Soil Mapping Units Research Articles

The nature of information and the implication for making predictions about soil properties using soil maps

Information theory is one method to evaluate how soil data can be utilised to estimate the amount of information produced by grouping or classifying the soil into classes or spatial polygons. Information theory provides the means of making “information” a measurable quantity. This paper explores how information theory can be applied to an existing, conventional soil map for the Lower Macquarie alluvial plain in New South Wales. It uses stepwise interpretation tables to estimate information levels for pH, salinity, ESP and shrink swell potential. An estimate is made of the amount of information produced for each of the soil profile classes (SPCs) and the soil map units. The amount of information produced varied between soil properties and for different soil depths. It also varied between the SPCs and soil map units. The soil map identified high amounts of available information for some soil properties, particularly in the surface soils for salinity and ESP. Moderate levels of information were generally available for pH. For other soil properties, only low amounts of information were available, especially for salinity and shrink swell potential in the deep subsoils. The overall estimate indicated that the soil map provided 50% of the total potential available information. The amount of available information produced for the soil properties was shown to be highly correlated to the standard deviation of the soil properties. The application of information theory and the use of stepwise interpretation tables was shown to be a useful method of evaluating the amount of information produced by a soil map for a range of soil properties.

Physicochemical characteristics of andisols and their correlation to potato yield based on land mapping units

The high phosphate retention in andisol soil is often associated with a decrease in potato yield. Additionally, identification of the physical and chemical characteristics of andisols and their correlation to potato yield through soil mapping units (SMUs) is necessary to facilitate field surveys. Therefore, this study aimed to identify the physicochemical characteristics of andisols with a focus on available phosphorus (P) and the correlation to potato production based on SMUs. The experiment was conducted in Karo District, North Sumatra, Indonesia, from July 2022 to February 2023. A descriptive-analytical method was used by overlaying maps of slope, soil types, and altitude until 10 SMUs were selected that were planted with potatoes. Soil physicochemical properties were identified, while Pearson correlation analysis was performed on available-P and potato yield using IBM SPSS software. The results showed that the silt and clay fractions positively correlated with available-P in andisols. All soil physical characteristics were categorized as very weak to weak in supporting potato yield. A total of four SMUs including 1, 5, 8, and 10 were found to have lower available-P and very low to moderate correlations with soil pH, organic-C, C:N ratio, cation exchange capacity (CEC), as well as total-P. Based on the results, potato yield could increase by 1.765 and 0.380 tons ha-1 through the addition of organic-C and C:N ratio in Karo District. Therefore, soil amendment is required as an alternative to improve andisols soil.

Regional and farm level droughts characteristics for southwestern Uganda during 1981–2017

An increase in drought events associated with rising temperatures indicates that Uganda is facing a growing challenge from climate variability. Despite these challenges, there is a lack of comprehensive information on how climate variability affects soils, particularly drought characteristics. In an effort to address this limitation, this study utilised high-quality, in-situ climate data and soil Available Water Capacity (AWC) specific to south-western Uganda. The study employed the Palmer Drought Severity Index (PDSI) and the Standardised Precipitation-Evapotranspiration Index (SPEI) to assess drought occurrences over the period 1981–2017. Notably, the results from the 3-month SPEI indicated higher frequencies across all drought categories. Meanwhile, the 12-month SPEI exhibited more stabilised negative and positive truncations for drought and wet events, respectively. Analysing the temporal evolution of monthly PDSI values for five major soil mapping units revealed distinct patterns. Moderate droughts were observed over Lixic Ferralsols between 1981 and 1992 and between 1998 and 2008. Extreme drought events occurred during the first 5–7 months of 2017. Luvisols exhibited prolonged negative truncation levels, indicating a water deficit during several periods: 1982–1984, 1990–1994, 1998–2000, 2010, and 2012–2014. Histosols experienced drought conditions from 1982 to 1986, interspersed with wet events in 1988, 1997, 1999–2002, and 2005. The study emphasises the differential response of soil units to drought and wet conditions. As a result, the research recommends implementing water management practices such as irrigation, mulching, conservation tillage, zero tillage, and drainage for all soils to enhance resilience and sustainable agricultural practices in the region.

