Soil Management Assessment Framework Research Articles

Artificial neural networks in soil quality prediction: Significance for sustainable tea cultivation

In today's era artificial intelligence is quite popular, one of the most effective algorithms used is Artificial Neural Networks (ANN). In this study, the determination of soil quality using the Soil Management Assessment Framework (SMAF) model in areas where tea cultivation is carried out at the micro-watershed scale and the predictability of soil quality using ANN were evaluated. According to the results, the soil quality indices of tea-growing areas were generally classified as “medium” between 55 and 70 %. Among the evaluated features for determining soil quality, the highest relative importance value was for soil organic carbon content (13 %) and potential mineralizable nitrogen (13 %), whereas the lowest values were for exchangeable potassium (4 %) and sodium adsorption ratio (SAR) (4 %). In addition, when comparing the actual and predicted values for soil quality prediction using ANN, the Lin's concordance correlation coefficient (LCCC), ratio of performance to deviation (RPD), and R2 values were found to be 0.93, 2.95, and 0.89, respectively. Significant properties for the determined values within a 90 % predicted interval were found to be organic matter, microbial biomass carbon, bulk density, and aggregate stability of the soils. Moreover, the uncertainty values (standard deviation) in the model predictions were determined to be within the range of 1.01–4.56 %. Consequently, the Soil Quality Index (SQI) obtained from the SMAF model using 12 soil properties in tea-growing areas could be accurately predicted using ANN. As a result of this study, digital maps showing the spatial distribution of SQI and the predicted uncertainties can help monitor SQI levels in this area.

Long-term effects of tillage systems on soil health of a silt loam in Lower Austria

Tillage is an essential practice for soil preparation in agriculture that influences a broad variety of soil parameters. However, the long-term implications of tillage on soil health are complex, context specific, and need to be better understood. The aim of our study is to evaluate soil physical, chemical, and biological effects of three different tillage practices: conventional tillage (CT), mulch tillage (MT), and no-till (NT). A long-term experiment in Mistelbach, Lower Austria, was launched in 1994 and comprehensively sampled in 2002 and 2021. To evaluate tillage-impacts over the two decadal monitoring we assessed soil health indicators in the 0–20 cm soil depth (conventional ploughing layer) and below 20 cm. A "Soil Management Assessment Framework" (SMAF) procedure was applied to assess and compare soil quality using the Soil Quality Index (SQI). Considering multiple indicators, we found overall quality improvements in all three tillage-experiments over time. However, particularly the conservation practices (MT and NT) enhanced soil quality, predominately soil organic carbon (SOC) and soil physical indicators (e.g. water holding capacity, coarse pores). The study confirms that SOC in the 0–20 cm layer significantly increased under no-till (46 Mg C ha−1) compared to conventional tillage (26 Mg C ha−1). At the same time aggregate stability and water holding capacity increased under conservation agriculture (MT and NT). The proven positive impacts on soil health will further help to promote agricultural practices that sustain productivity while pushing forward climate change mitigation actions in temperate climate.

A framework for selecting and assessing soil quality indicators for sustainable soil management in waste dumps

The primary objective of this study was to develop soil quality indexes (SQIs) to reveal the changes in SQ during the restoration of vegetation in the reclaimed waste dumps of the Hequ open-pit coal mine. The study built an SQI evaluation model for waste dumps based on the soil management assessment framework. The total data set (TDS) consisted of nine physicochemical property indicators. The selection of the minimum data set (MDS) involved the utilization of principal component analysis (PCA) and Norm values. The SQ was comprehensively evaluated for nine indicators, taking into account the non-linear membership function and the improved Nemerow index. The findings suggested a notable disparity in the SQ between the reclaimed area and the unreclaimed area, yet the overall SQ fell short. In the TDS index system, the organic matter has the highest weight and a greater contribution to the soil quality of the waste dumps. In the MDS indicator system, the weights of organic matter and total nitrogen are both 0.5. According to Nemerow index method, the average SQIN of 5 plots is calculated to be 0.4352 ± 0.194. The average value obtained from TDS is 0.581 ± 0.236, and the average value obtained from MDS is 0.602 ± 0.351. The weighted additive method was employed to compute three SQIs, all of which yielded satisfactory outcomes. And the above evaluation methods indicate that the overall soil quality level of the waste dumps is at a moderate level. The sequence of SQ in various waste dumps was as follows: No.4lower > No.1 > No.2 > No.3 > No.4upper. Specifically, the non-linear membership function indicated that pH, available nitrogen (AN), available phosphorus (AP), surface moisture content (SMC), and bulk density (BD) were crucial in limiting SQIs in total waste dumps. The crucial limiting SQIs in unreclaimed areas were total phosphorus (TP) and total nitrogen (TN). This analysis demonstrates its efficacy in formulating strategies for the SQ evaluation and targeted soil reclamation plans of waste dumps.

