Assessing long term impact of nutrient management and rainfall variability on the agroecological resilience of maize (Zea mays)- wheat (Triticum aestivum) system in NW India

A long-term (2000-2010) field experiment was carried out in the lower Shiwalik foothills of Punjab to study the carry over effect of organic manures and fertilizers on the productivity of maize (Zea mays L.)- wheat (Triticum aestivum L.) cropping system for efficient N management and resource use under rainfed conditions and to develop predictive models describing relationship between yields and seasonal rainfall. N management strategies involving combined application of 15 kg N/ha either through compost or leucaena loppings along with 20 kg N/ha through inorganic fertilizer for maize-wheat cropping sequence utilized growth resources most efficiently and maintained stable yield performance culminating in significantly higher system productivity, better resource use efficiencies and sustainable yield index, suggesting partial N substitution through compost or locally available plant material. The regression models developed to predict the effects of N sources on crop yields using monthly rainfall would be of interest to estimate the yield at a given level of rainfall with the likely fluctuation (as error) particularly under rainfed conditions

Short-term exposure to ambient air pollution and individual emergency department visits for COVID-19: A case-crossover study in Canada

BACKGROUND: Ambient air pollution is thought to contribute to increased risk of COVID-19, but the evidence is controversial. OBJECTIVE: To evaluate the associations between short-term variations in outdoor concentrations of ambient air pollution and COVID-19 emergency department (ED) visits. METHODS: We conducted a case-crossover study of 78 255 COVID-19 ED visits in Alberta and Ontario, Canada between 1 March 2020 and 31 March 2021. Daily air pollution data (ie, fine particulate matter with diameter less than 2.5 µm (PM2.5), nitrogen dioxide (NO2) and ozone were assigned to individual case of COVID-19 in 10 km × 10 km grid resolution. Conditional logistic regression was used to estimate associations between air pollution and ED visits for COVID-19. RESULTS: Cumulative ambient exposure over 0-3 days to PM2.5 (OR 1.010; 95% CI 1.004 to 1.015, per 6.2 µg/m3) and NO2 (OR 1.021; 95% CI 1.015 to 1.028, per 7.7 ppb) concentrations were associated with ED visits for COVID-19. We found that the association between PM2.5 and COVID-19 ED visits was stronger among those hospitalised following an ED visit, as a measure of disease severity, (OR 1.023; 95% CI 1.015 to 1.031) compared with those not hospitalised (OR 0.992; 95% CI 0.980 to 1.004) (p value for effect modification=0.04). CONCLUSIONS: We found associations between short-term exposure to ambient air pollutants and COVID-19 ED visits. Exposure to air pollution may also lead to more severe COVID-19 disease

A review on carbon pools and sequestration as influenced by long-term management practices in a rice–wheat cropping system

The drastic increase of atmospheric CO2 concentrations and depletion of soil organic carbon (SOC) have prompted interest in exploiting the sink potential of soil to sequester carbon. The role of soils to mitigate climate change by the “4 per 1000” concept to increase global SOC stocks by 0.4% has been acknowledged. However, the potential of soils to sequester C depends on the cropping system, the magnitude of antecedent C depleted from soil, properties of the soil profile, climate and agricultural management practices. To formulate long-term agricultural management practices that lead to C sequestration, it is important to study their effect on SOC pools. Certain labile pools of C are considered sensitive indicators that show quick change after a modification in management practice. In contrast, changes in total SOC are relatively less detectable over the short to medium term. Most SOC pools are interrelated and vary in proportion. Rice–wheat, an intensive and dominant cropping system occupying 24 million hectares of cultivated land globally, significantly contributes to the global warming potential. Therefore, this review aims to identify the best management practices in the rice–wheat system that lead to C sequestration by improving SOC. These include the use of manure, compost, crop residues, balanced fertilization used conjointly with farmyard manure (FYM), mulch farming, conservation tillage, and inclusion of cover crops. The paper provides a comprehensive review of C pools and sequestration as influenced by long-term management practices under a rice–wheat cropping system

