The pine bark beetle is a devastating forest pest, causing significant forest losses worldwide, including 25% of pine forests in Honduras. This study focuses on Dendroctonus frontalis and Ips spp., which have affected four of the seven native pine species in Honduras: Pinus oocarpa, P. caribaea, P. maximinoi, and P. tecunumanii. Artificial intelligence (AI) is an essential tool for developing susceptibility models. However, gaps remain in the evaluation and comparison of these algorithms when modeling susceptibility to bark beetle outbreaks in tropical conifer forests using Google Earth Engine (GEE). The objective of this study was to compare the effectiveness of three algorithms—random forest (RF), gradient boosting (GB), and maximum entropy (ME)—in constructing susceptibility models for pine bark beetles. Data from 5601 pest occurrence sites (2019–2023), 4000 absence samples, and a set of environmental covariates were used, with 70% for training and 30% for validation. Accuracies above 92% were obtained for RF and GB, and 85% for ME, along with robustness in the area under the curve (AUC) of up to 0.98. The models revealed seasonal variations in pest susceptibility. Overall, RF and GB outperformed ME, highlighting their effectiveness for implementation as adaptive approaches in a more effective forest monitoring system.

Soil microbes perform important functions in the soil organic carbon (SOC) cycle and soil microbial decomposition activity is a major determinant of the carbon budget of a soil. It is well-established that soil microbial physiology is directly affected by temperature and moisture. However, it is less clear to what extent the environmental setting (i.e. long-term climatic conditions, soil physicochemistry) vs. the microbial actors (i.e. soil bacterial and fungal community composition) control the cycling of SOC in the absence of strong direct physiological constraints such as temperature and moisture limitation.To address this knowledge gap, we used 35 grassland topsoils (0 – 10 cm) from 10 WRB major soil groups along a north-south transect in Chile, which ranged from arid steppe to tundra. We compiled climatic data and relevant physicochemical soil properties, together with an in depth characterization of OM quality. We then incubated the soils for 1 week in conditions favorable for microbial activity (20 °C, 50 % of water holding capacity). After incubation, we quantified soil microbial carbon and nitrogen, enzyme kinetics of three groups of relevant extracellular enzymes, basal heterotrophic respiration as well as microbial growth rates and carbon use efficiencies by incorporation of 18O into DNA. In addition, we characterized the microbial actors by DNA extraction and Illumina barcoding of a region of the 16S rRNA gene (bacteria) and a section of the ITS region (fungi). Finally, to investigate how strongly the measured microbial SOC functions were linked with the environmental setting vs. the microbial actors, we applied three different cross-validated regression approaches.The resulting data highlights the links between environment, microbial community composition and SOC cycle functions under conditions without direct temperature and moisture limitation. Our findings show that the environmental setting controlled the amount of microbial biomass, and in extension biomass dependent SOC cycle functions such as heterotrophic respiration. In contrast, microbial community composition was a better predictor of SOC cycle functions that are independent of microbial biomass such as carbon use efficiency and relative microbial growth rates. These insights help to disentangle the roles of the environmental setting and the microbial actors in the context of microbial SOC cycle functions.

Agroforestry contributes to slowing deforestation, favoring ecosystem regeneration and improving land use sustainability. This study evaluated the impact of silvopastoral systems on soil recovery and their capacity to sequester and stabilize carbon (C) and nitrogen (N) in degraded soils of a native Nothofagus obliqua forest in Ranchillo Alto (37°04′52″ S, 71°39′14″ W), Ñuble Region, Chile. Three open (Op), semi-open (SOp), and semi-closed (SC) silvopastoral systems were analyzed and compared with a control (Ctr) without silvopastoral management across four soil depths (0–10, 10–20, 20–30, 30–60 cm). Physical, chemical, and biological analyses were performed, along with soil physical organic matter (SOM) fractionation. The highest C levels were found in the 0–10 cm depth (13.9, 11.8, 11.5, and 8.5% for Op > SC > SOp and Ctr, respectively). Despite its higher degradation, Op presented the highest levels of C, N, and non-oxidizable C (Cnox), possibly due to pyrogenic carbon from old potato burns. Furthermore, the same trend was observed for mineral associated organic matter (MAOM) fraction and C stocks in all silvopastoral systems compared to the control. These results underline the potential of silvopastoral practices to improve soil quality and increase long-term carbon sequestration, contributing to sustainable soil restoration strategies.

