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Soil health assessment is fundamental to guiding sustainable soil management practices, ensuring healthy soil, crop productivity, and provision of other ecosystem services. Interpretation of soil health in intensive agriculture in the North China Plain (NCP) is still lacking due to an over emphasis on soil chemical management and large variations among smallholders’ farmlands. The objectives of this study were to (i) compare soil health assessment approaches in response to fertilization regimes, (ii) quantify relationships between soil health and agronomic outcomes, (iii) develop a minimum data set to simplify soil health assessment, and (iv) validate soil health assessment frameworks in smallholders’ fields on the NCP. We collected soil samples from eight wheat-maize rotation long-term experiments which were divided into three fertilization regimes: (1) NPK, application of chemical fertilizers only; (2) M, application of organic materials only; and (3) MNPK, combined application of organic materials with chemical fertilizer application. Three soil health indexing (SHI) approaches, Comprehensive Assessment of Soil Health (SHI-CASH), linear (SHI-L) and sigmoidal (SHI-Sig) were evaluated. SHIs in the M and MNPK treatments were significantly higher than those in the NPK treatment across assessment approaches and were positively correlated with maize yield. A minimum data set including subsurface hardness, wet aggregate stability, available K, available Fe, soil organic carbon and soil protein was established using best subset regression. The soil health indices of smallholders’ farmlands using CASH and MDS were 0.58 (0.42–0.73) and 0.63 (0.40–0.87), respectively. More than 60% smallholders’ fields was at middle or low level. The relationship between SHI-CASH and SHI-MDS (Sig) was better than those for the CASH and linear methods. Our results demonstrate that an MDS based on best subset regression is applicable for evaluating soil health in wheat-maize rotation systems in the NCP. Soil health assessment in smallholders’ farmland indicates that soil health constraints are related to soil and biomass management, which provides insights on pathways towards addressing soil health gaps.

Understanding yield potential and yield-limiting factors is essential for improving profitability and grain yields while avoiding adverse environmental effects. In the USA, grain yield monitors are widely used but the information they provide is rarely used to understand within-field yield variations and associated yield constraints. The objectives of this research were to understand the influence of in-season precipitation on within-field spatio-temporal variation of maize (Zea mays L.) yield and to determine manageable yield variation in two contrasting Major Land Resource Areas of the Mid-Atlantic USA. It does this by assessing the association of grain yield monitor data and in-season precipitation information to be used for variable rate management. Maize yields, as evaluated by baseline functions, were more closely associated with in-season precipitation in the Coastal Plain than in the Piedmont. The study then used standardized principal component analysis (stdPCA) to reveal within-field yield patterns. These varied only under moisture-limited conditions in the Coastal Plain. In the Piedmont, the within-field yield pattern was more consistent under a range of in-season precipitation conditions. In Coastal Plain rainfed fields, the yield predictability increased at the end of June, indicating the possibility of predicting within-field spatial patterns in mid-season. These approaches were successful in deciding whether within-field site- and time-specific management is beneficial for a particular region or field. The presented method, combining stdPCA and geostatistical assessment, is useful in strategizing precision crop management, but do not reveal causes. Detailed soil information and topography could additionally be valuable for understanding constraints to crop yield.

Irrigation consumes three quarters of global water withdrawals each year. Strategies are needed to reduce irrigation water use, including increasing the efficiency of transfer methods and field application. Comprehensive restoration of soil health, specifically through organic matter amendments, can substantially reduce irrigation demand and increase crop yield. A program to restore severely degraded and desertified soils by incorporating coarse woodchips into the soil successfully increased rainfall capture and elevated soil moisture for several weeks between rainfall events at both Ningxia, north-west China and North Dakota, USA. With addition of fertilizer, woodchip incorporation further increased growth of wheat and alfalfa. Comprehensive soil health assessment of remnant grasslands was used to develop target reference soil profiles by which to guide restoration efforts. Given that most agricultural soils are degraded to some degree, soil health restoration can provide a powerful strategy toward achieving global food and water security.

Soil health assessment may be enhanced by monitoring changes in bacterial populations that are indicators of various biological, physical, and chemical properties of soil. However, the lack of ecological information for many abundant bacteria in agricultural soils limits our understanding of indicator responses and, thus, their utility for guiding management. We identified bacterial indicators of twelve conventional measures of soil health, and tillage intensity, from a 16S rRNA gene-based survey of farmland across North America. We then analyzed trends according to bacterial life-history frameworks and an environment-wide association survey (EWAS) to gain ecological insights. Life-history traits were assessed using genomic traits inferred from taxonomic classifications and included: genome size,rrncopy number, and coding density. An EWAS was conducted using 89 studies of agricultural land management. Most bacterial indicators were positively correlated with biological measures and negatively correlated with physical and chemical measures of soil health, revealing broad differences in the way management shapes bacterial associations with soil health. High soil health ratings corresponded with life-history traits associated with metabolic dependency (smaller genome and lower coding density), while lower health scores corresponded with traits selected for by environmental instability and disturbance (larger genome and multiplerrn). Trade-offs in community-weighted genome size explained most variation in overall health score. EWAS confirmed the importance of disturbance-adapted bacterial indicators, underscoring the impacts of tillage on soil bacterial communities. These findings provide insights into the ecological relationships between bacterial indicators and soil health and illustrate new approaches for interpreting patterns in microbiome data.