Effect of long-term fertilization in maize-wheat cropping system on carbon mineralization in soil

Quantitative information on mineralization of soil organic carbon (SOC) under different long-term nutrient management practices is essential for better assessment of carbon (C) loss from soil. With an aim to evaluate long-term nutrient management effects on C mineralization kinetics in soils, a laboratory incubation study was conducted with soils collected from different depths (0–15, 15–30, 30–60, and 60–100 cm) of a 46-year old maize-wheat experiment. The treatments in the field involved long-term application of 100% N, 100% NP, 100% NPK, 150% NPK, 100% NPK + FYM (farmyard manure), and an unfertilized control. Long-term application of fertilizers significantly (p < 0.05) influenced organic C concentration and C mineralization kinetics in soil. Integrated application of inorganic fertilizers and organic manure (100% NPK + FYM) resulted in greater SOC accumulation and higher potentially mineralizable C in soil compared to other treatments. The microbial biomass carbon (MBC), basal soil respiration (BSR), carbon mineralization (Cmin), and microbial quotient (qMic) values were significantly higher under integrated application of NPK and FYM in maize-wheat system. The results showed that long-term application of FYM along with inorganic fertilizer enhanced SOC pool compared to solitary application of mineral fertilizers

Assessing long term impact of nutrient management and rainfall variability on the agroecological resilience of maize (Zea mays)- wheat (Triticum aestivum) system in NW India

A long-term (2000-2010) field experiment was carried out in the lower Shiwalik foothills of Punjab to study the carry over effect of organic manures and fertilizers on the productivity of maize (Zea mays L.)- wheat (Triticum aestivum L.) cropping system for efficient N management and resource use under rainfed conditions and to develop predictive models describing relationship between yields and seasonal rainfall. N management strategies involving combined application of 15 kg N/ha either through compost or leucaena loppings along with 20 kg N/ha through inorganic fertilizer for maize-wheat cropping sequence utilized growth resources most efficiently and maintained stable yield performance culminating in significantly higher system productivity, better resource use efficiencies and sustainable yield index, suggesting partial N substitution through compost or locally available plant material. The regression models developed to predict the effects of N sources on crop yields using monthly rainfall would be of interest to estimate the yield at a given level of rainfall with the likely fluctuation (as error) particularly under rainfed conditions

Short-term exposure to ambient air pollution and individual emergency department visits for COVID-19:a case-crossover study in Canada

Abstract Background: Ambient air pollution is thought to contribute to increased risk of COVID-19, but the evidence is controversial. Objective: To evaluate the associations between short-term variations in outdoor concentrations of ambient air pollution and COVID-19 emergency department (ED) visits. Methods: We conducted a case-crossover study of 78 255 COVID-19 ED visits in Alberta and Ontario, Canada between 1 March 2020 and 31 March 2021. Daily air pollution data (ie, fine particulate matter with diameter less than 2.5 µm (PM2.5), nitrogen dioxide (NO₂) and ozone were assigned to individual case of COVID-19 in 10 km × 10 km grid resolution. Conditional logistic regression was used to estimate associations between air pollution and ED visits for COVID-19. Results: Cumulative ambient exposure over 0–3 days to PM2.5 (OR 1.010; 95% CI 1.004 to 1.015, per 6.2 µg/m³) and NO₂ (OR 1.021; 95% CI 1.015 to 1.028, per 7.7 ppb) concentrations were associated with ED visits for COVID-19. We found that the association between PM2.5 and COVID-19 ED visits was stronger among those hospitalised following an ED visit, as a measure of disease severity, (OR 1.023; 95% CI 1.015 to 1.031) compared with those not hospitalised (OR 0.992; 95% CI 0.980 to 1.004) (p value for effect modification=0.04). Conclusions: We found associations between short-term exposure to ambient air pollutants and COVID-19 ED visits. Exposure to air pollution may also lead to more severe COVID-19 disease