Understanding how microbiomes influence the life cycle and fitness of crops, and how global change drivers disrupt this network, is pivotal for an understanding of the crop as a holobiont, and of how to provide solutions for Nordic agricultural crop resilience under climate change. Despite decades of use of plant growth-promoting rhizobacteria (PGPR), there is an intrinsic problem with their applications, as it has become evident that their functionality and performance rely on interactions with the environment and with other microorganisms. The synthetic crop promoting rhizobacterial community strains are being outcompeted by native communities, or their colonisation and active principles are being reduced to ineffective levels. This is the result of the communities being selected on taxonomic criteria rather than qualitative analysis of the microbiome associated plant phenotypes. In this context there in an urgent need for an approach studying the microbial community and plant complementarity traits from indigenous communities. Here we report the pattern of bacterial distributions at the Evolution Canyon (EC) in Israel to gain insight into microbiomes exposed to contrasting microclimates at the North Facing Slope (NFS) and South Facing Slope (SFS) sun and shade areas using high-throughput sequencing. While the NFS and SFS shaded areas bacterial distribution didnt differ, our results show significant differences between the NFS and the SFS sunny areas. The families Geodermatophilaceae, Beijerinckiaceae, and Pseudonocardiaceae are dominant in the NFS sun area, and the families Rubrobacteriaceae, unclassified Solirubrobacterales bacterium 67 14, unclassified Actinobacteriota, class Gaiellales dominate at the SFS sun area. Likewise, both Shannon and inverse Simpsons diversity indices are higher at the NFS sun area compared to the NFS shaded area. There was no substantial difference between diversity indices in SFS sun and shaded area. Our results advance our understanding of the bacterial distributions at what is in effect a natural laboratory of ecosystems that probably evolved 5 to 7 million years ago. The data are an important step towards using transcriptomics, metabolomic profiles and selective plating for figuring out key strains and the supporter strains that strengthen the ecological functions of the key strains. Collectively, this will enable us to assemble redundant and stable synthetic PGPR communities consisting of key and supporter strains for promoting plant health and stress tolerance under changing climates. ### Competing Interest Statement The authors have declared no competing interest.

The use of organic waste in agricultural soil can enhance crop yields, improve waste management, and boost soil carbon (C) sequestration. However, more field data are required to fully understand the impacts of pyrolyzed and unpyrolyzed animal manures. The objectives of this study were (i) to analyze the impact of two pyrolyzed and unpyrolyzed manures on soil properties, soil C storage, and clover productivity and (ii) to examine the biochar’s movement through the soil profile. Poultry litter (PL), dairy manure (DM), poultry litter biochar (PLBC), and dairy manure biochar (DBC) were applied at rates of 8 t ha−1 in a field experiment with red clover (Trifolium pratense L. var. Quiñequeli) in an Andisol. We monitored changes in soil chemical properties, foliar properties, and crop yield after three clover cuttings. To examine the movement of biochars through the soil profile, we set up a lab experiment where field conditions were simulated. PLBC, DBC, and PL increased soil pH by 0.5 (6.44), 0.28 (6.22), and 0.25 (6.19) units, respectively. Soil available P increased in both pyrolyzed and unpyrolyzed PL treatments (by 8.53 mg P kg−1, on average). Clover yields only increased in treatments with amendments that provided more available P and increased the pH. The addition of DBC increased soil total C (30.3%). Both biochars added to the soil surface exhibited little movement through the soil profile (2 to 4 cm). In this study, the pyrolysis of manures emerged as an option for reducing waste volume from the farming industry. Manure biochars proved useful at low rates for enhancing crop yields (PLBC) and storing C in the soil (DBC).

