Abstract Small‐scale vegetable farms are increasingly important to local food systems, but their soils are not well understood, particularly in high tunnels. We sampled soil in 100 Minnesota vegetable farm fields and high tunnels with three objectives: (1) Compare soil nutrients and soil health metrics in high tunnels and nearby open fields. (2) Document soil nutrient accumulation and assess loss potential. (3) Explore the impacts of specific management practices (input use, cover crops, tillage, and soil testing) and demographics on soil health and soil nutrients. Overall, vegetable farms had high organic matter in both high tunnels and fields (average 6.34% and 4.7%, respectively), and soil phosphorus levels were “very high” in 87% of high tunnels and 84% of fields. Just under half of the high tunnels studied had slightly to moderately saline soil (sufficiently saline to impact sensitive crops), and soluble salts were associated with higher soil nitrate concentrations. The pH of many high tunnel soils was above the optimal range for crop production, which correlated with irrigation water alkalinity. Some high tunnel soils had rapid water infiltration rates, with implications for irrigation management. Our preliminary risk assessment suggested a high to medium risk of nitrate leaching in two thirds of the fields and three quarters of the high tunnels studied. Farmer experience and more years in vegetable production were negatively associated with soil health metrics like aggregate stability and organic matter, but reduced tillage, organic management, and application of plant‐based compost were weakly positively associated with soil health indicators.
Abstract Soil thermal properties are essential for quantifying the coupled heat and moisture flow in the vadose zone and important for developing soil and crop models. This study evaluated the thermal properties of soils at the West Mesa land application site near Las Cruces, NM, which has been irrigated with treated industrial and municipal wastewater (TIMW) for 0 (control), 8, and 14 years. Core and bulk soil samples were collected from 0 to 20‐cm depth and analyzed for bulk density, volumetric water content ( θ ), thermal conductivity ( λ ), thermal diffusivity ( D ), and volumetric specific heat capacity ( C ). The λ and D were significantly lower in soils irrigated with TIMW for 8 and 14 years compared with the control. Long‐term irrigation also increased θ across all soil water pressures, reflecting structural alterations and salt accumulation in pore spaces. Strong negative correlations between sodium (Na + ) concentration and λ ( r = −0.93, −0.92, and −0.94 for 0, 8, and 14 years, respectively) indicate that increasing Na + reduces soil heat conductivity. In contrast , C exhibited a strong positive relationship with θ ( R = 0.94, 0.98, and 0.97), confirming that higher moisture content enhances soil heat storage capacity. Elevated Na + likely promoted salt‐layer formation on soil particles and altered pore geometry, reducing particle contact and thermal pathways. Overall, the findings highlight the importance of monitoring Na + concentrations in wastewater and adopting management strategies to minimize salt buildup, while supporting the improved modeling of soil temperature and moisture dynamics in semi‐arid environments.
Abstract Abiotic stressors, including drought, salinity, and heavy metal contamination, pose escalating threats to global food security, challenges further exacerbated by climate change and progressive soil degradation. As a strategic geochemical amendment, biochar is increasingly proposed to enhance soil resilience and agricultural sustainability, directly supporting sustainable development goal (SDG) 2 (Zero Hunger) and SDG 13 (Climate Action). This review critically evaluates biochar in stress mitigation, focusing on production principles, soil physicochemical adjustments, and changes in the soil‐plant microbiome and soil–plant–microbe interactions. Specifically, we synthesize data demonstrating biochar's multifaceted efficacy: regulating ion homeostasis to reduce Na + uptake by 20%–40% under saline conditions, enhancing water use efficiency by 15%–30% in arid environments, and immobilizing heavy metals to reduce cadmium (Cd) accumulation by 25%–50%. These synergistic soil–plant interactions further contribute to SDG 6 (Clean Water and Sanitation) and SDG 15 (Life on Land). However, significant challenges remain regarding feedstock variability, dosage optimization, and long‐term field stability. Furthermore, performance discrepancies under combined multi‐stress scenarios underscore the urgent need for standardized biochar formulations. Integrating biochar into precision frameworks offers a promising geobiochemical frontier for modulating multi‐stress crop resilience and shifting soil–plant–microbe dynamics toward climate‐adaptive landscapes. Such advancements are essential for ensuring global food security for a projected population of 9.7 billion by 2050.