Model calibration using hydropedological insights to improve the simulation of internal hydrological processes using SWAT+

AbstractSoils affect the distribution of hydrological processes by partitioning precipitation into different components of the water balance. Therefore, understanding soil‐water dynamics at a catchment scale remains imperative to future water resource management. In this study, the value of hydropedological insights was examined to calibrate a processes‐based model. Soil morphology was used as soft data to assist in the calibration of the Soil Water Assessment Tool (SWAT+) model at five different catchment scales (48, 56, 174, 674, and 2421 km2) in the Sabie River catchment, South Africa. The aim of this study was to calibrate the SWAT+ model to accurately simulate long‐term monthly streamflow predictions as well as to reflect internal soil hydrological processes using a procedure focusing on hydropedology as a calibration tool in a multigauge system. Results indicated that calibration improved streamflow predictions where R2 improved by 2%–8%. Nash‐Sutcliffe Efficiency (NSE) improved from negative correlations to values exceeding 0.5 at four of the five catchment scales compared to the uncalibrated model. Results confirm that soil mapping units can be calibrated individually within SWAT+ to improve the representation of hydrological processes. Particularly, the spatial linkage between hydropedology and hydrological processes, which is captured within the soil map of the catchment, can be adequately reflected within the model simulations after calibration. This research will lead to an improved understanding of hydropedology as soft data to improve hydrological modelling accuracy.

Cotton cultivar response to potassium fertilizer under irrigated and dryland conditions

AbstractCotton (Gossypium hirsutum L.) cultivars vary in their response to environmental factors. Recently, interest in cotton cultivars' response to varying potassium (K) fertilizer application rates and irrigation has increased. As such, the effect of cotton varieties (early and mid‐maturing), K fertilizer application rates, and irrigation on cotton growth, development, and yield were investigated in Starkville, MS, on two soil mapping units (SMUs): a Leeper silty clay loam (LSCL) and a Marietta fine sandy loam (MFSL). Cotton plant height was positively correlated with SMU, especially LSCL, reaching 60–110 cm on average, in both irrigated and rainfed conditions. Cotton lint yield, fiber quality, and leaf K concentration responded to K and irrigation, and these responses were SMU specific. Particularly, in LSCL, the early‐maturing cultivar, DP 1518 B2XF, responded to K application rate in a positive linear manner in terms of lint yield under both irrigated and rainfed conditions, whereas mid‐maturing DP 1646 B2XF did not. Moreover, lint yield in irrigated MFSL soil increased with K application rate, whereas no responses were observed in rainfed conditions. These data suggest that irrigation, SMU, and cultivar combination could have an impact on K response of cotton and should be considered when making fertility recommendations or decisions.

Reclamation, land suitability evaluation and management strategy for soils of Tin mined area of Barkin Ladi, Plateau State, Nigeria

The rate of increase in land area used by man is continuously increasing with population growth, with resultant environmental degradation caused by mining and other anthropogenic activities. However, reclamation as well as land suitability evaluation are considered the basis and critical steps for determining the reuse direction of degraded land caused by several years of mining activities. Therefore, the present study was carried out to evaluate the land suitability for different crops production and suggest management practices for their reclamation. Parcel of land covering 224.29 ha on the northern part of Barkin Ladi in Plateau State, Nigeria was surveyed at a detailed scale of 1:6,000. Soil physical condition (petroplinthite), chemical fertility (nutrient retention and availability), low to moderate plant available water, poorly drained condition and erosion hazard were the land qualities that critically limited the suitability of soil mapping units BL II to BL V for the different crops. The evaluation showed that BL I was highly suitable under current suitability for maize, cowpea, green bean, onion and mango (55.55 % of the crops). The crop proportion rated as S1 increased to 88.88 % under potential suitability. The upgrade is expected to occur when the limitations identified are properly managed. Soil unit BL V degraded by previous mining is the least rated with most of the crops as temporarily and permanently not suitable. Land levelling or terrace construction and planting of mango as well as avoidance of bush burning were among management practices suggested to reclaim the deep gully associated with the degraded mined lands. For sustainable crops production and management of the study area; contour ridges, incorporation of organic matter and inorganic fertilizers as well as construction of drainage canals are recommended.

