Switchgrass (Panicum virgatum L.) has been recognized as a potential bioenergy feedstock due to its high yield potential and benefits to the environment. However, little is known about the impacts of ...nitrogen fertilization and landscape position on soil properties in switchgrass fields at multiple locations in the USA. The objective of this study was to assess the impacts of application of nitrogen fertilization rate (N rate; zero, 0; medium, 56; and high, 112 kg ha−1) and landscape position (shoulder, backslope, and footslope) on soil pH, electrical conductivity (EC), soil organic carbon (SOC), total nitrogen (TN), nitrate-N (NO3−-N), and ammonium-N (NH4+-N). This experiment was established in 2008 at four sites in Oklahoma (OK), South Dakota (SD), New York (NY), and Virginia (VA). Data showed that the N rate significantly increased NO3−-N for the 0–5 and 5–15 cm depths at the SD, NY, and VA sites. Compared with the zero N rate, the high N rate averagely increased NO3−-N by 75.7% for the two depths and three sites. The SOC and TN increased with the increase in N rate at most of the depths. The landscape position significantly reduced soil pH and increased EC, SOC, TN, NO3−-N, and NH4+-N at the footslope compared with the shoulder and backslope positions in most depths at the SD site (no position data at the NY and VA sites). The pH generally increased and the SOC, TN, and NO3−-N reduced with the increase in soil depth. These findings indicate that switchgrass production has the potential to improve or maintain soils in the USA.
•N rate significantly increased soil NO3−-N at the SD, NY, and VA sites.•There was an increasing trend in SOC and TN with N rate at the four sites.•Position significantly impacted soil properties at SD site but not for OK site.•Lower pH and higher EC, SOC, TN, and NO3−-N at footslope than shoulder at SD.•pH increased and SOC, TN, and NO3−-N reduced with increasing soil depth.
Biofuel production from crop residues is widely recognized as an essential component of developing a bioeconomy, but the removal of crop residues still raises many questions about the sustainability ...of the cropping system. Therefore, this study reviews the sustainability effects of crop residues removal for biofuel production in terms of crop production, soil health and greenhouse gas emissions. Most studies found little evidence that residue management had long‐term impacts on grain yield unless the available water is limited. In years when water was not limiting, corn and wheat removal rates ≥90% produced similar or greater grain yield than no removal in most studies. Conversely, when water was limiting, corn grain yield decreased up to 21% with stover removal ≥90% in some studies. Changes in soil organic fractions and nutrients depended largely on the amount of residue returned, soil depth and texture, slope and tillage. Reductions in organic fractions occurred primarily with complete stover removal, in the top 15–30 cm in fine‐textured soils. Soil erosion, water runoff and leaching of nutrients such as total nitrogen (N) and extractable soil potassium decreased when no more than 30% of crop residues were removed. Stover management effects on soil bulk density varied considerably depending on soil layer, and residue and tillage management, with removal rates of less than 50% helping to maintain the soil aggregate stability. Reductions in CO2 and N2O fluxes typically occurred following complete residue removal. The use of wheat straw typically increased CH4 emissions, and above or equal to 8 Mg/ha wheat straw led to the largest CO2 and N2O emissions, regardless of N rates. Before using crop residues for biofuel production, it should therefore always be checked whether neutral to positive sustainability effects can be maintained under the site‐specific conditions.
Biofuel production from crop residues is widely recognized as an essential component of developing a bioeconomy, but the removal of crop residues still raises many questions about the overall sustainability of the cropping system. Before using crop residues for biofuel production, it should therefore always be checked whether neutral to positive sustainability effects can be maintained under the site‐specific conditions.
Core Ideas
Nitrogen rate did not affect soil properties for Oklahoma, South Dakota, and Virginia.
Landscape position affected soil properties under higher slope.
Nitrogen rate affected root N, ...surface area, and weight for the total profile.
Landscape position affected the root C and N.
Switchgrass roots can increase C accumulation and reduce risk of N loss in soils.
ABSTRACT
Switchgrass (Panicum virgatum L.) has been recognized as a potential bioenergy feedstock, and can positively impact soils and the environment. The experimental sites were established in 2008 at three locations with each in Oklahoma (OK), South Dakota (SD), and Virginia (VA) to assess the impacts of N fertilization rate (N rate; low, 0 kg ha−1; high, 112 kg ha−1) and landscape position (shoulder, backslope, and footslope) on select soil properties and root growth parameters. Data indicate that N rate did not affect soil bulk density (BD), pH, electrical conductivity (EC), soil organic carbon (SOC), and total nitrogen (TN) for any of five depths. Landscape position impacted some of these properties by depth, depending on location. The N rate influenced root weight (RW), root surface area (RSA), and root total nitrogen (RTN) for the total profile (0–100‐cm depth) depending on local site conditions. The landscape position impacted RW, root total carbon (RTC), and RTN for total profile according to different site conditions. The interactions of landscape position by N rate on switchgrass root parameters were significant. The findings in this study indicate that the root system of switchgrass could improve soils and increase C accumulation and reduce the risk of N loss to benefit the environment.
