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The complex and multi-dimensional nature of droughts in Tamil Nadu state and its impact on agricultural sector and farming community requires a thorough analysis for developing short and long-term adaptation and mitigation measures with institutional arrangement and policy support. In the present investigation, drought analysis was made for Tamil Nadu state using 148 years (1871 - 2018) monthly rainfall data obtained at district scale from India Meteorological Department (IMD) and Tamil Nadu Agricultural University by employing various drought indices. Larger co-efficient of variation (139 and 149 %) during the major growing seasons (Southwest and Northeast monsoon)evidenced high undependability of rainfall over Tamil Nadu. Drought Index (DI) analysis indicated a 51 per cent drought years in SWM and 48 per cent in NEM season, while Standardized Precipitation Index (SPI) exhibited 43 and 48 per cent of drought years in SWM and NEM respectively, indicating occurrence of drought once in every four years. More number of Consecutive Drought years (CDY) posed serious impacts on food production and livelihoods. Drought management framework as well as input for designing drought policy for Tamil Nadu. [ABSTRACT FROM AUTHOR]

Over the last century, mean annual temperatures increased by ~1°C. UNFCCC has proposed to limit warming below 1.5°C relative to pre-industrial levels. A study was conducted on rice (C3 pathway) and maize (C4 pathway) over Tamil Nadu using DSSAT to understand the climate change impacts with projected temperature increase of 1.5°C.The future climate under RCP 4.5 and RCP 8.5 indicated 1.5°C increase in temperature to happen by 2053 and 2035, respectively over Tamil Nadu. Annual rainfall deviations in RCP4.5 showed drier than current condition and RCP8.5 projected wetter SWM and drier NEM (90% of current rainfall).Impact of 1.5°C warming on crop phenology indicated 8 days reduction in duration for rice and maize. The WUE of rice would decrease by 17 per cent at current CO2 whereas, enrichment (430 ppm) would reduce by12 per cent and rice yield is reduced by 21 per cent with 360 ppm CO2 and 430 ppm reducedby 17 per cent. There is no considerable varaition (- 5 to 1%) in maize productivity with 1.5 °C warming. The above results indicated that 1.5 °C warming has more negative impacts on plants with C3 compared to C4 pathway. [ABSTRACT FROM AUTHOR]

Sugarcane is an important cash crop, contributing to 4.6 per cent of total agricultural output. In a few regions, though sugarcane had widespread area, the productivity is very less. In a few other regions, the productivity is very high but acreage under sugarcane is low. This warrants delineation of effective cropping zones for sugarcane. District wise statistics on area, production and productivity of sugarcane for southern Indian states was collected to compute Relative Spread Index (RSI) and Relative Yield Index (RYI) to classify the zones into Most Efficient Cropping Zone (MECZ), Area-Efficient Cropping Zone (AECZ), Yield Efficient Cropping Zone (YECZ) and Inefficient Cropping Zone (IECZ). Analysis indicated that the maximum efficient cane growing zone is in Tamil Nadu, followed by Karnataka, Andhra Pradesh and Telangana. Sugarcane is not preferred in Kerala due to the prevailing climatic conditions. This analysis helps in the identification of options for improving the sugarcane area and production. [ABSTRACT FROM AUTHOR]

Global climate change has increased the events and intensity of extreme events. Tamil Nadu is located in the southern peninsula region of India, which has benefitted both from the south-west monsoon (SWM) and the north-east monsoon (NEM). Although variations in the monsoon pattern increased events of drought. The IMD gridded (1991–2020) and projected global climate model data (EC_Earth3_Veg_LR) were used to anticipate the drought-risk-prone zones over Tamil Nadu by using the standardized precipitation index. During both the SSP245 and SSP585 scenarios of the near (2021–2050) and mid (2051–2080) century periods, an increase in rainfall amount was expected with a high coefficient of variation (CV) across the region. The CVs of the future SWM and NEM seasons were expected to range from 20% to 60% and 25% to 50% respectively. Increased variability often leads to an increase in number of drought events. Regardless of scenarios, the southern zone was expected to experience more drought events, followed by the northwestern zone during SWM. Drought events during the NEM were expected to increase in northeastern zone districts. Changes in cropping patterns and policymaking for future risk-prone areas were undertaken as a proactive response to mitigate potential agricultural challenges. [ABSTRACT FROM AUTHOR]