Soil-site suitability assessment for major cereal crops in the Ganjigatti sub-watershed, Karnataka using remote sensing and geographic information systems

Land evaluation is the assessment of the suitability for specified land uses. Land evaluation and quantitative landuse systems analysis support the planning of sustainable use of land. Twenty-one soil series and their phases (sixty-one)identified and mapped during land resource inventory were evaluated for their soil-site suitability for major cereal crops inGanjigatti sub-watershed, Dharwad district in Hilly zone (zone 9) of Karnataka for sustainable land use planning. The soilseries were AKT (Attikatti), ASR (Adavisomapura), BGD (Bagadgeri), BGH (Bigudihala), BNK (Bhogenagarkoppa), BTP(Bettadapura), GJG (Ganjigatti), HNL (Hirehonnalli), HRG (Harugeri), KDK (Kadanakoppa), KMD (Kamadhenu), KRK(Kuradikeri), MLP (Mahalingpur), MRK (Mishrikoti), MVD (Mevundi), RMN (Ramanhala), SDK (Sangedevarakoppa),SGL (Singtalur), SSK (Surashettykoppa), UGK (Ugginakeri) and YSJ (Yelisirunj). Based on texture, depth, slope, erosion,graveliness and stoniness, the twenty-one soil series were mapped into sixty-one mapping units by using Arc GIS version10.8. The soils were evaluated for potential soil site suitability for major cereal crops viz., rice, wheat, maize, sorghum andpearl millet. Majority of soil mapping units are moderately (S2) and marginally suitable (S3) for cultivation due to moderateto severe limitations in climate, soil, drainage and slope per cent. The soil series BGD and MLP were currently not suitabledue to very severe limitations of soil depth. These results could be used as baseline information for identifying specific soilresource constraints for sustainable production of these cereal crops in the study area.

Soil health and carbon storage in community gardens in the Perth metropolitan area, Australia

AbstractCommunity gardens, as common spaces where people gather to grow food, help foster public health, greener urban environments, life‐long learning and vibrant communities. However, despite being promoted as sustainable horticulture and conservation agriculture, their soil health and carbon (C) sequestration potential, with implication for climate change mitigation, remains underexplored. This study assessed soil samples collected from raised beds (gardening area) and adjacent bare ground (control) at six community gardens in the Perth metropolitan area, Australia. These sites covered three soil mapping units (SMUs): calcareous deep sands, coloured sand and pale sands The soil in raised beds exhibited superior characteristics than surrounding urban soil including lower bulk density, higher pH buffering capacity, available nutrients including nitrogen (N), phosphorus (P) and potassium (K), cation exchange capacity (CEC), total C and microbial biomass. Notably, we estimated that raised bed soils accumulated significant levels of C in the top 10 cm layer (0.55 kg/m2 or 5.5 T/ha). Our findings also indicate no significant heavy metal contamination in any of the community garden soils. Although the global area of community gardens is marginally small, these results suggest they hold potential for carbon sequestration, especially in urban and peri‐urban environments. The improved soil health and C storage potential in community garden soil are largely attributed to the regular application of compost produced within the community gardens.

