Cation Saturation Research Articles

Abiotic Stress Effect on Agastache mexicana subsp. mexicana Yield: Cultivated in Two Contrasting Environments with Organic Nutrition and Artificial Shading.

Research on medicinal plants is essential for their conservation, propagation, resistance to environmental stress, and domestication. The use of organic nutrition has been demonstrated to improve soil fertility and plant quality. It is also important to study the effects of the Basic Cation Saturation Ratio (BCSR) approach, which is a topic where there is currently controversy and limited scientific information. Evaluating the growth and yields of Agastache mexicana subsp. mexicana (Amm) in different environments is crucial for developing effective propagation and domestication strategies. This includes examining warm and subhumid environments with rain in summer in comparison to mild environments with summer rain. Significant differences were observed in the effects of cold, waterlogging, and heat stresses on the plant's biomass yield and the morphometric-quantitative modeling by means of isolines. The biomass yield was 56% higher in environment one compared to environment two, 19% higher in environment one with organic nutrition, and 48% higher in environment two with organic nutrition compared to using only BCSR nutrition. In the second harvesting cycle, the plants in environment one did not survive, while the plants in environment two managed to survive without needing additional nutrition. Statistical and mathematical analyses provided information about the population or sample. Additionally, further analysis using isolines as a new approach revealed new insights into understanding phenology and growth issues.

Geo-spatial sensing of physical properties a leeway to agricultural soil assessment

The demand for economical means of evaluating soil nutrients’ unpredictability triggered the use of physical factors against the costlier, laborious, and time-consuming chemical approach. This drive led to resolving its capability in evaluating intricate soil properties as a productivity checker. This study aimed at assessing the physical parameters as a useful alternative to the conventional chemical examination of nutrient inconsistency. A petrographic examination was conducted on four rock samples for their classifications. Apparent Electrical Conductivity (ECa) measurements were seasonally executed in the wet (912-station) and dry (906-station). Ten cored soil samples were subjected to a permeability test. Twenty soil samples were examined for pH, Electrical Conductivity (EC), available phosphorus, acidity, Na, Mg, K, and Ca using standard soil science procedures. The mineralogical composition of six samples was determined with X-ray diffraction. The rock is biotite granite gneiss containing plagioclase (22%), microcline (24%), orthoclase (4%), quartz (25%), biotite (7%), and others (18%). The soils ECa were 10-344 µS/cm; categorised as low (1-49 µS/cm), moderate (50-99 µS/cm), and high (>100 µS/cm). The ECa distribution varied from moderate (61%) to high (64%) suggesting a heterogeneous pattern of soil attributes. The infiltration rate was slow in high ECa (5.56x10-5-1.67x10-4 cm/s) signifying good retention capability whereas the low and moderate ECa (moderate-moderately rapid) sections promote nutrient leaching. The cation exchangeable capacity was low (2.99 cmol/kg) in the low ECa and moderate (3.30-4.85 cmol/kg) in the moderate and high ECa; with varying basic cation saturation in the high (81.38%), moderate (73.34%) and low (71.89%) ECa regions and high ECa had higher fertility status. The high ECa had low quartz (41.3%) and microcline (15.7%), but high kaolinite (31.1%) had an affinity to ads orb more cations compared to other ECa regions. ECa variability is practicable in predicting the spatial distribution of soil properties and delineating the management zones. Key words: Granite gneiss, electrical conductivity, permeability, soil composition, mineral assemblages

Biochar has positive but distinct impacts on root, shoot, and fruit production in beans, tomatoes, and willows