Abstract In an arid pre‐Saharan climate where rainfall is scarce, agricultural activity in the traditional oasis of El Guettar relies heavily on groundwater for irrigation. The quality of these water resources is influenced by local hydrogeology, geological structures, topography, rainfall, evaporation, interactions between rocks and water, and irrigation methods. This study provides an assessment of groundwater quality and its suitability for irrigation using six water samples collected from five wells and one borehole. We measured physicochemical parameters (pH, temperature, electrical conductivity, and total dissolved solids) and major ion concentrations (calcium, magnesium, sodium, potassium, bicarbonate, chloride, and sulfate). Water quality was evaluated using five indices: sodium adsorption ratio (SAR), cation ratio of soil structural stability (CROSS), residual sodium carbonate (RSC), sodium percentage (Na%), permeability index, and magnesium hazard (MH), along with Wilcox and Riverside (United States Salinity Laboratory) diagrams. The results reveal that the groundwater is very saline but not sodic, with SAR values below 10 and negative RSC values for all samples, indicating no risk of soil sodification. >66% of the samples show a high risk of soil structure disintegration, according to CROSS. The Wilcox diagram and electrical conductivity measurements indicate very high salinity, requiring salt‐tolerant crops and effective drainage. Only wells P1 and P4 offer optimal quality, while the others (P2, P3, P5, and P6) have excess magnesium (high MH > 50), which can be corrected by gypsum, a locally abundant resource. Thus, appropriate management can maintain the productivity of this oasis despite the water salinity.
Abstract The decomposition of soil organic matter and nutrient cycling are largely mediated by extracellular enzymes, yet the effect of soil management on enzyme kinetic (Michaelis constant [ K m ] and maximum velocity [ V max ]) remains poorly understood. We investigated the long‐term effects of three cropping systems—annual maize ( Zea Mays )–soybean ( Glycine max (L) Merr.) (CS), unfertilized prairie (UPr), and fertilized prairie (FPr)—on the kinetic parameters of β‐glucosidase(BGase) and leucine‐aminopeptidase (LAPase). We focused our research on two contrasts: (1) The comparison of enzyme activities in a fertilized perennial cropping system with an annual rotational cropping system (FPr vs. CS) and (2) the effect of fertilizer nitrogen (N) on enzyme activity in a perennial cropping system (FPr vs. UPr). First, we hypothesized that perennial roots would enhance soil biological activity in FPr and increase both enzymes’ V max and K m compared to CS; and second that N fertilizer added to FPr would decrease LAPase V max due to decreased microbial demand for N. In partial support of our first hypothesis, FPr increased BGase V max by 85% compared to CS, but had no effect on LAPase V max . Supporting H2, fertilizing prairie significantly decreased LAPase V max by 36% compared to UPr, likely due to either lower N demand or indirectly via long‐term changes in prairie plant species. Overall, for both enzymes, however, K m was insensitive to long‐term management. The diversified, perennial cropping system increased soil microbial biomass regardless of fertilizer application, and the activities of carbon‐ and N‐acquiring enzymes depended on whether or not the perennial crop was fertilized.
Abstract Cover crops are widely used in corn ( Zea mays L.)–soybean ( Glycine max ) systems to improve soil health, yet seasonally dynamic responses of soil biological properties to long‐term cover cropping remain not fully understood, particularly in the low‐organic matter Alfisols of the eastern Corn Belt. We evaluated the effects of more than a decade of cereal rye ( Secale cereale L.) cover cropping on soil biological properties in a no‐till corn–soybean rotation in southeastern Indiana in a field experiment established in 2011. Soil samples were collected at two depths (0–10 and 10–20 cm) during fall, spring, and summer in 2023–2024 and analyzed for microbial biomass carbon and nitrogen (soil microbial biomass carbon [SMBC] and soil microbial biomass nitrogen [SMBN]), potentially mineralizable carbon (PMC), permanganate‐oxidizable carbon (POXC), autoclaved citrate‐extractable (ACE) protein, and enzyme activities associated with carbon (C), nitrogen (N), and phosphorus (P) cycling. Cover cropping increased SMBC, SMBN, and PMC, with treatment effects varying by season and soil depth. Cover crop effects on microbial biomass and PMC were most pronounced during spring and were largely confined to the 0–10 cm. In contrast, POXC, ACE protein, and enzyme responses were indicator‐specific; acid phosphatase activity increased under cover cropping and peaked in summer, whereas POXC, ACE protein, and activities of β‐glucosidase and N‐acetyl‐β‐glucosaminidase showed limited overall treatment effects. These findings indicate that long‐term cereal rye cover cropping enhances biologically mediated C and nutrient cycling in no‐till systems, with effects expressed in a seasonally and vertically stratified manner rather than as uniform, sustained increases.
