A field study was conducted in 2016–2017 and 2017–2018 to evaluate the effects of air injection into an irrigation stream during the subsurface drip irrigation (SDI) process on the nutritional values and productivity of potato grown in clay loam soil. Two irrigation treatments (non-aerated and aerated) and six fertilizer applications (chicken, cow, rabbit, compost, mineral, and chicken + biochar) were compared. In the first growing season, the maximum yield occurred under aerated treatment with cow fertilizer (36.25 ton ha−1), while the minimum yield occurred under non-aerated treatment with chicken fertilizer (24.00 ton ha−1). On the other hand, the maximum and minimum yields in the second growing season were 35.00 and 24.74 ton ha−1 under aerated and non-aerated treatments with cow fertilizer, respectively. Maximum water productivity was achieved under aerated treatment with cow fertilizer (10.04 and 9.13 kg m−3 for the first and second growing seasons, respectively), while minimum water productivity was achieved under the non-aerated treatment with chicken + biochar fertilizer (5.91 and 5.26 kg m−3 for the first and second growing seasons, respectively). Fertilization using aerated treatment yielded the best results and the highest coupling after air injection, compared with the traditional methods of adding soil fertilizer without aeration. The plant growth parameters significantly increased following aeration relative to non-aerated treatments for all fertilizer applications in both growing seasons. Air injection into the soil for potatoes, unsurprisingly, not only benefitted the crop by increasing the soil–air exchange rate but also promoted water infiltration rates and nutrient absorption and reduced drainage water, thus increasing water productivity and reducing the overall irrigation requirements.

Three alluvial soil samples with different textures were artificially polluted with chloride solutions of Cd, Pb, Co and chromate solution for Cr. The aqua-regia extracted concentration ranges in the artificially polluted soils were 1134 - 1489 mg·kg^-1 for Pb, 854 - 938 mg·kg^-1 for Cr, 166 - 346 mg·kg^-1 for Co and 44 - 54 mg·kg^-1 for Cd. The aqua-regia extracted metals were the highest in the spiked clay soil due to its high adsorption capacity. Rock phosphate (PR), lime-stone (LS) and Portland-cement (Cem) were mixed with the spiked soils at 1% and 2% rates (w/w) and incubated at 30 C for 2, 7, 14, 30, 60, 150 and 360 days. The extracted DTPA metals significantly decreased with different magnitudes with increasing the incubation period accompanied by increases in both pH and EC. The data showed that cement (Cem) treatment dropped the DTPA-Pb from @ 1000 to @ 400 mg·kg^-1 in all the studied soils (60% decrease) in the first 2 months while it gradually decreased from 400 to 200 mg·kg^-1 (20% decrease) in the next 10 months. Limestone (LS) and rock phosphate (PR) materials were relatively less effective in lowering DTPA-Pb after 12 months of incubation. The data showed also that cement (Cem) treatment was the most effective one in lowering DTPA-Cd by @ 60% as compared to the un-amended soils after 12 months of soil incubation. Extractable DTPA-Co and Cr showed consistent decreases with time down to nearly 50% of un-amended soils due to the effect of the added amendments after 12 months of incubation with superior reductions for the cement treatment in all the investigated soils. The statistical analysis confirmed that in all the studied metals and treatment, cement treatment (Cem) was significantly the most effective in lowering the DTPA extracted metals as indicated from LSD test. It was found that up to 73% and 57% of the applied Pb and Cd, respectively, were fixed by only 1% cement. However, the present study showed that from the practical and economic points of view, that 1% Cement was the best treatment to immobilize Pb and Cd from all the artificially polluted soils.

The current study was conducted to assess whether organic fertilisation could replace mineral fertilisation in lettuce production without adverse effects on yield, quality, and postharvest behaviour. The effect of either mineral or organic fertiliser on soil fertility or the microbial community was also studied. Control plots were fertilised with recommended rates of mineral fertiliser (150: 45: 65 kg/ha NPK) and the other treatments were 15 t/ha compost, 10 t/ha rabbit manure, and 10 t/ha chicken manure. Our results indicated that all sources of organic fertiliser significantly increased total nitrogen, organic carbon, total fungi, and bacteria contents of soils compared with mineral fertiliser. Rabbit and chicken manure fertilisers resulted in a significant increase in yield. Compared with conventional fertiliser and other organic treatments, plots receiving rabbit manure showed a lower weight loss and microbial load on fresh lettuce head. Moreover, rabbit manure significantly reduced polyphenol oxidase and peroxidase activity. Hence, these results suggest that rabbit manure fertiliser could be an alternative to conventional production without significant reduction in yield and with low enzymatic browning and better storability.

Crop production faces challenges in achieving high fertilizer use efficiency. To address this issue, slow-release fertilizers (SRFs) have emerged as effective solutions to minimize nutrient losses caused by leaching, runoff, and volatilization. In addition, replacing petroleum-based synthetic polymers with biopolymers for SRFs offers substantial benefits in terms of sustainability of crop production and soil quality preservation, as biopolymers are biodegradable and environmentally friendly. This study focuses on modifying a fabrication process to develop a bio-composite comprising biowaste lignin and low-cost montmorillonite clay mineral for encapsulating urea to create a controllable release fertilizer (CRU) with a prolonged nitrogen release function. CRUs containing high N contents of 20 to 30 wt.% were successfully and extensively characterized using X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). The results showed that the releases of N from CRUs in water and soil extended to considerably long periods of 20 and 32 days, respectively. The significance of this research is the production of CRU beads that contain high N percentages and have a high soil residence period. These beads can enhance plant nitrogen utilization efficiency, reduce fertilizer consumption, and ultimately contribute to agricultural production.