Soil microbial traits and functions play a central role in soil organic carbon (SOC) dynamics. However, at the macroscale (regional to global) it is still unresolved whether (i) specific environmental attributes (e.g., climate, geology, soil types) or (ii) microbial community composition drive key microbial traits and functions directly. To address this knowledge gap, we used 33 grassland topsoils (0-10 cm) from a geoclimatic gradient in Chile. First, we incubated the soils for 1 week in favorable standardized conditions and quantified a wide range of soil microbial traits and functions such as microbial biomass carbon (MBC), enzyme kinetics, microbial respiration, growth rates as well as carbon use efficiency (CUE). Second, we characterized climatic and physicochemical properties as well as bacterial and fungal community composition of the soils. We then applied regression analysis to investigate how strongly the measured microbial traits and functions were linked with the environmental setting versus microbial community composition. We show that environmental attributes (predominantly the amount of soil organic matter) determined patterns of MBC along the gradient, which in turn explained microbial respiration and growth rates. However, respiration and growth normalized for MBC (i.e., specific respiration and growth) were more linked to microbial community composition than environmental attributes. Notably, both specific respiration and growth followed distinct trends and were related to different parts of the microbial community, which in turn resulted in strong effects on microbial CUE. We conclude that even at the macroscale, CUE is the result of physiologically decoupled aspects of microbial metabolism, which in turn is partially determined by microbial community composition. The environmental setting and microbial community composition affect different microbial traits and functions, and therefore both factors need to be considered in the context of macroscale SOC dynamics. Soil microbial traits and functions are central for soil organic carbon (SOC) dynamics. However, at regional to global scales it is still unresolved whether the environment (climate, geology, soil types) or microbial community composition drive key microbial traits and functions directly. Using 33 soils from a temperate grassland gradient, we show that the environment determined the biomass and absolute respiration and growth of microbes. However, microbial carbon use efficiency was best explained by microbial community composition. The environment and the microbiome affect different microbial traits and functions, and therefore both factors need to be considered in macroscale SOC dynamics.image

Organic matter accumulation in soil is understood as the result of the dynamics between mineral-associated (more decomposed, microbial derived) organic matter and free particulate (less decomposed, plant derived) organic matter. However, from regional to global scales, patterns and drivers behind main soil organic carbon (SOC) fractions are not well understood and remain poorly linked to the pedogenetic variation across soil types. Here, we separated SOC associated with silt- and clay-sized particles (S + C), stable aggregates (>63 mu m, SA) and particulate organic matter (POM) from a diverse range of grassland topsoils sampled along a geoclimatic gradient. The relative contribution of the two mineral-associated fractions (S + C & SA) to SOC differed significantly across the gradient, while POM was never the dominant SOC fraction. Stable aggregates (>63 mu m) emerged as the major SOC fraction in carbon-rich soils. The degree of decomposition of carbon in stable aggregates (>63 mu m) was consistently between that of the S + C and POM fractions and did not change along the investigated gradient. In contrast, carbon associated with the S + C fraction was less microbially decomposed in carbon-rich soils than in carbon-poor soils. The amount of SOC in the S + C fraction was positively correlated to pedogenic oxide contents and texture, whereas the amount of SOC associated with stable aggregates (>63 mu m) was positively correlated to pedogenic oxide contents and negatively to temperature. We present a conceptual summary of our findings, which integrates the role of stable aggregates (>63 mu m) with other major SOC fractions and illustrates their changing importance across (soil-)environmental gradients.

