Promoting green manure : its benefits and productivity

Last Updated12/05/2022

Punjab agriculture department is promoting the cultivation of green manure and providing subsidies.

Green manures are crops grown specifically for maintaining soil fertility and structure.
They are normally incorporated back into the soil, either directly, or after removal and composting.
There are three main varieties of green manure, including Dhaincha, Cowpea, and Sunhemp.
Some crops such as summer moong, mash pulses, and guar act as green manure.
Green manure varieties are incorporated into the soil when the crop is 42-56 days old.
Pulses crops are incorporated into the soil after plucking beans after 60 days.
Green manure must be leguminous in nature and bear maximum nodules on its roots to fix a large amount of atmospheric nitrogen in the soil.
Seeds of green manure should be easily available to the farmers at a low price.

Punjab’s per hectare fertilizer consumption is one of the highest in the country and is also higher than the national average.
Growing green manure can curtail this consumption to a large extent by 25 to 30% and can save huge input costs for the farmers.
In Punjab high-intensity agricultural practices are prevalent as farmers take two-three crops in a year, which requires lots of chemical fertilizers such as urea, diammonium phosphate (DAP), etc.
This leads to deficiencies of micronutrients like iron and zinc, especially in the soils where rice is cultivated thus affecting productivity.
In such a situation, green manuring helps improve soil health and enhance the productivity of the crops.
PH level of the soil in several parts of the state is more than 8.5 and 9 percent and green manure is beneficial to maintain it at the required level which is 7 percent.

They improve soil nutrients and protect against soil erosion.
Green manures provide forage for pollinating insects.
Root systems of many green manure crops efficiently penetrate compact soils thus increasing the aeration of the soil.
Deep rooting properties of many green manure crops make them efficient at suppressing weeds
They fix nitrogen in the soil, thus fewer chemical fertilizers are required.
Provide habitat for predatory beneficial insects, they kill and eat the pests / harmful insects thus fewer pesticides are required.

Leguminous plants require a good amount of irrigation, hence unsuitable for arid farmers.
Time factor: Farmer cannot plant the primary marketable crop during the green manuring phase.
If not properly decomposed, the green crop may hamper the germination and growth of subsequent crops by immobilization of plant nutrients.
Decomposition is not proper in the absence of good rainfall.
An increase of diseases, insects, and nematodes is possible if the green manure crop is not properly decomposed before sowing the next crop.

Green manuring is an important source of nutrients for sustaining crop yields, especially under organic farming practice.
Though it is old and established technologies many farmers are not aware of the benefits of these technologies.
Extension workers should train more farmers about the proper use of biofertilizers for maximum benefits.
The timely availability of quality biofertilizers and green manure crop seeds can help in meeting the demands of organic producers, especially in distant areas.

Prelims take away