Water shortages are an issue of growing worldwide concern. Irrigated agriculture accounts for about 70% of total freshwater withdrawals globally, therefore alternatives to use of conventional sources need to be investigated. This paper critically reviews the application of treated wastewater for agricultural fertigation (i.e., water and nutrient recovery) considering different perspectives: legislation, agronomic characteristics, social acceptability, sustainability of treatment technologies. Critical issues that still need further investigation for a wider application of fertigation practices include accumulation of emerging contaminants in soils, microbiological and public health implications, and stakeholders' acceptance. A techno-economic methodological approach for assessing the sustainability of treated wastewater reuse in agriculture is subsequently proposed herein, which considers different possible local conditions (cultivated crops and effluent characteristics). The results showed that tailoring effluent characteristics to the desired nutrient composition could enhance the process economic sustainability; however, water savings have a major economic impact than fertilizers’ savings, partly due to limited P reuse efficiency. The developed methodology is based on a practical approach and may be generalized to most agricultural conditions, to evaluate and encourage safe and efficient agricultural wastewater reuse practices.

Excess of water irrigation and fertilizer consumption by crops has resulted in high soil nitrogen (N) losses and underground water contamination not only in China but worldwide. This study explored the effects of soil N input, soil N output, as well as the effect of different irrigation and N- fertilizer managements on residual N. For this, two consecutive years of winter wheat (Triticum aestivum L.) –summer maize (Zea mays L.) rotation was conducted with: N applied at 0 kg N ha⁻¹ yr⁻¹, 420 kg N ha⁻¹ yr⁻¹ and 600 kg N ha⁻¹ yr⁻¹ under fertigation (DN0, DN420, DN600), and N applied at 0 kg N ha⁻¹ yr⁻¹ and 600 kg N ha⁻¹ yr⁻¹ under flood irrigation (FN0, FN600). The results demonstrated that low irrigation water consumption resulted in a 57.2% lower of irrigation-N input (p < 0.05) in DN600 when compared to FN600, especially in a rainy year like 2015–2016. For N output, no significant difference was found with all N treatments. Soil gaseous N losses were highly correlated with fertilization (p < 0.001) and were reduced by 23.6%–41.7% when fertilizer N was decreased by 30%. Soil N leaching was highly affected by irrigation and a higher reduction was observed under saving irrigation (reduced by 33.9%–57.3%) than under optimized fertilization (reduced by 23.6%–50.7%). The net N surplus was significantly increased with N application rate but was not affected by irrigation treatments. Under the same N level (600 kg N ha⁻¹ yr⁻¹), fertigation increased the Total Nitrogen (TN) stock by 17.5% (0–100 cm) as compared to flood irrigation. These results highlighted the importance to further reduction of soil N losses under optimized fertilization and irrigation combined with N stabilizers or balanced- N fertilization for future agriculture development.

In agriculture, wastewater is used as an alternative source to meet the water and nutritional requirements of plants. However, long-term application of wastewater may degrade soil attributes. This study aimed to evaluate the soil physical quality of Oxisol fertigated with treated sewage effluent (TSE). The experiment was conducted in an area under TSE application for 4 years in Oxisol (625 g kg⁻¹ clay) cultivated with Urochloa brizantha. The treatments consisted of six levels of TSE in irrigation depth, 0%, 11%, 31%, 60%, 87%, and 100%, with four repetitions. Undisturbed and disturbed soils samples were collected in three layers (0.00–0.10 m; 0.10–0.20 m, and 0.20–0.30 m). Aggregation, porosity and water infiltration attributes were evaluated. This work concludes a long-term study on the effects of TSE application on soil properties and on the Urochloa brizantha crop. In other works, carried out in the experimental area of the present study, it was found that TSE fertigation increases the yield and quality of Urochloa brizantha, increases soil fertility and does not lead to soil heavy metal contamination. We note the TSE fertigation does not change the aggregation, porosity, water infiltration rate and organic carbon content in the soil. Irrigation with TSE is recommended in areas with clayey soil and those cultivated with perennial grasses as it does not cause any damage to the physical quality of the soil. Thus, the TSE fertigation can be used on many crops as a source of water and nutrients, reducing the environmental contamination potential.

