Impacts of Long- and Short-Term of Irrigation with Treated Wastewater and Synthetic Fertilizers on the Growth, Biomass, Heavy Metal Content, and Energy Traits of Three Potential Bioenergy Crops in Arid Regions

Abstract

The availability of suitable water is an important factor for increasing the cultivated areas and sustainability in arid (i.e., less than 200 mm precipitation per year) and semiarid regions (i.e., 200–700 mm precipitation per year). Therefore, this study aimed to analyze the impact of treated wastewater (TWW) and groundwater (GW) as well as synthetic fertilizers (50% and 100% of the recommended NPK dose; 150–150–60 kg N–P2O5–K2O ha−1) on the growth, biomass, energy traits, and macro and trace elements of maize (Zea mays L.), sorghum (Sorghum bicolor L.), and pearl millet (Pennisetum glaucum L) grown in old cultivated (first location; L1) and virgin soil (L2 and L3) as potential bioenergy crops. The soil in L1 has been irrigated with treated wastewater for the last 15 years and continued to be irrigated with treated wastewater in this investigation. The virgin soil was divided into two parts: the first part was irrigated with TWW, and the second part was irrigated with GW. The experiments were laid out in a split-plot with a randomized complete block design with water treatments (TWW in old and virgin soil, and GW in virgin soil) in main plots, and the two treatments of fertilization (50% and 100% of the recommended NPK dose) were distributed randomly in subplots. Compared with the crops irrigated with GW, the crops irrigated with TWW, whether grown on old or virgin soil, showed higher plant height, total chlorophyll content, leaf area per plant, total biomass, energy content, and gross energy with low ash. They also contained higher (but lower than permissible limits) concentrations of macro-elements (NPK) and trace elements (Fe, Mn, Cu, Zn, Cd, Pb, Ni, and Co). In addition, the application of a 50% recommended dose of NPK with TWW showed equivalent results to a 100% recommended dose of NPK on all measured parameters with few exceptions. In conclusion, the TWW can be used to irrigate field crops allocated for bioenergy production in arid regions because it does not harm the plants and environment. In addition, the 50% recommended dose of NPK fertilizer exerted no negative effects on the growth and energy production of field crops, thereby protecting the environment and reducing the leaching of excessive fertilizers into GW.

Impact of Irrigation with Treated Domestic Wastewater on Squash (Cucurbita pepo L.) Fruit and Seed under Semi-Arid Conditions

“…Similarly, dry matter of the naked seeds was higher in the TWW treatment (68.18%) compared to the FW plants (66.43%). Several studies reported an increase in the dry matter as a result of using TWW in irrigation plants because of its content of the nutritional elements required by plants to grow [48][49][50]. According to Table 4, the highest crude protein (CP) content in the squash seeds was found in naked seeds of the plants that were irrigated by TWW (41.28%), whereas the lowest content was found under FW treatment of the whole seeds (33.57%).…”

Ecological Risk Assessment of Heavy Metals in Adjoining Sediment of River Ecosystem

“…Higher Pb levels pose threat to fishery resources. In plants, (beyond 5 mg kg −1 ) it causes severe growth retardation, discoloration, and morphological abnormalities, which cause adverse effects on aquatic biota [34,36,37]. The highest Cu values was recorded at Atali A (29.2 mg kg −1 ) and Titavi A (28.8 mg kg −1 ), and these values much higher than the IRS standard (28 mg kg −1 ).…”

Integrative Effects of Treated Wastewater and Synthetic Fertilizers on Productivity, Energy Characteristics, and Elements Uptake of Potential Energy Crops in an Arid Agro-Ecosystem

“…However, global climate change is disrupting water cycle patterns and leading to extreme water scarcity in different parts of the world [1][2][3][4]. Thus, a search for alternative irrigation sources is believed to be essential to ensure food, feed, and fuel security and to preserve natural water sources [5][6][7][8]. Hence, using treated wastewater (TWW) in the agriculture sector is becoming a desirable alternative source of irrigation [6,8,9], especially in countries confronted with water shortages [5,10,11].…”

“…Thus, a search for alternative irrigation sources is believed to be essential to ensure food, feed, and fuel security and to preserve natural water sources [5][6][7][8]. Hence, using treated wastewater (TWW) in the agriculture sector is becoming a desirable alternative source of irrigation [6,8,9], especially in countries confronted with water shortages [5,10,11]. The use of TWW in agriculture benefits the environment, human health, the economy, and it can reduce the pressure on freshwater sources used in agriculture [8,10,12,13].…”

“…Hence, using treated wastewater (TWW) in the agriculture sector is becoming a desirable alternative source of irrigation [6,8,9], especially in countries confronted with water shortages [5,10,11]. The use of TWW in agriculture benefits the environment, human health, the economy, and it can reduce the pressure on freshwater sources used in agriculture [8,10,12,13]. Additionally, TWW is a potential source of macro-(N, P, and K) and trace-elements (Ca, Mg, B, Mg, Fe, Mn, and Zn) [8,[14][15][16] and therefore makes it possible to reduce the use of synthetic fertilizers [8,16].…”