> Development > Climate change  
Prabir Kumar Talukdar
Date of Publish: 2016-08-13

Assam faces the onslaught of climatic change


Assam, country's 17th largest state is currently fighting the worst ever flood that has inundated millions of hectares of land known for its rich alluvial soil for agriculture. But the recent upsurge in the variation of climate has yielded a catastrophic blow to the economy of the state. In the wake of this climatic change, scientists and farmers, baffled with experiments and adaptation policy struggle to keep its head up.

Impact in Agriculture:

According to R.L Deka, Scientist at Assam Agriculture University said, '' Climatic change in the state of Assam has both negative and positive impacts on the state's agriculture production as it's mostly rice-based and rain-fed''. Climatic change is a buzz word until its effects are felt everywhere.  Kaushal Barua, a researcher in AAU  explains that the reason behind the disappearance of many local indigenous crop to the state. ''Climate Change. The character of the soil seems to be losing the minerals dilapidated by the rise in temperature''.


Graph : Minimum Temperature v/s Month at Tocklai


According to a study by the AAU, it has been observed that there is a negative impact on the production of autumn rice (ahu) and positive impact in the production of summer rice (boro). Autumn rice which is dependent on the fluctuation of pre-monsoon and early monsoon rainfall, decreased in the production in the central and lower Brahmaputra valley whereas area under summer rice production increased significantly.  Deka who has been studying the change in climate refers to a simulation model where they have studied the response of rice crop on a projected climate change scenarios of 2030 under the agro-climate of upper Brahmaputra valley.

The study concludes that if the temperature is increased by 4 degrees from the baseline climate, the rice productivity actually increases and that simultaneously increase in CO2 levels from the present 394ppm levels to the 750ppm levels would affect rice productivity positively under the present management conditions.  However, beyond that productivity would likely to fall off.

Impact in Tea :

Assam is the largest producer and exporter of tea which churns around 620 million kgs annually, almost half of the nation's annual production of 1233 million kgs.  Tea plantations in this area are responsible for providing livelihood options for millions of people whose history can be traced back to the colonial period of the British Empire. But during the recent years, tea production is seriously affected by climate-driven factors of biotic and abiotic stresses. As tea crop remains in the field for many years, repeated intervention in the form of plucking/pruning and external factors like climate change results in severe deterioration of quality. According to Tocklai Tea Research Institute in Jorhat, climatic factors affecting local weather conditions resulting in changing rainfall patterns, drought, flash flood, change in minimum temperature, change in relative humidity and sunshine hours affects the production of tea significantly. The possible fallouts of these factors lead to loss of yields and high management cost for coping/adaptation strategies.

Dr. R.N Bhagat, Scientist at Assam's Tocklai Tea Research Institute said, ''An ambient temperature of 13degree to 32degree is conducive for tea farming. Temperature above 32degree is unfavorable for optimum photosynthesis and if accompanied by low humidity, it will only lead to a disastrous crop''.  The rise of temperature and enrichment of ambient carbon dioxide have a profound impact on the tea crop. ''Productivity is also affected by pest behaviour and disease infestation which are also impacted by environmental change'', Dr. Bhagat said. According to the data provided by the Tocklai Meteorological Department, a long-term analysis of 100 years has revealed that rainfall in Northeast declined by more than 200mm along with an increase in the minimum temperature. Another study reveals that atmospheric concentration of carbon Dioxide has catapulted to almost 394ppm from 310ppm in 1959.  Analysis has found that the number of days having temperature >32degree is generally increasing along with the increase in average minimum temperature.

Impact of Climate Change :

Tea being a rain-fed crop requires certain soil and air temperature as well as moisture conditions for its growth. But excess and shortage of water affect the tea bushes significantly. Tea bushes need adequate and well-distributed rainfall, but heavy and erratic rainfall are responsible for causing massive damage to the bushes in terms of soil erosion, lack of sunshine hours, breeding different diseases and flooding.  According to the soil scientists at Krishi Vigyan Kendra (KVK), heavy rain washes away the topsoil converting the rich cultivable piece of land into barren and unproductive.  Loss of fertility leads to a reduction in the water holding capacity. exposure of root systems and decreased microbial activities due to loss of organic matter.  Every year, Brahmaputra river overruns large area in its floodplain causing massive water-logging in the productive tea growing areas. Water-logging is one of the major abiotic stresses which prohibits the growth of tea bushes. Every year 15-20% crop gets damaged due to surface waterlogging, localized waterlogging and profile water-logging in different areas of tea growing regions. Due to the ferocity of the Brahmaputra that flows from the Arunachal Pradesh, many large areas gets eroded by the constant thrashing of high currents. Bank erosion is, therefore, any problem that needs to have a solution as many areas from different growing estates have lost their land from Hathikhuli to Rohmoria in Dibrugarh district. According to the Meteorological Department, changes in the rainfall pattern is mostly contributed by the rising of the minimum temperature by almost 1.2 degrees to the added woes of a premature or delayed monsoon.