Temperature is one of the most important environmental factors that influence the crop growth, its development, and yield. With the increase in the accumulation of GHGs in the atmosphere, there is a rise in surface temperature as compared to pre- industrial period. An experiment was conducted during rabi season of 2013- '14 to study the impact of elevated temperature with and without CO2 fertilization on rice (C3) and maize (C4) crops, using Temperature Control Chamber and Soil plant Atmospheric Research system at the Agro Climate Research Centre of Tamil Nadu Agricultural University, Coimbatore. Temperature elevation of 4 °C from the ambient level in the TCC and temperature elevation of 4 °C with 550 ppm CO2 in the SPAR chamber were considered for experimentation. Increase in temperature with or without CO2 enrichment affected the phenology and productivity of C3 and C4 plants under different magnitude. Rice and maize crops grown under 4 °C elevated temperature attained panicle initiation, flowering and maturity earlier than the crop grown under ambient condition. The treatment 4 °C elevated temperature also recorded reduced number of tillers in rice, number of leaves in maize and dry matter production in rice and maize. This treatment did record lower rice grain and straw yields . Maize grain and stover yields also got reduced. As far as the physiological response of C3 (rice) and C4 (maize) was considered, the photosynthetic rate was significantly low when the plants were kept under warmer environment than under ambient condition and the rate of decrease was higher in rice compared to maize. However, the CO2 enrichment compensated this reduced photosynthetic rate. The interaction effect between temperature and CO2 in rice indicated that CO2 enrichment had minimized the yield loss by 10 per cent as compared to three per cent obtained under maize crop. The transpiration rate and stomatal conductance were significantly increased in both rice and maize crops under elevated temperature compared to ambient condition and the rate of increase was higher in rice than in maize, yet, CO2 enrichment compensated these ill effects of elevated temperature to certain extent in maize, and to a considerable extent in rice. [ABSTRACT FROM AUTHOR]

A field experiment was conducted at Tamil Nadu Agricultural University, Coimbatore in the rabi season in order to assess the sustainability of SRI in changing climate. Three aspects of rice cultivation, GHG emission, water use, and Energy consumption were accounted to vindicate the sustainability of SRI over other cultivation systems. Three rice cultivation systems SRI (System of Rice Intensification), AWD(Alternate Wetting and Drying) and conventional were selected which differ in agronomic and water management practices. CH4, N2O and CO2 gas emissions from field were collected using static closed chamber and was analyzed using a gas chromatograph equipped with FID. Water irrigated to the field was measured in m3 using a water meter. The results showed that SRI method of cultivation recorded less GHG emissions and water use with higher yield. Alternate wetting and drying method of water management reduced methane emission in AWD by 41 per cent and SRI by 44.3 per cent when compared with conventional system. [ABSTRACT FROM AUTHOR]

The lowland rice cultivation is recognized as one of the major methane sources. The application of amendments that contain high amount of electron acceptors would inhibit the methanogenic activity and hence methane emission. Fly ash is a by-product containing ferro- alumino- silicate minerals whereas gypsum is sulphate of calcium. A field experiment was conducted to estimate the effect of fertilizers like Urea and Neem treated Urea and soil amendments like fly ash and gypsum along with recommended dose of fertilizers on the methane emission from the rice field. Gas samples were collected from the field using Static open-bottom perplex chamber technique and estimated in a Shimadzu GC-2014 gas chromatograph equipped with FID. The rate of methane emission was found to be lesser at the active tillering stage which attained a peak at the panicle initiation stage and then got declined till maturity stage. This trend was noticed irrespective of the treatments evaluated. The substitution of neem treated urea instead of urea had no significant impact on the methane emission whereas the application of either gypsum or fly ash or in combination along with RDF significantly decelerated the methane emission. [ABSTRACT FROM AUTHOR]