Positive relationships have been documented between the amount of biochar added to soils and various aspects of plant growth and fertility such as root, shoot, and fruit production. However, these effects depend on biochar source materials, soil characteristics and species of plant examined. This makes it impossible to systematically compare and generalize findings across previous studies that have used different soils and biochar. We conducted a novel investigation to assess the effects of a single source of biochar (hazelnut wood), in a constructed organic soil, on the different plant tissues in three functionally distinct species: tomatoes (Solanum lycopersicon), green beans (Phaseolus vulgaris), and willow (Salix sp.). Five levels of biochar soil amendment were assessed: 0% (control), 3, 9, and 26% by dry weight. We found a highly significant positive relationship between biochar concentration and total plant biomass (roots + shoots + fruits) in all species, with no significant difference in total biomass response among species. Fruit production increased with increased biochar in both beans and tomatoes. However, tomatoes exhibited significant differences in response among plant tissues; fruit production and shoot biomass increased significantly with biochar, but root tissue did not. Bean germination success increased significantly with biochar concentration. Date of first flowering was earlier with increasing soil biochar in beans but not in tomatoes. Control over both sources of biochar and soil composition in this experiment enables us to conclude that biochar addition can have different impacts on different plants and, in some cases, species-specific impacts on different plant tissues and other measures of fertility. Our results are contrary to prior research that found inhibiting effects of biochar at levels comparable to our 26% treatment. Biochar impacts on soil properties such as CEC and percent base cation saturation do not explain our findings, leading us to conclude that microbial interaction with biochar is an important factor that may explain the positive impacts of soil biochar on plant fertility observed. Further research that repeats this experiment in other soil types, with other biochar sources, and with other plant species is necessary to determine the generalizability of these important findings.

Unveiling a Technosol-based remediation approach for enhancing plant growth in an iron-rich acidic mine soil from the Rio Tinto Mars analog site

This paper explores the potential of Technosols made from non-hazardous industrial wastes as a sustainable solution for highly acidic iron-rich soils at the Rio Tinto mining site (Spain), a terrestrial Mars analog. These mine soils exhibit extreme acidity (pHH2O = 2.1–3.0), low nutrient availability (non-acid cation saturation < 20 %), and high levels of Pb (3420 mg kg−1), Cu (504 mg kg−1), Zn (415 mg kg−1), and As (319 mg kg−1), hindering plant growth and ecosystem restoration. To address these challenges, the study systematically analyzed selected waste materials, formulated them into Technosols, and conducted a four-month pot trial to evaluate the growth of Brassica juncea under greenhouse conditions. Technosols were tailored by adding varying weight percentages of waste amendments into the mine Technosol, specifically 10 %, 25 %, and 50 %. The waste amendments comprised a blend of organic waste (water clarification sludge, WCS) and inorganic wastes (white steel slag, WSS; and furnace iron slag, FIS). The formulations included: (T0) exclusively mine Technosol (control); (T1) 60 % WCS + 40 % WSS; (T2) 60 % WCS + 40 % FIS; and (T3) 50 % WCS + 16.66 % WSS + 33.33 % FIS. The analyses covered leachate quality, soil pore water chemistry, and plant response (germination and survival rates, plant height, and leaf number). Results revealed a significant reduction in leachable contaminant concentrations, with Pb (26.16 mg kg−1), Zn (4.94 mg kg−1), and Cu (2.29 mg kg−1) dropping to negligible levels and shifting towards less toxic species. These changes improved soil conditions, promoting seed germination and seedling growth. Among the formulations tested, Technosol T1 showed promise in overcoming mine soil limitations, enhancing plant adaptation, buffering against acidification, and stabilizing contaminants through precipitation and adsorption mechanisms. The paper stresses the importance of tailoring waste amendments to specific soil conditions, and highlights the broader implications of the Technosol approach, such as waste valorization, soil stabilization, and insights for Brassica juncea growth in extreme environments, including Martian soil simulants.

Managing Soil Acidity, Not Soil Balancing, Affects Yield

AbstractIt can be hard to convince people of something when they think their lived experience suggests otherwise. That’s the challenge facing scientists trying to convince organic farmers that soil balancing—specifically through the base cation saturation ratio method—doesn’t actually improve crop yield. New research echoes previous work showing crop yields are affected by pH but not the calcium‐magnesium ratio soil balancing. Earn 0.5 CEUs in Soil &amp; Water Management by reading this article and taking the quiz at https://web.sciencesocieties.org/Learning‐Center/Courses.