Land degradation is a deleterious process affecting the biophysical environment of soils and reduces the natural or agricultural capacity of soil to support plant growth and net primary productivity, promoting a broad-scale, net loss of soil organic carbon (SOC) to the atmosphere through increased CO2 emissions from soil to the atmosphere and lower carbon storage in aboveground biomass. Consequently, land degradation represents the main threat to food security worldwide, especially in Africa and Asia. At present, about 40% of the global land area is affected by land degradation, 9% being severe. Silvopastoral systems, which are planned combinations of trees, forage-herbs and livestock, constitute one of the main forms of agroforestry systems currently covering about 28% of the global area of these. This chapter demonstrates that silvopastoral systems represent the principal land uses for land conservation-reclamation and reducing-offset C emissions from soil by promoting the formation of soil organic matter and increasing SOC named carbon sequestration (CO2→SOC), enhancing soil quality and improving ecosystem services like water and nutrient cycling and livestock well-being. In this review, we have identified 25 major mechanisms responsible for soil organic matter, soil quality, and carbon emission offset including: 12 individual functions for the woody (6), herbaceous (3) and animal (3) components, in addition to 13 symbiotic drivers (8 mutualistic and 5 tripartite interactions), whereas the reported values of C fixation in silvopastoral systems are 1–5 Mg C ha−1 year−1 and CO2→SOC range from 1.8 to 7.5 Mg C ha−1 year−1, demonstrating the potential of silvopastoral systems to ameliorate or reverse land degradation. However, the scientific reports related to silvopastoral systems and their benefits are mainly concentrated in certain global zones (e.g. developed countries), which suggests that this may be potentially useful in addressing land degradation in other priority regions such as Asia and Africa.

Agroforestry systems (AFSs) have gained recognition as a land use strategy to address food security and climate change. They involve intentionally cultivating trees alongside crops and/or animals. AFSs cover approximately 5% of the global forest area and promote sustainable soil conservation, including soil organic carbon (C) sequestration (CSEQ). In some areas of Chile, AFSs are used to preserve the ecological value of native forests. This study evaluates the effects of two AFSs, namely, an agroforest for fodder production (AGROFRST) and Silvopastoral (SPS), within a degraded native forest (Nothofagus obliqua sp.). The evaluation focuses on their impact on CSEQ capacity and soil quality (SQ), using soil quality indexes (SQIs) derived from 30 soil quality indicators (SINDs) related to physical, chemical, and microbiological properties at two depths (0–5 and 5–20 cm). The results for the total depth analyzed (0–20 cm) indicate an average CSEQ of 6.88 and 4.83 Mg C yr−1 and a global SQI of 37.8% and 31.0% for AGROFRST and SPS, respectively. Among the thirteen SINDs that demonstrated significant differences (p < 0.05), five were associated with the considered depths (P+, Ca2+, S, ECEC, and AlSAT), three differed between AGROFRST and SPS (BD, NH4+, NO3−), while SOC, K+, and Mg2+ varied across all conditions (e.g., combinations of systems and depths), and β-GLU and NMIN differed in a single condition. However, almost all 30 SINDs analyzed showed higher values at the 0–5 cm depth, indicating the positive effects of soil organic matter (SOM)/SOC additions. Significant interactions (Pearson’s correlation) revealed that SOC correlated with most SINDs (e.g., N, NH4+, P+, K+, Ca2+, Mg2+, S, ECEC, NMIN). These findings suggest that both AGROFRST and SPS systems have similar capabilities in restoring the ecological value of native Nothofagus forests while providing conditions for productive and complementary use. This sustainable option offers opportunities for cattle production alongside ecological restoration efforts and provides a possible strategy to generate public policies related to the ecosystem services of agroforestry systems.

Abstract Organic matter accumulation in soil is understood as the result of the dynamics between mineral-associated (often more decomposed, microbial derived) organic matter and free particulate (often less decomposed, plant derived) organic matter. However, at global scales, the patterns and drivers behind main SOC reservoirs are not well understood and remain poorly linked to the pedogenetic variation across soil types that may impact SOC stabilization. Here, we separated soil organic carbon (SOC) associated with silt- and clay-sized particles (S + C), stable microaggregates (> 63 µm, SA) and free particulate organic matter (POM) from a diverse range of grassland topsoils sampled along a geo-climatic gradient. The relative contribution of the two predominantly mineral-associated fractions (S + C & SA) differed significantly across the gradient while free POM was never the dominant SOC reservoir. Rather, stable microaggregates emerged as the major SOC reservoir in soils with high SOC content. The SOC content in the two mineral-associated reservoirs was related to distinct climatic and mineralogic proxies that followed predictable patterns across the gradient. Furthermore, carbon quality in stable microaggregates was clearly distinct from carbon associated with silt- and clay-sized particles and free particulate organic matter. We summarize our findings in a conceptual framework, which integrates the role of stable microaggregates with other major SOC reservoirs and illustrates their changing importance across (soil) environmental gradients.

