A greenhouse study was conducted to explore the effect of various rates of potassium sulfate (K 2 SO 4 ) nanoparticles on alfalfa (Medicago sativa L.) growth and physiological response under salt stress. One salt-tolerant genotype (Mesa-Sirsa) and one salt-sensitive genotype (Bulldog 505) were selected based on germination under salt and were planted in pots containing 2 kg of sand. The two genotypes were subjected to 0 and 6 dS•m −1 salt levels using CaCl 2 •2H 2 O: NaCl (2:1) mixed with Hoagland solution. Three K 2 SO 4 nanoparticle treatments consisting of, 1/4, 1/8, and 1/10 of the potassium (K) level in full strength Hoagland solution (235 mg•L −1 ) were applied. Adding K 2 SO 4 nanoparticles at the 1/8 level resulted in the highest shoot dry weight, relative yield, root length and root dry weight in both genotypes. The different rates of K 2 SO 4 nanoparticles affected significantly Na/K ratio and the concentrations of Calcium (Ca), Phosphorus (P), Copper (Cu), Manganese (Mn), and Zinc (Zn) in plant tissue. The application of K 2 SO 4 nanoparticles at the 1/8 rate enhanced the plant's physiological response to salt stress by reducing electrolyte leakage, increasing catalase and proline content, and increasing antioxidant enzymes, activity. These results suggest that the application of K nanoparticles may have better efficiency than conventional K fertilizers in providing adequate plant nutrition and overcoming the negative effects of salt stress in alfalfa.

Salinity is a major impediment to crop production. This study was undertaken to compare the effect of seaweed extract, humic acid, and potassium sulfate nanoparticles in alleviating salt stress in Alfalfa (Medicago sativa L.). Seeds of ten alfalfa genotypes were germinated in a growth chamber at five salt concentrations (0%, 0.5%, 1.0%, 1.5%, and 2.00%). Salt concentrations above 1% reduced seed germination by more than 70% in most genotypes. One salt tolerant genotype (Mesa-Sirsa) and one salt sensitive (Bulldog 505) were selected and planted in greenhouse pots containing 2 kg of sand and subjected to two salt levels (10 and 15 dS·m . Plant biomass was reduced under both salt concentrations in both genotypes, with a greater magnitude in the salt sensitive genotype. Application of seaweed extract resulted in higher relative water content and proline under both salt concentrations (10 and 15 dS·m −1 ) in the salt sensitive genotype, and lower electrolyte leakage in both salt tolerant and salt sensitive genotypes, under both salt concentrations. Seaweed extract also resulted in higher catalase and SOD activities in both genotypes under 10 dS·m −1 . Catalase and SOD activities were associated with significantly (p < 0.01) reduced electrolyte leakage and increased shoot dry weight. Overall, seaweed extract seemed to have a positive effect in alleviating salt stress in alfalfa.

Soil salinity and sodicity is a potential soil risk and a major reason for reduced soil productivity in many areas of the world. This study was conducted to investigate the effect of different biochar raw materials and the effects of acid-modified biochar on alleviating abiotic stresses from saline-sodic soil and its effect on biochemical properties of maize and wheat productivity. A field experiment was conducted as a randomized complete block design during the seasons of 2019/2020, with five treatments and three replicates: untreated soil (CK), rice straw biochar (RSB), cotton stalk biochar (CSB), rice straw-modified biochar (RSMB), and cotton stalk-modified biochar (CSMB). FTIR and X-ray diffraction patterns indicated that acid modification of biochar has potential effects for improving its properties via porous functions, surface functional groups and mineral compositions. The CSMB treatment enhanced the soil’s physical and chemical properties and porosity via EC, ESP, CEC, SOC and BD by 28.79%, 20.95%, 11.49%, 9.09%, 11.51% and 12.68% in the upper 0–20 cm, respectively, compared to the initial properties after the second season. Soil-available N, P and K increased with modified biochar treatments compared to original biochar types. Data showed increases in grain/straw yield with CSMB amendments by 34.15% and 29.82% for maize and 25.11% and 15.03% for wheat plants, respectively, compared to the control. Total N, P and K contents in both maize and wheat plants increased significantly with biochar application. CSMB recorded the highest accumulations of proline contents and SOD, POD and CAT antioxidant enzyme activity. These results suggest that the acid-modified biochar can be considered an eco-friendly, cheaper and effective choice in alleviating abiotic stresses from saline-sodic soil and positively effects maize and wheat productivity.

Background: In Egypt, calcareous soils represent a large part of desert soils suffering from a shortage of nutrients and organic matter, affecting production and biological diversity in agroecosystems. Organic wastes, negatively affect the environment, recycling it as a promising technology in different farming systems, and its impact on crop productivity and soil fauna is largely unknown. In this study, the effects of integrating poultry manure (PM) alone or combined with vinasse (V) at rates of 4.2 g kg− 1 and 6.3 g kg− 1 in pots, on improving soil fauna diversity, soil fertility, soil consistency and yield of barley (Hordeum aestivum L.) grown in a calcareous soil were investigated. Results: The results showed that the addition of PM alone or combined with V at different rates led to a significant increase in the microbial biomass carbon (MBC), organic matter (OM), NPK soil availability and yield of barley. The addition of 6.3 g PM and 4.2 g V kg− 1 soil have the best results in OM with 65.0% compared to control, and V contributes more than 16% of them. Prostigmata and Collembola were the dominant groups and accounted for 43.3% and 50.0% in the PM1 and 50.0% and 20.0% in the PM2 of the total individuals, respectively. Shannon and Evenness indices increased significantly with the soil amended by PM alone or combined with V. Soil fauna plays a key role in soil consistency because of a significant relationship between soil fauna and soil OM, MBC and soil fertility index. The addition of 6.3 g PM and 4.2 g V kg− 1 soil gave the best results in grain yield by 76.90% compared to the control. Conclusion: In conclusion, the interaction between PM and V can be used as a promising organic amendments to increase barley yield and improve efficiency of a recycled PM and V on soil fauna and soil fertility of calcareous soil.

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