A Soil Analysis Approach to Assessing Potential Loss of Productive Lands Under Agricultural Land Conversion

Land provides physical space and is usually required for various sectoral developments needed to meet the needs of increasing population. Land is a finite natural resource; thus, conflict arises over land use and development. The strategic location of the municipality of Pura in Tarlac province, Philippines within the urban beltway of Central Luzon and the recent opening of the Tarlac–Pangasinan–La Union Expressway provide Pura excellent opportunities for urban and industrial development. However, the precursor to this is agricultural land conversion (ALC), which can change or reduce in the area of productive lands. This paper assessed the degree of productivity of the agricultural lands in the study area that are predisposed to ALC using FAO’s land suitability framework and the revised Storie index for soil productivity. Soil survey and composite soil sampling at 20 cm depth in the selected 34 sampling points were done to analyze the relevant soil physical and chemical properties. Five soil mapping units (SMU) were grouped based on the soil surface texture. The results show that the SMUs are only marginally suitable (S3f) for producing rice and other crops due to their current low soil organic carbon content. However, these SMUs can be highly suitable (S1) for crop production with appropriate soil management. Using the Storie index, the entire tract of land of Pura has an index rating of 58 percent, which corresponds to a grade 3 soil suitable for planting a number of crops with expected good results. The results of the land suitability evaluation and soil productivity assessment further show that the land in the municipality of Pura is productive, and thus can benefit both agricultural production and ALC. As such, whichever spatial strategy or policy direction for ALC that the municipal government chooses to adopt, the municipality of Pura will lose productive land.

Genosoil and phenosoil mapping in continental Australia is essential for soil security

The intensification of human pressures on soil can reduce pedodiversity and decrease soil multifunctionality impacting soil security. Mapping genosoils (least modified soils within a soil class or soil map unit by contemporary drivers of soil change) and phenosoils (variants resulting from land use history and management) can be a preliminary step for quantifying soil security dimensions and prioritising areas for soil preservation and regeneration. Genosoil properties can be used as a baseline for assessing the effects of management on soil condition for a particular pedological, climatic and landscape context. In this study, we stratified Australia into 1370 pedogenons (i.e., groups with relatively homogeneous environmental covariates, proxies of soil-forming factors) that represent soil classes prior to the European settlement from 1788 onwards. We overlayed the maps of global Human Modification and the Habitat Condition Assessment System for Australia for identifying areas with minimum human influence on terrestrial ecosystems and soils. Areas with very low human influence were defined as genosoils at the continental level. The percentage of land mapped as genosoils accounted for 56% of the continent and had a median area of 2550 km2. There were 32 pedogenon classes that did not have any remaining genosoils while 218 pedogenon classes had less than 5% of their area as genosoils. The proportion of genosoils protected in conservation areas or managed resource protection varied widely, although almost 25% of the genosoils had at least half of their area under conservation. In addition to soil multifunctionality, the criteria for prioritising soil conservation areas could consider: 1) endangered genosoils and 2) genosoils closest (in the scorpan feature space) to the phenosoils without an existing reference soil.

Characteristics of Soil Chemical Properties Associated with Inceptisols in Various Land Use in Jasinga, Bogor

Inceptisols are soils with low to moderate fertility and have not experienced further development. This study aims to characterize the chemical properties of inclusions and base exchange fractionation of P of soil on Inceptisol soil map units of forest land, dry land, and paddy fields in Jasinga. Soil samples were taken at three horizons (Ao or Ap, AB/B1, and B/Bt) on forest soil profiles and dry land, while on paddy fields, they were taken at a depth of 0-20 cm, 20-40 cm, and 40-60 cm from the surface land. The chemical properties of the soil analyzed were soil pH, C-organic, soil bases, P-total, CEC, base saturation, and P fractionation. The results showed that the chemical properties of inclusions in the Inceptisol Jasinga soil map unit included high CEC and BS and low Mn-dd. The dominant soil inclusions are in paddy fields, followed by forests, and the lowest is in dry land. The chemical properties findings did not significantly differentiate the available inorganic P, Al-P, (Fe, Mn)-P, and (Ca, Mg)-P fractions. The inclusion of chemical characteristics did not result in a reversal of the correlation with the inorganic P fraction.