Carbon dioxide (CO2) and nitrous oxide (N2O) are important greenhouse effect gases (GHG). Soil gas emissions have a lack of research on volcanic ash soils under contrasting land uses in Chile. We propose that different intensities of land use affect soil gas fluxes. We incubated volcanic soils (5 cm depth) from crops, grasslands, silvopastures, and forestry plantations, under three levels of moisture (WFPS, water-filled pore space: 30%, 60%, and 90%), with different contents of nitrate already pre-existing in the soil. Air samples were measured by gas chromatography after 2 h of soil gas effluxes from closed passive airtight chambers. There was no significant effect of soil use intensity on CO2 fluxes, but a significant effect of WFPS was found. The N2O fluxes also responded to WFPS; soil use effects were found at 90% WFPS, where only agriculture crops surpassed permanent grasslands. The soil nitrate content had a negative and significant relation with CO2 fluxes. The legacy of the original soil may have contributed to the general absence of land use effect on gas emissions, irrespective of its management history, because soil use changes from agriculture to forest plantations are recent (only 10–12 years ago) following intensive use during centuries that may have exhausted the soil carbon and nitrogen pools. However, the fluxes were more responsive to soil water content and nitrate, suggesting that if land uses were more coupled to these driving environmental factors, differences among land use GHG emissions should occur.

The "soils of the Anthropocene" are predominately agricultural. To understand them, we analyzed agri- and silvicultural intensification of Uruguayan grasslands (GLs) in a country-wide survey on fertility proxies, pH and trace metals in topsoils originating from different land uses across the whole country. Thus, our results reflect interactions of both the natural diversity of Uruguayan soil formation and the impacts of land use change. We observed a loss of nutrients, trace metals and organic matter from GLs, croplands and timber plantations (TPs). As an example, the cation exchange capacity was 160 % higher in native forests (NFs) compared to GLs and lowest in TPs, reaching only half of the cation exchange capacity (CEC) in GLs. Acidification of topsoils continues as three-fourths of all samples are "extremely acidic" and "very strongly acidic". Topsoils of riverine forests accumulate more trace metals compared to the other uses. We assume an accumulation in the topsoils of riverine forests, where high levels of nutrients, trace metals and organic carbon (OC) are found. The translocation of nutrients and organic matter across the landscape to the erosion base depends on local land use trajectories. Increasing soil acidification is driving a positive feedback loop, and land use intensification has lead to degradation of local black soils within a few decades. Our data raise questions about the resilience and carrying capacity of Uruguayan soils with regard to currently implemented highly productive management forms, including the use of TPs for carbon sequestration, and supports more conservative forms of extensive management on the GL biome.

Mapping the spatial distribution of soil organic carbon (SOC) in lands covered by tropical forests is important to understand the relationship and dynamics of SOC in this type of ecosystem. In this study, the Random Forest (RF) algorithm was used to map SOC stocks of topsoil (0–15 cm) in forest lands of the Dominican Republic. The methodology was developed using geospatial datasets available in the Google Earth Engine (GEE) platform combined with a set of 268 soil samples. Twenty environmental covariates were analyzed, including climate, topography, and vegetation. The results indicate that Model A (combining all 20 covariates) was only marginally better than Model B (combining topographic and climatic covariates), and Model C (only combining multispectral remote sensing data derived from Landsat 8 OLI images). Model A and Model B yielded SOC mean values of 110.35 and 110.87 Mg C ha−1, respectively. Model A reported the lowest prediction error and uncertainty with an R2 of 0.83, an RMSE of 35.02 Mg C ha−1. There was a strong dependence of SOC stocks on multispectral remote sensing data. Therefore, multispectral remote sensing proved accurate to map SOC stocks in forest ecosystems in the region.

