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•Soil surface roughness is an important factor in runoff and soil erosion.•Smooth surfaces became rougher due to dislocation of particles by raindrop impacts.•Surface roughness ...(oriented and random) degraded after the rainfall.•Random roughness produced the highest runoff and soil loss and lowest infiltration.•Oriented roughness across-slope does not always reduce runoff and soil loss.
Soil erosion by water is a result of detachment of particles or small aggregates from the soil surface followed by transport of the detached material. One of the elements that affects surface runoff and soil erosion is the soil surface roughness (SSR). Prior research reports that increasing SSR reduces generation of runoff and soil loss. In addition to that, it is widely reported that across-slope oriented roughness is better at controlling soil and water losses. However, to date there have been few studies into the effect of both magnitude and orientation of SSR on runoff, infiltration and soil erosion at the sub process level (i.e. by raindrop splash and overland flow), occurring simultaneously. In this study, the effects of up-down-slope oriented SSR (Treatment A), across-slope oriented SSR (Treatment B) and random SSR (Treatment C) were compared, along with a smooth surface (Treatment D). A moderate slope gradient of 10 %, a simulated rainfall intensity of 90 mm hr−1 and storm durations of 15 or 30 min were considered. The SSR was measured using the chain method, before and after the rainfall event. Images of the soil surface were taken using a hand-held laser scanner to monitor the effect of rainfall on the surface morphology. The outcome of this study shows that rainfall erosivity increases the SSR of the initially smooth surface, but decreases that of the initially rough surface, particularly in the random SSR treatment, where the decrease in SSR was 64 % of the pre-rainfall condition. This was due to the effects of raindrop impacts and overland flow. The random SSR treatment generated significantly more runoff and soil loss, and less infiltration than all other treatments (p < 0.001), but for raindrop splash erosion, there was no significant difference between random SSR and the other treatments. Contrary to expectations, the across-slope oriented SSR did not always reduce runoff and soil erosion compared to the up-down-slope orientation. This can be explained by degradation of surface microtopography by rainfall and runoff, as confirmed by the post-rainfall SSR measurements.
Salinity and sodicity are the most agricultural challenges in arid and semi-arid regions. A pot experiment was undertaken, to evaluate the effect of Phosphogypsum (PG) and Gypsum (G), to remove ...salts, nutrients and trace elements in leached water from saline and saline-sodic soils. In order to determine the efficiency and safety of these amendments, as an affordable strategy, for overcoming salinity and sodicity stress. The PG at 0, 15, 30 and 45 t/ha and G at 15 t/ha were mixed with the upper 9 cm soil in the pot before being leached. The soils were collected from Sed El Masjoune and Sidi El Mokhtar areas of morocco with ECe of 140.6 mS/cm and 11.7 mS/cm respectively. The highest doses of PG (≥30 t/ha) removed significant amount of salts and nutrients. Calcium sulfate supplies calcium ions to replace salt ions (sodium, especially). The replaced salts are leached from the soil. The PG was more efficient compared to G in terms of salts leaching. Quantities of trace elements in the leachate, for most analyzed elements, were below the recommended limits of drinking and irrigation water. Because the experiment’s alkaline conditions (basic water and soil) reduce the solubility and mobility of trace elements. The amendment application did not affect saturation index (SI) of the main minerals. However, water passing through the soil increased the SI. which could result in groundwater mineral precipitation.