Arsenic (As) in rice is posing a serious threat worldwide and consumption of As contaminated rice by human is causing health risks. A pot experiment with different levels of sulfate dosage (0, 20, 40, 60 and 80 mg/kg) was set up in this study to explore the influence of sulfate fertilizer on rice plant growth, yield, and As accumulation in rice grain. Apart from As bioaccumulation in rice grains, the As fraction of cooked rice was quantified, and the health risks associated with cooked rice consumption were also investigated. The sulfate application significantly (p ≤ 0.05) enhanced the chlorophyll, tiller number, grains per panicle, grain and biomass yield under As stressed condition. The sulfate application also reduced the oxidative stress and antioxidant activity in rice plants. Sulfate fertigation improved the accumulation of total sulfur (S) and reduced the uptake and translocation of As in rice plants. Arsenic concentration in rice grain was reduced by 50.1% in S80 treatment (80 mg of sulfate/kg of soil) as compared to S0 set. The reduction percentage of As in cooked parboiled and sunned rice with correspond to raw rice ranged from 55.9 to 74% and 40.3–60.7%, respectively. However, the sulfate application and cooking of parboiled rice reduced the potential non-cancer and cancer risk as compared to sunned rice. The S80 treatment and cooking of parboiled rice reduce the As exposure for both children and adults by 51% as compared to cooked sunned rice under S80 treatment and this trend was similar for all treatments. Therefore, sulfate application in soil can be recommended to produce safer rice grains and subsequent cooking of parboiled rice grain with low-As contaminated water need to be done to avoid any potential health risk in As endemic areas.

It remains unclear how the source and rate of nitrogen (N) fertilizers affect N₂O concentration and effluxes along the soil profile under the drip-fertigated agricultural system. A plot-based field study was performed in 2017 and 2018 in a cotton field in arid northwestern China, with an objective to elucidate the impact of the applications of conventional urea (Urea), polymer-coated urea (ESN) and stabilized urea (SuperU) at rates of 120 and 240 kg N ha⁻¹ on concentration and efflux of N₂O in the soil profile and its relationship with N₂O surface emissions. The in-situ N₂O concentrations at soil depths of 5, 15, 30 and 60 cm were measured and used to estimate soil profile N₂O effluxes. Estimates of surface N₂O flux using the concentration gradient-based (GM) were compared with those measured using the chamber-based (CM) method. In both years, soil N₂O concentrations at all depths increased in response to basal N application at planting or in-season fertigation events. However, N rate or source did not affect soil N₂O concentrations or effluxes at each depth. Surface emissions of N₂O were mostly associated with that presented in the top layer of 0–15 cm. Surface N₂O efflux determined by GM was poorly or not associated with those of chamber measurements, which was attributed to the low N₂O production restricted by soil moisture condition under the drip-fertigated condition. These results highlight the challenge of applying the enhanced efficiency N fertilizer products in the drip-fertigated agricultural system.

Vegetable production in solar greenhouses in northern China results in the excessive use of nitrogen (N) fertilizers and water via flooding irrigation. Both factors result in low N use efficiency and high environmental costs because groundwater becomes contaminated with nitrate (NO3−). Four consecutive tomato (Lycopersicum esculentum Mill.) cropping seasons were tested whether drip fertigation and/or the incorporation of maize straw (S) may significantly reduce NO3− and dissolved organic N (DON) leaching while increasing the water-use efficiency (WUE) and partial factor productivity of applied N (PFPN) of the tomatoes. The following treatments were used: ① conventional flooding irrigation with overfertilization (CIF, 900 kg N ha−1 season−1), ② CIF + S, ③ drip irrigation with optimized fertilization (DIF, 400 kg N ha−1 season−1), ④ DIF + S. We found that (1) DIF significantly increases the PFPN and WUE by 262% and 73% without compromising the yield compared with CIF, respectively. (2) For CIF, approximately 50% of the total N input was leached at a NO3−/DON ratio of approximately 2:1. (3) Compared with CIF, DIF reduced NO3− and DON leaching by 88% and 90%, respectively. Water percolation was positively correlated with N leaching (p < 0.001). (4) Straw application only reduced NO3− leaching losses in the first year and did not affect DON leaching overall, although DON leaching was increased in DIF in the first growing season. In conclusion, DIF significantly reduces NO3− and DON leaching losses by approximately 90% compared with the current farmer practice (CIF). Considering the significant DON leaching losses, which have been overlooked because previous measurements focused on NO3−, DON should be considered as a primary factor of environmental pollution in conventional solar greenhouse vegetable production systems.