Abstract The Proctor compaction test is the standard method for determining the maximum bulk density (Dbmax) of a soil, a key parameter for obtaining the degree of compaction. However, this method is labor‐intensive and time‐consuming, making it impractical for routine soil quality assessment. We developed pedotransfer functions to estimate Dbmax of agricultural soils in Brazil from texture, soil organic carbon (SOC), and bulk density (Db). A dataset consisting of 234 compaction curves from peer‐reviewed studies was used to compare linear regression (LR) and machine learning methods using cross‐validation and two independent validation datasets, including additional data from Brazil and the Americas. Random forest (RF) and support vector regression (SVR) reduced prediction variance for the validation dataset of Brazilian soils but overestimated Dbmax; however, including Db reduced this bias. For the Americas dataset, LR showed high variance and low bias, SVR resulted in low variance but higher bias, whereas RF presented the best bias–variance trade‐off. Although RF provided the best predictions (RMSE of 0.069 and 0.078 g cm −3 with and without Db, respectively), Dbmax for soils within the range represented by our dataset can also be estimated by Dbmax = 2.355 + 0.6 × SAND 2 − 0.4 × SILT 2 − 0.44 × ln(SAND) − 0.52 × ln(CLAY) − 0.38 × (CLAY:SAND) − 0.81 × (SOC/CLAY + SILT) and Dbmax = 1.41 + 0.32 × SAND 2 − 0.10 × SILT 2 − 0.23 × SOC + 0.37 × Db (texture and SOC in g kg −1 and Db in g cm −3 ), with RMSE values of 0.084 and 0.066 g cm −3 , respectively. This facilitates the estimation of Dbmax and supports the wider use of the degree of compaction in soil quality assessment.
Abstract Located in a transitional climatic zone of the Antarctic continent, James Ross Island (JRI) presents soils that reflect complex interactions between lithology, topography, and pedogenesis. This study characterizes soils along a toposequence to evaluate how slope position and parent material control soil properties and weathering patterns in a semiarid Antarctic setting. Five soil profiles were analyzed and classified according to the World Reference Base and Soil Taxonomy systems: three on volcanic tuffs ( Terrapin Hill Fm .) and two on sedimentary rocks ( Whisky Bay Fm .). Soils were classified. To characterize and compare their properties, physical, chemical, mineralogical, and geochemical analyses were performed, including the application of weathering indices. Four profiles (three on Terrapin Hill Fm . and one on Whisky Bay Fm .) were identified as Cryosols and one as a Regosol. Chemically, all soils exhibited alkaline pH (>7.6) and elevated sodium concentrations (1195.2–4093.0 mg kg − 1 ). Results indicate that soils on volcanic tuffs show evidence of possible dry permafrost, a feature not previously reported on JRI, whereas soils on sedimentary rocks exhibit higher quartz content and more advanced weathering signatures. Sodium enrichment from marine aerosols is widespread, and weathering indices highlight clay enrichment driven by sodium and calcium. These findings advance the understanding of soil–landscape evolution in transitional Antarctic environments and underscore the role of microtopography and lithology in shaping pedogenic pathways, with implications for permafrost vulnerability and pedogeomorphic modeling under climate change, particularly by identifying soil–landscape controls on thaw sensitivity and sediment distribution patterns.