Soil microbial biomass and functions are the most affected soil components by environmental changes. Therefore, determining the factors affecting soil microorganisms is very important for forest ...management. This study was conducted to determine the influence of forest type and seasonal variations on microbial biomass and activities in soil. For this, a total of 360 soil samples were collected (120 from each of the Black Pine, Lebanon Cedar, and Oriental Beech) during four seasons of the year in the Eastern Mediterranean Karst Mountain of Taurus, Turkey. Soil samples were used to determine soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon (Cmic), microbial biomass nitrogen (Nmic), and microbial respiration (MR). With these data, the metabolic quotient (MR/Cmic ratio) and microbial quotient (qCO2 = Cmic/SOC ratio) were calculated. Soil Cmic and Nmic were significantly higher in Cedar (789.5 ± 438 μg C g−1; 305.26 ± 93 μg N g−1) than in the Beech (691.8 ± 246 μg C g−1; 148.18 ± 43 μg N g−1) and Pine forests (659.4 ± 224 μg C g−1; 130.1 ± 22 μg N g−1). Microbial properties were highly sensitive to forest tree species and seasonal patterns, which can be further used as potential indicators of the effects that forest management practices may have on SOC dynamics. The three forest types showed significant differences in the seasonal Cmic and Nmic patterns, with maximum values occurring in the fall and minimum in the winter season. However, averaged across forest species, SOC did not vary among different seasons. The qCO2 was higher in Cedar forest in the winter season and lower in the Beech forest during the spring season. These findings show that Cedar forest could be more conducive to higher microbial activity and overall soil quality than the Beech and Pine forests.
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•Effect of forest type and season on microbial biomass and activities were studied.•Maximum microbial biomass C and N had in autumn and minimum in winter.•Microbial biomass C and N were higher in cedar than in beech and pine forests.•Metabolic quotients were higher in cedar in winter and lower in beech in spring.
Ecosystem degradation as a result of coal mining is a common phenomenon in various regions of the world, especially in arid and semi-arid zones. The implementation of appropriate revegetation ...techniques can be considered crucial to restore these degraded areas. In this regard, the additions of spent mushroom compost (SMC) and wood biochar (WB) to infertile and degraded soils have been reported to enhance soil fertility and plant growth under water (W) deficit conditions. However, the combined application of W, SMC and WB to coal mine degraded soils, to promote Althaea rosea growth and facilitate subsequent restoration, has not been explored yet. Hence, in the current study a pot experiment was carried out by growing A. rosea on coal mine spoils to assess the influence of different doses of W, SMC and WB on its morpho-physiological and biochemical growth responses. The results indicated that several plant growth traits like plant height, root length and dry biomass significantly improved with moderate W-SMC-WB doses. In addition, the simultaneous application of W-SMC-WB caused a significant decrease in hydrogen peroxide (H2O2) (by 7–56%), superoxide anion (O2●‒) (by 14–51%), malondialdehyde (MDA) (by 23–46%) and proline (Pro) contents (by 23–66%), as well as an increase in relative water content (by 10–27%), membrane stability index (by 2–24%), net photosynthesis rate (by 40–99%), total chlorophylls (by 43–113%) and carotenoids (by 31–115%), as compared to the control treatment. The addition of SMC and WB under low-W regime enhanced leaf water use efficiency, and soluble sugar content, also boosting the activity of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase in leaf tissues, thus reducing the oxidative stress, as proved by low levels of H2O2, O2●‒, MDA and Pro contents. Finest growth performance under optimum doses of W (60% field capacity), SMC (1.4%) and WB (0.8%) suggest that revegetation of A. rosea with the recommended W-SMC-WB doses would be a suitable and eco-friendly approach for ecological restoration in arid degraded areas.
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•Revegetation of A. rosea was tested with water (W), compost (SMC) and biochar (WB).•A. rosea improved morphological attributes with moderate W, SMC and WB doses.•High W-SMC-WB doses improved gas-exchange traits, leaf water and chlorophyll contents.•SMC-WB impeded oxidative damage by boosting osmolytes and enzyme activity at low-W.•Revegetation of A. rosea in coal mine arid area with W60SMC1.4WB0.8 is recommended.
