Managing paddy straw in Cauvery delta

Paddy straw is the staple food for cattle in Cauvery Delta, as rice is for humans. Consequent to the labour scarcity and escalating wages, farmers have started harvesting paddy with combined harvesters.

Cauvery Delta farmers heavily depend on harvesting machines resulting in spill over of chopped paddy straw in the field.

Large-scale use of combined harvesters led to the situation wherein disposal of paddy straw became an issue resulting in burning of paddy straw in a few pockets. On an average, about 4 to 6 tons of paddy straw/ha is obtained per crop.

Combined harvestor

During khariff season, rice crop is harvested by combine harvester using the chain type of harvester because of the excess soil moisture.

The left over paddy straw is incorporated into the soil by puddling owing to the availability of canal water/ North East monsoon after the harvesting during rabi season.

During summer, burning of paddy straw by a few farmers causes human health problems, emission of green house gases especially carbon dioxide, loss of plant nutrients due to ammonia and potassium volatilisation, loss of beneficial microorganisms in the soil surface and adverse impact on soil properties in addition to wastage of valuable crop residue.

Advantages

Instead, the paddy straw if mulched back into the fields has the following advantages:

Weed growth is arrested, straw acts as a soil mulch leading to conservation of soil moisture and one third of potash requirement can be saved for the succeeding rice crop.

Another option to solve this problem is, modifying the combine harvester to collect and remove the paddy straw from field by proper adjustment in the harvester which needs to be designed and tested under field conditions by agricultural engineers.

(R. Rajendran is Director in charge, Tamil Nadu Rice Research Institute (TRRI), and R. Natesan is Prof, Tamil Nadu Agricultural University (TNAU), Aduthurai 612 101, Tamil Nadu, Phone : 0435- 2472098, email: dirtrri@tnau.ac.in)