Soil health (SH) of managed lands in India is affected by anthropogenic activities such as nutrient mining, excessive tillage, and monocropping, which reduce the productive capacity of soils. A comprehensive SH characterization was conducted in 27 catchments in six districts of Jharkhand, India. Each was stratified into four landscape positions: (i) uncultivated upland in tree vegetation, (ii) cultivated upland in garden or orchard use, and (iii) midland and (iv) lowland areas in rice-fallow fields, yielding 113 soil samples from 0 to 15 cm and 20 from 30 to 40 cm depths. Soil textural separates as well as 15 dynamic physical, biological, and chemical properties were assessed using the Comprehensive Assessment of Soil Health framework. Nutrient analyses indicate low to very low P and K values, but high micronutrient levels. A district level ANOVA shows effects of inherent soil factors on the indicators. The influence of tillage, nutrient extraction as well as landscape hydrology on soil health indicators was apparent, notably showing uncultivated soils with higher overall SH. Puddle tillage affected the surface and subsurface soil, the latter showing reduced water holding capacity and less favorable biological indicators. Multivariate analyses showed directional separation of biological and chemical indicators in the first two principal components. A Best Subsets Regression analysis revealed organic matter, soil respiration and active carbon as the most predictive in determining overall SH scores (R2adj = 0.87). In conclusion, a comprehensive soil health assessment using a spatial framework in Jharkhand, India identified multiple SH constraints related to farmer management, associated organic matter dynamics, and natural factors.

Tillage and no-tillage result in different soil mechanical responses which in turn may affect crop growth. Better understanding of soil compressive behavior, therefore, is relevant for the assessment of tillage practices in agricultural systems. We studied the change in soil compressive properties and their relationship with soil physical attributes and plant growth through a chisel tillage chronosequence in a Nitisol where soil was untilled after chiseling for 24 months, 18 months, 12 months, 6 months, and zero months, and was under continuous (12-year) NT. The effects were measured for three soil depth layers: 0 to 7-cm, 7 to 17-cm and 20 to 30-cm. Mechanical chiseling was found to reduce both the degree of compactness and the pre-compression pressure compared to continuous NT, but made the soil more susceptible to new compaction. The effects of chisel tillage generally persisted for a period of 12–24 months. The degree of compactness and soil pre-compression pressure were found to be strongly correlated, and were strongly correlated with other soil physical attributes (soil penetration resistance, soil macroporosity, and soil aggregate stability). They were negatively correlated with root length, root density, and root volume, as well as stalk diameter, linking soil structure indicators to plant growth. Our results also showed that soil compressive parameter values can be estimated based on other soil physical properties that influence plant growth. These findings have potential for studies of crop response to soil structure and soil compaction and could be used to aid in choosing optimal soil management practices, in order to reduce the risk of soil compaction, linking soil compressive behavior and soil physical conditions to plant growth.

Soil organic carbon (SOC) influences several soil functions, making it one of the most important soil health indicators. Its quantity is determined by anthropogenic and inherent factors that must be understood to improve SOC management and interpretation. Topsoil (&le, 15 cm) SOC response to tillage depth and intensity, cover crops, stover removal, manure addition, and various cropping systems was assessed using 7610 observations from eight U.S. regions. Overall, including cover crops, reducing tillage depth and intensity increased SOC. The positive effects of cover crops were more noticeable in South Central, Northwest, and Midwest regions. Removing high rates (&gt, 65%) of crop residue decreased SOC in Midwestern and Southeastern soils. Depending on region, applying manure increased SOC by 21 to 41%, compared to non-manured soils. Diversified cropping systems (e.g., those utilizing small mixed vegetables, perennials, or dairy-based systems) had the highest topsoil SOC content, while more intensive annual row crops and large-scale single vegetable production systems, had the lowest. Among inherent factors, SOC increased as precipitation increased, but decreased as mean annual temperature increased. Texture influenced SOC, showing higher values in fine-texture than coarse-texture soils. Finally, this assessment confirmed that SOC can be a sensitive soil health indicator for evaluating conservation practices.