Abstract This study identifies the parent material (PM) and examines cation exchange capacity (CEC) across the Busoga catena. In 2022 and 2023, we described 32 pedons and collected 147 samples. Laboratory analyses were particle size analysis, organic carbon (OC) content, pH, and CEC. Results indicate that the Busoga catena occurs across a Precambrian granitic residuum plateau that is dissected by Holocene and modern aged nearly level alluvial valleys filled with sediment from the Nile River back flooding and local stream sediment. Connecting the residual plateau uplands with the alluvial valleys are colluvial backslopes. Alfisols and Oxisols dominated the residual and colluvial PM. In contrast, Entisols, Mollisols, Ultisols, and Vertisols dominated the alluvial PM in the lowland landscape positions. Pedotransfer analysis revealed CEC to be a function of OC, clay, and pH. The best‐fit multiple linear relationship was CEC predicted = 1.77 pH + 0.08% clay + 4.76% OC, n = 44, Adj. ( R 2 ) = 0.94**. In turn, clay and OC content could be explained using PM and landscape position.
Abstract Improving soil health is an important goal for developing cropping systems in the mid‐southern United States. A long‐term nonirrigated cotton ( Gossypium hirsutum L.) field study in Stoneville, MS, assessed effects of conservation management systems on soil characteristics. Soil total C (TC) and N (TN), moisture, and enzyme activity were consistently higher in the 0‐ to 5‐cm depth in reduced tillage rye ( Secale cereal cv. Wren Abruzzi) cover crop (RTCC) and no‐tillage (NTNC) treatments compared to those with no cover crop and those that received tillage (reduced [RTNC] and conventional [CTNC] tillage). Tillage and cover crop effects were less consistent at depths below 5 cm due to stratification in NTNC or mixing from tillage in RTCC. Averaged over the 0‐ to 20‐cm soil depth, conservation practices that increased residue cover led to an average 10% and 12% TC increase for RTCC and NTNC, respectively, versus 7% and 8% for RTNC and CTNC. While soil TN across the 0‐ to 20‐cm depth did not increase over time for all treatments, the highest concentrations were in NTNC and RTCC. Fluorescein diacetate hydrolytic activity (FDA) levels in the cover crop across the 0‐ to 20‐cm depth were higher than other treatments, but due to stratification, FDA was lowest in NTNC. No major differences between management treatments were observed for Mehlich 3 extractable nutrients, except for stratification in the NTNC with higher concentrations measured in the 0‐ to 5‐cm soil depth. Findings support the potential to improve soil health in agricultural fields through conservation management under conditions in the humid, southern United States.
Abstract Organic amendments are applied to enhance soil carbon (C) storage, improve nutrient cycling, and mitigate greenhouse gas (GHG) emissions, yet their interaction with soil moisture regimes in regulating C and nitrogen (N) cycling is largely overlooked. A study was designed to assess the interaction between soil moisture regimes and organic amendments in regulating C and N cycling through a laboratory incubation experiment. We quantified carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) emissions following biochar, compost, and a 50:50 biochar + compost (BC mix) amendment in soils at field capacity (FC), 80% of FC (FC80), and 60% of FC (FC60). Results showed that biochar at FC had the highest cumulative CO 2 ‐C and N 2 O‐N emissions, with 40% and 50% higher emissions than control (CTRL), respectively. The FC80 level increased CO 2 ‐C emissions by 20% in CTRL, while it reduced CO 2 ‐C emissions by 4% in biochar treatment. Soil N 2 O‐N release increased with reduced moisture levels to FC80 and FC60, except in biochar treatment. At FC60, biochar reduced cumulative CO 2 ‐C and N 2 O‐N emissions by 23% and 9%, respectively. Soil C mineralization correlated positively with soil C content ( r = 0.74) at the beginning of the incubation, while N mineralization had a positive correlation with soil C ( r = 0.50) and a negative correlation with soil total N ( r = −0.47). A double exponential model (DEM) captured the mineralization kinetics of labile C and N following amendment application. Overall, soil moisture regulates C and N mineralization following organic amendment application. Optimized water management can offset the elevated GHG emissions following biochar application in water‐limited agroecosystems.
