Go in for green manure to improve soil health: PAU

Manav Mander

Ludhiana, March 29

The state Agriculture Department is promoting the cultivation of green manure these days. Using green manure has come as a solution for improving soil health which is depleting due to adoption of intensive rice-wheat cropping system along with cultivation of high yielding varieties.

Increases nitrogent content

• Green manure increases nitrogen content of soil and improves the availability of other nutrients
• The nitrogen requirement of the next crop is decreased after incorporation of green manure. When sesbania is incorporated in soil before rice, it requires only 55 kg urea per acre
• Green biomass addition increases the water retention capacity of soil
• Green manuring improves the physical, chemical and biological properties of soil by increasing the soil’s organic matter content

Approximately 40 per cent cultivated area of Punjab has brackish underground irrigation water and this poor quality water has a bad effect on soil productivity as well as on soil fertility. A poor soil is deprived of the availability of essential plant nutrients causing deficiency of nutrients like iron (Fe), zinc (Zn) and manganese (Mn). For getting sustainable high crop yields, soil fertility status must be maintained.

Punjab Agricultural University’s research shows that inclusion of green manuring in crop rotation improves soil health, increase crop yields and reduces the harmful effects of brackish underground irrigation water.

“To sustain soil health, incorporation of crop residues along with inclusion of green manures in crop rotation is of utmost importance. Among organic manures, the importance of green manure is manifold. The green manure crops increase the nitrogen (N) content of the soil through symbiotic association with rhizobium bacteria in their root nodules,” said Pritpal Singh from PAU’s Farm Advisory Service Centre, Bathinda.

The important green manure crops are sesbania, sunhemp, clusterbean, cowpea and moongbean. These crops can be ploughed (generally before flowering) for the better soil health or for maximum benefits, added Gagandeep Dhawan and Harinder Singh from PAU’s Krishi Vigyan Kendra, Kapurthala.

Among different green manure crops, sunhemp is best suited green manure crop as it requires less water to produce biomass in large quantities and has little attack of insect-pests. Sesbania and sunhemp are not much sensitive to poor quality water and soil salinity, added Navneet Kaur from the same centre.

Using green manure in different cropping cycles increases nutrient storage in the soil and nitrogen availability after incorporation. When there is no crop sown for several months of the year (after the harvesting of wheat and before sowing of paddy), the use of green manure increases soil fertility and preserves nutrients in the upper layer of the soil, said Mandeep Singh from PAU’s Krishi Vigyan Kendra, Kapurthala.

PAU has recommended the cultivation of sesbania, sunhemp, cowpea and cluster bean as green manure crops, before rice cultivation. However, sesbania and sunhemp are best green manure crops as they have can produce highest green biomass in a short duration period and can easily be decomposed in soil. These two crops are not sensitive to excess concentration of soluble salts (soil salinity), and require less water, said Angrej Singh from PAU’s Farm Advisory Centre.