The performance of no-till (NT) in temperate regions may be enhanced through the integration of additional conservation practices such as cover cropping and crop rotations. This study assessed the long-term impacts of continuous (20+ years) NT in comparison to plow-till (PT) management on soil properties and corn (Zea mays L.) yields in New York. The effects of tillage were assessed in combination with different cropping systems (24 years corn monoculture vs. 12 years corn monoculture; and with or without interseeded cover crops) on three soil textures: clay loam, loamy sand and silt loam. We measured four soil biological indicators - organic matter (OM), active carbon (ActC), respiration (Resp) and protein (Prot); four soil physical indicators - available water capacity (AWC), water stable aggregation (WSA), penetration resistance (PR) and water infiltration rate (InfRate); soil chemical indicators (plant available nutrients, pH and total N), and corn yield. Soil managed under long-term NT showed the most favorable soil biological, physical and chemical conditions for plant development, with higher levels of OM, Prot, Resp, WAS, total N, P and Zn, and InfRate. Benefits of introducing a grass-legume cover crop mixture into the cropping system were evident after 4 years for OM, Prot, Resp, AWC, Fe and Zn. Cover crop effects were greater under NT than PT, and additive to the NT benefits. On the clay loam soil, the effects of a 6-year interruption of continuous corn production with a perennial grass crop were still discernable with several soil health indicators 12 years after resuming corn production under NT. The better soil conditions under NT resulted in higher corn yields in both the loamy sand and silt loam soils, but not the clay loam. Our study shows that long-term NT can be viable in temperate regions, promoting significant improvement in soil health and crop yield and that these benefits are enhanced when NT is combined with crop rotation (perennial grass) and cover crops.

Human waste contains ample plant-available nitrogen (N) and phosphorus (P), which can be used to address soil nutrient deficiencies. Biological and thermochemical sanitization methods have been proposed for safely treating the solid fraction of human waste (called human solid waste [HSW] in this study) but have rarely been compared directly. Furthermore, interactions between amendments and soil properties are also unclear, as pH, texture, and the presence of oxides all affect N and P availability. We therefore evaluated the effect of three HSW sanitization methods, thermophilic composting (60°C), torrefaction (200°C), and pyrolysis (300°C, 500°C), on N and P availability following incubation in four soils with different pH (4.6–7.4), textures (clay loam to loamy fine sand), and mineralogy. We also evaluated the effect of added urine with pyrolyzed HSW (500°C) on N and P availability in soils. A trade-off between N and P availability was observed with highest heating temperature of HSW, the magnitude of which varied with soil type. Compared with pyrolyzed HSW (500°C), composted HSW increased available soil N by 15% to 25%, whereas torrefied HSW increased available soil N by 40% to 57%. The change in P availability over time increased with pyrolyzed HSW (500°C) by 41% to 106% and 84% to 165% compared with composted and torrefied HSW, respectively. Multivariate linear regression highlighted the negative correlation between P availability and both soil oxides and amendment dissolved organic carbon. Combined fertilization with pyrolyzed HSW (500°C) and urine ameliorated low N, while preserving high soil P availability, which was 44% to 147% greater than soils fertilized with urine alone. Pyrolyzed HSW (500°C) lowered pH by 0.06 to 0.38 units compared with urine-amended soils with no pyrolyzed HSW. In conclusion, low N and P availability was observed with composted HSW (29–46 kg N ha, 6–15 kg P ha); ample N and moderate P were available with torrefied HSW (71–107 kg N ha, 12–30 kg P ha), whereas excess mineral N and ample P were provided in soils amended with pyrolyzed HSW (500°C) together with urine (404–486 kg N ha, 33–81 kg P ha) albeit at the expense of mild soil acidification.

Farmers, food supply-chain entities, and policymakers need a simple but robust indicator to demonstrate progress toward reducing nitrogen pollution associated with food production. We show that nitrogen balance—the difference between nitrogen inputs and nitrogen outputs in an agricultural production system—is a robust measure of nitrogen losses that is simple to calculate, easily understood, and based on readily available farm data. Nitrogen balance provides farmers with a means of demonstrating to an increasingly concerned public that they are succeeding in reducing nitrogen losses while also improving the overall sustainability of their farming operation. Likewise, supply-chain companies and policymakers can use nitrogen balance to track progress toward sustainability goals. We describe the value of nitrogen balance in translating environmental targets into actionable goals for farmers and illustrate the potential roles of science, policy, and agricultural support networks in helping farmers achieve them.

Specialty coffee markets that recognize coffee-quality price premiums can improve business conditions for smallholders and promote agro-ecological practices. We studied the Relationship Coffee Model (RCM), a business model that supports long-term partnerships between coffee buyers and smallholders based on product quality. We examined how biophysical conditions and production practices affect smallholders’ ability to participate in this model. Furthermore, we considered common unobservable variables driving growers’ participation such as farm soil quality and connection to social networks. In turn, we evaluated key environmental, socio-economic and technological outcomes, including tree and bird population diversity. Our estimations indicated that RCM participants employed more sustainable resource management practices, had better access to credit and were more informed and optimistic about the coffee business. However, we did not find significant farm-gate price differences. Increased adoption of organic farming and shade-grown systems to elevate coffee quality can stimulate sustainable business strategies. Copyright © 2018 John Wiley & Sons, Ltd and ERP Environment

