In the Indo Gangetic plains, crops residue is mainly disposed of by burning to ensure timely and easy planting of wheat crop in the rice-wheat cycle. Besides increasing environmental pollution, the practice of burning crop residue reduces soil health by decreasing soil organic matter and major nutrients, and harming soil microflora and fauna. These, in turn, lead to multi-nutrient deficiencies.
To sustain soil health, the retention of crops residue in the field, zero-tillage and diversified crop rotation, especially using legumes, are advised by scientists.
But does the advice really work?
Recently, a team of ICAR scientists reported their long-term experiments with conservation agriculture.
They started experimenting in 2009 at the ICAR-Central Soil Salinity Research Institute, Karnal.
Farmers in the region burn crop residue and cultivate rice and wheat crops, one after another, in the same field. But the researchers tried a third crop, mung bean, in the cycle under conservation agriculture.
Every year, the researchers sowed rice and maize in June before the onset of the monsoon. After harvesting only the grains, they left the remaining biomass in the field which acts as mulch for the succeeding crop.
Wheat was sown between the last week of October and the first week of November. For sowing, the researchers used the Happy Seeder – a machine used for sowing under crop residue retention. The machine is mounted on a tractor. When the tractor runs through the field, the Happy Seeder cuts and removes rice straw, makes slits in the ground, deposits seeds and fertilisers in the slits and deposits the cut straw as mulch on top.
“This reduces evaporation from the soil and retains moisture. And weed growth is suppressed”, explains Dibakar Roy, ICAR-Directorate of Weed Research, Jabalpur.
After harvesting wheat, mungbean is sown in the same field in the first week of April, using the same technique.
“We maintained a row to row distance of 22.5 centimetres for direct seeded rice, wheat and mung bean. For maize, it was higher – 67.5 centimetres”, says Ashim Datta, ICAR-CSSRI.
“From 2016, we started using subsurface drip irrigation in half the plots of the direct seeded rice-wheat-mung bean and maize-wheat-mung bean cropping systems,” says H S Jat, ICAR- CSSRI.
In the last week of May 2019, the researchers collected and analysed soil samples from different depths.
“Soil organic carbon, nutrient availability and biochemical parameters – the prime pillars for sustainable crop production – had all improved significantly at all depths of soil tested,” says Madhu Choudhary, ICAR-CSSRI.
“The maize-wheat-mung bean cropping system was better at improving soil quality, indicating its potential to replace the conventional rice–wheat cropping system followed in North West India,” says P C Sharma, ICAR-CSSRI, Karnal.
Three crops per year while improving soil quality and reducing air pollution! Are the farmers listening?
Geoderma, 405: 115391(2022);
STEAMindiaReports: providing energy for national development
Science news free for Indian media houses