The effects of a short-term exposure (40s) to 50°C on the prompt fluorescence (PF), delayed fluorescence (DF) and 820nm reflection (MR) signals in three different photosynthetic organisms: Pisum ...sativum (angiosperm plant), Ginkgo biloba (gymnosperm tree) and thalli of Parmelina tiliacea (Hoffm.) Ach (lichen) were investigated. The aim of this study was to understand the relationship between prompt PF, DF and MR when the oxygen evolving complex (OEC) is destroyed. The signals of PF, DF and MR were measured simultaneously in plants in vivo to probe heat-induced damages in the photosynthetic electron transfer. PF is characterised by a polyphasic fluorescence rise OJIPSMT and DF induction curve has several maxima (In) and numbered in sequence according to their appearance during illumination. In control condition (25°C) leaves of pea plants yield a typical OJIP rise with a flat P-step (0.2–2s) and in G. biloba and P. tiliacea thalli, the P-level was split into two peaks, the first peak P (0.2s) is followed by a decrease of the fluorescence intensity to a dip (S) and a subsequent rise to a second peak (M). An antiparallel relation between J–I–P–S and DF curves was also observed. Methyl viologen (MV) reduced the amplitude of the I–P phase of the PF curve and this change was accompanied by a disappearance of the PSM transient. In the presence of MV, the DF intensity remained higher; and the I4 peak disappeared. We suggested that P-S-M rise from PF and I4 peak might be related to an acceleration of intersystem electron transport. After 50°C incubation, significant changes appeared in the PF, DF and MR transients and that were dependent on the photosynthetic sample. Heat treatment provoked a down regulation of electrons donation by the OEC in the three plant species and the re-reduction of P700+ and PC+ started earlier and began already after 10 ms of illumination. Inhibition of the donation of electrons by OEC after 50°C incubation indicates that DF induction depends on the concentrations of QA− and P680+ and the proton gradient.
Abstract
Rising soil and water salinity endanger plant growth and crop productivity, putting global food security at risk. As plants are sessile, their adaptation to rapidly changing environments is ...slow, endangering their survival. As a result, mitigation efforts should shift to developing smart crops capable of withstanding dynamic and heterogeneously distributed salinity. Recent breakthroughs in bioinformatics and high throughput genomics can cost-effectively accelerate the introduction of superior varieties for saline regions. Sugar plays an essential role in biomass accumulation and is thus a viable target for forage crop improvement programs. Sugars Will Eventually be Exported Transporter (SWEET) gene family transcribes for source-sink carbon allocation in the form of sugar in higher plants. However, little is known about SWEET’s role in maize's phenotypes of agronomic interest for forage production. Here, through a genome-wide analysis, we identified and characterized 19 SWEET genes that are expressed across various shoot phenotypes. Eleven of the genes are salt-responsive, and
ZmSWEET7
is most abundant in high-sugar-yielding varieties compared to low-sugar varieties. Homologous overexpression of the
ZmSWEET7
increases the maximum quantum yield of photosystem II photochemistry (F
V
/F
M
), CO
2
assimilation rate (A), soluble sugar content, and dry matter, with the quantum yield for CO
2
fixation efficiency (phiCO
2
) showing the most significant increase. There is a strong positive association between phiCO
2
and soluble sugar content, dry matter, and F
V
/F
M
in
ZmSWEET7
overexpressing mutants compared to the wild. These findings indicate that
ZmSWEET7-
mediated CO
2
fixation efficiency rather than assimilation rate plays a positive pleiotropic role in C accumulation in the form of sugar or dry matter via increased F
V
/F
M
. This work lays a strong foundation for salt-tolerant forage maize genetic improvement.
Solar drying and liming are commonly used for sludge treatment, but little is known about their efficiency on antibiotics and Polycyclic Aromatic Hydrocarbons (PAHs) removal. This study aimed to ...investigate the removal of antibiotics and PAHs during solar drying of Limed Sludge (LS) and Non-Limed Sludge (NLS). Thus, organic matter fractionation and 3D fluorescence were used to assess the accessibility and the complexity of organic matter. 2 experiments have been conducted using LS and NLS for 45 days of drying in a pilot scale tunnel. Physicochemical results indicated significant decrease of water content (90%) for both sludge samples within 15 days of drying. For both treatments, the removal of total organic carbon and total nitrogen was low and similar for both treatments. Through this study, it has been confirmed that liming and drying contributed to a strong modification of the organic matter quality with an increase of its accessibility. On the other hand, drying alone increased the less accessible compartments, while the presence of lime affected the interconnexion between the organic matter pools. 3D fluorescence confirmed the obtained results and indicated that LS leads to obtaining more simple molecules in the most accessible compartments, while NLS leads to obtaining more complex molecules in the less accessible compartments. In addition, solar radiations and leaching may contribute to the significant removal (p < 0.01) of roxithromycin, benzo(a)anthracene, chrysene, benzokfluoranthene, benzoapyrene, and benzo(g, h, i) perylene in the presence of lime. Furthermore, the evolution of organic matter pools in terms of accessibility and complexity may drive the bioavailability of these pollutants, leading to their significant removal.