Grazing, liming, and fertilization: Shifts on soil fertility and microbial community in a no-till sheep-soybean integrated system

Integrated crop–livestock systems are recognized for intensifying food production as long as adequate management of grazing, fertilization, and liming is practiced. There is still a lack of information about the effect of these factors on the soil microbiological community. This study evaluated the effects of grazing, liming, and different P and K fertilization strategies on the soil microbial community and its relationship with soil chemical properties. For this purpose, a field experiment was established in 2017 on a subtropical Acrisol. Treatments consisted of two production systems: (i) integrated crop-livestock system (with winter sheep grazing) and (ii) specialized system (ungrazed), combined with two periods of P and K fertilization: (i) conventional fertilization (at soybean planting) and (ii) system fertilization (in the Italian ryegrass pasture). The effect of liming (with and without) was also evaluated. Eighteen months after lime application, the soil was sampled in the 0–5 and10–15 cm soil layers to evaluate soil chemical properties (pH, exchangeable Al, Ca, and Mg, available P and K, cation (Ca+Mg+K) saturation, and Al saturation) and soil microbial community composition. In the surface soil layer, a negative impact of lime application was observed for Gram+ bacteria (−29 %) and actinomycetes (−21 %), consequently decreasing the total bacterial community (−26 %) and total microbial biomass (−27 %). This negative impact of liming on Gram+ bacteria and actinomycetes was negatively related to the increase in soil pH, exchangeable Ca and Mg concentrations, and positively related to Al saturation and available K. The combination of an integrated system or system fertilization with lime increased arbuscular mycorrhizal fungi community 3.0-fold compared to a specialized system or conventional fertilization in the subsurface soil layer. In addition, sheep grazing increased saprophytic fungi biomass by 50 % in the subsurface soil layer compared to the specialized system. These positive impacts on the soil fungal community were probably associated with increased plant residue input. Sheep grazing and the fertilization strategy did not affect soil chemical properties or the microbial community at the soil surface. Liming, system fertilization, and sheep grazing benefitted the soil fungal community, thus improving soil health in highly weathered agricultural soils.

Managing soil acidity vs. soil Ca:Mg ratio: What is more important for crop productivity?

AbstractSoil balancing (SB), or base cation saturation ratio (BCSR), is a soil management approach that strives to maintain specific soil calcium (Ca) and magnesium (Mg) levels to improve soil health, decrease pest problems, have better crops, and increase crop yield. To achieve ideal levels of Ca to Mg, BCSR practitioners apply gypsum (calcium sulfate) and high‐calcium lime (Hi‐Cal lime) amendments, with the former increasing Ca base saturation and the later increasing both Ca base saturation and soil pH. We hypothesized that positive benefits ascribed by BCSR practitioners are due to increasing soil pH, rather than increasing Ca levels, both of which occur after lime application. Thus, we conducted successive applications of gypsum or epsom (magnesium sulfate) with and without Hi‐Cal or dolomitic lime, to either increase or lower soil Ca:Mg ratio and pH in an Ohio‐based experiment over 6 yr and evaluated soil and yield responses in a corn (Zea mays L.)–soybean (Glycine max L.)–small grain rotation. Repeated applications of gypsum with and without Hi‐Cal lime significantly increased soil Ca:Mg ratio and repeated applications of epsom with and without dolomitic lime significantly decreased the soil Ca:Mg ratio. Crop yield was not affected by soil Ca:Mg ratio for any crop in any year. However, over the 6 yr of the study, corn yields were positively related to increases in soil pH. We conclude that balancing soil Ca and Mg levels did not impact corn or soybean yields but managing soil acidity remains a fundamental tool to improve crop yields.

Assessment of potential mobility of selected micropollutants in agricultural soils of the Czech Republic using their sorption predicted from soil properties