Effect of cover crops and tillage systems on soil quality and sugarcane yield

AbstractThe management adopted in the establishment and replanting of sugarcane fields, with conventional tillage followed by fallow, is one of the main causes of soil quality degradation. In this context, the soil quality index (SQI) is an important tool to guide the use of more sustainable practices and management. This study aimed to monitor the effect of different cover crops in association with different tillage systems on sugarcane yield based on key indicators and an SQI developed using the Soil Management Assessment Framework (SMAF). The experiment was carried out on a sugarcane expansion area located in the municipality of Ibitinga, São Paulo, Brazil. The following soil physical and chemical attributes were analyzed: soil bulk density, macroaggregates, available phosphorus and potassium. Soil carbon content was also analyzed and used to calculate the SQI. Productivity over the 4 years of sugarcane cultivation was also analyzed. The use of subsoilers for soil tillage proved efficient in managing compaction by providing lower soil bulk density values in the first years of cultivation (1.59 and 1.63 g cm−3); however, these effects occurred in the short term with a 10% increase in later years. The use of millet in association with subsoiling showed the best results for soil quality (0.59), reflected in the maintenance of yields at 100 Mg ha−1 over time. Thus, our study reinforces the importance of using soil conservation systems in sugarcane replanting areas to achieve production longevity.

Soil Quality Evaluation in Mono and Mixed Eucalypt Plantation

Soil quality (SQ) pertains to the intricate and ongoing capacity of soil to function as a thriving ecosystem that supports the growth of plants and animals. However, there is a limited understanding of SQ assessment in mixed forest plantations. Therefore, we formulated and tested the hypothesis that the inclusion of a nitrogen-fixing tree species (such as Acacia mangium) improves SQ indicators in mixed treatments involving Eucalyptus trees. To evaluate the changes in SQ, we conducted a field experiment that employed the Soil Management Assessment Framework (SMAF) tool to analyze pure and mixed plantations of Eucalyptus grandis and A. mangium. Soil samples were collected at a depth of 0–20 cm from different treatments, including pure E. grandis without nitrogen fertilization (E), pure A. mangium (A), pure E. grandis with nitrogen fertilization (E + N), and mixed E. grandis and A. mangium (E + A). Sampling took place at 27 and 39 months after planting. We selected seven indicators of SQ: two biological indicators (soil microbial biomass carbon and β-glucosidase enzyme activity), four chemical indicators (soil organic carbon, pH, available phosphorus, and potassium), and one physical indicator (bulk density). By applying the SMAF tool, we determined the SQ scores for each indicator. The results revealed that E + A stands exhibited higher SMAF scores than pure stands, particularly in terms of pH (0.49 and 0.52 at 27 and 39 months, respectively) and phosphorus levels (0.84 and 0.82, at 27 and 39 months), respectively. Forest management practices and the sampling period had the most pronounced impact on biological and chemical indicators. Notably, significant positive correlations were observed between SMAF scores and pH, available phosphorus content, enzymes, soil organic carbon, and microbial biomass in both sampling periods. This study effectively provided novel information that introducing a nitrogen-fixing tree species in combination with eucalyptus trees enhances SQ, as indicated by the SMAF tool, which could reduce the need for external inputs (e.g., mineral fertilizers) by the farmers. Future studies should analyze the effects of A. mangium not only with other E. grandis varieties but also with other forestry essences.