Soil health encompasses a range of biological, chemical, and physical soil properties that sustain the commercial and ecological value of agroecosystems. Monitoring soil health requires a comprehensive set of diagnostics that can be cost-prohibitive for routine analyses. The soil microbiome provides a rich source of information about soil properties, which can be assayed in a high-throughput, cost-effective way. We evaluated the accuracy of random forest (RF) and support vector machine (SVM) regression and classification models in predicting 12 measures of soil health, tillage status, and soil texture from 16S rRNA gene amplicon data with an operationally relevant sample set. We validated the efficacy of the best performing models against independent datasets and also tested best practices for processing microbiome data for use in machine learning. Soil health metrics could be predicted from microbiome data with the best models achieving a Kappa value of ∼0.65, for categorical assessments, and a R2 value of ∼0.8, for numerical scores. Biological health ratings were better predicted than chemical or physical ratings. Validation with independent datasets revealed that models had general predictive value for soil properties, including yield. The ecological profiles of several taxa important for model accuracy matched the observed relationships with soil health, including Pyrinomonadaceae, Nitrososphaeraceae, and Candidatus Udeaobacter. Models trained at the highest taxonomic resolution proved most accurate, with losses in accuracy resulting from rarefying, sparsity filtering, and aggregating at higher taxonomic ranks. Our study provides the groundwork for developing scalable technology to use microbiome-based diagnostics for the assessment of soil health.

Understanding the impact of soil degradation on crop productivity is essential for decision-makers to predict agronomic, economic, and environmental outcomes of agricultural operations. Soil organic carbon (SOC) is influenced by the cropping system and affects soil health through its effect on other soil physical, chemical, and biological properties. Data from a 56-year long-term experiment in Uruguay’s Pampa region were analyzed to quantify the effects of soil degradation on wheat (Triticum aestivum L.), and barley (Hordeum vulgare) yields. A significant degree of soil degradation was generated by six rotations with variable annual crop and pasture proportions (0%, 33%, 50%, and 66% of non harvest pasture). Yield records (n = 368) and annual values of 14 explanatory variables containing soil, climatic, and management indicators were evaluated using random forest regressions. Rotation-induced SOC variation ranged from 1.2% to 2.6%, and robust relationships between SOC, soil physical, chemical, and biological properties were established. Over time, yields increased in crop pasture systems but plateaued for the annualized crop rotation (0% pasture). Yield improvements due to agronomic technology advances partly mask soil degradation effects. SOC losses lead to a reduction in yield, even when the SOC level was above 2%. Thus, no critical level of SOC could be determined. SOC interacted with climate indicators to impact yield. This analysis confirms the central role of SOC in yield outcomes beyond nutrient availability, and its potential to represent a wide range of soil functions. Our findings indicate that crop rotations with a higher percentage annual vs. perennial crops negatively impact SOC, associated soil properties, and yield potential.

N itrogen (N) is an essential nutrient for crop production, and the manufacture of synthetic N fertilizer has facilitated impressive advances in food production that have assisted in the avoidance of widespread hunger despite a rapidly growing twentieth century global population. However, this nutrient also causes major environmental concerns, including nitrate (NO3−) contamination of groundwater in agricultural regions and hypoxia and dead zones in estuaries. Also, gaseous forms of N contribute to air quality issues. Nitrous oxide (N2O), a potent greenhouse gas, contributes to climate change, and ammonia (NH3) emissions contribute to fine particulate air pollution, a cause of respiratory diseases (Pinder et al. 2007). Anthropogenic N pollution, therefore, has large social costs, with estimated potential ecosystem and health damages of US$157 billion annually (Sobota et al. 2015). Despite many mitigation efforts, the N loss from agricultural systems continues to be a major concern, and in 2017 the hypoxic zone in the Gulf of Mexico reached the greatest extent ever recorded (NOAA 2017). There is a pressing need to improve the management of agricultural N, and the 4R concept has been proposed as a conceptual path toward more efficient N management (Snyder et al. 2009; TFI 2017). This approach promotes field…

In the northern Great Plains vast amounts of native grassland have given way to crops, mostly small grains and corn, over the past half century. It is well understood that over the long-term, grassland conversion accelerates erosion and generally decreases many soil functions. It is less clear, however, what short-term effects occur to the soil from grassland conversion; after the first or second year of conversion. The objectives of this study were to assess the short-term (first year) effects of converting land that is considered long-term grassland to small grain production through either conventional tillage (CT) or no-till (NT) practices using various indicators of soil health and to demonstrate how tools such as the Comprehensive Assessment for Soil Health (CASH), can be used to document soil health indicator decline immediately upon conversion from grassland to small grains. The CASH offers a suite of chemical, physical and biological soil tests to broadly assess soil health. In general, these indicators showed a more rapid decline in soil health under CT than NT. After the first year of grassland conversion, aggregate stability declined by 7% and 19% in the NT and CT plots, respectively when compared to the grassland control. Likewise, CT produced significantly greater declines in permanganate oxidizable carbon (POX-C) and soil protein (ACE-Protein), particularly under reduced precipitation. This study highlights how the CASH can provide an intuitive framework for monitoring the effects of land use change and can be used by land managers to identify potential soil constraints and formulate potential interventions.