One of the major resultants of abiotic stress is the upsurge of pest infestation. The probability of pest infestation increases with increase in temperature. The productivity also reduces as a result. As temperature increases, the plants become stressed due to water deficit. The stressed plant then becomes very susceptible to pest attack.  Large tea growing areas in Assam faces massive crop loss due to pest infestation which includes tea mosquito bug, looper caterpillar and red-rust disease of tea leaf. Furthermore, the usage of chemical pesticide is very hazardous and toxic. These harmful pesticides run down to nearby water bodies during heavy rainfall and give rise to a new phenomenon known as Weeds. Parthenium hysterophorous, Lantana Camara and Dichanthum are commonly found invasive weed which is known to cause widespread devastation to crops, animals, biodiversity and human beings. According to the Jaipur-based Directorate of Weed Science Research, nearly 4.25million hectares in India are under direct threat, which if controlled can help yield crop production by 20-30%.


Adaptation :

According to Dr. Deka, AAU, ''There is a greater need for a symbiotic relationship as this is most natural way to help prevent the destruction of biodiversity''.  Dr. Rafiul Hussain,  AAU said, '' Traditional farmers have significantly changed their patterns of farming. In earlier days, farmers used to grow a single crop but the recent drastic change and increased periods of drought have forced the farmers to try out different local varieties of rice''.  Farmers now are trying to introduce the more traditional 'bao-dhan' and 'ahu-dhan' in their fields due to their ability to resist floods. According to farmers, the local variety of Bao-dhan has a unique tolerance to stress. The seedlings can withstand high drought conditions as well as in the months of May- September during the second flush of monsoon due to its unique ability to grow rapidly with the rising water levels. Floods being the most common phenomenon in the state and rice being the staple food, a balance between the two has to be worked out in order to maintain the production.

Dr. R.S Sharma of Krishi Vigyan Kendra (KVK) explains the case of soil and the benefits of crop rotation. ''Normally when a flash flood occurs, the rich soil is layered with different other matters. For a farmer, this seems to be devastating as agriculture is the only source of income. Then, we advise them to try out different varieties of other crops like watermelons, kidney beans, peanuts which can be easily grown over in that soil.  We advise them to put as much organic manure as possible as microbial matter helps to make the soil more fertile. The natural reclamation of land normally takes around 6 years. But the introduction of such crops will help maintain the minerals of the soil as one rotates the crop''. Farmers are shunning the hybrid varieties of crop and going to the old route of farming the local varieties of joha and bokadhan. Scientists at Assam Agricultural University have developed two different varieties of flood resistant rice seeds namely, Jalkuwari and Jalashree. According to AAU, these two varieties have already withstood the second flush of monsoon and can be a boon for the farmers in the flood-prone areas of Assam.  

Irrigation also plays a pivotal role in water deficit areas during the period of no rainfall to high rainfall. Certain strategic location where downhill water can be channelized to provide water to many areas. Dr. R.N Bhagat said, '' Tocklai has developed almost 33 tea clones, more than 150 garden clones. These clones are characterized on the basis of their yield, quality, tolerant capabilities, and susceptibility. New or replanting of these tea clones can be a major step in fighting the erratic climatic change''. Introduction of vermicompost is also another way of combating the ill effects of climatic change. It's efficient and eco-friendly way to convert bio-degradable into added manure thereby fighting the abiotic stress.  Integrated Pest Management is also another effective way to keep the pest in control by combining biological, chemical, physical and cultural tools in a way that minimizes economic and health risk.

''Adaptation and mitigation strategies leads to high production costs but one cannot deny the incoming onslaught of climatic change that threatens to overthrow everything that falls on its way. A rise in the minimum ground temperature of 1.4degree is catastrophic to say the least'' said Dr. Bhagat. Charles Darwin's Origin of Species said that the species that can best adapt to any climate and adjust itself to the environment are the ones who will survive to see the new dawn. 

Prabir Kumar Talukdar

( Prabir Kumar Talukdar is a freelance journalist. He travels around the country to capture stories. He is a recipient of  2015 Trust Women Photo Award by Thomson Reuters Foundation and Microsoft.  He can be reached at prabir008@gmail.com. His mobile no is  73995-02650 )


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