Assessing soil health in a thermic region of the southern great plains, using the soil management assessment framework (SMAF)

The soil management assessment framework (SMAF) has been widely used as a tool to quantify soil health. However, SMAF was developed using data from only a few climate conditions in the United States and regional verification is often suggested. We evaluated SMAF's short-term performance in a thermic/hyperthermic region, aiming to 1) evaluate the sensitivity of SMAF scores to changes in individual soil properties and 2) quantify soil health changes using SMAF. Treatments include two levels of summer crop and two levels of tillage in an annually planted wheat system. SMAF soil health metrics were measured for Burleson clay soil (BC site) and Parrita sandy clay loam soil (PSCL site) for 0–5 cm soil depth. At the BC site, βgluc and SOC SMAF scores displayed no statistical differences when compared to their respective soil properties. βgluc measurement also helped to highlight the treatment difference observed for wheat yield. This suggests that scoring curves of βgluc used in SMAF may need to be modified, especially for clayey soils. The results also show that SMAF scores were not correlated with wheat yield at both sites, suggesting that multiple year data may be needed to understand this relationship. Overall, in a thermic region, SMAF was found to be helpful to understand short-term soil health status. However, due to clay correction in SMAF algorithm, SMAF scores can show lower sensitivity in the clayey soils of these thermic regions.

Tracking Soil Health Changes in a Management-Intensive Grazing Agroecosystem

Management-intensive Grazing (MiG) has been proposed to sustainably intensify agroecosystems through careful management of livestock rotations on pastureland. However, there is little research on the soil health impacts of transitioning from irrigated cropland to irrigated MiG pasture with continuous livestock rotation. We analyzed ten soil health indicators using the Soil Management Assessment Framework (SMAF) to identify changes in nutrient status and soil physical, biological, and chemical health five to six years after converting irrigated cropland to irrigated pastureland under MiG. Significant improvements in biological soil health indicators and significant degradation in bulk density, a physical soil health indicator, were observed. Removal of tillage and increased organic matter inputs may have led to increases in β-glucosidase, microbial biomass carbon, and potentially mineralizable nitrogen, all of which are biological indicators of soil health. Conversely, trampling by grazing cattle has led to increased bulk density and, thus, a reduction in soil physical health. Nutrient status was relatively stable, with combined manure and fertilizer inputs leading to stabilized plant-available phosphorous (P) and increased potassium (K) soil concentrations. Although mixed effects on soil health were present, overall soil health did increase, and the MiG system appeared to have greater overall soil health as compared to results generated four to five years earlier. When utilizing MiG in irrigated pastures, balancing the deleterious effects of soil compaction with grazing needs to be considered to maintain long-term soil health.

Grazing exclusion restores soil health in Brazilian drylands under desertification process

The Brazilian drylands (Caatinga biome) are facing accelerated soil desertification due to human activities (e.g., overgrazing). However, restoration practices (e.g., grazing exclusion), are promising to curb soil desertification and, eventually, increase soil functioning. However, the understanding of soil health (SH) changes, induced by desertification and restoration in the Caatinga biome remains, poorly understood. Here, the SMAF (Soil Management Assessment Framework) was applied to assess the impact of desertification and long-term grazing exclusion on the SH in the Caatinga biome. Three conditions were assessed: i) native vegetation (NV), ii) degraded soil by overgrazing (DE) and iii) restored soil by grazing exclusion (RE). Soil samples (0–10 cm) were collected in both rainy and dry seasons, and chemical (pH, sodium adsorption ratio (SAR), K+, and P), physical (bulk soil density), and biological (soil organic carbon (SOC), microbial biomass carbon (MBC), and β-glucosidase activity) indicators were analyzed. Then, integrated soil health indexes (SHI) were calculated using the SMAF algorithms. Briefly, DE reduced (0.44 and 0.47 in rainy and dry seasons, respectively) the SHI compared to NV (0.72 and 0.82 in rainy and dry seasons, respectively). Importantly, RE recovered SH after two decades of implantation (0.65 and 0.79 in rainy and dry seasons, respectively). Bulk soil density and SAR were the indicators that presented a higher negative correlation with SH, mainly in DE, while SOC, MBC, and β-glucosidase activity correlated with SH in NV and RE soils. Biological soil health indicators increased in dry season, which may be due to the deciduous behavior of Caatinga vegetation, which could intensify microbial activity. We provided novel evidence that SMAF can be a user-friendly tool to monitor changes in SH under Brazilian drylands soils. In addition, long-term grazing exclusion can restore SH, contributing to curbing the desertification process in the region.