The sorption of organic contaminants in soils and sediment is a crucial factor affecting their mobility in the vadose zone environment. The Freundlich sorption isotherms were evaluated for eleven micropollutants and eight soils. The highest Freundlich sorption coefficients, KF, were obtained for triclosan (324 ± 153 cm3/nμg1–1/ng−1) followed by sertraline (120 ± 74), venlafaxine (74.3 ± 41.2), telmisartan (33.3 ± 13.6), atorvastatin (8.66 ± 4.78), bisphenol S (8.03 ± 4.87), lamotrigine (6.92 ± 3.02), 2-phenylbenzimidazole-5-sulfonic acid (3.77 ± 2.25), memantine (3.42 ± 1.64), 1-methyl-1H-benzotriazole (2.05 ± 0.99), and valsartan (0.88 ± 0.89). The KF values for the individual compounds were correlated with soil properties. Multiple linear regressions were used to derive equations for predicting the KF values using the soil properties. The first set of equations contained mainly properties with the strongest correlations with the KF values, e.g., a base cation saturation for positively charged compounds or a hydrolytic acidity for negatively charged compounds. The second set of equations contained properties included in the map of agricultural soils of the Czech Republic. These equations always indicated positive correlations with oxidizable organic carbon and clay content. They also included either a negative or positive correlation with pHKCl. A positive correlation with pHKCl was obtained for venlafaxine, memantine, and sertraline, which were mostly positively charged. A negative correlation with pHKCl was obtained for the remaining compounds. The second set of equations, the soil map, and the database of soil properties were used to predict the KF value distributions within the Czech agricultural soils. It resulted in similar KF distributions' patterns for valsartan, lamotrigine, atorvastatin, and telmisartan (with a positive correlation between KF and hydrolytic acidity), which considerably differed from the KF patterns for the other compounds. These maps were used to delineate areas with a leaching potential of the compounds toward groundwater that will serve as a tool for assessing a potential groundwater vulnerability.

Far- and mid-infrared examination of nontronite-1 clay mineral – Redox and cation saturation effects

Infrared Spectroscopy is a very useful tool studying clay minerals in a structural level as well as interactions on their surfaces. In this study, middle- and far- infrared spectroscopy was utilised to better understand how iron-bearing smectites and more specifically the nontronite-1 (NAu1) alters upon iron reduction. Changes in the middle-infrared spectral range have been studied extensively, such as the 3570 cm−1, 1020 cm−1 and 823 cm−1, while far-infrared spectral range changes have not drawn much attention. In this study, NAu1 spectra of oxidised, partially, and fully reduced state are presented noting the differences that occur on different vibration bands at this low frequency infrared range. Key changes took place at the region of 430–494 cm−1, as well as the 145 cm−1 band. From the 175 cm−1 to the 380 cm−1 region, vibrating bands disappeared or convoluted in a wider spectral envelope, upon full iron reduction. At the same time, NAu1 is saturated with different cations, such as Na+, Ca2+, K+, isolating effects on vibrating bands, depending on these cations, across the oxidation states and infrared range examined. These effects are more prominent at the region of 1620–1650 cm−1, where adsorbed H2O bending vibration takes place, for the middle-infrared range. Far-infrared range changes, due to the cation present, are less prominent, but recorded and discussed in detail. Eventually, the redox state of iron-bearing clay minerals controls the structural configuration of the lattice and consequently the interaction strength of clay mineral/saturating cations. The increasing interaction strength observed was Ca2+ < Na+ < K+, which will govern clay mineral hydration and cation exchange processes taking place on the clay mineral surface, as demonstrated, and discussed in this study. These outcomes can be useful in agriculture, waste disposal, and the oil & gas industry.

Evaluating the changes of Ultisol chemical properties and fertility characteristics due to animal manure amelioration

Amending Ultisols using organic matter encourages a paramount improvement in its chemistry and fertility characteristics. This study was aimed to evaluate the changes in soil chemical properties due to the animal manure amelioration in Ultisol in the Jasinga, Bogor, West Java, using classical and advanced statistical methods. Composite soil samples were collected then incubated with three types of animal manure (cow, chicken, and goat) and four rate levels (0, 2.5, 5, and 7.5% of dry weight). The dynamics of eleven soil variables (pH, organic C, total N, cation exchange complex/CEC, base saturation/BS, and exchangeable Al, H, Ca, Mg, K, and Na) were observed four times (0, 2, 4, and 6 weeks). Basic cation saturation ratio/BCSR and sufficiency level of available nutrients/SLAN soil fertility approaches were applied. Modeling comparison was done among multiple linear regression/MLR, machine learning/ML (tree regression/TR, random forest/RF, gradient boosting machine/GBM), and deep learning/DL (multilayer perceptron/MLP). Most of the soil chemical and fertility parameters exhibited strong relation among three applied factors. Generally, their values failed to reach the BCSR’s ideal soil and national SLAN’s sufficiency criteria; oppositely, they were categorized as sufficient based on the global SLAN approach. Multivariate analysis revealed the similarity among manure type and rate, whereas incubation time showed the opposite trend. MLR usage was convenient in modeling BS, pH H2O, and Al saturation. Meanwhile, CEC modeling requires more sophisticated methods. This study highlighted the possible improvement of Ultisol chemical properties and fertility characteristics by amending it with a higher rate and low C/N ratio of animal manure, and using ML to capture non-linear relationships in soil.