Both surface and subsoil layers can be a significant source of soil moisture and nutrients for crop growth, but the changes in subsoil properties due to management are rarely assessed. This study was conducted to determine tillage and residue management effects on soil nutrient availability, as well as soil biological and physical conditions throughout soil layers ranging from 0 to 60 cm. We utilized an experiment with 40-year long continuous maize (Zea mays L.) cropping under crossed plow-till (PT) vs. no-till (NT) and residue removed (Harv) vs. residue returned (Ret) treatments on a silt loam soil in Chazy, NY. We assessed soil properties that are indicative of soil processes important for crop growth. Soil physical indicators (texture, bulk density (BD), water stable aggregation (WSA), available water capacity (AWC), and air-filled porosity (AFP)), soil biological indicators (soil organic matter (SOM), permanganate oxidizable carbon, mineralizable carbon, and soil protein), and soil chemical indicators (pH and plant available nutrients) were measured at five depth increments (0–6, 6–18, 18–30, 30–45, and 45- to 60-cm depth). A novel statistical approach of marginal R2 (R2m) was used to show percent variance of each measured soil indicator explained by tillage and residue management as well as the depth of soil sample. R2m was higher for soil biological indicators (0.66

On the Cornell University campus a long-term study has measured the impacts of a soil remediation strategy on plant growth and soil quality using the Cornell Soil Health Test. The Scoop & Dump (S&D) process of soil remediation consists of physically fracturing compacted urban soils, incorporating large quantities (33% by volume) of compost with the use of a backhoe, and annually top dressing with mulch. This study was designed to investigate the impact of this remediation technique for the amelioration of compaction and degradation of soils in the urbanized environment. The study finds that over a 12-year period remediated soils exhibit improved (reduced) bulk density (R2 = 0.50) (P

Soil health, or soil quality, is defined as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans. Traditional views of soil quality often considered soils from the perspective of crop productivity and soil chemical properties, which generally led to an undervaluation of soil biological and physical processes. Soil health is a complex concept that requires a broader understanding of soil properties. It can be implemented through the comprehensive assessment of soil health (CASH) approach, which measures 15 physical, biological, and chemical soil indicators that can be linked to management recommendations. This chapter discusses all 15 tests, including the soil sampling and sample preparation methodologies. The methodology of the eight biological and physical tests is also covered in detail. These measures are interpreted through scoring functions that provide an overall soil health score. A comparison of indicator values between India, Colombia, and three US regions illustrates the need for scoring functions to be regionally adapted to production environments.

Environmental nitrogen (N) losses (e.g., nitrate leaching, denitrification, and ammonia volatilization) frequently occur in maize ( L.) agroecosystems. Decision support systems, designed to optimize the application of N fertilizer in these systems, have been developed using physically based models such as the Precision Nitrogen Management (PNM) model of soil and crop processes, which is an integral component of Adapt-N, a decision support tool providing N fertilizer recommendations for maize production. Such models can also be used to estimate N losses associated with particular management practices and over a range of current climates and future climate projections. The objectives of this study were to update the PNM model to include an option for simulating soil-water processes in artificially drained soils, and to calibrate the revised PNM model and test it against multiyear field studies in New York and Minnesota with different soils and management practices. Minimal calibration was required for the model. Denitrification rate constants were calibrated by minimizing the error between simulated and observed nitrate leaching for each study site. The normalized root mean squared error of cumulative daily drainage for the validation sets ranged from 10 to 23%. For cumulative daily nitrate leaching, the normalized root mean squared error ranged from 11 to 28% for the validation sets. The minimal calibration required and relatively simple data inputs make the PNM model a broadly applicable tool for simulating water and N flows in maize systems.

Low-cost approaches for measuring soil organic C (SOC) stocks are essential for verifying farm management effects on C sequestration in agroecosystems. This study compared sampling and data analysis optimization approaches for estimating SOC stocks of a complex agroecosystem. Soil samples were collected from a 232-ha area of a working dairy farm with multiple land uses, crop rotations, topographic features, and manure application rates. The SOC stocks were estimated by (i) simple mean, (ii) ordinary kriging, (iii) regression kriging, and (iv) using the USDA Soil Survey Geographic (SSURGO) database. Relationships among sampling schemes, estimation approaches, auxiliary information, and SOC stocks were explored. Slope, elevation, soil type, and land use types displayed a high degree of variation at the study site, yet relationships with SOC stocks were weak or nonsignificant. Systematic sampling provided the best coverage of both geographic and attribute space, allowing reliable variogram estimates and RMSEs that increased little with reduced sample number. Random and stratified random sampling approaches resulted in reduced accuracy. Ordinary kriging had lower RMSEs than either regression kriging or the simple mean, and total SOC stocks estimates fluctuated less when sample sizes were reduced. Using SSURGO overestimated total SOC stocks by up to 5.1% compared with the other approaches, suggesting that this approach may be worthy of evaluation for circumstances with a low budget and low confidence level requirements. Systematic sampling and ordinary kriging can provide an optimal strategy for estimating SOC stocks in agroecosystems with complex topography and land uses.