In India, agriculture sector provides the largest livelihood support and contributes by 17.3 percent to the Gross Domestic Product (GDP). Maize is the third most important food crop after rice and wheat, occupying about 7.5 million hectares of land area in India. In Tamil Nadu maize is cultivated mainly as rainfed crop during Rabi season. Requirement of maize is growing fast and given the importance, a study was carried out at Agro Climate Research Centre, Tamil Nadu Agricultural University, Coimbatore during 2015-2016 to assess the impact of climate change on rainfed maize productivity over Tamil Nadu during mid-century (2040 to 2069) period. The Representative concentration pathway 4.5 and 8.5 was selected to represent the stabilization and over shoot pathways of emission. Maximum temperature was expected to increase to a maximum up to 4.7°C while minimum temperature to 5.7°C. Rainfall is anticipated to vary from a decrease of -33.0 percent to and increase of +45.1 percent.The future climate projected by these models was integrated with DSSAT to simulate the impact on rainfed maize productivity over Tamil Nadu. Under changing climate, rainfed maize productivity is expected to decline to a maximum of 30 percent from the current yield levels. [ABSTRACT FROM AUTHOR]

An investigation was undertaken to understand the impact of climate change on biomass availability and no assess the pressure of livestock on available total feed and fodder. Biomass productivity of both rice and maize was simulated using DSSAT model. The average biomass productivity of maize single and double cropping system under baseline was 8708 kg/haand 9441 kg/ha and for rice was 4810 kg/ha and4737 kg/ha respectively for baseline period (1980-2009). Simulation of future biomass productivity under changing climatic conditions indicated that it was decreasing in both maize and rice. A decrease of 27.6 and 22 per cent was expected in maize and by 27.2 and 26.5 per cent in rice single and double cropping system, respectively. The results revealed that the livestock production systems need to be adjusted through adoption of possible feed and forage management strategies to reduce the vulnerability to climate change. [ABSTRACT FROM AUTHOR]

The article focuses on the study on the impact of El Niño-Southern Oscillation (ENSO) induce rainfall on the productivity of maize farm in Tamil Nado, India. Topics discussed include the measurement of ENSO condition using the Southern Oscillation Index (SOI), the influence of SOI phases on the characteristics of rainfall during the rainfed cropping period, and the statistical analysis of the effect of SOI phase son maize growth and yield.

Drought is one of the recurrent climate phenomenon that crippling the societal and economic development of the agrarian country. It occurs almost everywhere, although its features vary from region to region. The present study was undertaken to assess the drought in Tamil Nadu using the precipitation data of historic climatic period (1981-2017) with high spatial resolution (17 Km). Rainfall deviation from the long term mean during SWM, NEM and annual time scale was calculated at district level for identifying the drought prone districts in Tamil Nadu. The results showed that the frequency of the drought events was higher during the SWM as compared to NEM. Results indicated that Tirunelveli, Theni, Tiruppur, Karur, Tiruchirapalli districts were prone to the drought during SWM. As the NEM is the primary rainfall season and active crop growing period, suitable drought mitigation strategies need to be designed for the districts viz., Kanyakumari, Salem, Thiruvallur, which are highly affected due to deficit rainfall during NEM. [ABSTRACT FROM AUTHOR]

El Niño Southern Oscillation (ENSO) is one of the most important drivers of climate variability. To study the impact of ENSOonseasonal rainfall over Tamil Nadu, historical weather data for the period of 43 years (1971-2013) were categorized based on the ENSO episodes and the analysis was performed for assessing ENSO linked climate variability (onset and cessation) for North east monsoon rainfall (NEM: October - December) and rainfed cropping period (September - December) over Tamil Nadu. Onset was determined using the pentad analysis performed from 1st October through 31th October, considering first pentad with quantum of 10 mm of rainfall followed by four consecutive pentads of 10 mm of rainfall per pentad. The same approach was followed for deciding the onset of sowing rains for rainfed cropping period starting from 1st September to 10th October. In NEM and rainfed cropping period, cessation of monsoon was seen in December month. If the cessation didn't occur during December, the cessation time was noted in November month and the season was considered as the last day that received rainfall amount of > 2.5 mm. In NEM, higher per cent of years had onset in the slot from 1st to 5th of October (65.0, 63.4, 65.2 per cent of El Niño, La Niña and Neutral years, respectively). Few years were in neutral phase (26.3 %) and in El Niño (19.4 %) andunderLa Niña (15.2%) phase the results showed the onset happened between 6th and 10th of October. In most of the El Niño years (68 %), sowing rain occurred during 1st week of September (1st to 7th September), while in 40 per cent of the La Niña years sowing rain was delayed by one week and received during 2nd week of September. Cessation was earlier in most of the La Niña years as compared to El Niño and neutral years. [ABSTRACT FROM AUTHOR]