Change of ecochemical indicators as a result of introducing beech undergrowth into pine stands

The aim of the presented research was to assess the changes in selected ecochemical indices along the vertical precipitation profile - rainwater passing through the tree canopy and penetrating the topsoil. Two Scots pine stands were selected for this comparison (at one of them beech undergrowth was introduced), located at the Tuczno research site near the existed eddy covariance tower. The concentration of basic cations and anions in the collected water samples was measured and the following indices were calculated: Acid Neutralising Capacity (ANCaq), Alkalinity (ALK), Basic Cation Saturation (BS%) and Calcium to Aluminum ratio (Ca/Al). Additionally, Dry Deposition Factor (DDF) and Canopy Exchange for potassium, calcium, and magnesium cations were estimated (CE_K+, CE_Ca2+and CE_Mg2+, respectively). Observed changes in these variables values in throughfall (TF), as compared to bulk precipitation, at both pine stands during the investigated period 2013–2015 indicate that rainwater was enriched with almost all analyzed ions after passing through the canopy. Moreover, the mean annual deposition of all elements in throughfall was higher in the pine stand with beech undergrowth (SP + Bch) than at the plot with Scots pine only (SP). The average value of the DDF index was almost 3 times higher in the pine stand with beech undergrowth than at solely pine stand. Along with the depth in the soil profile, the ANCaq and ALK decreased. The main conclusion was that introduction of beech undergrowth in the pine stand most likely resulted in the accumulation of more organic matter and thus a slower decomposition rate, as suggested by an increase in acidification of the topsoil (0–15 cm). However, such an effect was not visible in the deeper layers. Higher values of ALK, ANCaq, and pH value under pine stand with beech undergrowth indicate positive effect of beech undergrowth in pine stands.

Base cation saturation ratios, soil health, and yield in organic field crops

AbstractBase cation saturation ratio (BCSR) is a soil management philosophy that postulates having an ideal ratio of base cations for maximizing crop yields. This practice is widely used on organic farms, and BCSR practitioners commonly describe improvements in soil health and crop productivity. However, studies evaluating the efficacy of BCSR on soil biological and physical properties are lacking. This 6‐yr field study evaluated the effects of changing soil calcium/magnesium (Ca/Mg) ratios on organic corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] yields and comprehensive soil health properties at two sites in Ohio with contrasting soils. Three soil amendments—(a) control, (b) gypsum (calcium sulfate), and (c) epsom (magnesium sulfate)—were applied to drive soil Ca and Mg levels in opposite directions. Amendment application resulted in soil Ca/Mg ratios 1.6 and 2.5 times higher in gypsum soils relative to epsom soils. Soil biological health, measured by permanganate oxidizable carbon, mineralizable carbon, and soil protein, was not affected by either gypsum or epsom applications. Likewise, soil physical quality measured by aggregate stability, infiltration, and penetration resistance was not significantly affected by gypsum or epsom additions at either site. Amendment application did not affect crop yields and there was no significant relationship between crop yields and the range of soil Ca/Mg ratios. Results from this study do not provide any evidence that BCSR improves soil health and organic field crop productivity.

Base cation saturation ratios vs. sufficiency level of nutrients: A false dichotomy in practice

AbstractBase cation saturation ratio (BCSR) or “soil balancing” is a soil management philosophy which strives to maintain targeted base cation saturation percentages in soil. Despite lack of Land Grant University (LGU) endorsement for decades, BCSR is widely practiced by many farmers in the United States, particularly in the organic farming community. Here, we explore BCSR persistence and present a framework around BCSR that reflects how it is conceived and practiced on working farms, with a key premise that BCSR practitioners typically use both LGU‐endorsed sufficiency level of available nutrients (SLAN) and BCSR in a hybrid approach. Drawing on (a) a survey of LGU soil fertility scientists’ perspectives on BCSR, (b) decades of published literature on impacts of lime and gypsum application, (c) soil test data from organic corn fields in a four‐state region of the Midwest, and (d) a large state‐wide soil test dataset from Ohio, we examined and tested five unique hypotheses about BCSR. We provide evidence to support the following statements: (a) published peer‐reviewed literature on BCSR is limited and dated, (b) there is widespread agreement among soil fertility scientists that BCSR is not a legitimate practice of soil management, (c) studies of lime and gypsum application on soils can lend insight into the efficacy of BCSR, and (d) in many soils, managing soil acidity will also balance soils in BCSR ideal saturation percentages. Collectively, we summarize key findings from our interdisciplinary effort to provide an updated overview and a more nuanced perspective of BCSR in practice.