Highlights • Monetary value based on agronomic components was highest with HSW pyrolyzed at 600 °C. • HSW pyrolyzed at 700 °C was of greatest monetary value compared to organic amendments. • High mass recovery with torrefaction maximizes monetary value per unit weight feedstock. • Compost had the lowest value under any scenario., Biological and thermochemical sanitization of source-separated human solid waste (HSW) are effective technologies for unsewered communities. While both methods are capable of fecal pathogen sterilization, the agronomically-beneficial properties of waste sanitized between methods remains unclear. Therefore, this study compared recovery and quality of soil amendments produced by compostation, torrefaction, and pyrolysis of HSW, established their financial value, and quantified tradeoffs between product value and conversion efficiency. Temperature and associated mass losses significantly affected the physical and chemical properties of thermochemically-treated HSW. Thermophilic composting, a biological sanitation method practiced in informal settlements in Nairobi, Kenya, produced an amendment that contained between 16 and 858-fold more plant-available nitrogen (N; 214.5 mg N/kg) than HSW pyrolyzed between 300 and 700 °C (0.2–15.2 mg N/kg). Conversely, HSW pyrolyzed at 600 °C had four-fold higher plant-available phosphorus (P; 3117 mg P/kg) and five-fold higher plant-available potassium (K; 7403 mg K/kg) than composted HSW (716 mg P/kg and 1462 mg K/kg). Wide variation between international fertilizer prices on the low end and regional East African prices on the high end resulted in broad-spaced quantiles for the value of agronomic components in HSW amendments. Phosphorus and K comprised a disproportionate amount of the value, 52–87%, compared to plant-available N, which contributed less than 2%. The total value of treated HSW, summed across all agronomic components per unit weight amendment, was greatest for thermochemically-treated HSW at 600 °C, averaging 220 USD/Mg, more than four-fold that of composted HSW, 53 USD/Mg. In contrast, torrefaction provided the highest monetary value per unit weight feedstock, 144 USD/Mg, as low heating temperatures engender minimal mass loss and higher nutrient densities per unit weight feedstock, compared to composted or pyrolyzed HSW. When benchmarked against total N, P, and K of eight commonly-applied organic amendments, including sewage-sludge (Milorganite), compost, and alfalfa meal, HSW pyrolyzed at 700 °C was of greatest value per unit weight of amendment, 365 USD/Mg, compared to 89 USD/Mg for composted HSW, and contained 2.9% total N (0.5 mg available N/kg), 3.1% total P (7640 mg available P/kg), 3.5% total K (17,671 mg available K/kg).

Soil health deterioration due to intensive agricultural activity is a worldwide problem. To better understand this process, there is a prime need to map soil health over wide areas. This paper aims to quantify soil health in a spatially explicit manner over a large area using soil health indicators. The methodology includes sampling design, autocorrelation analysis and Kriging interpolation. The following variables were measured from vertisol clayey soils: aggregate stability (AS); available water capacity (AWC); surface and subsurface penetration resistance (PR15 and PR45 respectively); root health (RH); organic matter (OM); pH; electrical conductivity (EC); cation-exchange capacity (CEC); exchangeable K; nitrification potential (Np); and P. Stratified random sampling was found to be a more efficient method than random sampling for representing a large area with a limited number of sampling locations. The variogram envelope method was found to be more conservative in determining the significance of autocorrelation than the classical Moran’s I approach. Phosphorus, CEC, PR15, EC, and K exhibited strong autocorrelation in space; other variables showed no autocorrelation. Land management factors were found to control the spatial variability of most soil variables. Kriging with an external drift (KED) was found to be the most useful approach for spatial prediction of soil health. A positive correlation was found between the interpolated soil health index and NDVI (Normalized Difference Vegetation Index). These results suggest that soil health maps can be used to explore how cultivation activities limit crop yields at the catchment scale, and to determine whether these activities create distinctive soil characteristics.