Carbon (C) mineralization and turnover in soil rely on complex interactions among environmental variables that differ along latitudinal gradients. This study aims to quantify the relationship between the variation in δ 13 C signature with soil depth (∆δ 13 C) and soil C turnover across a large geo-climatic gradient. Thirteen grassland sites were sampled along a 4000 km latitudinal gradient in Chile. Maximizing climatic and physicochemical soil’s diversity to test the index with the widest range of application. We used near-infrared spectroscopy (NIRS) to estimate δ 13 C of SOC at several soil depths. To assess soil C mineralization rates (CMR) and specific potential respiration (SPR) as proxies for C mineralization and turnover, using ∆δ 13 C, soil incubations were performed. Highest 13 C isotope abundance was found at low latitude (− 22.57‰, 35.5°S) and lowest at high latitude (− 27.43‰, 53.2°S). Our results show 13 C’s enrichment in parallel with decreasing C content with depth. The analysis of the relationship between ∆δ 13 C values versus CMR and SPR showed a significant positive relationship across all data points ( p < 0.0001, R 2 = 0.62; p < 0.01, R 2 = 0.29, respectively). Partial correlation analysis of control variables indicates a relationship between ∆δ 13 C with CMR and SPR when controlling for climatic and soil physicochemical variables. ∆δ 13 C calculated from NIRSs may serve as a proxy to research the potential degradability of SOM and its interaction with soil geochemistry. Uncertainty and variability in the prediction power of our model reveals the importance of considering the latitudinal changeability in soil types as a control on properties controlling ∆δ 13 C.

Greenhouse gas emissions from managed peatlands have not been extensively studied in Western Patagonia. The objective of this study was to assess the annual CO 2 emission from microbial carbon (C) mineralization in a peatland site under not saturated conditions at Tierra del Fuego. The annual CO 2 emissions were measured from unsaturated soil samples ( n = 41) under soil incubation at seasonal local temperatures to simulate CO 2 emissions for a year, using a non‐dispersive infrared gas analyser. Spatial models for total soil C and CO 2 were calculated using discrete and continuous variables. The annual mean of measured cumulative CO 2 was 1,358 µg CO 2 g soil −1 , lower than Northern peatlands, and 82% of the C mineralization occurred in the warmer season. The modelled CO 2 in the warmer season showed levels of CO 2 as high as 4 mg CO 2 g soil −1 , but 66% of the area showed between 600–2000 µg CO 2 g soil −1 , which is 28%–92% and 9%–32% of CO 2 values reported for crop rotations. Consequently, after a potential habilitation of the study area for agricultural use, the soil CO 2 emissions from heterotrophic activity would become a C source to the global CO 2 emissions. This ecosystem is highly exposed to the effects of the land‐use change, and global temperature increase.

