Despite strong agricultural intensification in India after 1960, the overall average crop diversity did not decline at the national level, a new study has found. The primary reason is neutralising effects, whereby a decline in diversity in one region was offset by an increase in another.
The average crop species diversity at the district level has been stable but increased at the country-level, the peer-reviewed study, published on December 11, said.
“While there was a decline in diversity in the major rice and wheat producing regions of north-western India, associated with intensification of the production of these crops, diversity in western and southern India, increased due to expansion of oilseeds and horticultural crops that replaced millet and sorghum,” the authors wrote in their paper.
A decrease in diversity associated with crop intensification and specialisation in one area may be associated with increased diversity elsewhere.
The scientists attempted to address the “substantial gaps” in the understanding of how different levels of agricultural biodiversity change over space and time, what drives these changes, and the impact of these changes at scales larger than individual farms.
There is considerable debate over the exact extent of loss of genetic diversity in crop plants, more so because good baseline data and surveys are few or absent, according to the scientists.
There is also lack of clarity on whether, how and to what extent agricultural intensification, including increased mechanisation, crop specialisation and increase in farm plot sizes have impacted diversity, and how these impacts work out at the national level.
The authors cite the example of the US, where species-level crop diversity actually increased between 1870 and 1950 at both the state- and country-levels, in the period in which industrialised agriculture practices were being widely adopted.
Similarly, in the southern Quebec region in Canada, the biodiversity of agricultural crop species was stable between 1911 and 1960 and increased thereafter.
The scientists chose India for analysis as it is a large and diverse country whose agricultural sector has changed drastically since its independence in 1947. After 1960, the country’s ‘green revolution’, which used more fertilisers and other agrochemical inputs together with short-straw varieties to intensify rice and wheat production in many parts of the country, particularly in the northwest.
In the past couple decades, production of maize for animal feed and of oilseed crops and high-value horticultural crops for domestic and export markets has increased.
For the India study, the scientists analysed change in crop diversity at the district, state and national level between 1947 and 2014. The country-level data covered 31 crops from 1947 to 1961 and 80 crops from 1961 to 2014, using 1966 state boundaries as the baseline. The district-level data covered 20 crops from 1956 to 1987 from India Agricultural and Climate dataset and 24 crops from 1966 to 2011 from the International Crops Research Institute for Semi-Arid Tropics, Hyderabad.
The analysis shows that country-level crop diversity in India increased after the green revolution took off in the early 1960s. This national trend is actually the aggregate of opposing trends at the sub-national level.
For example, while farmers in the Indo-Gangetic plains focused on wheat and rice, its diversity also decreased. “This region is of fundamental importance for food security in India and a loss of diversity could make agriculture more sensitive to shocks such as the outbreak of a new disease,” the study notes.
There were also significant environmental problems in the region, notably groundwater depletion, but that these concerns are a result of intensification and not of low diversity per se.
In southwest India, crop diversity increased as sorghum and millet were partly replaced with oilseeds and horticultural crops. In these regions, where crop production is predominantly rainfed, cropping systems have remained less intense, and crop diversity increased, driving an overall increase in country-level diversity from the 1960s.
“These changes, at least in part a response to the specialisation and intensification in the north, have contributed to somewhat higher national-level crop diversity and provide the supply for more diverse diets,” the study says.
“We show that while it is true that crop diversity declines in the Indo-Gangetic plains, as a result of the ‘green revolution’ rice-wheat intensification and specialisation,” Robert Hijmans, one of the study authors from the University of California, Davis, told The Wire. “We emphasise that in other areas of India, agriculture diversified. We suggest that this was related to the specialisation in the Indo-Gangatic plains, as agriculture there provides cheap grain.”
According to Hijmans, while it is good that agriculture in India is increasingly productive and diverse, which suggests people can improve their diets and farmers find new opportunities, there is a strong dependency on intensive production of rice and wheat, which in turn are linked to groundwater depletion. Thus, India’s R&D policy needs to focus on keeping rice and wheat productivity high while diminishing their environmental footprint.
The country should also provide support to further develop fruit and vegetable, sorghum, millet and beans crop production.
Rai S. Rana, a former director of the National Bureau of Plant Genetic Resources, New Delhi, and a former member of the National Biodiversity Authority (NBA), said that while the study is largely useful, there are still some issues with it.
For example, he said, it hasn’t addressed the impact of agricultural intensification upon crucial components of agrobiodiversity: the genetic diversity within crop plants varieties, and the relationship between agricultural intensification and crop diversity.
Rana is also cautious because the study banks on data available in various surveys conducted by several agencies – “but such survey datasets have their own limitations for drawing inferences depending on their objectives, assumptions and designs.”
The authors developed ways to suitably aggregate the available data at district, state and country levels to check for any relationships between the level of agricultural intensification and crop diversity (as reflected by area under a crop and its total production) on the other. “Changes in crop area and production are largely affected by several socio-economic considerations, among many other factors, and establishing cause and effect relationship is risky,” Rana said.
Instead, he suggested a better way to aggregate the data would have been at the “agro-ecological zone level rather than at the levels of administrative boundaries (such as district and states), but such data is not available.”
The results show that agricultural intensification, measured by relative, was associated with increased specialisation in rice and wheat production (particularly in Indo-Gangetic plains), resulting in an overall decline in crop diversity. Government policies, including input subsidies, price controls and creation of improved grain distribution networks, also contributed to this process.
T.V. Padma is a freelance science journalist.