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•The lime addition leads to increase the accessibility of sludge organic matter.•Significant removal of some antibiotics and PAHs was obtained after liming.•The persistence of antibiotics and PAHs needs to be well considered.•Fractionation leads to better understand the fate of antibiotics and PAHs.
In semi-arid context, the development of anthroposol from phosphate industry by-products and sewage sludge could be a new approach for sustainable phosphate mining soils. The objective of this 2 ...years field study carried out at Benguerir phosphate mine, was to evaluate nutrients and heavy metals dynamics in the soil-plant system of three species planted on anthroposol consisting of a mixture of 65% phosphogypsum (PG), 30% phosphate sludge (PS), and 5% sewage sludge (SS). The experimental layout was a randomized complete block design with six replicates and three species: argan, olive, and carob. No fertilizer was applied to the different plots. Heights and diameters of the different species were measured. Species were pruned, and leaves and stems were separated. The nutrients (N, P, K, Ca, and Mg) and heavy metals (Cd, Cu, Cr, Pb, Ni and Zn) contents in both soil and plant part were determined. The results of the Pearson correlation showed significant correlations between height and diameter of the different species. The strongest correlation was observed for the argan tree. Furthermore, nutrient contents in the rhizosphere of species were significantly reduced, excepted Ca. Also, nutrient contents in leaves were significantly higher than those in the stems. In addition, the concentration of heavy metals in argan, olive and carob leaves, were below international standards. In semi-arid contexts, argan tree could be the best candidate for revegetating mining sites and this anthroposol (65% PG – 30% PS – 5% SS) could be a new approach to rehabilitate mining site on large scale.
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•Anthroposol has been successfully prepared using a promising, cost-effective process.•Argan tree was the species best adapted to withstand difficult conditions.•Significant differences were recorded between tree nutrient contents.•Low Heavy metals transfer from anthroposol to argan, olive, and carob leaves with contents below international standards.
Abstract Organic fertilizers have the potential to improve soil quality and quinoa ( Chenopodium quinoa Willd.) yields, but their long-standing benefits are unknown. Therefore, a three-years field ...experiment (2019–2022) was conducted in Morocco to investigate the residual effects of organic fertilizers on the productivity and mineral status of quinoa. Compost and manure were applied during the first season at 5, 10, and 20 t ha − 1 and 10, 20, and 40 t ha − 1 , respectively. Soil organic matter (SOM), plant growth, and quinoa yield were monitored during the year of organic fertilizer applications and two and three years after the applications. 40 t ha − 1 of manure produced the highest SOM, plant height, and chlorophyll content index. Compost at 20 t ha − 1 produced the highest grain yield (4.6 t ha − 1 ) during the first year, but the residual effect of 40 t ha − 1 of manure exceeded other treatments in the second and third years (3.4 t ha − 1 and 1.4 t ha − 1 , respectively). Average quinoa grain yield over the three years was highest with 10 and 20 t ha − 1 of compost and 20 and 40 t ha − 1 of manure and average quinoa nutrient content was 1.8 kg N, 0.3 kg P, 4.1 kg K, 0.5 kg Ca, 0.6 kg Mg, 0.5 g Cu, 1.9 g Zn, 7.9 g Mn, and 7.9 g Fe per 100 kg of total biomass. A single application of manure at 20 t ha − 1 was optimal to increase quinoa productivity for three growing seasons, promoting agricultural sustainability in arid regions.