Agricultural practices to improve near-surface soil health and crop yield in subtropical soils

Integrated crop and livestock systems (ICLS) have the potential to minimize soil degradation, improve soil health, and maximize food production. Our goal was to evaluate the impact of no-till (NT) in association with ICLS on soil health and soybean yield in Inceptisol and Oxisol soils in Southern Brazil. The response of physical, chemical, and biological soil health indicators to soil and crop management systems was measured over the short- (<5 years) and long-term (>10 years) under ICLS with soybean in spring/summer and forage grazed by cattle in the autumn/winter. A soil management index was calculated for each soil based on ICLS management. Independent of soil type, ICLS in association with NT for 10+ years improved chemical and biological properties in the near soil surface (0–6 cm depth). The Soil Management Assessment Framework (SMAF) scores for soil organic carbon (SOC), phosphorus (P), and bulk density were close to 1.0 in the Inceptisol, independent of management or soil depth, while the pH scores were lower in the ICLS topsoil. For the Oxisol, the SMAF scores for SOC and P were approximately 1.0 in the 0–6 cm depth under long-term ICLS. The SMAF overall soil quality index was high (approximately 0.9) for both soils and there were no significant differences between management practices. Overall, the adoption of ICLS in association with NT (i) improved or maintained soil health, (ii) promoted soil carbon sequestration, and (iii) increased soybean yield in the studied soils. This study confirmed the potential for conservation practices (ICLS combined with NT) to improve soil quality with environmental sustainability.

The Clean Water Act and biosolids: A 45‐year chronological review of biosolids land application research in Colorado

The 1972 U.S. Clean Water Act set forth the generation of biosolids. In Colorado, biosolids land application research began in 1976 and continues today. Pastureland research suggested that sewage effluent could effectively be land applied to benefit aboveground plant growth and to polish water prior to reaching receiving waters. Forest wildfire-affected ecosystems can also benefit from biosolids applications; application rates of up to 80 Mg ha-1 can lead to greater plant establishment, soil microbial activity, and nutrient turnover and reduced nutrient and heavy metal concentrations in runoff below livestock and USEPA drinking water standards. Long-term (24-yr) observations in oil shale-mined lands showed that biosolids (up to 224 Mg ha-1 ) can have a positive effect on microbial-mediated nutrient cycling and, in turn, on aboveground plant community structure. Biosolids applications of up to 40 Mg ha-1 in high-elevation shrubland ecosystems, dominated by Mo-containing shale deposits, can aid in reducing imbalances between Mo and Cu in soils and plants; excessive plant Mo, when consumed by ruminants, can lead to molybdenosis. Biosolids and lime applications (both at 224 Mg ha-1 ) have been shown to improve long-term reclamation success on acid-generating, heavy metal-containing fluvial mine tailings. Thirty years of grazing land research, focused on soil and aboveground plant benefits, illustrate that soil health and plant productivity can be improved to the greatest extent at biosolids application rates close to 10 Mg ha-1 . Finally, 40 yr of dryland agroecosystem research (a) have helped identify biosolids N fertilizer equivalency (∼8kg N Mg-1 ) and thus dryland winter wheat application rates (e.g., 4.5-6.7 dry Mg ha-1 ); (b) have identified first-year mineralization rates of 25-32%; (c) dispute the "time bomb" theory by showing that plant metal uptake follows an exponential rise to a maximum; (d) showcase economic return to producers via increased wheat grain protein content; (e) suggest that biosolids-borne proteins and their degradation products are labile C and N sources; (f) have led to long-term tracking of micronutrients and heavy metals in soils and revealed that plants-soil concentrations will not lead to groundwater degradation and that plants are safe for human consumption; and (g) have shown that biosolids provide Zn, helping to overcome soil deficiencies and enhancing Zn biofortification in wheat grain. This latter point is important because ∼2 billion people globally suffer from Zn deficiencies. Forty-five years of research in Colorado have proven that biosolids can enhance environmental quality, improve soil health, and produce healthy food products.

