Climate warming and population growth pose significant challenges to global food security. Intensive agriculture has led to soil degradation, reducing arable land available for food production. The urgency to increase food production while mitigating climate change necessitates climate-resilient land management strategies. Conservation agriculture (CA), incorporating reduced or no-tillage, permanent soil cover, and diverse crop rotations, is promoted as a sustainable solution to enhance soil health and maintain food production. While CA offers various environmental benefits, including improved soil organic carbon (SOC) stocks and biodiversity, the long-term effects of climate warming on its efficacy remain uncertain. Long-term field experiments directly comparing CA with conventional agriculture under warming conditions are scarce but crucial for understanding the interactive effects of management and warming on crop yields and soil health. Predicting the effectiveness of CA under warming conditions is complex due to the intricate interactions between warming, soil management, crop yields, and individual soil properties. Climate warming negatively impacts agriculture through yield reductions, SOC loss, and impaired ecosystem functions. Rising temperatures reduce crop yields, particularly at low latitudes, due to drought, disrupted crop cycles, and increased pathogen pressure. SOC, a crucial soil health indicator, is expected to decline under warming due to accelerated microbial decomposition. Conversely, CA, through residue retention, promotes SOC accrual by increasing plant biomass inputs and improving soil conditions to counteract the negative impacts of climate change. However, uncertainties remain regarding the response of the soil microbiome—a key driver of agroecosystem processes—to the interplay between warming and crop management practices. This study aims to assess the effects of warming on soil health and crop yields under CA versus conventional agriculture, and the contribution of the soil microbiome to these outcomes. The hypotheses are that under warming, CA enhances crop productivity by increasing carbon inputs, stimulating microbial growth, and promoting soil health; that improvements in crop yield and soil health depend on changes in the soil microbiome; and that the benefits of CA are cumulative over time. To test these hypotheses, an eight-year field experiment was conducted on the North China Plain, using a winter wheat-summer maize rotation system with two warming levels (+2°C and ambient) imposed using infrared heaters.

A substantial body of research highlights the benefits of conservation agriculture (CA) for improving soil health and sustaining crop yields. Studies have consistently shown that CA practices, such as no-till farming and residue retention, lead to increased soil organic carbon (SOC) stocks and enhanced biodiversity. However, the literature also reveals concerns about the potential negative impacts of climate warming on these benefits. Some studies indicate that warming can accelerate SOC decomposition, potentially negating the positive effects of CA. Furthermore, the impact of warming on soil microbial communities and their role in soil health under different management systems remains a subject of ongoing investigation. There is a general consensus that warming negatively impacts agricultural productivity, particularly at lower latitudes, through various mechanisms such as drought stress and increased pest pressure. However, the response of crops to warming can vary depending on factors such as latitude, crop type, and soil conditions. The interactive effects of warming and soil management on soil health and crop yields are not fully understood. While process-based crop simulation models exist, they often lack the empirical data from long-term field warming experiments needed to accurately predict the effects of climate change on agroecosystem functions. A major gap in the existing literature is the lack of long-term, in situ studies comparing CA and conventional agriculture under warming conditions, particularly in arable lands. This study addresses this gap by providing empirical data from an eight-year field experiment.

This study utilized a long-term field experiment conducted at the Yucheng Comprehensive Experiment Station in the North China Plain. The region has a temperate semi-arid climate with an annual mean temperature of 13.6 °C and annual precipitation of 575 mm. The soil type is Calcaric Fluvisol. The experiment employed a randomized complete block design with four treatments: conventional agriculture with and without warming (Conven-Warm and Conven-Amb), and conservation agriculture with and without warming (Conserv-Warm and Conserv-Amb). Warming (+2 °C) was achieved using infrared heaters, with control plots receiving dummy heaters to simulate shading effects. Each plot measured 2 m × 2 m, and a winter wheat-summer maize crop rotation system was implemented since 2010. In the conventional agriculture treatment, crop residues were removed, and the soil was tilled annually. In the conservation agriculture treatment, residues were retained on the soil surface, and no tillage was practiced. Both treatments received the same total nitrogen application rate, but with different sources. Soil temperature and moisture were continuously monitored using in-situ sensors. Soil samples (0–5 cm and 5–15 cm depths) were collected after each winter wheat harvest from 2010 to 2019, passed through a 2 mm sieve, and analyzed for seventeen soil health indicators: mean weight diameter (MWD), aggregate content (R0.25), soil moisture (SM), bulk density (BD), pH, dissolved organic carbon (DOC), soil organic carbon (SOC), NO3−-N, NH4+-N, dissolved organic nitrogen (DON), total nitrogen (TN), available phosphorus (AP), total phosphorus (TP), available potassium (AK), total potassium (TK), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN). The Cornell Soil Health Assessment (CSHA) scoring method was used to calculate overall soil health scores. Amplicon sequencing of the 16S rRNA gene and ITS gene was performed to assess soil bacterial and fungal diversity and community composition. Crop yields (wheat and maize) were determined by hand harvesting and threshing. Linear mixed models (LMMs) were used to analyze the effects of warming and management on soil properties, biodiversity, and crop yields. Non-metric multidimensional scaling (NMDS) and nested permutational multivariate analysis of variance (nested PERMANOVA) were used to analyze microbial community composition. Linear mixed-effects models were used to assess correlations between microbial diversity, soil health indicators, and crop yields. Hierarchical partitioning analysis determined the relative importance of environmental factors.