Liming represents a common agricultural practice for abating soil acidity. Nevertheless, elevated amounts of agricultural lime in Oxisols, with or without cultural residue addition, could alter soil physicochemical properties and impact soil structure. In this context, the physical, chemical, and structural behaviors of an Oxisol under the addition of lime and straw were assessed. Lime doses (0, 3.9, 7.8, and 15.6 Mg ha–¹) were either applied on the surface or incorporated into the 0- to 5-cm soil layer. Straw applications followed the same procedure with quantities of 0, 4, 12, or 16 Mg ha–¹. The effects on the soil profile were evaluated through physicochemical (specific surface area, ζ potential, and pH), physical (density, penetration resistance, water dispersible clay, and total porosity), and micromorphological properties (surface area, volume, connectivity, size, and pore anisotropy) 1 yr after soil incubation in polyvinyl chloride cylinders 30 cm long and 14.5 cm in diameter. Lime application on the surface or into the 0- to 5-cm layer increased soil pH to values above 7.0 and the electronegative potential of soil colloid surface, promoting clay dispersion. Water-dispersed clay migrated in the soil profile, causing pore obstruction, and higher soil density and penetration resistance. In addition, excessive lime decreased specific surface area, anisotropy degree and the connectivity of the soil pore system. Straw addition promoted a slight increase of colloids electronegative potential but did not alter soil physical properties.

Increased interest in practical, routine evaluation of soil health has created a need for rapid and inexpensive indicators that reflect soil nitrogen (N) status. Here we propose a soil protein measurement as an indicator of a functionally relevant and sensitive pool of organic N that can be rapidly quantified in soil testing laboratories. The procedure is based on a method that was historically used to measure “glomalin,” a pool putatively of arbuscular mycorrhizal fungal origin. Laboratory validation experiments demonstrate that the procedure extracts proteins from a wide range of sources, not just glomalin, and that continued use of the term is inaccurate and limits the application of the method. Therefore, we propose that the pool of proteins extracted by this method can be viewed more broadly as a soil health indicator that reflects the primary pool of organically bound N in soil and thus as potentially available organic N. We provide a laboratory protocol that details autoclaving soil in a neutral sodium citrate buffer solution followed by clarification and protein quantification steps.

Soil quality refers to the ability of soils to perform their functions well. The soils of the Harran Plain, Turkey, have been put into intensive crop production with the introduction of an irrigation scheme and become increasingly degraded due to unsustainable management and cropping systems that resulted in the loss of production potential. The goal of this study was to quantify the quality of common soil series in the Plain using soil quality indexes (SQI) and to compare SQIs of two long-term crop rotations, cotton and wheat-corn cultivation, and different soil types. Over 400 samples were collected at a 0-to 30-cm depth and analyzed for 31 soil variables. The best representative soil quality variables forming a minimum data set (MDS) were selected using principal component analysis (PCA), and soil quality scores were obtained using both linear and non-linear scoring functions. The MDS included three physical (hydraulic conductivity, bulk density, and plant available water content), two biological (soil organic matter and catalase enzyme activity), and nine chemical soil quality indicators (CEC, pH, plant available Cu and Fe, exchangeable Na and K, soluble Ca, Mg, and Na). Because of the low level of SOM, soil qualities were overall low with indexes obtained using two scoring functions ranging from 38.0/100 to 48.7/100. Correlations between SQI obtained using two approaches (linear vs. non-linear; r > 0.61) and using two data sets (all data vs. MDS; r > 0.79) were high. Non-linear scoring functions were more sensitive to management impacts. ANOVA models testing the individual impacts of soil types and crop management on soil quality were statistically different (p < 0.01), but the models including interactions were not. Overall, the fields under cotton cultivation were generally associated with higher clay contents and had the lowest SQIs as a result of intensive cultivation.

Large temporal and spatial variability in soil nitrogen (N) availability leads many farmers across the United States to over-apply N fertilizers in maize (Zea Mays L.) production environments, often resulting in large environmental N losses. Static Stanford-type N recommendation tools are typically promoted in the United States, but new dynamic model-based decision tools allow for highly adaptive N recommendations that account for specific production environments and conditions. This study compares the Corn N Calculator (CNC), a static N recommendation tool for New York, to Adapt-N, a dynamic simulation tool that combines soil, crop, and management information with real-time weather data to estimate optimum N application rates for maize. The efficiency of the two tools in predicting the Economically Optimum N Rate (EONR) is compared using field data from 14 multiple N-rate trials conducted in New York during the years 2011 through 2015. The CNC tool was used with both realistic grower-estimated potential yields and those extracted from the CNC default database, which were found to be unrealistically low when compared with field data. By accounting for weather and site-specific conditions, the Adapt-N tool was found to increase the farmer profits and significantly improve the prediction of the EONR (RMSE = 34 kg ha⁻¹). Furthermore, using a dynamic instead of a static approach led to reduced N application rates, which in turn resulted in substantially lower simulated environmental N losses. This study shows that better N management through a dynamic decision tool such as Adapt-N can help reduce environmental impacts while sustaining farm economic viability.