Abstract The distribution of soil moisture, resulting from the movement of infiltrated water, plays a fundamental role in the hydrological dynamics of hillslopes and in the triggering of landslides. Although water flow in soils occurs in multiple directions due to combined vertical and lateral fluxes, one‐dimensional (1D) flow models are widely adopted as a simplifying assumption in slope‐scale studies, frequently without explicit verification of their validity by researchers. This study evaluates the applicability of the one‐dimensional flow hypothesis under different hydrological conditions and over time. Soil moisture dynamics were simulated using the Hydrus‐1D model, driven by observed precipitation data and calibrated and validated against in situ soil moisture measurements collected at different depths. The results suggest that, at temporal scales associated with rainfall events capable of triggering landslides, one‐dimensional modelling can adequately to represent soil moisture dynamics in slope environments when coupled with measured soil moisture data for the calibration of hydraulic parameters. In contrast, simulations using soil hydraulic parameters estimated from pedotransfer functions showed limited ability to represent the hydraulic behavior of the soils.
Abstract Soil physical stability and aggregate‐associated carbon pools are essential for sustaining soil health (SH), yet limited research has explored management impacts on their relationship. Active carbon, or permanganate oxidizable carbon (POXC), an emerging indicator of SH reflecting the labile pool of soil organic carbon (SOC) is sensitive to management practices. This study investigates the simple and interactive effects of variable soil disturbance (strip tillage [ST] vs. conventional tillage [CT]), crop residue levels (high residue [HR] vs. low residue [LR]), and nitrogen (N) fertilization rates (0%, 60%, 80%, 100%, 120%, and 140% of the recommended N), maintained since 2012, on POXC, SOC, total N (TN), and their distribution across various aggregate size fractions (>0.053, 0.15, 0.30, 0.80, and 2.00 mm). Both SOC and TN were highest in ST‐HR‐0% N (23.4 g/kg SOC, 2.78 g/kg TN) and lowest in CT‐LR‐140%N (13 g/kg SOC, 1.26 g/kg TN). POXC varied significantly across treatments, with the highest POXC (632 mg/kg) found under ST‐HR‐80% N, and the lowest (151 mg/kg) under CT‐LR‐140% N. Aggregate size significantly influenced SOC and TN stabilization, with the highest SOC (22.3 g/kg) in 0.30 mm aggregates under ST‐HR and the lowest (12.5 g/kg) in 0.053 mm aggregates under CT‐LR. The ratio of POXC to SOC proved to be a promising metric for evaluating SOC stability within soil aggregates, showing strong correlations with SOC, TN, and aggregate stability. These findings emphasize the potential of combining ST, HR, and moderate N rates (60%–80% N) to enhance soil physical stability and promote POXC retention.
Abstract Sulfur (S) deficiency is a relatively new concern for farmers in industrialized nations due to the decline of atmospheric S deposition in recent decades. Sulfur is mobile in the soil but can be retained in subsoil where it is adsorbed to iron (Fe) and aluminum (Al) oxyhydroxides and aluminosilicate clays, leading to stratification with depth. In this experiment, we evaluated the effectiveness of S fertilizers in a corn ( Zea mays L.)–soybean ( Glycine max L.) rotation, how S concentration varies with depth through time, and how soybean rooting depth interacts with soil profile S distribution. We applied S at a rate of 45 kg ha −1 as gypsum, ammonium sulfate (AMS), poultry litter, or elemental S to corn in the rotation and found that corn yield was similar to an untreated control (10.1 Mg ha −1 mean). We collected 80‐cm soil samples, which revealed increased S in subsoil layers after corn harvest and before soybean planting. During the soybean year of the rotation, we applied the same rate of S using gypsum and AMS to plots that were untreated during the corn year of the rotation. Soybean rooting depth reached the soil profile layers with the highest S concentrations by the R1 growth stage. Soybean yield was unaffected (2.7 Mg ha −1 mean), but grain S and cysteine concentrations increased with S fertilization, whether applied in the corn or soybean year. Results of this study support the development of flexible and economical S fertilization programs spanning multiple years by taking advantage of S storage in the soil profile.