When a mixture of thick sewage sludge (10
m
3) and green waste (5
m
3) was composted, the thermogenic phase (72
°C) improved the hygiene of the final product. After 135 days of composting, overall ...decomposition reached 60%, with percentage decomposition of hemicellulose, cellulose and lignin 70%, 61% and 37%, respectively. The C/N ratio was 12 and the NH
4
+/NO
3
− ratio was 0.24, illustrating the maturity of the final product. During composting, the humification process resulted in an increase in humic acids from 26 to 39.5
mg
g
−1, and a decrease in fulvic acids from 38 to 18
mg
g
−1. The different humification indices and the Fourrier transform infra-red (FTIR) spectroscopic analysis revealed an increase in aromaticity and degree of polycondensation, with a decrease in aliphatic groups and a reduction in the easily assimilated peptide and carbohydrate components. The germination index for both lettuce (
Lactuca sativa) and turnip seed (
Brassica rapa) was 98% after 135 days of composting, showing that the final compost was not phytotoxic.
This study aimed to assess the effectiveness of solar drying process, for limed and non-limed sludge, in terms of reducing heavy metals mobility and toxicity in a sewage sludge (SS) generated from an ...activated sludge wastewater treatment plant (WWTP). The total quantification of heavy metals indicated a high concentration of Chromium (Cr), Copper (Cu), Lead (Pb) and Nickel (Ni) (2739.09, 174.48, 68.59 and 31.97 mg/kg respectively). At the first stage of solar drying (for limed and non-limed sludge), speciation analysis showed that Cr, Pb and Cu are mostly associated to the oxidizable fraction; contrary wise, Ni is mostly associated to the reducible fraction. By the end of the solar drying process, the oxidizable fraction decreased significantly from 80 to 15%, 80 to 25% and from 70 to 27% respectively for Cr, Cu and Pb. On the other hand, the residual fraction (the most stable in the environment) increased significantly from 17 to 78%, 18% to 73% and 28 to 71% respectively for Cr, Cu and Pb. Phytotoxicity risk assessment during the solar drying process revealed a significant increase of the germination index (GI) for both Cress and Turnip (from 4.3 to 98.5% and 15 to 94% respectively). These results highlighted the considerable effectiveness of solar drying process in terms of heavy metals’ mobility and phytotoxicity reduction. Thus, the solar dried sludge could be potentially applied on the agricultural soils.
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•Impact of Solar drying and liming processes on sewage sludge quality was investigated.•Solar dried sludge is for a high agronomic value.•Solar drying process affected significantly heavy metals speciation.•Solar drying decreased sludge phytotoxicity.•Liming did not promote solar drying effect on sludge quality.
Among the phthalic acid esters (PAEs) targeted by the United States Environmental Protection Agency (USEPA) as priority pollutants, di-ethyl-hexyl phthalate (DEHP) is the major pollutant identified ...at high concentration level in lagooning sludge (LS), at about 28.67
mg/kg, and in activated sludge (AS), at about 6.26
mg/kg. Other phthalic acid esters, such as di-butyl phthalate (DBP) and di-methyl phthalate (DMP) show very low concentrations. During sludge composting, after the stabilization phase, the subsequent appearance of DEP and then DMP occurred indicating that microbial metabolism begins by alkyl side-chain degradation before aromatic ring-cleavage. The appearance and accumulation of PAEs with a short alkyl side-chain in the last stages of AS and LS composting is suggested originating from the degradation of phthalates with a much long side-chain. The DEHP showed a rate of biodegradation that follows a first-order kinetic model during composting of both AS and LS. The calculated DEHP half-lives are 45.4 days for LS and 28.9 days for AS. The better DEHP biodegradation rate (2.4
×
10
−2 day
−1) have been observed in the case of AS composting compared to LS compost (1.53
×
10
−2 day
−1). The mono-ethyl-hexyl phthalates MEHP has been shown to follow the same order of biodegradation as DEHP indicating that the same mechanism is followed (hydrolysis or dealkylation of each DEHP side-chain). Composting could be suggested as a detoxification process for the removal of PAEs (mainly DEHP) from sludges after a sufficient time of treatment to provide a safe end product.
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