The arbuscular mycorrhizal (AM) fungi (phylum Glomeromycota) are important for the functioning of terrestrial ecosystems because of their influence on plant nutrient relations and plant responses to stress. To assess the impact of dispersal limitation and identify niche-related environmental gradients affecting AM fungal community composition and structure, we studied AM fungal communities in an assemblage of maize fields across an eastern New York State landscape. We expressed AM fungal community differences in terms of abundance structure (Bray–Curtis dissimilarities), the presence of unique phylogenetic lineages (UniFrac), and mean phylogenetic relatedness between samples (mean patristic distance, MPD). We did not find strong evidence of dispersal limitation or isolation by distance within or between field sites. To identify environmental factors that may be related to community differentiation, we projected vectors of edaphic variables onto nonmetric multidimensional scaling (NMDS) ordinations of community dissimilarity measures. Of these factors, soil textural components appeared most strongly related to AM fungal community differences. We speculate that this pattern may be explained by the relationship between texture and soil moisture availability. In addition to soil textural components, phylogenetic measures of community differentiation suggested that AM fungal community structure was affected by nutrient concentrations, particularly Mg. Of the two phylogenetic indices of community differentiation, MPD was more consistent and stable with our data, whereas the UniFrac metric failed to be interpretable in several cases. Overall, our data suggest that, rather than phosphorus or pH, soil texture may have an influence on AM fungal community structure over large agroecological scales.

Soil carbon (C) content, often found at elevated levels in manured soils, can play a critical role in regulating nitrous oxide emissions. Nitrate availability and oxygen status are the other primary drivers of emissions, yet the interaction of these three variables and the dynamics of the denitrification process are inadequately known. Emissions of N2O and N2 were measured from two New York State soils that were historically managed either with regular cattle manure applications (M) or without manure (NM). For 168 h, repacked soil cores were maintained at 80 % water-filled pore space after the application of 0, 50, 100, and 200 kg ha−1 of labeled K15NO3. Significant differences were found in the N2O emission profiles between the two treatments with a simultaneous increasing trend in emissions with higher fertilizer applications. The M soil produced 53-, 15.5-, and 8.6-fold increases in N2O emissions over the NM soil at the 50-, 100-, and 200-kg ha−1 N rates, respectively. Additionally, the mean ratio of nitrous oxide to total denitrification (N2O/(N2O + N2)) was higher for M soil. It increased to values of 0.17, 0.25, and 0.43 for fertilizer rates of 50, 100, and 200 kg ha−1, respectively, in contrast to ratios in the NM soil of 0.01, 0.03, and 0.14.

Yields vary spatially and temporally at the field scale, and recent adoption of yield monitoring has accumulated large amounts of yield data. We assessed within-field spatial patterns of profitability using grower-collected yield data and input cost information for fields in the Mid-Atlantic United States. Three types of profitability pattern categories were identified: economically sensitive, clear profitable–unprofitable zones, and all-profitable. For fields with areas of permanent yield constraints, we demonstrated that the removal of unprofitable areas can increase overall field profitability. The combination of site- and time-specific profitability and yield constraint information can inform future management optimization, including removing field areas from crop production and improving site-specific in-season management strategies.

A number of scientists have named our age the Anthropocene because humanity is globally affecting Earth systems, including the soil. Global soil change raises important questions about the future of soil, the environment, and human society. Although many soil scientists strive to understand human forcings as integral to soil genesis, there remains an explicit need for a science of anthropedology to detail how humanity is a fully fledged soil-forming factor and to understand how soil change affects human well being. The development and maturation of anthropedology is critical to achieving land-use sustainability and needs to be nurtured by all soil disciplines, with inputs from allied sciences and the humanities,. The Soil Science Society of America (SSSA) has recently approved a cross-divisional Working Group on Soil Change, which aims to advance the basic and applied science of anthropedology, to facilitate networks of scientists, long-term soil field studies, and regional databases and modeling, and to engage in new modes of communications about human–soil relations. We challenge all interested parties, especially young scientists and students, to contribute to these activities and help grow soil science in the Anthropocene.

Reducing the tillage and application of mulch are important strategies for soil and water conservation and sustainability of agricultural systems. Soil can be a source or sink for carbon (C) depending on management strategies and plays a major role in the global C cycle. These interacting practices can alter nutrient movement and availability to the crops, reduce water loss, slow down organic-matter (OM) decomposition, and thus enhance C sequestration. A 2-year field study was conducted to quantify the tillage and mulching effect on soil organic C (SOC), OM, nitrogen (N), phosphorus (P), and potassium (K) at two depths (i.e., 0–15 and 15–30 cm deep) in the soil profile and N, P, and K concentrations (g kg−1) in plant shoots at harvest on a Typic Calciargids in wheat–maize rotation. The four tillage systems used were zero tillage (ZT), minimum tillage (MT), conventional tillage (CT), and deep tillage (DT), and four mulch rates [control, 2 (M2), 4 (M4), and 6 (M6) Mg ha−1 year−1 wheat (Triticum aestivum L.)...