The current research aims to study the impacts of adding corncob biochar to a sandy soil irrigated with drainage water on wheat productivity, heavy metals fate, and some soil properties that reflect healthy soil conditions. This research consists of two separate experiments under field (lysimeters) and pot incubation conditions conducted on sandy soil irrigated with drainage water and treated with corncob biochar at the rate of 0.0, 1, 2, and 3% as mixing or mulching. Results specified that drainage water electrical conductivity value (5.89 dS m⁻¹) lies under the degree of restriction on use of “Severe”, indicating that nonstop irrigation with such drainage water may cause a severe salinity problem in soil in the long run. A comparison of heavy metal concentrations of biochar-treated soils with the control showed that total heavy metals had accumulated significantly in the topsoil layer. Most of the available heavy metal concentrations in all soil leachate fractions were below the method detection limits. Mean concentrations of Ni, Cd, and Pb in wheat crops were far below the concentrations considered phytotoxic to wheat plants. More than 90% of the Ni, Cd, and Pb contained in the drainage water of the Al-Moheet drain were significantly present (p ≤ 0.05) and adsorbed by biochar in the top 20 cm of soil lysimeters, indicating the high biochar adsorptive capacity of heavy metals. Total counts of bacteria and fungi gradually and significantly increased over the soil incubation time despite irrigation with contaminated drainage water. Soil resistance index (SRI) values for microbial biomass were positive throughout the experiment and increased significantly as the application rate of corncob biochar increased. These results indicated the high feasibility of using corncob biochar at a rate of 3% to temporarily improve the health of sandy soil despite irrigation with drainage water.

Among crucial factors that control flooding events are extreme climate, urban growth, and mismanagement. Islands in the Nile River have experienced successive cycles of flooding and drying due to recent rainy years in the Nile Basin countries. This paper focuses on the impact of floods on the amounts of ammonium-N released, total concentrations of heavy metals, enzyme activities, and microbial biomass (C and N) in flood soils of 11 Nile River islands. Field moist soils and their airdried counterparts were collected from the outskirts of the island and incubated for 15 days at 30 °C to be analyzed. Results reflected that the amounts of released NH₄-N were higher in airdried than in wet soils. The average hydrolysis rates of the studied six enzyme substrates were correlated significantly with organic C, organic N, microbial bio-mass C and N in the field moist soils. The highest correlation coefficients (r) were with rates of hydrolysis of substrates of asparaginase, amidase, and β-glycosaminidase. A significant intercorrelation between rates of hydrolysis of the six studied enzyme substrates and r values which range from 0.81 to 0.98. At 10 mmol kg⁻¹ soil, Co⁺², Cd⁺², Pb⁺², Cu⁺², Cr⁺³, and Ni⁺² inhibited the release of NH₄-N. Arginine hydrolysis was inhibited by the six heavy metals at 5 mmol kg⁻¹ soil; the most effective inhibitors were Pb⁺², Ni⁺², and Cr⁺³. Due to the complex soil enzymatic and organic nitrogen hydrolase activities that occur during floods, fertile fields on the Nile River islands should not be fertilized before the summer flood seasons, which will prevent contamination of the Nile River water and loss of its island soil fertility.

Dual use of water for fish and crop production could be a promising approach to improve irrigation under arid conditions. A watercress pot study was carried out to assess the effects of irrigation by catfish and tilapia aquaculture water on the sandy soil properties as well as the growth parameters of watercress with various combinations of artificial NPK fertilizers at El-Minia Governorate of Egypt (28°18′16″ N latitude and 30°34′38″ E longitude). Catfish aquaculture water had the greatest phytoplankton abundance at 83,762 units (×10⁴/L), while the minimum number of phytoplankton existed in tilapia aquaculture water, recorded at 14,873 units (×10⁴/L). There were significant average changes that varied from 120 to 237 (×10⁴ cfu/mL⁻¹) in total bacterial counts in tilapia and catfish waters. Watercress growth quality parameters closely paralleled at all NPK application rates, indicating that the highest quality plants were produced in pots receiving 25% of the recommended levels and irrigated with catfish aquaculture water. Nitrate concentrations of watercress plants were determined under pollution levels established by the European Commission for leafy and tuber vegetables. In conclusion, the use of microbial and phytoplankton-rich aquaculture water to irrigate vegetables and as fertilizer can maintain a balanced soil ecosystem.

Biochar ash is a waste product of traditional charcoal production process in the absence of oxygen and consists of cement-like organic matter dust collected from traditional kilns floor. This study tested the changes in some soil physical properties and the establishment of ryegrass cover area as a natural landscape resulting from the application of biochar ash mixed with organic waste in clay and sandy soil. Biochar ash (BA) collected from kiln dust waste was applied as an equal mixture with farmyard manure (BA/FM) and poultry manure (BA/PM) at dry weight basis to 10 kg soil pots in the greenhouse at different rates of 0, 2, 4, 6, 10%. Mixtures of BA/FM or BA/PM addition increased clay and sandy soils water holding and available water capacities at all application rates compared to control. Soil aggregate stability against water increased significantly as the mixture rate addition increased. Relative to the control, mixture of biochar ash and manure amendment decreased the dispersibility of soil aggregates and had significant effects on soil aggregate stability. Soil physical improvements were not significantly different when BA mixed with FM or PM. Incorporation of biochar ash mixture into sandy or clay soil has established sufficient landscape of ryegrass covering area to prevent erosion compared to control. Once the agronomic benefits and environmental impacts of using biochar ash as a soil amendment have been identified, an environmental and economic feasibility study should be conducted to determine whether landfilling biochar by-products is better or using them in sandy soil reclamation projects.

Two experiments were conducted at the Agricultural Research Center in Giza, Egypt, the first one was done in nursery during 2022, while, the second one was undertaken in the greenhouse in 2023 to compare the germination rate of stevia (Stevia rebaudiana, Bertoni) seeds under salinity stress conditions. The first experiment was conducted to evaluate three varieties (Spanti, China1 and Egy1) of stevia under salinity levels of 0, 600 and 1200 ppm, NaCl which was realized from Cynor Laboratories in factorial experiment (3x3) using completely randomized design (C.R.D.) with three replicates. The second experiment was conducted under normal conditions of green house, including three different types of soil i.e., [peat moss, peat moss + compost (1:1) v/v) and peat moss + compost + sand (1:1:1 v/v/v)], three varieties (Spanti, China1 and Egy1) and three levels of salinity 0, 600 and 1200 ppm, NaCl. Randomized complete block design in split-split plot design arrangement with three replicates was used. Soil media occupied the main plots, while, varieties occupied the sub-plots and salinity occupied the sub-sub-plots. Spanti variety recorded the highest germination rate index ( GRI) of stevia seeds at the lowest salinity level (0.0 ppm). On the other hand, Egy1 variety showed the lowest GRI under salinity level of 0.0 ppm salinity level. Generally, the highest value of number of seedlings was recorded for Spanti variety with mixture peat moss + compost sown in under salinity level of 600 ppm., while the lowest one was obtained for Egy1 variety peat moss with under salinity level of 1200 ppm. The highest value of seedling length was recorded for Spanti variety sown in peat moss + compost under 600 ppm salinity level, but the highest value of seedling root fresh weight was recorded for Spanti variety sown in peat moss + compost under 0.0 ppm salinity level, While, the highest value of seedling stem fresh weight was recorded for Spanti variety sown in peat moss under 0.0 ppm salinity level.