Organic farming system aims at cultivating and raising crops, which at the same time keeps the soil fertile and in good health. Use of organic wastes i.e., crop residue, animal and farm waste, aquatic waste and other biological material along with beneficial microbes i.e., biofertilizer to release nutrients to crops for increasing production in an eco-friendly, pollution free environment.
Azolla is one of the potential components available for nutrient management in organic agriculture. Azolla, a small free floating water fern belonging to the family Azollaceae, is available naturally on moist soils, water surface of flooded rice fields, small ponds and canals. Its size is about 1.5-3.0 cm in length and 1.0-2.0 cm in breadth. The locally found Azolla is Azolla pinnata, while some better species like A. caroliniana can be obtained from research institutes. Azolla supplements nitrogen to rice crop by fixing atmospheric nitrogen in the soil for crop growth, crop production and thereby maintaining of soil fertility. Azolla can be incorporated in paddy field as it fixes atmospheric nitrogen which increases rice yield by 20-30 %, reduces evaporation from water surface and increases water use efficiency in rice. In lowland field, small beds of the size 3x2x1 m is made in the field and only 10-15 cm standing water is allowed in the ponds. Fresh Azolla of about 400gm is mixed and spread in the beds for further growth and multiplication of Azolla. Azolla multiplies rapidly and form a thick mat in just 2 weeks. This Azolla is harvested and released in the transplanted rice field for further multiplication, as dual cropping with rice for fixing nitrogen to rice crop. A thick Azolla mat does not allow the aquatic weeds to grow in rice field thus, azolla suppresses the weed growth and creates a congenial condition for rice production.
Besides fixing atmospheric nitrogen, Azolla can also be used as a feed for pig, duck and fish. It has high protein content and on dry weight basis, Azolla can be mixed up to 10 % of the purchased animal feed. Also, Azolla can also be used as compost at it contents N-2.73 %, P- 0.67% and K- 2.93 %.
T Esther Longkumer
ACTO-Soil Science
KVK Phek, ICAR-NRCM
