Researchers using satellite images and data in cohesion with ground reports to map potential areas for for growth and expansion of cultivation
In Meghalaya’s tough hill terrains that limit field visits, space technology is aiding the selection of areas that are suited for growing and expanding cultivation of boro rice which is sown in winter and harvested in spring/summer, officials said.
Boro refers to a special type of rice cultivation on residual or stored water in low-lying areas after the harvest of kharif (winter) rice. Space technology has zoomed in on potential stretches in the state and offered a bird’s eye view of tracts that are best suited for growing boro season rice.
This will help bridge the demand-supply gap in Meghalaya where 81 percent of the population is dependent on agriculture but the net cropped area is proportionately quite less: only about 10 percent of the total geographical area of the state.
So to identify areas for expansion of boro rice in Meghalaya, the North Eastern Space Applications Centre (NESAC) at the request of Directorate of Agriculture, Government of Meghalaya, tapped into a suite of geospatial technologies.
These technologies such as remote sensing and Geographic Information Systems are a range of modern tools contributing to the geographic mapping and analysis of a range of data about people, such as population, income, or education level and also about landscapes.
Space tech can reduce time lost on trial and error
“By using satellite images and data with ground information on parameters such as slope, soil and climate, we mapped potential areas for expansion of boro rice cultivation. This was one of the first of its kind project in the northeast,” Pratibha T Das of NESAC said.
Having space technology focus on potential areas saves time and money in implementation by skipping the field trial stage, explained Das.
In an email communique, officials at Meghalaya’s agriculture department also reiterated that this approach eliminates the trial and error method “saving time, effort and money and scale of implementation in a given (short) period of time.”
Das further said: “Even though the identified areas are small, the agriculture department need not conduct field trials; they can directly select the potential areas from the maps and start cultivation.”
The mapping exercise covered landscapes spread across nearly 5000 square km at elevation below 200 metres and excluding forest, built up and barren rocky areas. The findings published in Current Science show that out of 4903 sq. km study area only 807 sq. km (16.5 percent) is suitable for boro rice cultivation.
Though 16.5 percent area is suitable for boro rice, only 0.8 percent (6.35 sq. km) area is highly suitable, which is found in West Garo hills district. Around 581.74 sq. km is marginally suitable whereas 219.07 sq. km area is moderately suitable.
“The data tells us that slope, soil texture, soil fertility (acidity) and soil drainage are the major limiting factors/problems, because of which maximum areas are found marginally and moderately suitable for boro rice expansion,” said Das.
Based on problems/limitations of the land, land users and planners can decide on crop management strategies to increase productivity, she said.
Thematic maps like soil drainage, soil texture, soil depth, flooding and gravel/stoniness and land use maps were dovetailed with soil sample analyses and digital elevation models to get a clear picture on ground.
Soil samples were collected from 121 locations and analysed, revealing that sandy clay soil texture, that was best fit for boro rice, was distributed in six percent of the area examined.
Space data can strengthen ground data
Ecology and sustainable development professor Ruth DeFries at Columbia University, New York, stressed though satellite data can provide a bird’s-eye view to observe many features of the landscape, one needs to factor in social and community dynamics.
“The project to map potential areas for rice cultivation using satellite data makes it possible to identify suitable locations over large areas, which is much more difficult from the ground,” said DeFries.
However, she said, satellites cannot detect social and community dynamics, so one needs to combine different sources of information for a complete view of which places would be ecologically and socially suitable for cultivation.
The most important aspect for accessing the suitability of boro rice is availability of surface or groundwater for irrigation during the dry season, especially in the months of February, March and April, pointed out Parvesh Kr. Chandna, Scientist – Remote Sensing & GIS, South Asia at International Rice Research Institute (IRRI).
The conditions suited for boro rice production are level fields, warm temperature, adequate sunshine hours and assured irrigation. These conditions are generally found in low altitude plain areas that are close to water sources (surface or groundwater irrigation), the state government’s agriculture department added.
“Fortunately, Garo hills have a good potential for ground water exploitation, especially in the alluvial plains of the West Garo Hills. According to the analysis of the Central Ground Water Board of the Government of India, these alluvial plains have large replenishable reserves of ground water and the current utilisation of groundwater is very low,” the agriculture department explained.
Chandna agrees on this (potential for groundwater exploitation) but also elaborates on the choice of crops.
“If we have potential for ground water development, then the next question is whether we are choosing the most profitable crop, considering the total water requirements for boro rice and the availability of alternative options (high profitable cash crops) in dry season in comparison to wet season where rice is the only option,” Chandna said.
Meghalaya on a rice mission
The move to expand area of rice grown in the boro season comes under the Meghalaya State Rice Mission (MSRM) aimed at narrowing the gap between rice production and consumption by doubling the production of rice – a major staple food of the northeastern state, accounting for over 80 percent of the food grain production.
In West Bengal and Bangladesh, expansion of irrigation, essential for supporting the boro rice production, led to a rapid increase in boro rice area and production during the past two decades and Meghalaya can benefit by deploying a similar strategy of expanding the boro season area, the state agriculture department opined.
Previous estimates from the rice mission document peg the consumption at approximately 400,000 tonnes annually during the years 2010-11. This estimate is double the rice produced during that period.
“Rice recorded an annual production of 3,01,076 metric tonnes during the year 2015-16 at an average productivity of 2.72 metric tonnes per hectare. Our spring rice/boro paddy produces an average yield of 4.28 metric tonnes per hectare under assured irrigation,” the agriculture department said.
In Meghalaya the rice crop is distributed in three rice ecosystems. They are low altitude rice that covers 70 percent of total rice growing areas, mid altitude rice covers 25 percent and high altitude rice that covers five percent.
In a report submitted to NITI Aayog, Indian government’s think tank, the Meghalaya government has said that the under-utilisation of land during the winter season has resulted in shortage of rice for the ever-increasing population.
In addition, with assured irrigation, boro paddy yield is double the average yield per hectare compared to sali rice.
“Boro paddy gives an average yield of 4 MT per hectare compared to the average yield of 2 MT per hectare of sali paddy,” according to the report.
Further, winter planting is free from flash floods and is well-suited for SRI (System of Rice Intensification) technique with yields of 6-7 MT per hectare, the report said, justifying the augmentation of boro paddy cultivation in areas where this practice was not in vogue.
With the NESAC data at disposal, the department of agriculture has initiated steps for application of the findings by taking a policy decision to link the activity for growing boro rice with the Indian government’s National Rural Employment Guarantee (NREGA) program.
“This will achieve both the objective of providing assured employment under NREGA and also productive output and income for the NREGA wage earner cum farmer,” an agriculture department official said.
(The article first appeared in Mongabay-India)