Subaqueous pedology and soil‐landscape model evaluation in South River, Maryland, USA

AbstractUsing a subaqueous soil‐landscape conceptual model previously developed in an adjacent subestuary, a subaqueous soil survey was undertaken for the South River subestuary of Chesapeake Bay. Using available bathymetry, subaqueous landforms and soil map units were delineated prior to the initiation of any field work. To evaluate the predictive usefulness of the conceptual model, the study area was subsequently sampled at 52 points along specified transects. The soils were described and classified, and the observed soils were compared to the predicted soils from the model using a bootstrapping analysis approach. We concluded that the conceptual model did provide significant positive guidance to generate a useful soil map in South River, by successfully predicting the distribution of soil material types. It did not, however, address the distribution of hypersulfidic materials prevalent in South River soils. The additional information gained on the soils and pedogenic processes gained during this study were incorporated into the final soil survey for the subestuary, and they were also used to refine the soil‐landscape conceptual model to improve its potential usefulness in future mapping of western shore subestuaries of Chesapeake Bay.

Improving digital soil mapping in Bogor, Indonesia using parent material information

Digital soil mapping depends on the accurate representation of soil forming factors in the form of spatial layers called scorpan. Within the scorpan factors, digital elevation model (DEM) and its derived data are the most commonly used covariates, while parent materials and soil age received the least attention. This may be due to the coarse resolution or complex interpretation of parent material maps. This study examines the role of parent material derived from a semi-detailed soil map as a covariate for improving the accuracy of digital soil maps. The study was conducted in Bogor, West Java (2663.81 km2). Observations of 56 soil map units consisting of 19 soil subgroups of the USDA Soil Taxonomy were made on an existing 1:50,000 soil map. The study evaluated the contribution of covariates representing soil, organisms, relief and parent material in predicting soil classes using random forest models. The results show that the inclusion of parent material covariate can increase the total accuracy of predicting soil classes from 44.60 to 66.19% to 59.91–73.89%. The combination of 13 covariates representing topography, soil, organisms and parent materials achieved the highest accuracy above 70%. On the other hand, the most parsimonious set of covariates that can achieve 66.02% accuracy includes DEM, NDVI, NDWI, and parent material. The use of parent material covariate derived from detailed soil maps can improve the accuracy of digital soil mapping of soil classes in regions derived from complex volcanic materials.

Effect of potassium application rate on cotton growth and yield under irrigated and dryland conditions

AbstractPotassium (K) deficiency in cotton (Gossypium hirsutum L.) grown on soils with adequate soil test K levels has become more prevalent. Field experiments were conducted with or without irrigation as the main plot and K fertilizer rates as subplot treatments. Granular K was applied preseason at rates of 0, 45, 90, 134, 179, and 224 kg K ha−1. Two in‐season foliar K programs applied a total of either 2.8 or 5.6 kg K ha−1 were included to compare against the check. Experiments were set up on two distinct soil mapping units (SMUs) in Starkville, MS, including a Leeper silty clay loam (LSCL; fine, smectitic, nonacid, thermic Vertic Epiaquepts) and a Marietta fine sandy loam (MFSL; fine‐loamy, siliceous, active, thermic Fluvaquentic Eutrudepts). Response variables collected include lint yield and fiber quality, leaf K concentrations, and cotton growth and development parameters. Across all years of the experiment, LSCL lint yields increased at a rate of 41 and 118 kg ha−1 per 45 kg K ha−1 under rainfed and irrigated conditions, respectively. On the MFSL, lint yield increase was not significant for either rainfed or irrigated conditions. Leaf K concentrations at first bloom and 4 weeks after first bloom responded quadratically to K rate, with peak leaf K concentrations occurring between 134 and 179 kg K ha−1. Differences in cotton growth parameters were observed; however, differences were likely physiologically insignificant. For all parameters, foliar K application programs did not differ from the untreated check. This investigation showed that foliar K application alone are insufficient, and responses to granular K and irrigation were dependent on SMUs.

