‘Aerobic’ rice cultivation: Mitigating water stress for the future climate change

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Introduction

Food  and  water  are  two  of  the  most  important  necessities  for  survival, but, with an increasing demand for food and a looming water crisis, a shortage of both may be on the horizon unless innovative technologies are developed considering the risk factor Scientists  are  now  taking  on the challenging  task  of developing  rice  production  systems  that  can  cope  with  water  scarcity. 

Present day conventional method of rice cultivation utilises 5,000 litres of water for producing one kg of rice than its actual requirement of 3,000 litres. About 2,000 litres is lost due to flooding and seepage losses. Further, decline in water table necessitates the need for improved water-use efficiency and water productivity in agriculture, particularly in rice cultivation.

What is aerobic rice cultivation ?
The newly upcoming approach of rice cultivation called aerobic rice cultivation is a  fundamentally  different  approach  to  grow  rice  like  an  upland  crop, such  as  wheat,  on  nonflooded aerobic  soils,  thereby  eliminating  continuous  seepage  and  percolation  and  greatly  reducing  evaporation. In simple words aerobic rice cultivation means growing rice plant as irrigated crop like cultivating maize and wheat in aerobic condition, where oxygen is plenty in soil.

Geographical conditions required for aerobic rice cultivation ?

  • The suitable areas for aerobic rice cultivation includes irrigated lowlands, where rainfall is insufficient to sustain rice production, delta regions where there is delay in water release from reservoir, irrigated system of rice cultivation, where pumping from deep bore well has become so expensive and favourable upland system has access to supplementary irrigation.
  • Tamil Nadu, Jharkhand, Chhattisgarh, parts of Bihar, Odisha, Karnataka, and eastern Uttar Pradesh are the projected area where there is uneven distribution and frequent occurrence of soil moisture limitation

How is aerobic rice cultivation different from traditional rice cultivation ?

  • In aerobic rice cultivation, rice is cultivated as direct sown in non-puddle aerobic soil under supplementary irrigation and fertiliser with suitable high yielding rice varieties. 
  • Throughout the growing season, aerobic rice field is kept under unsaturated condition and field is irrigated by surface or sprinkler system to keep soil wet due to which water productivity is reported to be higher in aerobic rice by 64-88 per cent (calculated as grams of grain produced per kg of water input) and utilises 3,000 to 3,500 litres of water to produce 1 kg of rice compared to rice raised under transplanted flooded system.

Aerobic rice cultivation is a " Mechanised way of sowing" 

  • Aerobic rice cultivation system involves mechanised way of sowing with no puddling, transplanting and not need of frequent irrigation, which reduce labour usage more than 50 per cent, compared to irrigated rice but  aerobic rice cultivation needs suitable rice varieties having the characteristics of both upland and high yielding lowland varieties to get good yield under the new unconventional system of cultivation.
  • Aerobic rice cultivation is an alternative option to reduce labour drudgery and to increase water productivity. Further, in environmental point of view, emission of methane is lower substantially in aerobic rice.
  • Therefore, in recent days it is gaining momentum among rice researchers and farmers. However, extra care should be taken, since poorly managed field may cause partial to complete failure of crop, which might happen due to weeds and micronutrient non-availability.

Disadvantages involved with aerobic rice cultivation :-

  • Increased weed growth, poor crop stand, crop lodging, high percentage of panicle sterility and root-knot nematode infestation are some of the constrains in aerobic rice cultivation
  • High weed infestation is the major constraint for aerobic rice and cost involved in weed control is higher. Further, due to high infiltration rate of water and imbalanced availability of nitrogen makes the aerobic soil further ailing for micronutrients (iron and zinc) and rise in nematode population

However in recent days aerobic rice cultivation is gaining momentum among rice researchers and farmers. However, extra care should be taken, since poorly managed field may cause partial to complete failure of crop, which might happen due to weeds and micronutrient non-availability. Efficient nutrient management techniques along with integrated weed management are researchable areas for successful aerobic rice cultivation and research is in progress.

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