Abstract Selecting the most effective phosphorus (P) fertilizer source is essential for maximizing crop yields. However, there is little information to guide the choice between the widely used soluble granular sources: ammonium phosphates and superphosphates. The aims of this study were to examine whether there are differences in wheat ( Triticum aestivum L.) grain yield response to ammonium phosphate and superphosphate fertilizers in field conditions, and if these differences relate to diffusion of P from fertilizer granules. Two field experiments were conducted on acidic gravelly soils in Western Australia where P deficiency occurs to compare wheat growth response to P applied as monoammonium phosphate (MAP), diammonium phosphate (DAP), single superphosphate (SSP) or double superphosphate (DSP). A diffusion study was conducted to quantify the effect of P source on P diffusion from the fertilizer granules. Grain yield with MAP was up to 18% higher than SSP at one field experiment, and 10% higher than DSP at the other. The extent of P diffusion around the granules in the diffusion study showed the same order as the wheat growth response in the field experiments. The difference among P sources is attributed to greater precipitation or adsorption of phosphate near the granule with superphosphates, likely due to the presence of calcium (Ca) in the fertilizer. Our results reinforce the continued use of MAP as a source of P for crops grown on the acidic, gravelly, P responsive soils in Western Australia.
Abstract Increasing soil organic carbon (SOC) has many benefits for crop productivity, water storage, and reduced soil crusting and erosion, but finding practical crop and soil management methods for increasing organic matter has proven very difficult in the dryland wheat ( Triticum aestivum ) region of the Pacific Northwest. This paper reports on a large, 15‐year replicated plot study where annual winter wheat could be compared to the common 2‐year winter wheat–fallow rotation to see if a difference in soil carbon could be measured. SOC was 12% greater in the surface 0–120 kg dry soil m −2 (about 0–10 cm), and 6% greater when measuring to a depth of 0–1200 kg dry soil m −2 (about 0–1 m). Expressed as soil carbon stocks, annual winter wheat was 5.30 Mg ha −1 greater at a 1200 kg dry soil m −2 depth compared to the 2‐year wheat–fallow systems. To confirm these results, a second soil sample was collected 18 months after the first. Again, SOC in the surface 0–120 kg dry soil m −2 was significantly greater in annual winter wheat compared to winter wheat–fallow rotation. In this second sample, the difference was 20%, representing 3.75 Mg ha −1 . We conclude that in rainfall zones with adequate moisture for producing annual winter wheat, it is possible to increase soil carbon stocks compared to a 2‐year wheat–fallow rotation, with substantial amounts accumulating in the top 10 cm.
Zinc (Zn) is an essential micronutrient that plays a vital role in maintaining the productivity and health of plants, animals, and humans, yet its bioavailability in soils can be limited. Poultry litter (PL) serves as a cost-effective organic amendment that not only improves soil fertility but also supplies essential micronutrients, such as Zn. The objective of this study was to assess the extractability and leachability of Zn in sandy clay loam (SCL) and clay loam (CL) soils amended with three types of PL: breeder chicken (BC), broiler chicken (BrC), and domestic chicken (DC). The litter was incorporated into soils at a 5% rate and incubated for 4 weeks under controlled room conditions. Overall, PL application effectively enhanced Zn availability in soils. SCL soil contained higher initial Zn concentrations than CL soil, and PL application significantly increased both total Zn and water-soluble Zn concentrations. Among the treatments, BC litter caused the greatest enrichment of Zn, Ca, Mg, and Fe, with the overall trend in Zn concentrations found in the following order BC > BrC > DC. The lowest amount of total Zn was observed in both untreated SCL soil (20.4 mg kg(-)(1)) and CL soil (18.0 mg kg(-)(1)). BC litter produced the highest Zn concentration of 59.0 mg kg(-)(1) in SCL and 52.0 mg kg(-)(1) in CL soil. BrC litter increased total amount of Zn to 45.3 mg kg(-)(1) in SCL and 44.0 mg kg(-)(1) in CL soil, while DC litter resulted in 38.5 and 32.0 mg kg(-)(1) in SCL and CL soil, respectively. Zn leachability was highest in BC-amended soils. This study indicated that the addition of poultry manure can potentially enhance Zn in soils. However, litter and soil factors are critical determinants of Zn retention and leaching.
