Enhancing the wheat growth through micronutrients enriched biochar under salt stress

Crop irrigation with brackish water having high Na+ is a common practice in developing countries like Pakistan; hence increasing the saline-sodic soils throughout the region. Therefore, two independent studies were conducted to evaluate the impact of minerals enriched contrasting biochars (MECBs) in mitigating Na+ toxicity on soil physicochemical properties, wheat growth, and physiology. In 1st trial, an incubation experiment was conducted having 32 treatments including simple biochar (SBc), manganese enriched biochar (MnBc), zinc enriched biochar (ZnBc), and iron enriched biochar (FeBc) applied at two rates (0.1% and 0.5%) with four different salinity levels such as 10, 20, 30, and 40 dSm−1. The soil was sampled after the 8th, 16th, and 24th day of incubation. Among the four sources of biochar, MnBc (0.1%) + 40 dSm−1 and FeBc (0.5%) + 40 dSm−1 showed efficient results to tolerate salinity stress in soil by efficiently reducing the availability of Na+ (60% and 30%) when compared to SBc (0.5%) + 40 dSm−1. Then, a pot study was conducted with 20 different treatments (control, SBc, MnBc, ZnBc, and FeBc) at four different salinity levels, i.e., 0, 5, 10, and 15 dSm−1. There were four replicates and the crop was harvested after 60 days of germination. The application of brackish water (control+15 dSm−1) significantly reduced the fresh weight of root (28%) and shoot (34%) of wheat (Triticum aestivum L.) as compared to FeBc+15 dSm−1. However, the soil Na+ toxicity was significantly decreased (23%) by the application of FeBc+15 dSm−1 as compared to control+15 dSm−1. Similarly, a significant increase was observed in leaf chl. a, b and photosynthetic rate (75%, 3 and 2-folds); however, a significant decrease was observed in transpiration rate (50%) in T. aestivum L. treated with FeBc+15 dSm−1 as compared to control+15 dSm−1. Interestingly, FeBc+15 dSm−1 also played a vital role to prevent oxidative damage by controlling the shoot CMP (63%) in T. aestivum L. by efficiently triggering the activities of shoot antioxidant enzymes such as APX (30%) and CAT (52%) when compared to control+15 dSm−1. In summary, it was evaluated that FeBc showed the highest adsorption capacity of Na+ ions to regulate salinity stress by improving soil health and crop physiology

Changes of Microbial Diversity in Rhizosphere of Different Cadmium-Gradients Soil under Irrigation with Reclaimed Water

Water scarcity and the uneven distribution of water resources in China have resulted in water shortages for agricultural irrigation in arid and semi-arid areas. Reclaimed water used for agricultural irrigation has become an effective solution in the context of the global water shortage. In order to improve soil productivity and solve the shortage of water resources, we carried out reclaimed water irrigation experiments on polluted soil. Compared with full irrigation treatments, the EC value of reclaimed water under deficit irrigation treatments decreased by 2.89–42.90%, and the content of organic matter increased by 6.31–12.10%. The proportion of Acidobacteria community in soils with different cadmium concentration gradients irrigated with reclaimed water ranged from 13.6% to 30.5%, its relative abundance decreased with the increase of soil cadmium concentration. In particular, the relative abundance of Pseudomonas pathogens in deficit irrigation treatments was lower than that of the full irrigation treatments. RDA analysis showed that the environmental factors that played a leading role in the change of microbial community structure were organic matter and pH. Furthermore, the metabolic function potential of the rhizosphere soil bacterial community in deficit irrigation treatments was higher than that of full irrigation treatments with reclaimed water. This study proved that reclaimed water irrigation for cadmium contaminated soil did not aggravate the pollution level and promoted the soil ecological environment with better microbial community diversity

Changes of Microbial Diversity in Rhizosphere of Different Cadmium-Gradients Soil under Irrigation with Reclaimed Water

Water scarcity and the uneven distribution of water resources in China have resulted in water shortages for agricultural irrigation in arid and semi-arid areas. Reclaimed water used for agricultural irrigation has become an effective solution in the context of the global water shortage. In order to improve soil productivity and solve the shortage of water resources, we carried out reclaimed water irrigation experiments on polluted soil. Compared with full irrigation treatments, the EC value of reclaimed water under deficit irrigation treatments decreased by 2.89–42.90%, and the content of organic matter increased by 6.31–12.10%. The proportion of Acidobacteria community in soils with different cadmium concentration gradients irrigated with reclaimed water ranged from 13.6% to 30.5%, its relative abundance decreased with the increase of soil cadmium concentration. In particular, the relative abundance of Pseudomonas pathogens in deficit irrigation treatments was lower than that of the full irrigation treatments. RDA analysis showed that the environmental factors that played a leading role in the change of microbial community structure were organic matter and pH. Furthermore, the metabolic function potential of the rhizosphere soil bacterial community in deficit irrigation treatments was higher than that of full irrigation treatments with reclaimed water. This study proved that reclaimed water irrigation for cadmium contaminated soil did not aggravate the pollution level and promoted the soil ecological environment with better microbial community diversity