Impact of Long Term Nutrient Management on Soil Quality Indices in Rice-Wheat System of Lower Indo-Gangetic Plain

Globally, soil degradation is an important issue for sustainable crop production. Soil quality indicators are the soil attributes that address the ecological functions of soil. Therefore, indicator-based soil quality assessment has been emphasized for quantifying the relative soil quality changes in different nutrient management systems. Soil quality underthe rice (Oryza sativa L.) and wheat (Triticum aestivam L.) cropping system was assessed using a modified “Soil Management Assessment Framework (SMAF)” model. Soil’s physical, chemical, nutritional, and biological indices were analyzed for different nutrient management strategies, viz., inorganic fertilizer (NPK), NPK + 7.5 Mg ha−1 farmyard manure (NPKF), NPK + 10.0 Mg ha−1 paddy straw (NPKP) and NPK + 8.0 Mg ha−1 Sesbania sesban L. green manure (NPKG). Nutrient management strategies significantly influenced soil quality indices. NPKF showed the highest SMAF score for soil physical quality index followed by NPKP &gt; NPKG &gt; NPK and control; whereas the score of soil chemical quality was greater in NPKP followed by NPKF/NPKG &gt; NPK &gt; control (p &gt; 0.05). Overall, the soil nutritional quality index was greater in NPKF (0.96) followed by NPKG &gt; NPKP &gt; NPK, and the least was in control. The SMAF score of soil biological quality index was highest in NPKF compared to NPKG &gt; NPKP &gt; NPK &gt; control. The wholesome index of SMAF (SQI) was developed withthehighest score in NPKF (0.94) followed by NPKG (0.90) &gt; NPKP (0.89) &gt; NPK (0.79) &gt; control (0.71). The β-glucosidase activity, mineralizable C, KMnO4 oxidizable N, microbial biomass C, and total water-stable aggregates explained 82% variability in the dataset and represented a good agreement with system yield (R2 = 0.89, p &lt; 0.05). This study concludes that the conjunctive application of NPK with manures restores the overall soil quality more than other management practices, and thatthe SQ indices can be utilized for screening the best management practices for rice-wheat and other similar cropping systems.

Short-term effects of conservation agriculture strategies on the soil quality of a Haplic Plinthosol in Eastern Cape, South Africa

The improvement of soil quality in agro-ecosystems is one of the major objectives of conservation agriculture (CA) strategies. The objective of this study was to evaluate, quantify and compare the effects of two tillage practices, four crop rotation sequences, two residue management systems and their interactions on the soil quality of a Haplic Plinthosol in South Africa using the Soil Management Assessment Framework (SMAF). The evaluation was done on a CA field trial established in 2012 in the Eastern Cape Province of South Africa. The trial was laid out in a split-split-plot design with tillage: conventional tillage (CT) and no-till (NT) as main plot treatments. Sub-treatments were crop rotations: maize-fallow-maize (MFM); maize-fallow-soybean (MFS); maize-wheat-maize (MWM); maize-wheat-soybean (MWS). Residue management treatments: removal (R-) and retention (R+) were in the sub-sub plots. Soils from the CA trial were sampled at 0 – 5 and 5 – 10 cm depths after five cropping seasons (2012–2015). Thirteen soil quality indicators were determined to assess soil quality. The SMAF soil quality index (SMAF-SQI) was used as an indicator of overall soil quality. The study results demonstrated the dominance of tillage practices in significantly affecting soil biological, chemical and physical properties in the short term than crop rotation sequences and residue management systems. The soil biological indicators viz. SOC, MBC and BG activity were more sensitive to CA strategies, which confirmed their effectiveness as tools for soil quality assessments in the short-term. The study also revealed the short-term significant effects of tillage on the overall SMAF-SQI while crop rotation and residue management had no significant effects. Overall soil quality assessment using the SMAF technique provided a sound basis for distinguishing the short-term impacts of CA strategies on the function of the Haplic Plinthosol in Eastern Cape, South Africa.