The diagnostic continua of the soils of Europe

Diagnostic horizons, properties and materials are commonly applied building units of national and international soil classification systems. The presence, depth or absence of diagnostic information supports the process of objective soil classification, such as the World Reference Base (WRB). While the diagnostic units and associated descriptive qualifiers convey information that reflect pedogenesis, they also indicate important, and often complex properties that are related to soil fertility and other soil functions. The spatial extent or the continuum of diagnostic information is often different from the spatial extent of the mapping units in general soil maps (mostly reflecting soil types). This paper presents the spatial distribution of selected diagnostic units and qualifiers for the European Union and describes their significance for key soil functions. The derivation of selected diagnostics was performed based on the information provided in the European Soil Database and by taking into consideration the definitions, rules and allocation procedure of soils to the appropriate Reference Soil Group (RSG) defined by the WRB key. The definition of the presence/absence of the diagnostic units were performed by extracting information related to the first level of the WRB classification and to the qualifiers provided by the ESDB on the Soil Taxonomic Units (STU) level. The areal percentage of the STUs (thus, the derived diagnostics) within Soil Mapping Units (SMUs) was calculated and was visualized on separate maps. The study demonstrated the importance of the spatial information that the diagnostic elements convey, especially related to soil functions.

Application and evaluation of a subaqueous soil‐landscape conceptual model in the West River subestuary, Maryland

AbstractA soil‐landscape conceptual model developed in the Rhode River subestuary of Maryland was applied to create a soil survey for the adjacent West River subestuary. The survey for the West River subestuary was completed before samples were collected there to evaluate the soil‐landscape conceptual model used to generate the soil survey. The West River subestuary was then sampled along transects that crossed soil map units to compare observed soil taxa with predicted soil taxa. Observed transect samples were classified and scored based on their similarity to predicted taxa in soil map units. These data were resampled via a bootstrapping method to determine if the predictions of the West River subestuary soil survey were significantly different from random predictions. Significant information was provided by the survey, and therefore by the soil‐landscape conceptual model used to generate it.

Estimating land cover-based soil organic carbon to support decarbonization and climate resilience planning in Massachusetts

Land management and land cover change exert a strong influence on soil organic carbon (SOC) storage. As scientific, political, and business communities increase their awareness of the essential roles SOC plays in climate regulation and ecosystem functions, efforts to quantify the impacts of land use and management on SOC have increased rapidly. Existing methods of estimating SOC stocks from widely available data do not account for land cover, and are therefore of limited usefulness in understanding the impacts of past and future land use change. This project explores a method of linking land cover to SOC using data from public datasets and the scientific literature, to provide an SOC Inventory for Massachusetts, and compares the results to those derived from a common baseline approach. Our method derives average land cover SOC values by combining data from the USDA-NRCS Rapid Carbon Assessment and the National Cooperative Soil Characterization Database with values from a meta-analysis of scientific literature. These are applied to the total area of the 20 most abundant land cover classes of Massachusetts. We compare this land cover-based approach with a baseline using SOC values found in the Soil Survey Geographic Database (SSURGO), applied to each soil map unit found within Massachusetts. Our approach produced an estimated stock of 481 million metric tons of SOC, 29% and 109 million metric tons greater than the SSURGO baseline. We use these estimates to explore the use of the land cover based SOC values to project the impacts of likely land cover change by 2050.

The Role of Digital Soil Information in Assisting Precision Soil Management

Soil information is the basis for the site-specific management of soils. The study aimed to digitize soil information and classify it into soil mapping units (SMUs) using geostatistics. The study area was grouped into 12 SMUs, or management zones. The pH of the soils ranged from 7.3 in SMU2 to 8.6 in SMU5. Most SMUs exhibited low total nitrogen (TN) that could be attributed to very low soil organic carbon (SOC) in the soils. Available phosphorus (AvP) was very low in all the mapping units. The exchangeable K varied between 0.12 cmol(+) kg−1 (SMU7) and 0.95 cmol(+) kg−1 (SMU10). SMU12 was identified as marginally sodic and at a high risk of developing severe alkalinity unless possible management measures are implemented. Our findings show that a lack of soil information causes an imbalance between soil requirements and external nutrient inputs, negatively affecting crop production. Therefore, high-resolution digital soil information can assist the site-specific application of soil nutrients and amendments based on spatial variability in line with soil requirements.

