Sesbania spp also known as dhaincha is a quick-growing succulent green manure crop that can be incorporated at bout 8-10 weeks after sowing. This crop adopts a varying condition of soil and climate.it can be grown even under the adverse condition of drought, water logging, salinity, etc. It could be grown as animal feed and fodder, ground cover, providing wood, firewood and other uses in traditional agroforestry system most common species used in Nepal are Sesbania cannabine (former name accurate) and Sesbania rostrata.
Sesbania rostrata can fix nitrogen even in a waterlogged condition because it bear stem nodule above the soil surface. This species can fix 267 kg atmospheric nitrogen which is utilized by 1/3 rd by the following rice crop and rest by the following crop in another year.rostrata is unique as it has a nitrogen-fixing nodule on the root, stem and branches of the plant and process 5-10 times more nodule than most legume, it grows well in moist soil type and can be grown at an altitude of up to 3000-4000 feet.
Advantages of dhaincha as a green manure
- The green manure is not only to incorporate the nitrogen but also to improve the soil health by improving the physical and chemical properties of the soil.
- It also helps to maintain the organic matter of the soil.
- Green manuring improves the aeration in rice soil by stimulating the activities of the surface layer of algae and bacteria.
- Green manure crop absorb nutrient from the deeper soil layer and leave them on the soil surface layer when incorporated for use of rice
- Depending upon the humus formed green manuring increases the water holding capacity of light soils
- Every year we should import urea or other n containing fertilizers from the countries and big amount of foreign currency has to be paid to purchasing the fertilizer.by the use of dhaincha total amount of urea n can be cut down at least by 50% to the rice crop, and hence can save money
- It can be easily grown in our condition in terai inner terai, river valleys and basins, foot hill and middle mountains of Nepal, its seeds are available in NARC research station, DADO offices, and DOA agriculture centre.
- Nutrient derived from dhaincha are very cheap as compared to those of chemical fertilizers, soil physical and biological properties are increased, soil organic matter is added in larger quantities and it gives long term residual effect to the following crops
- Enhancement of organic farming, the high price of organic products in Nepal and abroad.no risk to human health hazards.it is environmentally friendly
- Research evidence shows that 21-25% yield increment observed in rice by the application of dhaincha reports also prove that 50 kg of dhaincha n is added after a single crop of dhaincha in a ha of land
- It can also be grown as an intercrop or relayed with cereals
Why dhaincha in rice?
Organic matter and nitrogen produced by dhaincha help the soil and subsequent rice growth. Under some circumstances growing green manuring is a cheaper and renewable source of nitrogen especially when inadequate infrastructure and transport means are available. A green manure yield of 15-20 t/ha equivalent to 150-180 kg n/ha is obtained within 8-10 weeks. Whereas from Sesbania acculeata green matter yield is 10-20 tons/ha quantity of nitrogen fix is 70-80 kg/ha.
The traditional, as well as modern tall varities of paddy, may not need chemical fertilizer if grown after dhaincha. In Nepal, the use of dhaincha, in general, has produced 20-25% higher rice yield and the use of rostrata resulted in 87% more rice yield over the control. An experimental result from Pakhribas Agriculture Centre showed that dhaincha relayed at first and second hoeing of maize and green manured increased rice grain and straw yields significantly compared to control (no green manuring).reports also showed that green manuring of dhaincha significantly increased available phosphorous levels in the soil.
Methods of dhaincha farming
Climate and temperature: Can be grown in all season when sufficient moisture is available grow best at a temperature above 25-degree celsius.
Land preparation: After harvest of previous season crop one tillage of the field should be done.
Seed treatment: To get uniform germination and vigorous seedling seed have to be scarified with concentrated sulphuric acid for 15 seconds and then wash thoroughly with fresh water and sown immediately
Seed rate: Generally for green manuring crops 30-40 kg /ha is needed
Methods of sowing: Seed can be sown by broadcasting
Sowing time: 45-60 days before planting rice
Irrigation: Once in 15-20 days
Harvesting /incorporation into the soil: After about 45-60 days and before it becomes woody incorporate it into the soil using a hydro tiller or with a tractor-drawn rotary tiller.