Applying the Soil Management Assessment Framework (SMAF) to Assess Mangrove Soil Quality

Soil quality (SQ) refers to its capacity to perform its functions. Thus, the SQ index (SQI) is a potentially useful tool for monitoring soil changes induced by mangrove restoration initiatives. Although the soil management assessment framework (SMAF) is a well-developed tool for SQ assessments in diverse ecosystems, it has never been tested on mangrove soils. In this study, we tested the SMAF to evaluate the shifts in the SQ of mangroves in a reforestation initiative using three- and seven-year plantations, which were compared with degraded and mature mangroves. A minimum dataset, composed of the pH and available P as chemical indicators, bulk density as a physical indicator, and soil organic carbon as a biological indicator, was used to calculate the SQI. The SMAF scores facilitated the monitoring of improvement in the mangrove SQ with vegetation development, mainly driven by physical and biological indicators. The SMAF may be a useful tool for monitoring SQ in mangroves under protection and recovery initiatives. Nevertheless, we suggest the inclusion of additional biological and chemical indicators in the minimum dataset for future studies to better represent specific processes and functions (e.g., microbial redox reactions and contaminant immobilization) that can alter the SQ of mangroves.

Relationships of on‐farm soil health scores with corn and soybean yield in the midwestern United States

AbstractSoil health assessments are interpretive frameworks that estimate a soil's health by scoring various soil biological, chemical, and physical attributes to guide soil and crop management. Few large‐scale analyses of soil health assessment scores exist. Thus, our objectives were to (a) summarize soil health scores at farms across much of the midwestern United States, (b) evaluate how individual soil health indicators influence assessment composite scores, (c) assess correlations among composite scores, and (d) determine the strength of significant correlations between soil health assessment scores and crop yield at three spatial and temporal scales: individual site‐year, individual site, and all sites and years combined. Soil health and yield data were collected from 96 Soil Health Partnership (SHP) farmers across nine midwestern states over 2–5 yr. Soil texture influenced soil health indicator values and scores in the study region. Correlation strengths among the comprehensive assessment of soil health (CASH), the soil management assessment framework (SMAF), and the Haney soil health tool (HSHT) composite scores were soil texture dependent. Multiple years of data at individual sites improved the statistical correlations between yield and soil health scores compared with individual site years. When practitioners judge how well crop yield relates to soil health scores, examining data over time should enhance relationships. These results demonstrate that a multiyear commitment greatly improves soil health monitoring at the site level.

Evaluating the impact of midwestern cropping systems on soil health and soil carbon dynamics

Crop producers are becoming more interested in improving the health of their soils. The effects of cropping practices on soil health have been studied extensively, but much uncertainty remains. This study investigated the impacts of standard midwestern US agronomic practices on soil health indicators. The Soil Management Assessment Framework was used to quantify soil quality index (SQI) scores for each system. Corn–soybean (<i>Zea mays</i> L.–<i>Glycine max</i> L.) rotations received 168 kg N ha^–1 applied prior to corn. Treatments were the following: spring-applied urea ammonium nitrogen (SU168), fall-applied manure (FM) in no-till (NT) for 2 years (FM168NT2), FM with 10 years of NT and cereal rye (<i>Secale cereale</i>) cover crop (FM168NT10+R), and FM with 38 years of NT management (FM168NT38). Continuous corn (CC) treatments had FM applied annually at 224 kg N ha^–1 with eight years of stover removal (FM224CC-S) and with no stover removal (FM224CC). Soil cores were taken to a depth of 15 cm in the spring of 2017 and analyzed for total carbon (TC), total nitrogen (TN), water-stable aggregates (WSA), bulk density (BD), and potentially mineralizable nitrogen (PMN). Results showed that FM168NT38 and FM224CC had significantly greater TC and TN than other treatments. There were minimal treatment differences in total WSA &gt; 0.212 mm. No significant differences in PMN were found. Bulk density levels were significantly higher in NT treatments. The FM224CC and FM224CC-S treatments had the highest SQI scores, and FM168NT10+R had the lowest SQI score due to having higher BD and lower TC. Results suggest that the effect of cropping practices on some near-surface soil health indicators may be small and difficult to quantify. This study also demonstrated the need to adjust management to minimize compaction and maximize yield and soil health in cover-cropped systems. The study also monitored soil TC levels to a depth of 120 cm from 2007 through 2017. The rate of change in TC over time at a given depth did not differ between treatments. Total C levels did not change significantly to a depth of 15 cm. Significant increases in TC were found in all treatments except FM224CC-S at 30 to 60 cm and 90 to 120 cm depths, and in all treatments at 60 to 90 cm depth. These results suggest that C accumulation deep in the soil profile may be typical in midwestern cropping systems. Deep sampling to ≥100 cm is needed to capture the complete picture of soil C dynamics to assess soil C accumulation potential.