Importance of the mapping unit on the land suitability assessment for agriculture

Land suitability assessment (LSA) provides geospatial information about growing crops where they are best suited and can play a crucial role in addressing contemporary challenges such as feeding 9 billion people by 2050, coping with climate change, and enabling sustainable production. Despite the known limitations of the current mapping units (conventional soil map units) used for LSA, alternative methods to objectively delineate mapping units, such as geographic object-based image analysis (GEOBIA) or geomorphons have never been tested for LSA. The objective of this work is to quantitatively assess the effects of different polygon-based mapping units on LSA for agriculture: 1) conventional soil map units; 2) units delineated semi-automatically using GEOBIA; 3) geomorphons. In addition, the three delineation procedures will be compared with the pixel-based LSA conducted as a benchmark. LSA is conducted within the framework of the existing Romanian rating methodology for land suitability, which was developed based on FAO guidelines for land evaluation. We use georeferenced soil profiles with field-measured soil properties and digital terrain models to digitally map 17 eco-pedological indicators (e.g. soil pH, soil texture, soil porosity, gleization, carbonate content, humus content). Based on several lookup tables, these maps are transformed into digital maps with suitability ratings for 14 crops, 7 fruit trees, and 2 land-use types, ranging from 0 (not suitable) to 1 (maximum suitability). The product (multiplication) of the 17 maps with LSA ratings is the final suitability map for each crop and land use. Overall, the best maps were obtained when the LSA was conducted using the GEOBIA units (similar accuracy to the pixel-based approach), whereas geomorphons and conventional soil map units resulted in much poorer maps. GEOBIA is much more suitable for LSA than the conventional soil map units and geomorphons, showing a much higher accuracy and internal homogeneity. Another conclusion is that the LSA based on conventional soil map units recorded the poorest accuracies by far. Our results show that the GEOBIA-based units or pixel-based approach are the right choices when conducting LSA, however, if the map user (eg. farmer, land manager) needs delineated units as semi-permanent and stable regions to manage them as stable spatial entities then GEOBIA technique should be used for LSA.

Cover crop management practices to promote soil health and climate adaptation: Grappling with varied success from farmer and researcher observations.

Soil health is a pathway through which farm and environmental outcomes can be improved together on agricultural landscapes, and management to improve soil health is increasingly recognized as a strategy for agricultural producers to adapt to climate change-related impacts such as erosion and flooding. Many incentive programs exist or are in development to support the adoption of practices that promote soil health for these reasons, but few on-farm trials have compared the intersections of farmer versus researcher observations of soil health or of soil health compared with climate adaptation. The purpose of our study was to assess soil health outcomes and adaptation to simulated climate change in response to cover cropping on working farms enrolled in a Minnesota Natural Resources Conservation Service (NRCS)-funded Environmental Quality Incentives Program. This incentive program required the inclusion of diverse cover crop mixtures into existing farm crop rotations. We conducted farmer surveys, NRCS protocol field soil assessments, and NRCS-recommended laboratory assays on farms from across the state of Minnesota in a paired design comparing fields on the same or adjacent farms of the same soil mapping unit. Although 85% of farmers reported improvements in soil attributes or productivity, most field and laboratory assessments produced a high amount of variability in responsiveness to cover cropping. Despite this variability, we saw a significant decrease in bare ground and significant increases in earthworm counts, cellobiohydrolase microbial activity, and the Visual Evaluation of Soil Structure (VESS). Although researcher measurements did not show improvement in physical characteristics or infiltration other than the VESS field assessment, 67% of farmers reported improvements to the physical structure of the soil, associated with improved outcomes such as earlier planting dates and consistent crop growth across fields. When more than five species of cover crops were present, the percentage of reported improvements increased to >80%. We also found no significant improvement to climate change adaptation measured by nutrient or sediment loss after a simulated storm event. Together, our results suggest that adding a diverse annual cover crop mix to increase continuous cover can improve characteristics associated with soil health and that there needs to be a stronger focus in understanding variation in realized soil health outcomes on farms, including more co-creation of research with farmer partners.