Future climate scenarios are predicting considerable threats to sustainable maize production in arid and semi-arid regions. These adverse impacts can be minimized by adopting modern agricultural tools to assess and develop successful adaptation practices. A multi-model approach (climate and crop) was used to assess the impacts and uncertainties of climate change on maize crop. An extensive field study was conducted to explore the temporal thermal variations on maize hybrids grown at farmer’s fields for ten sowing dates during two consecutive growing years. Data about phenology, morphology, biomass development, and yield were recorded by adopting standard procedures and protocols. The CSM-CERES, APSIM, and CSM-IXIM-Maize models were calibrated and evaluated. Five GCMs among 29 were selected based on classification into different groups and uncertainty to predict climatic changes in the future. The results predicted that there would be a rise in temperature (1.57–3.29 °C) during the maize growing season in five General Circulation Models (GCMs) by using RCP 8.5 scenarios for the mid-century (2040–2069) as compared with the baseline (1980–2015). The CERES-Maize and APSIM-Maize model showed lower root mean square error values (2.78 and 5.41), higher d-index (0.85 and 0.87) along reliable R² (0.89 and 0.89), respectively for days to anthesis and maturity, while the CSM-IXIM-Maize model performed well for growth parameters (leaf area index, total dry matter) and yield with reasonably good statistical indices. The CSM-IXIM-Maize model performed well for all hybrids during both years whereas climate models, NorESM1-M and IPSL-CM5A-MR, showed less uncertain results for climate change impacts. Maize models along GCMs predicted a reduction in yield (8–55%) than baseline. Maize crop may face a high yield decline that could be overcome by modifying the sowing dates and fertilizer (fertigation) and heat and drought-tolerant hybrids.

This study evaluated the effect of applying biofertilizer in the soil on the cultivation of corn. Different doses of biofertilizer associated with chemical fertilizer were applied in the soil to meet the plants’ nutritional demand. Four months after sowing, plant samples were collected and evaluated, by measuring the height and productivity of biomass, dry matter, neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), and nitrogen (N). Soil samples were also collected to measure the concentrations of macronutrients, base saturation, and exchangeable acidity. The biofertilizer application did not alter the levels of dry matter, NDF, ADF, CP, and N in the plants, or the concentrations of nitrogen, phosphorus, magnesium, and copper in the soil. Besides this, the largest average values of the plant heights and levels of potassium in the soil were found in the treatment with the highest biofertilizer dose. Notably, there was a significant increase in the quantity of fresh and dry matter in the treatments that received biofertilizer in comparison with the controls. The results obtained indicated the potential of substituting conventional fertilization with fertirrigation using biofertilizer, an alternative procedure that can help reduce the environmental impacts caused by dairy farming, regarding the release of wastewater into watercourses.

Ammonia (NH₃) volatilization is one of the main pathways of N loss from farmland soil. Saline water irrigation can have direct or indirect effects on soil NH₃ volatilization, N leaching, and crop N uptake. This study was conducted to evaluate the effects of irrigation water salinity and urea-N application rate on NH₃ volatilization and N use efficiency in a drip-irrigated cotton field. The experiment consisted of three levels of irrigation water salinity: fresh water, brackish water, and saline water (electrical conductivities of 0.35, 4.61, and 8.04 dS/m, respectively). The N application rates were 0, 240, 360, and 480 kg/ha. The results showed that soil salinity and soil moisture content were significantly higher in the saline water treatment than in either the fresh or brackish water treatments. Irrigation water salinity significantly increased soil NH₄-N concentration, but NO₃-N concentration decreased as water salinity increased. The amount of N leaching varied from 5.0 to 25.5 kg/ha, accounting for 1.81 to 4.79 % of the urea-N applied under different water salinity and N application rate treatments. Both the amount of N leaching and the proportions of applied N lost through leaching significantly increased as water salinity increased. N application increased the amounts of N leaching, but the ratios of applied N were not affected by N application rate. Soil NH₃ volatilization increased rapidly after urea fertigation, and peaked at 1–2 days after N application, then decreased rapidly. The amount of NH₃ volatilization varied from 9.0 to 33.7 kg/ha, accounting for 3.2 to 3.8 % of the N applied in all treatments. Soil NH₃ volatilization was significantly higher in the saline water treatment than that in either the fresh or the brackish water treatments. Cotton N uptake increased significantly as N application rate increased, but decreased with irrigation water salinity increased. In conclusion, saline water irrigation with high N application rate induced high N leaching and NH₃ volatilization losses, thereby dramatically reducing the apparent N recovery (ANR) of cotton.