Rice Physiological Response with Bacillus subtilis and Saccharomyces cerevisiae Inoculation into Soil under Reclaimed Water–Fresh Water Combined Irrigation

The increasing soil salinity levels under reclaimed water irrigation have a negative effect on plant growth. Greenhouse experiments were conducted in 2018 and 2019 under reclaimed water–fresh water combined irrigation. After transplanting (Day 1), rice was irrigated with clean water (tap water) for 10 days to facilitate rice root colonisation. Subsequently, rice was irrigated with reclaimed water for 50 days (Day 11 to 60), and then irrigated with clean water. B. subtilis and S. cerevisiae were mixed with clean water (tap water) and irrigated into soil at Day 61. B. subtilis (20 billion colony-forming units/g) and S. cerevisiae (20 billion colony-forming units/g) were mixed at the following proportions: 5 g and 0 (J1), 3.75 g and 1.25 g (J2), 2.5 g and 2.5 g (J3), 1.25 g and 3.75 g (J4), and 0 and 5 g (J5), respectively; rice treated with reclaimed water (CK) and clean water (J0) with no microorganisms applied were also used. We measured NO3--N and NH4+-N concentrations and electrical conductivity (EC) in the soil at 0–5, 5–15, and 15–25 cm layers; root activity; and malondialdehyde (MDA), soluble sugar, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and glutamine synthetase (GS) activity in leaves at Day 71. B. subtilis and S. cerevisiae combination could promote rice physiological indices, and B. subtilis had a greater effect than S. cerevisiae. There are obvious differences in the physiological performance and soil N between 2018 and 2019 due to the EC of reclaimed water. Redundancy analysis revealed that soil NO3−-N and the mass of B. subtilis applied were major factors influencing leaf physiological indices. Five grams of B. subtilis is recommended to facilitate rice growth after irrigation with reclaimed water. Our research provides a new agronomic measure for the safe utilisation of reclaimed water

Effect of Organic Amendments in Soil on Physiological and Biochemical Attributes of <i>Vachellia nilotica</i> and <i>Dalbergia sissoo</i> under Saline Stress

Vachellia nilotica (L.) P.J.H. Hurther & Mabb. and Dalbergia sissoo Roxb. are two of the most important multipurpose agroforestry tree species of the Indian sub-continent, but their growth in saline soils is greatly reduced. Recently, organic amendments have showed the potential to increase plant growth in salt-affected soils; however, the influence of using these amendments for growing the above-mentioned tree species under saline conditions is not yet quantified. Therefore, an experiment was devised to analyze the interactive effects of organic amendments in saline soils on the growth of V. nilotica and D. sissoo. Under controlled conditions, a pot experiment was conducted in sandy loam saline soils (EC = 20.5 dSm−1). Organic amendments from four diverse sources: farmyard manure (FYM), poultry manure (PM), slurry (SL), and farmyard manure biochar (FYMB) were employed in this study. At the harvesting time, data regarding morphological, physiological, ionic, and biochemical parameters were obtained. The current study results indicated that both tree species reacted differently, but positively, to diverse applied amendments. The maximum increment in total above-ground biomass, total below-ground biomass, and shoot length for V. nilotica (163.8%, 116.3%, and 68.2%, respectively) was observed in FYM amended soils, while the maximum increment for D. sissoo (128%, 86%, and 107%, respectively) was observed in FYMB amended soils, as compared to control. Minimum plant growth of both species was observed in untreated soils (saline soils). Likewise, the maximum potassium ion and minimum sodium ion concentrations were present in the root and shoots of plants (both species) treated with FYMB. The use of organic amendments resulted in decreased concentrations of malondialdehyde and hydrogen peroxide, and increased concentrations of antioxidant enzymes such as SOD, POD, and CAT. Moreover, higher photosynthetic rates and stomatal conductance were observed in the plants grown in amended soils. The findings of this study can be used to include the above-mentioned high-value tree species for future afforestation programs under saline conditions

Carbon Sequestration by Native Tree Species around the Industrial Areas of Southern Punjab, Pakistan

