Carbon offset potential of biochar based straw management under rice- wheat system along Indo-Gangetic Plains of India.

The Paris Agreement goal of a net-zero equation will require decarbonization technologies in agriculture. Agri-waste biochar offers huge potential for carbon abatement in agricultural soils. The present experiment was carried out to compare the effects of residue management, viz., no residue (NR), residue incorporation (RI), and biochar (BC), as well as nitrogen options for emission reduction and carbon capture under the rice-wheat cropping sequence (RWCS) of the Indo-Gangetic Plains (IGP), India. After two cycles of cropping pattern, the analysis revealed that the biochar application (BC) reduces the RWCS's annual CO2 emissions by 18.1 % over residue incorporation (RI), while CH4 and N2O emissions were reduced by 23 % and 20.6 % over RI and 11 % and 29.3 % over no residue (NR), respectively. The application of biochar-based nutrient composites with rice straw biourea (RSBU) at 100 % and 75 % significantly reduced greenhouse gases (CH4 and N2O) compared to commercial urea at 100 %. The global warming potential of cropping systems recorded with BC was 7 % and 19.3 % lower than NR and RI, respectively, while 6-15 % under RSBU over urea 100 %. The annual carbon footprint (CF) under BC and NR decreased by 37.2 % and 30.8 % over RI, respectively. The net CF under residue burning was estimated to be the highest (132.5 Tg CO2-Ce), followed by RI (55.3 Tg CO2-Ce), showing net positive emissions; however, net negative emissions were found under a biochar-based system. The estimated annual carbon offset potential of a complete biochar system over residue burning, incorporation, and partial biochar as calculated was 189, 112, and 92 Tg CO2-Ce yr-1, respectively. A biochar-based approach to managing rice straw had great carbon offset potential through a large drop in greenhouse gas emissions and an improved soil carbon pool under the rice wheat system along the IGP, India.

Characterization of Helicoverpa armigera spatial distribution in pigeonpea crop using geostatistical methods.

BACKGROUND: The gram pod borer, Helicoverpa armigera (Lepidoptera: Noctuidae) is an economically important pest of pigeonpea crop in India. Fixed plot surveys for H. armigera larvae were carried out at 28 pigeonpea fields located in the Southern Plateau and Hills agro-climatic zone of India for three crop seasons (nine sampling weeks per season). The spatiotemporal dynamics of H. armigera larvae in the experimental area (=Hanamkonda) was analysed using geostatistics tools, namely a variogram and Voronoi diagram, and H. armigera larval distribution patterns were further characterized and mapped. RESULTS: A significant difference in H. armigera larval incidence was noticed between sampling weeks, with greater larval incidence observed between 26 November and 2 December. Pod formation phenophase (Meteorological Standard Week 44) of pigeonpea favoured the initial H. armigera larval incidence. Variogram analysis revealed moderate to strong larval aggregation (spatial dependence) of H. armigera in all nine sampling weeks. Based on the range value of the variogram, the average aggregation distance of H. armigera larvae in pigeonpea was estimated to be 2425.48 m. Voronoi diagrams illustrated the spatial heterogeneity of H. armigera larva between sampling weeks, which can be linked to availability of food sources. CONCLUSION: This study witnessed intrapopulation variability in H. armigera larvae associated with geographical space and temporal patterns. Based on our findings, a sampling distance of 2425.48 m may be used in larger pigeonpea fields (experimental area) to reduce scouting fatigue. The interpolated maps generated in this study may be of value in developing effective H. armigera larva monitoring and management tools in pigeonpea crop.