The study was aimed to investigate the effects of bacterial fertilizer (BF) application and planting patterns on quantitative and qualitative yield of savory intercropped with common bean. An ...experiment was performed using a factorial based on randomized complete block design (RCBD) with three replications. The factors included microbial inoculation (mix of nitrogen-fixing + phosphate-solubilizing + potassium-solubilizing bacteria and non-inoculation), and planting patterns one row of savory + one row of common bean (1S:1CB), two rows of common bean + two rows of savory (2S:2CB), two rows of savory + one row of common bean (2S:1CB), one row of savory + two rows of common bean (1S:2CB), as well as the pure culture of both plants. The results showed that the seed yield of common bean and dry matter yield of savory was recorded in pure culture conditions treated with BF. The 2CB:2S intercropping pattern with BF fertilization produced the highest essential oil (EO) content of savory (1.96%). In addition, the application of BF enhanced the EO yield of savory by 35% compared to control. The major constituents of savory EO were carvacrol,
γ
-terpinene, α-terpinene,
p
-cymene, and β-myrcene. The 2CB:1S intercropping pattern with BF fertilization produced the maximum content of carvacrol and
p
-cymene. The maximum content of phenolic compounds including rosmarinic acid, coumaric acid, chlorogenic acid, cinnamic acid, and apigenin was recorded in the intercropping pattern of 2CB:2S treated with BF. Overall, intercropping pattern of 2CB:2S treated with BF could be recommended to farmers as eco-friendly strategies to improve EO quality and quantity as well as phenolic compounds.
Graphical abstract
The productivity of cereal crops under salt stress limits sustainable food production and food security. Barley followed by sorghum better adapts to salinity stress, while wheat and maize are ...moderately adapted. However, rice is a salt-sensitive crop, and its growth and grain yield are significantly impacted by salinity stress. High soil salinity can reduce water uptake, create osmotic stress in plants and, consequently, oxidative stress. Crops have evolved different tolerance mechanisms, particularly cereals, to mitigate the stressful conditions, i.e., effluxing excessive sodium (Na+) or compartmentalizing Na+ to vacuoles. Likewise, plants activate an antioxidant defense system to detoxify apoplastic cell wall acidification and reactive oxygen species (ROS). Understanding the response of field crops to salinity stress, including their resistance mechanisms, can help breed adapted varieties with high productivity under unfavourable environmental factors. In contrast, the primary stages of seed germination are more critical to osmotic stress than the vegetative stages. However, salinity stress at the reproductive stage can also decrease crop productivity. Biotechnology approaches are being used to accelerate the development of salt-adapted crops. In addition, hormones and osmolytes application can mitigate the toxicity impact of salts in cereal crops. Therefore, we review the salinity on cereal crops physiology and production, the management strategies to cope with the harmful negative effect on cereal crops physiology and production of salt stress.
There is a need for a more innovative fertilizer approach that can increase the productivity of agricultural systems and be more environmentally friendly than synthetic fertilizers. In this article, ...we reviewed the recent development and potential benefits derived from the use of nanofertilizers (NFs) in modern agriculture. NFs have the potential to promote sustainable agriculture and increase overall crop productivity, mainly by increasing the nutrient use efficiency (NUE) of field and greenhouse crops. NFs can release their nutrients at a slow and steady pace, either when applied alone or in combination with synthetic or organic fertilizers. They can release their nutrients in 40-50 days, while synthetic fertilizers do the same in 4-10 days. Moreover, NFs can increase the tolerance of plants against biotic and abiotic stresses. Here, the advantages of NFs over synthetic fertilizers, as well as the different types of macro and micro NFs, are discussed in detail. Furthermore, the application of NFs in smart sustainable agriculture and the role of NFs in the mitigation of biotic and abiotic stress on plants is presented. Though NF applications may have many benefits for sustainable agriculture, there are some concerns related to the release of nanoparticles (NPs) from NFs into the environment, with the subsequent detrimental effects that this could have on both human and animal health. Future research should explore green synthesized and biosynthesized NFs, their safe use, bioavailability, and toxicity concerns.
Drought stress, being the inevitable factor that exists in various environments without recognizing borders and no clear warning thereby hampering plant biomass production, quality, and energy. It is ...the key important environmental stress that occurs due to temperature dynamics, light intensity, and low rainfall. Despite this, its cumulative, not obvious impact and multidimensional nature severely affects the plant morphological, physiological, biochemical and molecular attributes with adverse impact on photosynthetic capacity. Coping with water scarcity, plants evolve various complex resistance and adaptation mechanisms including physiological and biochemical responses, which differ with species level. The sophisticated adaptation mechanisms and regularity network that improves the water stress tolerance and adaptation in plants are briefly discussed. Growth pattern and structural dynamics, reduction in transpiration loss through altering stomatal conductance and distribution, leaf rolling, root to shoot ratio dynamics, root length increment, accumulation of compatible solutes, enhancement in transpiration efficiency, osmotic and hormonal regulation, and delayed senescence are the strategies that are adopted by plants under water deficit. Approaches for drought stress alleviations are breeding strategies, molecular and genomics perspectives with special emphasis on the omics technology alteration i.e., metabolomics, proteomics, genomics, transcriptomics, glyomics and phenomics that improve the stress tolerance in plants. For drought stress induction, seed priming, growth hormones, osmoprotectants, silicon (Si), selenium (Se) and potassium application are worth using under drought stress conditions in plants. In addition, drought adaptation through microbes, hydrogel, nanoparticles applications and metabolic engineering techniques that regulate the antioxidant enzymes activity for adaptation to drought stress in plants, enhancing plant tolerance through maintenance in cell homeostasis and ameliorates the adverse effects of water stress are of great potential in agriculture.
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