The concept of distinct soil organic matter (SOM) fractions – with differing formation pathways, stabilization mechanisms and responses to change – is a promising avenue to improve our understanding of soil carbon (C) dynamics. While there is widespread consensus on the general usefulness of conceptual fractions with specific functional implications, there is still a lack of information on the patterns with which they contribute to bulk soil organic carbon (SOC) stock at larger scales and across climatic and soil physicochemical gradients. In this study, we aimed to assess first the quantitative importance of three key SOM fractions across a diverse range of 12 soil groups with global significance. Secondly, we wanted to gain insights on the environmental drivers that shape the contribution of these fractions to SOC stocks. Here we sampled a set of 35 grassland topsoils (0 – 10 cm) along a 3000 km north-south transect in Chile ranging from subpolar to Mediterranean climate, and covering 12 WRB major soil groups. Following a modified version of the protocol in Zimmermann et. al (2007), we partitioned the soils into three functional SOM fractions defined by particle size and density (free silt and clay, free particulate organic matter, stable microaggregates), enabling us to quantify SOC stocks and the relative contribution to SOC in these three fractions. In order to identify links between fractions and potential drivers of C stabilization, we further characterized extensively relevant physico-chemical properties of the soils, compiled climatic data of the sites and characterized OM maturity (DRIFT spectroscopy and Rock-Eval pyrolysis) as well as pedogenic, secondary Fe-, Al- and Mn-oxide concentrations through sequential extraction. We found that the contributions of mineral-associated SOM fractions to bulk SOC varied strongly across the soil gradient, while the contribution of free particulate organic matter was comparatively stable and low. SOM associated with free silt and clay sized particles are the most important C reservoir in soils with less than 4 % SOC, whereas in soils with higher SOC content, the majority of the SOC is contained in stable microaggregates. The SOC stock in various fractions was sensitive to changes in temperature, pedogenic oxides, and OM input vs. decomposition. Comparison of OM maturity showed that free particulate OM and free silt and clay associated OM can be clearly distinguished, while OM in microaggregates is likely a mixture of both. However, drivers of OM composition in microaggregates could not be identified. This study demonstrates that in SOC-rich soils, microaggregates represent a major fraction of bulk SOC, and that SOC stocks in key SOM fractions can be linked to distinct climatic and soil physicochemical factors.

Andisols are soils derived from volcanic ash that are characterized by high concentrations of phosphorus (P). However, most of the P is not readily available for plant uptake due to the physical–chemical properties of the soils. The objective of this field study was to evaluate the effects of liquid P fertilizers on the plant growth and yield of a potato crop cultivated in Andisol type soil located in southern Chile. Ten treatments were applied pre- and/or postemergence, including orthophosphate- or ammonium polyphosphatebased fertilizers applied alone or in combination with fulvic acid and granular fertilizers; in addition, an unfertilized control (T0) was also included. Significant differences were found in terms of yield, total number of stems, and tuber size. The application of liquid fertilizers resulted in similar levels of foliar P content, while the number of stems was higher with the combined application of ammonium polyphosphate and fulvic acid. Furthermore, liquid P fertilizers increased crop yield (38%) and the proportion of large tubers (17%). The effects of orthophosphate and polyphosphate liquid fertilizers on potato were enhanced by the addition of fulvic acid to the soil.

Pyrolysis is a useful alternative to current waste management practices. Manure biochars can be used as C-rich soil amendments, reducing the risk of greenhouse gas (GHG) emissions derived from unpyrolyzed manure decomposition. In this study, two manure biochars and their feedstock were used as soil treatments to evaluate the impact of pyrolysis on CO2 and N2O emissions, C stability, and global warming potential (GWP) for one year under field conditions. The experiment included five treatments: unamended soil (control), pig manure (PM), pig manure biochar (PMB), dairy manure (DM), and dairy manure biochar (DMB). The amendments were applied at a 1% w/w, adding approximately 0.5 kg C m(-2). All amendments increased soil CO2 emissions; however, C mineralization was lower in pyrolyzed manures than in their corresponding feedstocks. CO2-C emissions were 8.35%, and 63% of the C from biochar and manure treatments, respectively. Biochars reduced soil N2O emissions, producing a negative N2O emission factor (N2O Ef), whereas manure treatments induced N2O fluxes for 105 days, with an N2O Ef of 0.27% after one year. Soil C stock variations were 16.4 and 6.58 t CO2-eq avoided ha(-1) in treatments of biochars and manures, respectively. The mitigation potential of unpyrolyzed manure was affected by the high CO2 and N2O fluxes, whereas the biochar treatments reduced the GWP due to the changes in soil C stock with a low impact on soil emissions. Manure was more stable after pyrolysis, indicating that manure biochars are more favorable as soil amendments for environmental purposes. This could reduce the C footprint of pig and dairy farms, promoting the enhancement of soil C stocks.