Cations ratio and its relationship with other soil nutrients of Java intensified lowland rice

The soil cation ratio is the result of the interaction of various factors, including soil acidity, organic C content, clay minerals, and cultivation management. This paper aims were to study the cation ratio in lowland rice in Java and its relationship with the other nutrients. Soil chemical data were collected from survey for soil maps, soil nutrient status maps, and previously published data. The results showed that the average of cation saturation ratio in lowland rice in Java was 70.8:24.5:1.5 for Ca:Mg:K. The Ca, Mg, K, and Na nutrient contents vary by provinces, and there is a high content of Ca, especially in those soils derived from the calcareous parent materials. This high Ca of >50.0 cmol(+) kg−1 has noticed in Grobogan, Bojonegoro, and Gunung Kidul regencies. The domination of Ca cations in the soil can be seen when the Ca saturation >70%, spreading in 36 districts. Ca saturation is positively correlated with pH, P-Bray, and CEC, and negatively correlated with organic C, N-total, Mg, K, and Na saturation. Based on the regression there is a significant negative relationship between Ca and Mg saturations with R2 = 0.92 and a weak negative relationship between K and Na saturations.

The impact of pine self-afforestation on podzolization process in semi-natural grassland areas of Volyn Polissya (Ukraine)

Background. Several theories have been proposed to explain the podzolization process. Currently, the role of organic matter in both weathering and immobilization in the illuvial horizon is clearly stated. The origin of soil organic matter and, accordingly, the various mechanisms of its influence on the soil material, create the basis of these theories. We assume that in the base-poor sandy soils under rich herbaceous vegetation with a well developed sod layer, the process of podzolization may also depend on CO2 soil formation agent . Materials and Methods. Four localities along a Pinus sylvestris L. self-afforestation chronosequence with pine stands of 10, 20, 40 yrs and an adjacent semi-natural grassland area were investigated in order to determine the patterns of podzolization process on sandy glacial till deposits. Soil pH, exchangeable base, soil cation exchange capacity, total content of soil organic carbon, amorphous Fe, Si and Al and total contents of Al, Fe, Mn, Zn, Cd, Pb, Cu, Co, Ni, Na, K were determined. Statistical analysis of the results was performed using LibreOffice for Linux. Results. During the pine succession, a previously well differentiated into horizons podzolic soil under the grassland vegetation community gradually degrades. Previously well-defined albic and spodic diagnostic horizons disappear, the soil profile becomes more acidic, the soil organic carbon, the base cation content and the base cation saturation decrease, the leaching rate of aluminium and iron increases. Secondary podzolization features in the soil profiles were detected 40 years after the onset of afforestation. The podzolization has not been intensive enough to develop fully fledged albic and spodic diagnostic horizons over such a short period. Conclusions. Based on the obtained soil morphological, physical and chemical properties, three most important agents of podzolization are proposed as principal for the studied area. The main gent under pine forest is fulvic acids that are produced during coniferous litter decomposition. Low molecular weight organic acids and carbon dioxide produced to the rhizosphere by roots and a root associated microbiota are mainly involved in the podzolization process under the grassland ecosystem.