Efficient management of soil micronutrients is crucial for the yield and sustainability of cacao (Theobroma cacao L.), especially in tropical regions. However, specific availability classes for copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), extracted by Mehlich-1, had not yet been established for the crop in Brazil. This study presents, for the first time, the establishment of these classes, considering two soil layers (0-10 cm and 0-20 cm) in cacao-cultivated areas of southeastern Bahia, Brazil. A comprehensive database, generated by the Renova Cacau project and representative of the main cacao-growing region of the state, was used. Response curves of mean relative yield were fitted as a function of Cu, Fe, Mn, and Zn contents in the two soil layers, applying the boundary line approach. The analysis allowed the classification of these micronutrient availabilities into classes ranging from "very low" to "excessive." For the 0-20 cm layer, the content intervals associated with the adequate range (mg dm- 3) were Cu (1.02-1.52), Fe (33.0-61.0), Mn (9.5-15.8), and Zn (2.1-6.3). These results broaden the scientific basis for soil fertility interpretation in cacao-cultivated soils and support more precise fertilization recommendations, promoting rational micronutrient management and contributing to increased yield and sustainability in cacao cultivation.
Soil drainage leads to subsidence in organic-rich peat soils (histosols) due to compaction and accelerated soil oxidation, removing carbon (C). Research suggests mineral-associated organic matter (MAOM) promotes soil C persistence, but the prevalence of MAOM in cultivated histosols and its relationship with commonly measured soil health indicators (SHIs) are unknown. The objectives of this study were to (1) quantify soil C fractions and diverse SHIs in the Everglades Agricultural Area, Florida, to comprehensively evaluate the soil condition, and (2) determine if any existing SHIs, general soil properties, depth, or profile thickness may predict MAOM abundance. Soil cores were collected at 15 locations and up to 45-cm depth. Profile thickness (a proxy for oxidation) was determined by probing to bedrock, and C fractionation included both physical and density separation. Soil organic matter (SOM) content averaged 62% by mass, with nearly 50% of the soil aggregates >2 mm. Potassium-permanganate oxidizable C averaged 28.2 +/- 0.9 g kg(-)(1), and organic C concentration was five times greater than inorganic C. Particulate organic matter-Carbon (POM-C) accounted for >99% of soil (220.6 +/- 9.3 g kg(-)(1)), while mineral-associated organic matter-Carbon (MAOM-C) represented <1% (0.3 +/- 0.1 g kg(-)(1)). POM-C was predicted by soil profile thickness and several SHIs, but MAOM-C was not well predicted by almost any parameter measured. Results emphasize the predominance of unassociated organic C and suggest MAOM may serve as a unique SHI for organic soils. Management practices should focus on preventing further loss of vulnerable POM-C and promoting MAOM-C formation.
Tillage prepares soil for planting and plays a critical role in crop productivity, soil health, and greenhouse gas (GHG) emissions. Assessing long-term tillage is vital for expanding knowledge of these practices in semiarid environments. The experiment was conducted on the tillage plot initiated in 2007 to assess the long-term effects of no-tillage (NT), strip-tillage (ST), and moldboard plow (MP) on crop yield, soil properties, and GHG emissions in irrigated maize in western Nebraska. Maize yield, carbon dioxide (CO2), and nitrous oxide (N2O) emissions were measured in 2023 and 2024. Postharvest soil sampled from each tillage plot in 2024 were analyzed for selected soil health properties. Mean maize yield over 2 years was higher in ST (10.70 Mg ha(-)(1)) and MP (10.65 Mg ha(-)(1)) than in NT (8.45 Mg ha(-)(1)). Both NT and ST improved soil organic matter, organic carbon, and microbial activity relative to MP. Macroaggregate stability (>250 & micro;m) was greater under NT and ST, whereas MP had greater microaggregate stability (<63 & micro;m). Mean CO2 emissions did not differ among tillage systems, but N2O emissions were higher under NT and ST than under MP. There was a trade-off impact of NT on soil, GHG, and crop yield. The ST provided the benefit of localized tillage along crop rows while preserving NT conditions between rows. Understanding the trade-offs of known conservation practices on productivity and sustainability is critical to informing our efforts toward sustainable agriculture.