Industries have been a major culprit in increasing carbonaceous emissions and major contributors to global warming over the past decades. Factories in the urban periphery tend to warm cities more as compared with rural surroundings. Recently, nature-based solutions have been promoted to provide solutions related to climate adaptations and mitigation issues and challenges. Among these solutions, urban trees have proven to be an effective solution to remove air pollutants and mitigate air pollution specifically caused by carbon emissions. This work was designed to assess the role of tree species in mitigating air emissions of carbon around the vicinity of various industrial sites. For this purpose, three different industrial sites (weaving, brick kiln, and cosmetic) were selected to collect data. Selected industrial sites were divided into two areas, i.e., (a) area inside the industry and (b) area outside the industry. The samples were collected from 100 square meters inside the industries and 100 square meters outside the industries. Five different trees species comprised of four replications were selected for sampling. About twenty trees species from inside and outside of the industries were measured, making it 120 trees from all three selected industries for estimating aboveground and belowground biomass, showing their carbon estimation. The results showed that Moringa oleifera depicted overall higher total biomass from both inside (2.58, 0.56, and 4.57 Mg ha&minus;1) and outside sites from all three selected industries. In terms of total carbon stock and carbon sequestration inside the industry sites, Syzygium cumini had the most dominant values in the weaving industry (2.82 and 10.32 Mg ha&minus;1) and brick kiln (3.78 and 13.5 Mg ha&minus;1), while in the cosmetic industry sites, Eucalyptus camaldulensis depicted higher carbon, stock, and sequestration values (7.83 and 28.70 Mg ha&minus;1). In comparison, the sites outside the industries&rsquo; vicinity depicted overall lower carbon, stock, and sequestration values. The most dominant tree inside came out to be Dalbergia sisso (0.97 and 3.54 Mg ha&minus;1) in the weaving industry sites, having higher values of carbon stock and carbon sequestration. Moringa oliefra (1.26 and 4.63) depicted dominant values in brick kiln sites, while in the cosmetic industry, Vachellia nilotica (2.51 and 9.19 Mg ha&minus;1) displayed maximum values as compared with other species. The findings regarding belowground biomass and carbon storage indicate that the amount of soil carbon decreased with the increase in depth; higher soil carbon stock values were depicted at a 0&ndash;20 cm depth inside and outside the industries. The study concludes that forest tree species present inside and outside the vicinity of various industries have strong potential in mitigating air emissions

The Coupled Effects of Irrigation Scheduling and Nitrogen Fertilization Mode on Growth, Yield and Water Use Efficiency in Drip-Irrigated Winter Wheat

Sound irrigation and nitrogen management strategies are necessary to achieve sustainable yield and water use efficiency of winter wheat in the North China Plain (NCP). The coupled effects of irrigation scheduling and the nitrogen application mode (NAM) on winter wheat growth, yield and water use efficiency under drip irrigation were evaluated with a two-year field experiment, which consisted of three irrigation scheduling levels (ISLs) (irrigating when soil water consumption (SWC) reached 20, 35 and 50 mm, referred as I20, I35 and I50, respectively) and three nitrogen application modes (NAMs) (ratio of basal application and topdressing as 50:50, 25:75 and 0:100, referred as N50:50, N25:75 and N0:100, respectively). The experimental results showed that irrigating winter wheat at ISL I35 substantially (p &lt; 0.05) improved the grain yield by 15.89%, 3.32% and 14.82%, 4.31% and water use efficiency (WUE) by 5.23%, 16.03% and 5.26%, 12.36%, compared with those at ISL I20 and I50 in 2017–2018 and 2018–2019 growing seasons, respectively. NAM N25:75 appeared very beneficial in terms of grain yield, yield components and WUE as compared to other NAM levels. The maximum grain yield (8.62 and 9.40 t ha−1) and water use efficiency (1.88 and 2.09 kg m−3) were achieved in treatment I35N25:75 in two growing seasons over those in other treatments. The results in this study may deliver a scientific basis for irrigation and nitrogen fertilization management of the drip-irrigated winter wheat production in the NCP

Effects of Shallow Groundwater Depth and Nitrogen Application Level on Soil Water and Nitrate Content, Growth and Yield of Winter Wheat

The large amount of nitrogen application on the North China Plain has caused a serious negative impact on the sustainable development of regional agriculture and ecological environmental protection. Our aim was to explore the effects of nitrogen fertilization rate and groundwater depth on growth attributes, soil-water and soil-fertilizer contents, and the winter wheat yield. Experiments were carried out in micro-lysimeters at groundwater depths of 60, 90, 120, and 150 cm on the basis of 0, 150, 240, and 300 kg/ha nitrogen fertilization rates in the growth season for winter wheat. Results showed that plant height, leaf area index, soil plant analysis development, and yield without nitrogen application increased significantly with increases in groundwater depth. The optimal groundwater depths for growth attributes and yield were 60&ndash;120 cm and tended to be shallower with added nitrogen application. Soil moisture was lowered significantly with groundwater depth, adding a nitrogen application reduced soil moisture, and excessive nitrogen input intensified soil drought. Nitrate-N accumulation at the 120&ndash;150 cm depths was significantly higher than that at the 60&ndash;90 cm depths, and a 300 kg/ha (traditional nitrogen application rate) treatment was 6.7 times greater than that of 150 kg/ha treatment and increased by 74% more than that of the 240 kg/ha treatment at 60&ndash;150 cm depth. Compared with the yield of the 300 kg/ha rate, the yield of the 240 kg/ha rate had no significant difference, but the yield increased by 3.90% and 11.09% at the 120 cm and 150 cm depths. The growth attributes and yield of winter wheat were better, and the soil nitrate-N content was lower, when the nitrogen application rate was 240 kg/ha. Therefore, it can be concluded that nitrogen application can be reduced by 20% on the North China Plain

