Effects of fertilizer application schemes and soil environmental factors on nitrous oxide emission fluxes in a rice-wheat cropping system, east China

Nitrous oxide (N2O) is a potent greenhouse gas (GHG) with agricultural soils representing its largest anthropogenic source. However, the mechanisms involved in the N2O emission and factors affecting N2O emission fluxes in response to various nitrogenous fertilizer applications remain uncertain. We conducted a four-year (2012–2015) field experiment to assess how fertilization scheme impacts N2O emissions from a rice-wheat cropping system in eastern China. The fertilizer treatments included Control (CK), Conventional fertilizer (CF), CF with shallow-irrigation (CF+SI), CF with deep-irrigation system (CF+DI), Optimized fertilizer (OF), OF with Urease inhibitor (OF+UI), OF with conservation tillage (OF+CT) and Slow-release fertilizer (SRF). N2O emissions were measured by a closed static chamber method. N2O emission fluxes ranged from 0.61 μg m-2 h-1 to 1707 μg m-2 h-1, indicating a significant impact of nitrogen fertilizer and cropping type on N2O emissions. The highest crop yields for wheat (3515–3667 kg ha-1) and rice (8633–8990 kg ha-1) were observed under the SRF and OF+UI treatments with significant reduction in N2O emissions by 16.94–21.20% and 5.55–7.93%, respectively. Our findings suggest that the SRF and OF+UI treatments can be effective in achieving maximum crop yield and lowering N2O emissions for the rice-wheat cropping system in eastern China

Effect of NPK, organic manure and their combination on growth, yield and nutrient uptake of chilli (Capsicum Annum L.)

A field experiment was conducted at the research area of department of horticulture, Institute of tropical agriculture and forestry, Hainan University, Haikou, Hainan, China, during the winter season 2016-2017. The research was arranged in randomized complete block design with nine treatments of organic manures in combination with NPK fertilizers having three replications. The highest yield was recorded with T9 treatment (N: P: K 100:50:50+FYM@8 ton per hectare). Plant height at harvesting, number of branches plant-1, number of fruits plant-1, fruit width, fruit length and fruit weight increased significantly with T9 treatment (N: P: K 100:50:50+FYM@8 ton per hectare). Similarly application of NPK100%+FYM@8 ton per hectare increased oleoresin yield and ascorbic acid content. Application of FYM@8 ton per hectare in combination with NPK100% increased the uptake of nutrients (N, P, K, Ca, S, and Fe) as compared to control. Similar results were also found in other organic manures along with inorganic fertilizer. The highest net return (Rs. 30183 per hectare) was achieved with the application of NPK100%+FYM@8 ton per hectare followed by NPK100%+ PM@6 ton per hectare, NPK100%+VC@10 ton per hectare and NPK100%+C@7 ton per hectar

Effect of exogenous application of nicotinic acid on morpho-physiological characteristics of Hordeum vulgare L. under water stress

Abiotic stresses, such as high temperature and drought conditions, greatly influence the development of plants and the quality and quantity of products. Barley (Hordeum vulgare L.) crop production is largely impacted by drought, affecting growth, yield, and ultimately the productivity of the crop in hot arid/semi-arid conditions. The current pot experiment was directed to observe the outcome of nicotinic acid (NA) treatments on barley’s physiological, biochemical, and production attributes at two capacity levels, i.e., 100% normal range and withholding water stress. Randomized complete block design (RCBD) was used during the experimentation with the two-factor factorial arrangement. NA was applied exogenously by two different methods, i.e., foliar and soil application (fertigation). NA solution contained various application levels, such as T1 = control, foliar applications (T2 = 0.7368 gL−1, T3 = 1.477 gL−1, T4 = 2.2159 gL−1), and soil applications (T5 = 0.4924 gL−1, T6 = 0.9848 gL−1, and T7 = 1.4773 gL−1). Results depicted that, overall, foliar treatments showed better effects than control and soil treatments. Plant growth was preeminent under T4 treatment, such as plant height (71.07 cm), relative water content (84.0%), leaf water potential (39.73-MPa), leaf area index (36.53 cm2), biological yield (15.10 kgha−1), grain yield (14.40 kgha−1), harvest index (57.70%), catalase (1.54 mmolg−1FW−1), peroxidase (1.90 g−1FWmin−1), and superoxide dismutase (52.60 µgFW−1) were superior under T4 treatment. Soil plant analysis development (54.13 µgcm−2) value was also higher under T4 treatment and lowest under T7 treatment. In conclusion, NA-treated plants were more successful in maintaining growth attributes than non-treated plants; therefore, the NA foliar treatment at the rate of 2.2159 gL−1 is suggested to find economical crop yield under drought conditions. The present study would contribute significantly to improving the drought tolerance potential of barley through exogenous NA supply in water deficit areas

In-situ oxidative degradation of sulfamethoxazole by calcium peroxide/persulfate dual oxidant system in water and soil

Calcium peroxide (CaO₂) and persulfate (PS) dual oxidant system is an innovative in-situ chemical oxidation (ISCO) technique for the restoration of contaminated groundwater. Several field applications also confirm its efficacy in remediating the groundwater, however, published articles are rarely present. In this work, the performance of the CaO₂/PS system was examined for the degradation of sulfamethoxazole (SMX) in the SMX polluted soil and water. Results indicated that SMX could be efficiently degraded with CaO₂ and PS (2 g/L dosages for each oxidant) around neutral pH (7), and 95.8% pollutant removed after 36 h of reaction time. The removal efficiency of SMX improved as the concentrations of CaO₂ and PS were increased. Moreover, SMX removal was significantly decreased with the increase of initial solution pH. This dual oxidant system at 30 °C was also used for the remediation of SMX (10 mg/kg) spiked soil. Soil degradation experiment was performed at 150 rpm of shaking speed using soil slurry (soil/water; 1/1 ratio) at pH 7. Dual oxidant dosage was kept at 2 g/L CaO₂ and 2 g/L PS. The results showed that this dual oxidant system is also very efficient for the antibiotics SMX degradation in the soil system. Overall, an insight knowledge and practical information gained from this work will help in the treatment of SMX contaminated soil and water as well as wastewater with CaO₂/PS dual oxidant system

