate scenarios, we also explore potential shifts in Nmin patterns under future varying environmental conditions. Key factors influencing Nmin include mean annual precipitation, soil pH, total nitrogen, carbon-to-nitrogen ratio, and microbial biomass nitrogen, with microbial biomass nitrogen playing a particularly significant role. These findings underscore the potential of global-scale Nmin modeling to support informed decision-making, facilitating optimal fertilizer use and management practices that promote soil health and sustained productivity.

The ratio of mineral-associated organic carbon to particulate organic carbon (MAOC:POC) can serve as an indicator for assessing relative soil organic carbon (SOC) stability, which is closely linked to climate change mitigation and sustainable agriculture. However, the potential for enhancing relative SOC stability in global croplands, and the corresponding optimized integrated management strategies, remain unclear. Here, we developed a machine learning model that captured the interactions among cropland management practices, soil, and climate factors using a compiled global data set of 2,029 field observations, enabling systematic geospatial analysis of MAOC:POC across croplands worldwide. We found that cropland management practices, including tillage, fertilization, and irrigation, exert strong control over the MAOC:POC, and identified grid-specific optimal integrated combinations that achieve the highest ratio without compromising total SOC. Compared with the current global mean MAOC:POC of 6.32, implementing these strategies could increase this ratio to 9.58, representing a 51.5% improvement. Our findings provide the first global spatial diagnosis of relative SOC stability and demonstrate the potential of context-adapted strategies, offering actionable insights for carbon-smart and climate-resilient agriculture.

Decades of fertilizer intensification have reshaped phosphorus (P) cycling across China's croplands, driving a widespread transition from P deficiency to enrichment while leaving spatially heterogeneous legacies of accumulated soil P. However, the long‐term trajectories of soil available P, their regional divergence, and the drivers regulating P accumulation or depletion remain poorly resolved at the national scale, limiting the development of sustainable and region‐specific P management strategies. Here, we integrate nearly 190,000 soil samples from harmonized national soil surveys with long‐term fertilization experiments to quantify long‐term soil available P dynamics across China at 1 km resolution and to assess the importance of key environmental and management drivers using an interpretable, spatially explicit machine‐learning framework. Soil available P increased sharply from 1980 to 2018, with an overall increase of 20.6 mg kg ⁻¹ , shifting from widespread deficiency to pronounced enrichment, particularly in eastern croplands. Long‐term experimental evidence demonstrates that sustained fertilizer inputs play a central role in driving soil P accumulation. Interpretable machine learning revealed spatial heterogeneity in the dominant drivers of soil available P change, with management effects strongest in Central China, and climatic and environmental influences more pronounced in the Northwest and Northeast. Sensitivity‐based future projections indicated divergent potential trajectories to 2060, with climatic changes reducing soil available P, whereas management intensification increased soil available P by approximately 13%. These findings show that long‐term soil available P dynamics across China are governed by the combined effects of fertilization legacies, soil‐environmental context, and climate, providing a national basis for region‐specific and sustainable P management.

Soil acid–base status fundamentally regulates biogeochemical cycling and agroecosystem resilience by controlling nutrient solubility, cation exchange, and redox equilibria. However, the long-term evolution of soil pH and its spatial divergence under intensive agricultural expansion remain poorly quantified. Herein, we integrate three nationwide soil surveys (1980, 2012, 2018) encompassing over 190,000 cropland observations into a harmonized 1 km dataset to reconstruct four decades of soil pH change across China. National mean soil pH declined from 7.1 in 1980 to 6.7 in 2012 and 6.6 in 2018, revealing a sustained acidification trend. Nearly one quarter of neutral soils (pH 6.5–7.5) have shifted into acidic classes (<6.5) since 1980, reflecting widespread depletion of soil buffering capacity under intensive fertilization, high rainfall, and carbonate exhaustion. By integrating current pH conditions with standardized pH change rate, we delineate nine bidirectional soil pH risk zones that capture contrasting acidification and alkalization processes along climatic and edaphic gradients. Acidification-prone zones dominate humid southern croplands, whereas alkalization risk prevails in arid northern regions. Our results provide nationally consistent, grid-level evidence of soil acid–base evolution across nearly four decades, offering a quantitative foundation for region-specific soil management to sustain productivity and mitigate environmental risks.

Effective spatial arrangement in maize population can reduce inter-plant competition, promote root development, and enhance nutrient uptake. This study aimed to clarify how planting density and row spacing affect maize growth and yield. A four-year field experiment (2011–2014) was conducted using three planting densities (50,025, 67,500, and 100,050 plants ha⁻¹) combined with two row spacings. Grain yield increased with higher planting density, whereas plant dry weight and nutrient (N, P, K) contents declined. Higher density restricted root growth both vertically and horizontally, particularly in the 0–10 cm soil layer and inner root zone. Narrower row spacing increased grain yield, plant dry weight, and shoot nutrient contents and improved vertical and inner-zone root growth while reducing growth in the outer root zone. At the highest density, these effects were most pronounced in fine roots (−1) combined with narrower row spacing is optimal for balancing root development and yield.

New soil organic carbon (SOC) formation in cropland from straw/stover or manure input is a vital source of SOC for climate change mitigation. However, location and variations in the efficiency, specifically the ratio of new SOC formation to organic C input (NCE), remain unquantified globally. In this study, the spatial variability of cropland NCE from straw/stover or manure input and explanatory factors were determined by analyzing 897 pairs of long‐term field measurements from 404 globally distributed sites and by mapping grid‐level cropland NCEs. The global NCE for paddy and upland averaged 13.8% (8.7%–25.1%, 5th–95th percentile) and 10.9% (6.8%–17.3%), respectively. The initial SOC and the clay content of soil, rather than temperature, were the most important factors regulating NCE. A parabola with an apex at approximately 17 g kg⁻¹ between the initial SOC and NCE was resolved, and a positive correlation between soil clay content and NCE was observed. High‐resolution mapping of the global NCE derived from manure/straw and insight into NCE dynamics provide a benchmark for diagnosing cropland soil C dynamics under climate change and identifying priority regions and actions for C management.

Researchers have previously described the response of crop productivity and greenhouse gas (GHG) emissions to fertilizer nitrogen (N) additions, but they have not determined how to maximize yields while minimizing GHG emissions. We conducted an experiment at 2293 sites with four N levels to simulate both grain yield and yield-scaled GHG emissions in response to the N addition. The yield-scaled GHG emissions decreased by 16% as the N rate increased from treatments without the N addition to the minimum yield-scaled GHG emissions, which was comparable to the values associated with the maximum grain yields. The sites with both high soil productivity and high crop productivity had the highest yield and lowest yield-scaled GHG emissions, with 43% higher yield and 38% lower yield-scaled GHG emissions than sites with low soil and low crop productivity. These findings are expected to enhance evaluations of wheat production and GHG emissions in China, and thereby contribute to addressing disparities in the global food and GHG budget.