Furrow-irrigated corn residue management and tillage strategies for improved soil health

Conversion from conventional tillage to no-till in surface irrigated agroecosystems is low, mostly due to difficulties crop residue creates for water surface flow if no-till is implemented. A three-year continuous corn (Zea mays L.) study was conducted to evaluate the effects of residue management (retained yet mechanically moved out of the irrigation furrow, grazed, or baled/removed) and tillage (conventional tillage versus no-till) on soil health as verified using the Soil Management Assessment Framework. After three years of implementation, corn yields were 15% greater under no-till as compared to conventional tillage (13.1 versus 11.4 t ha−1), and followed the order baled (13.6 t ha−1) > grazed (12.5 t ha−1) > retained (10.6 t ha−1). In terms of corn residue management, soil health followed stover grazed = stover retained > stover baled/removed, a function of lower salts and greater plant-available K, beta-glucosidase activity, potentially mineralizable N, and microbial biomass C present – a result of greater water-stable aggregates and grazing’s influence on K and organic inputs. Reduced soil physical health was associated with a short-term increase in bulk density under no-till, while improved soil chemical health was associated with reductions in soil salts under no-till. Greater soil biological health was noted in the soil surface with no-till, due to greater beta-glucosidase activity, microbial biomass C, and a slight increase in soil organic C; the opposite was found with conventional tillage and soil depth. However, when combining the above observations, greater overall soil health was observed in the upper soil as associated with no-till as compared to conventional tillage; subsoil had greater overall soil health associated with conventional tillage. Understanding the importance of crop residue utilization in conjunction with no-till practices in surface irrigated agroecosystems can influence the adoption of sustainable management practices and should directly contribute to long-term soil health improvements and agroecosystem sustainability.

Long-Term Biosolids Applications to Overgrazed Rangelands Improve Soil Health

Overgrazed rangelands can lead to soil degradation, yet long-term land application of organic amendments (i.e., biosolids) may play a pivotal role in improving degraded rangelands in terms of soil health. However, the long-term effects on soil health properties in response to single or repeated, low to excessive biosolids applications, on semi-arid, overgrazed grasslands have not been quantified. Using the Soil Management Assessment Framework (SMAF), soil physical, biological, chemical, nutrient, and overall soil health indices between biosolids applications (0, 2.5, 5, 10, 21, or 30 Mg ha−1) and application time (single: 1991, repeated: 2002) were determined. Results showed no significant changes in soil physical and nutrient health indices. However, the chemical soil health index was greater when biosolids were applied at rates &lt;30 Mg ha−1 and within the single compared to repeated applications. The biological soil health index was positively affected by increasing biosolids application rates, was overall greater in the repeated as compared to the single application, and was maximized at 30 Mg ha−1. The overall soil health index was maximized at rates &lt;30 Mg ha−1. When all indices were combined, and considering past plant community findings at this site, overall soil health appeared optimized at a biosolids application rate of ~10 Mg ha−1. The use of soil health tools can help determine a targeted organic amendment application rate to overgrazed rangelands so the material provides maximum benefits to soils, plants, animals, and the environment.