The prevalence and practice of soil balancing among organic corn farmers

AbstractThe scientific community and most mainstream agriculturalists typically design fertilizer recommendations to provide a ‘sufficient level of available nutrients’ to meet the annual N, P and K requirements of common field crops. Soil balancing is another approach to managing soil fertility that focuses on the levels of Ca, Mg and K to achieve a desired base cation saturation ratio (BCSR). Soil balancing is believed to be practiced frequently by organic and other alternative farmers but is viewed skeptically by conventional agricultural scientists due to a lack of support for the idea in the published scientific literature. This study represents a pioneering effort to collect systematic data on the extent of soil balancing, how it is practiced and the types of outcomes reported by organic farmers. Our survey of over 850 farmers who grow certified organic corn in Indiana, Michigan, Ohio and Pennsylvania found that over half report using a soil-balancing approach based on BCSR. Their practice of soil balancing frequently includes more than management of base cations, but also uses a wide range of soil amendment products (such as purchased organic NPK fertilizers, micronutrients, microbial stimulants and soil inoculants) other than those applied specifically for cation balance. Farms that rely on vegetable and dairy production for most of their income, and Amish farmers who rely on horses for fieldwork, were more likely to report using a soil-balancing program. Self-described soil balancers perceived positive agronomic outcomes from the use of a BCSR program, including improvements in soil physical and biological properties and improved crop health and quality. Although farmers in our study report extensive use and positive perceived outcomes from soil-balancing methods, the scientific research literature has been unable to reproduce evidence that manipulating soil base cation levels has any systematic effect on crop yield. Future research could consider the interacting effects of BCSR with other field management practices to more closely approximate the actual practices of farmers.

Soil balancing within organic farming: negotiating meanings and boundaries in an alternative agricultural community of practice

Soil balancing is widely used in organic farming, but little is known about the practice because technical knowledge and goals for the practice are produced and negotiated within an alternative community of practice (CoP). We used a review of the private soil balancing literature and semi-structured interviews with farmers and consultants to document the knowledge, shared meanings, and goals of key actors within the soil balancing CoP. Our findings suggest this CoP is dominated by discourse between private consultants and farmers, with few contributions to or from scientists or the peer reviewed literature. The idea of soil balancing is centered around improving soil quality through adjustments in Base Cation Saturation Ratios (BCSR), and practitioners report a wide range of positive agronomic outcomes. For most soil balancers, however, BCSR is only one part of a broader approach to soil health management that also utilizes traditional soil fertility recommendations and soil health-building cultural management practices. Meanwhile, a survey of land grant university soil fertility specialists and the peer-reviewed literature documented a high degree of skepticism and a lack of scientific evidence that BCSR can boost crop yields. We conclude that this scientific discourse reflects a disconnect from the practices and meanings used in the soil balancing CoP. While tensions between the dominant and niche agricultural knowledge systems are not unique, we believe a better appreciation for the nuanced meanings and goals within the soil balancing CoP present an opening for expanded collaborations with scientists doing research on soil health.

Trading tree growth for soil degradation: Effects at 10 years of black plastic mulch on fine roots, earthworms, organic matter and nitrate in a multi-species riparian buffer

This study assessed the effects of two vegetation management treatments (black polyethylene mulch and a control treatment) on tree growth, fine root biomass of trees and of competing vegetation, earthworms, and physiochemical soil properties in a 10 year-old agricultural riparian buffer planted in southern Québec (Canada) with five trees species: Populus × canadensis Moench (hybrid poplar), Fraxinus pennsylvanica Marsh. (red or green ash), Quercus macrocarpa Michx. (bur oak), Quercus rubra L. (red oak), and Pinus strobus L. (eastern white pine). Vegetation management treatments had a significant effect on tree growth, fine root biomass, earthworms and on many soil properties. Overall, the use of plastic mulch increased tree growth in all species (not to the same extent), but locally decreased soil organic matter, total soil carbon, total soil nitrogen, earthworm biomass and abundance, competing vegetation fine root biomass and the biomass of the total pool of fine roots. Also, more than three times more soil nitrate was measured under mulch despite the higher tree growth. Lower soil phosphorus availability (in some species), base cation saturation and moisture content under the mulch suggested higher uptake of these soil resources to sustain high tree growth. Across treatments and species, significant and strong correlations were observed between total fine root biomass and soil carbon, between competing vegetation fine root biomass and earthworm biomass, and between total soil carbon and earthworm biomass. These highlight the central role of the total pool of fine roots in maintaining or enhancing soil carbon, the importance of understory herbaceous vegetation for earthworm populations and the importance of organic matter as a factor limiting earthworm activity. Species × Treatment interactions were observed on tree growth, fine roots, and earthworms. Pine growth was little enhanced by the mulch and its fine root biomass peaked in the control treatment, suggesting plasticity in allocation to fine roots in response to resource limitations. Pine had similar earthworm biomass across both vegetation management treatments, with two to three times less earthworm biomass than other tree species observed in control plots, reflecting its low needle litter quality. Only poplar and ash had higher tree fine root biomass under the mulch. Red oak was the species the most negatively affected by herbaceous competition. In practice, plastic mulch is rarely removed from tree plantation sites. This should change in a context where plastic mulch is increasingly used as an alternative to herbicide, and where riparian agroforestry projects need to meet both timber and non-timber objectives (carbon sequestration in the soil and in tree biomass, N and P storage in woody biomass, soil quality restoration), while minimizing their impacts in terms of nitrate leaching. Identifying alternative mulching materials and strategies that would provide high growth benefits without degrading the soil or water quality is a priority to optimize ecosystem services provision in tree plantations and riparian buffers.