Carbon Sequestration by Native Tree Species around the Industrial Areas of Southern Punjab, Pakistan

Industries have been a major culprit in increasing carbonaceous emissions and major contributors to global warming over the past decades. Factories in the urban periphery tend to warm cities more as compared with rural surroundings. Recently, nature-based solutions have been promoted to provide solutions related to climate adaptations and mitigation issues and challenges. Among these solutions, urban trees have proven to be an effective solution to remove air pollutants and mitigate air pollution specifically caused by carbon emissions. This work was designed to assess the role of tree species in mitigating air emissions of carbon around the vicinity of various industrial sites. For this purpose, three different industrial sites (weaving, brick kiln, and cosmetic) were selected to collect data. Selected industrial sites were divided into two areas, i.e., (a) area inside the industry and (b) area outside the industry. The samples were collected from 100 square meters inside the industries and 100 square meters outside the industries. Five different trees species comprised of four replications were selected for sampling. About twenty trees species from inside and outside of the industries were measured, making it 120 trees from all three selected industries for estimating aboveground and belowground biomass, showing their carbon estimation. The results showed that Moringa oleifera depicted overall higher total biomass from both inside (2.58, 0.56, and 4.57 Mg ha−1) and outside sites from all three selected industries. In terms of total carbon stock and carbon sequestration inside the industry sites, Syzygium cumini had the most dominant values in the weaving industry (2.82 and 10.32 Mg ha−1) and brick kiln (3.78 and 13.5 Mg ha−1), while in the cosmetic industry sites, Eucalyptus camaldulensis depicted higher carbon, stock, and sequestration values (7.83 and 28.70 Mg ha−1). In comparison, the sites outside the industries’ vicinity depicted overall lower carbon, stock, and sequestration values. The most dominant tree inside came out to be Dalbergia sisso (0.97 and 3.54 Mg ha−1) in the weaving industry sites, having higher values of carbon stock and carbon sequestration. Moringa oliefra (1.26 and 4.63) depicted dominant values in brick kiln sites, while in the cosmetic industry, Vachellia nilotica (2.51 and 9.19 Mg ha−1) displayed maximum values as compared with other species. The findings regarding belowground biomass and carbon storage indicate that the amount of soil carbon decreased with the increase in depth; higher soil carbon stock values were depicted at a 0–20 cm depth inside and outside the industries. The study concludes that forest tree species present inside and outside the vicinity of various industries have strong potential in mitigating air emissions

Role of Traditional Agroforestry Systems in Climate Change Mitigation through Carbon Sequestration: An Investigation from the Semi-Arid Region of Pakistan

Several agroforestry systems prevail in different agro-ecological zones of Pakistan, and cover a remarkable area of 19.3 million hectares. They not only play an important role in slowing down CO2 emissions, but also contribute to mitigating climate change. However, in many regions, the relevant effect of agroforestry systems on overall carbon (C) stock and their reliance on various factors are quite unidentified. This study was planned to assess the biomass accumulation and C stocks of different commonly practiced agroforestry systems (boundary, bund, scattered, agri-horticulture) and their constituent land use types (tree + cropland) through a non-destructive approach (allometric equations) in a semi-arid region of Punjab, Pakistan. The results showed that the highest plant biomass (87.12 t ha−1) increased by 46%, 17%, 78%, and 339%, and C stock (42.77 t ha−1) increased by 49.51%, 20%, 82%, and 361% in the boundary planting system compared to the bund, scattered, agri-horti and sole cropland, respectively. The soil organic carbon (SOC) stock at all three depths, 0–15 cm, 15–30 cm & 30–45 cm, was found in the following order: boundary planting system > bund planting system > agri-horti system > scattered planting system > agricultural system, with a maximum in the boundary planting system and minimum in the sole cropping system at all three depths. Overall, the total C stock of the ecosystem’s vegetation + soil C (0–30 cm) in the forested area was 275 t ha−1, equating to 37 t ha−1 in the agricultural system alone. Our results highlighted that agroforestry systems have the highest potential for C sequestration. We suggest that research and investment in agroforestry systems can be a successful way for Pakistan to achieve some of its climate change mitigation goals