The soil health assessment protocol and evaluation applied to soil organic carbon

AbstractThe concept of soil health has evolved over the past several decades, recognizing that dynamic soil property response to management and land use is highly dependent on site‐specific factors that must be considered when interpreting soil health measurements. Initially, the Soil Management Assessment Framework (SMAF) and Comprehensive Assessment of Soil Health (CASH) were developed and used globally for scoring soil health indicators. However, both SMAF and CASH frameworks were developed using a relatively small dataset and their interpretation curves were not validated at the nationwide scale. Expanding upon these concepts, we propose the Soil Health Assessment Protocol and Evaluation (SHAPE) tool. The SHAPE was developed using 14,680 soil organic C (SOC) observations from across the United States, and accounts for edaphic and climate factors at the continental scale. Data were compiled from the literature, the Cornell Soil Health Laboratory, and the Kellogg Soil Survey Laboratory. In this approach, scoring curves are Bayesian model‐based estimates of the conditional cumulative distribution function (CDF) for defined soil peer groups reflecting five soil texture and five soil suborder classes adjusted for mean annual temperature and precipitation. Specifically, SHAPE produces scores between 0 and 1 (0–100%) for measured SOC values that reflect the quantile or position within the conditional CDF along with measures of uncertainty. Herein, we focus on development of the SHAPE scoring curve for SOC with our case studies. SHAPE is a flexible, quantitative tool that provides a regionally relevant interpretation of this key soil health indicator.

Long-term biosolids land application influences soil health

Soil health assessments associated with organic amendment applications have primarily focused attention on manure or composts. Yet, quantifying specific changes in soil health associated with biosolids land applications has yet to be determined. Our objectives were to evaluate the changes in various soil indicators, and utilizing the Soil Management Assessment Framework (SMAF), quantify changes in soil indicator scores and soil health indices as affected by either increasing inorganic N fertilizer (0 up to 112 kg N ha−1) or biosolids (0 up to 11.2 dry Mg ha−1) applied every other year over 22 years. Soils were sampled (0 to 20 cm depth) following 22 years of N fertilizer or biosolids inputs to a dryland wheat-fallow (Triticum aestivum L.) rotation, 11 soil health indicators were monitored under SMAF guidelines, and indicators, indicator scores, and soil health indices were analyzed statistically. In general, increasing N fertilizer application rates had little effect on soil indicators, SMAF indicator scores or soil health indices. Increasing biosolids application rates increased soil organic C (SOC) and potentially mineralizable N (PMN). The SMAF indicator scores showed upward trends for soil pH, SOC, PMN, and microbial biomass C (MBC) associated with increasing biosolids application rates; discussing trends are important as these indicator scores are combined to provide soil health indices. Indeed, increasing biosolids application rates increased soil chemical and biological health indices, leading to an improvement in the overall soil health index. When comparing the overall N fertilizer to biosolids effect, biosolids applications significantly improved the soil biological health index. Results indicate that long-term biosolids land application to semi-arid, dryland wheat fallow rotations, similar to those studied, improve various aspects of soil health. These findings suggest that biosolids may play a pivotal role in dryland agroecosystem sustainability.

Soil health assessment after 40 years of conservation and conventional tillage management in Southeastern Coastal Plain soils

AbstractConservation tillage (CST) and cover crops are important components of soil health management. In the present study, we applied two independent soil health assessment approaches to evaluate the impacts of 40‐yr CST and additional 4‐yr cover cropping on a range of soil health indicators and the overall soil health in typical southeastern Coastal Plain soils. Soils were collected at 0–15 cm and analyzed for physical, chemical, and biological indicators. The Soil Management Assessment Framework (SMAF) and Cornell's Comprehensive Assessment of Soil Health (CASH) were used to calculate soil health indices. When compared to conventional tillage, 40‐yr CST increased active carbon (C) from 301 to 420 mg kg–1 and organic nitrogen (N) mineralization potentials from 0.78 to 0.91 mg kg–1 d–1, but it reduced soil electrical conductivity from 133 to 101 μs cm–1. No difference in soil aggregate stability, total C, extractable phosphorous and potassium, microbial biomass C, respiration, and glucosidase activities were observed between the two tillage treatments. Cover cropping had no impacts on any measured variables, except that it increased soil total N. Regardless of tillage and cover cropping, both the SMAF and CASH scoring functions suggested no changes in overall soil health. Soil organic C (SOC) was the only indicator positively correlated with both the SMAF and CASH indices, indicating its importance in maintaining the health of the tested soils. Moreover, CASH index recommended improving soil structure and SOC as the management priority to maintain or improve the overall soil health. Increasing organic inputs along with CST is seemingly the optimal management option.