Biogeochemical transformation of greenhouse gas emissions from terrestrial to atmospheric environment and potential feedback to climate forcing

Carbon dioxide (CO2) is mainly universal greenhouse gas associated with climate change. However, beyond CO2, some other greenhouse gases (GHGs) like methane (CH4) and nitrous oxide (N2O), being two notable gases, contribute to global warming. Since 1900, the concentrations of CO2 and non-CO2 GHG emissions have been elevating, and due to the effects of the previous industrial revolution which is responsible for climate forcing. Globally, emissions of CO2, CH4, and N2O from agricultural sectors are increasing as around 1% annually. Moreover, deforestation also contributes 12–17% of total global GHGs. Perhaps, the average temperature is likely to increase globally, at least 2 °C by 2100—by mid-century. These circumstances are responsible for climate forcing, which is the source of various human health diseases and environmental risks. From agricultural soils, rhizospheric microbial communities have a significant role in the emissions of greenhouse gases. Every year, microbial communities release approximately 1.5–3 billion tons of carbon into the atmospheric environment. Microbial nitrification, denitrification, and respiration are the essential processes that affect the nitrogen cycle in the terrestrial environment. In the twenty-first century, climate change is the major threat faced by human beings. Climate change adversely influences human health to cause numerous diseases due to their direct association with climate change. This review highlights the different anthropogenic GHG emission sources, the response of microbial communities to climate change, climate forcing potential, and mitigation strategies through different agricultural management approaches and microbial communities

[In Press] Atmospheric emission of nitric oxide and processes involved in its biogeochemical transformation in terrestrial environment

Nitric oxide (NO) is an intra- and intercellular gaseous signaling molecule with a broad spectrum of regulatory functions in biological system. Its emissions are produced by both natural and anthropogenic sources; however, soils are among the most important sources of NO. Nitric oxide plays a decisive role in environmental-atmospheric chemistry by controlling the tropospheric photochemical production of ozone and regulates formation of various oxidizing agents such as hydroxyl radical (OH), which contributes to the formation of acid of precipitates. Consequently, for developing strategies to overcome the deleterious impact of NO on terrestrial ecosystem, it is mandatory to have reliable information about the exact emission mechanism and processes involved in its transformation in soil-atmospheric system. Although the formation process of NO is a complex phenomenon and depends on many physicochemical characteristics, such as organic matter, soil pH, soil moisture, soil temperature, etc., this review provides comprehensive updates about the emission characteristics and biogeochemical transformation mechanism of NO. Moreover, this article will also be helpful to understand the processes involved in the consumption of NO in soils. Further studies describing the functions of NO in biological system are also discussed

Impact of integrated application of biochar and nitrogen fertilizers on maize growth and nitrogen recovery in alkaline calcareous soil

Biochar application has been considered as a rich source of carbon which helps to improve the physico-chemical properties and fertility of the soil. In Pakistan, excessive use of nitrogen fertilizer is considered a serious problem, so it is of vital importance to examine the effect of biochar on soil with varying doses of nitrogen fertilizer. We hypothesized that addition of biochar to an alkaline calcareous soil could improve not only soil quality and crop yield but also nitrogen use efficiency (NUE), reducing the loss of nitrogen (N) in the form of denitrification, ammonia volatilization, and nitrate leaching. A pot experiment was conducted under 2-factorial completely randomized design having three replications to evaluate the NUE in biochar amended calcareous soil. Biochar was applied at the rate of 0%, 1% and 2% (w/w) in pots filled with 17 kg of soil using various levels of N (0%, 50% and 100% of recommended dose) on maize (Zea mays L.). Several soil quality indicators, uptake, and yield of maize were monitored. Biochar application significantly decreased soil pH, increased water-holding capacity, total organic carbon, maize yield, stomatal conductance, and nitrogen uptake in plant. The results of the study indicated that addition of biochar could not only decrease the use of inorganic fertilizers by improving its quality and yield as in our case biochar at the rate of 1% and N at the rate of 50% provided optimum output minimizing the economic cost eventually

Seven years of pig slurry fertilization : impacts on soil chemical properties and the element content of winter barley plants

Intensive pig farming produces large amounts of slurry, which is applied to agricultural soils as fertilizer. A 7-year field study was performed to check the effect of pig slurry on soil properties and on the accumulation of some essential nutrients and heavy metals in a calcareous silty-loam soil (0–0.3 m) and in barley (Hordeum vulgare L.) plants in two cropping seasons with contrasting amounts of rainfall. Five fertilization treatments, control (no N applied), mineral fertilizer (90 kg N ha−1), and different N doses of pig slurry (146, 281, 534 kg N ha−1), were applied at sowing of a barley crop. Organic carbon, available P and K, and total P in soil increased with slurry dose. No differences were found in Co, Cr, Fe, Mn, Ni, and Pb soil concentrations. Slurries increased Cu, Mn, and Zn extractions and plant concentrations of P in straw and Zn in grain. However, the lowest slurry rate was able to maintain the highest grain yields while improving fertility. The results of this research study support the sustainability of pig slurry fertilization at appropriate rates in relation to soil chemical quality