Potassium–calcium antagonistic interaction under tomato magnesium deficiency and magnesium fertiliser regulation in solar greenhouse

This study sought to clarify the antagonistic interactions of potassium (K) and calcium (Ca) to magnesium (Mg) under a deficiency of Mg in tomato. Tomato leaves and soil samples that had differing levels of Mg deficiency were collected to study the relationship between symptoms of Mg deficiency and contents of soil K and Ca. Four different Mg fertiliser treatments were conducted to analyse the regulation of Mg for soil K, Ca and Mg. The results showed the following: (1) The yield of tomatoes decreased significantly with an increase in Mg deficiency, and the yield of tomatoes with moderate (MD) and severe (SD) Mg deficiency decreased by 38.02% and 59.53%, respectively, compared with treatments without Mg deficiency (ND). (2) The cation saturation ratio of K+ (CSRK+) was significantly higher with MD and SD compared with ND, while the CSRMg2+ was lower. The soil K/Mg and Ca/Mg values were higher than the critical value of imbalance. (3) The soil exchangeable K, CSRK+, Ca/Mg and K/Mg under SD increased significantly when compared with that under ND. (4) The content of Mg in tomato leaves and its yield were significantly negatively correlated with soil exchangeable K, CSRK+ and K/Mg. (5) With the increase in application of Mg fertiliser, the soil exchangeable K content, K/Mg and CSRK+ decreased significantly, while the Ca/K increased. The soil exchangeable K content, K/Mg and CSRK+ with 90 kg/ha MgSO4 and 234 kg/ha K2O applied (M2K1 treatment) were the lowest among all treatments. (6) The yields of tomatoes and uptake of Ca and Mg increased as supply of Mg increased. (7). Reducing the application of K was a much more efficient way to decrease soil K/Mg and restore cation imbalance than providing Mg fertiliser in calcareous soil.

Competitive and synergic sorption of carbamazepine, citalopram, clindamycin, fexofenadine, irbesartan and sulfamethoxazole in seven soils

Sorption of pharmaceuticals, which can occur in soils, may differ when present in a soil solution as a single compound or in a solution with other pharmaceuticals. Therefore, the sorption isotherms described by the Freundlich equations were evaluated for 6 compounds, which were applied in solutions of a single pharmaceutical, two pharmaceuticals or all pharmaceuticals to seven soils. Study mainly focused on a behavior of fexofenadine and irbesartan that occurred in soils in 3 forms (cationic, zwitter-ionic or neutral, anionic). Sorption of both compounds slightly increased (in some soils) when applied together, largely increased when applied with carbamazepine (neutral), and extremely increased when applied in solutions with citalopram (strongly sorbed cation), which could be explained by a cooperative multilayer sorption on soil constituents. On the other hand, sorption of both compounds moderately decreased when applied with clindamycin (cation and neutral) or sulfamethoxazole (neutral or anion). The magnitude of an increase or decrease in the Freundlich sorption coefficient (KF) for a particular compound depended on soil conditions, a form of compound's molecule and its interaction with molecules of other compounds. Despite sorption being influenced by other compound(s) in solution, the KF coefficients evaluated for a particular compound under the different conditions were mostly correlated with the same soil properties: KF,CAR with an organic carbon content, KF,CIT and KF,CLI with a base cation saturation, KF,SUL with hydrolytic acidity, and KF,FEX and KF,IRB with sorption complex saturation.