Experimental warming increased soil temperature but decreased soil moisture under both management systems. However, soils under conservation agriculture remained cooler and wetter than those under conventional agriculture. Wheat yields were significantly affected by warming, but there was no difference in yields between the two management systems. Warming increased wheat yields by 9.3% under conservation agriculture and 11.2% under conventional agriculture over the eight-year period. The positive warming effect on wheat yields strengthened over time under conservation agriculture but not under conventional agriculture. Maize yields were affected by soil management but not by warming. Conservation agriculture consistently yielded higher maize compared to conventional agriculture. Principal Component Analysis (PCA) identified key soil health indicators (DOC, MBC, SOC, TN). Warming increased the soil health score by 6.3% and 8.1% at 0–5 cm and 5–15 cm depths, respectively, under conservation agriculture, and only 5.2% at 5–15 cm depth under conventional agriculture. Conservation agriculture showed a 21.5% greater soil health score than conventional agriculture at 0–5 cm depth in ambient conditions. Warming amplified this difference, resulting in a 31.4% greater soil health score under conservation agriculture at 0–5 cm depth. Warming enhanced MWD and R0.25 under conservation agriculture, indicating better water infiltration and storage. Warming also promoted nutrient cycling under conservation agriculture, evidenced by increased DOC, SOC, TN, AK, and NO3−-N concentrations. MBC and MBN were higher under conservation agriculture under warming. Soil fungal and bacterial communities were affected by management, warming, and their interaction. Warming decreased fungal richness under conservation agriculture but not under conventional agriculture. Conservation agriculture supported greater AMF richness and lower saprogen and pathogen richness. Under conservation agriculture, MBC and saprogen richness at 0–5 cm depth were most strongly linked to wheat yields, with strong positive correlations between wheat yields and MBC and negative correlations with saprogen richness. Under conventional agriculture, soil microclimate (temperature and moisture) and DOC were most relevant to wheat yields. Key indicators of soil health were closely related to soil microbial richness and community composition, particularly under conservation agriculture. Soil MBC and SOC were more closely related to soil fungal richness/composition than bacterial richness/composition.

This study presents strong empirical evidence supporting the benefits of conservation agriculture (CA) in enhancing soil health and sustaining crop yields under long-term warming. The findings demonstrate that CA significantly improved several soil properties related to key soil functions, including water infiltration, carbon and nutrient cycling, and microbial activity. The increased soil organic carbon (SOC) and microbial biomass carbon (MBC) under CA, especially under warming conditions, highlight the importance of microbially-mediated mechanisms in soil carbon accrual. The positive effects of warming on wheat yields under CA were strongly linked to enhanced soil microbial quality, with MBC being a key driver. In contrast, under conventional agriculture, warming effects on wheat yields were primarily linked to improved soil microclimate. The lack of negative impacts of CA on crop yields, contrary to some previous studies, underscores the importance of considering regional climatic conditions and soil types when assessing CA's effectiveness. The observed reduction in fungal richness under CA with warming is likely a result of decreased saprophyte richness, potentially contributing to increased SOC accumulation. The higher diversity of arbuscular mycorrhizal fungi (AMF) and lower diversity of plant pathogens under CA further contribute to improved soil health and crop productivity. The study's findings reinforce the potential of CA as a crucial climate-smart agricultural practice to enhance resilience to climate change and secure global food production.

This long-term field experiment provides compelling evidence that conservation agriculture significantly enhances soil health and sustains crop yields under long-term warming, particularly for wheat. The study reveals the critical role of soil microbiome, especially fungi, in mediating these positive effects. Improved soil aggregate stability, enhanced carbon and nutrient cycling, and increased microbial activity contribute to the superior performance of CA compared to conventional agriculture under warming conditions. These findings underscore the potential of CA as a climate-smart agricultural strategy for mitigating the adverse effects of climate change on food security. Future research could focus on exploring the long-term impacts of CA across various soil types and climatic regions, as well as investigate the specific mechanisms driving the observed shifts in microbial communities.

This study was conducted at a single location in the North China Plain, limiting the generalizability of the findings to other regions with different climatic and soil conditions. The study focused on a specific crop rotation (wheat-maize), and the results may not be applicable to other cropping systems. While the study spanned eight years, longer-term experiments would further strengthen the conclusions regarding the long-term sustainability of CA under warming conditions. The analysis focused on the 0-15 cm soil depth, and further investigation is needed to understand the impacts of CA on deeper soil layers. Finally, the study primarily focused on the effects of warming and management, while other factors such as precipitation variability and nitrogen availability could also influence the observed outcomes.