Green Manuring - A Comprehensive Guide PDF

Green manuring Green manuring: It is the process of ploughing or turning in to soil, undecomposed gree n plant tissues for the purpose of improving physical structure as well as fertility of the soil. Type of green manuring... Green manuring in situ...

Green manuring Green manuring: It is the process of ploughing or turning in to soil, undecomposed gree n plant tissues for the purpose of improving physical structure as well as fertility of the soil. Type of green manuring... Green manuring in situ In the system , green manure crops are grown and buried in the same field, which is to be green manured. Ex.The most common green manuring crops are... Sun hemp(Crotalaria juncea) Dhaincha (Sesbania aculeata), Guar (Cyamppsns tetragonoloba) etc. Green leaf manuring This system refers to turning in to the soil, green leaves and tender green twigs collected from shrub and trees grown on bunds, wastelands and near by forest areas. Advantages of green manuring: It adds organic matter to soil...This stimulates the activity of soil micro-organisms. On decomposition it adds nutrients to soil. It improve the structure of soil. It increase water holding capacity and decreases run off. It holds nutrients, that would otherwise have been lost by leaching Limitations: Under rainfed conditions, proper decomposition of green mannuring crops may not take place. Inconvient sowing / planting of next crops. An increase in disease, insects etc may be there. A risk involved in obtaining satisfactory stand of green manure crop. Plants suitable for green manuring: It should be preferably legume with good nodular gro wth habit indicative of rapid N fixation. It should have little water requirement It should have a deep root system to tap the nutrient from sub- soil. Plant should have profuse foliage growth It should contain large quantities of non fibrous tissue  Photoperiod ins  ensitivity High N sink in undergr ound plant part Dhaincha green manuring  Facts on green manuring…  First res. on GM:1882 at Kanpur& Nagpur,1890 in coffea estate S. India  Area under GM: 22.5 lakh ha in India & 1.3 lakh ha in Orissa  GM plants are real nutrients integrators  About 80% of total plant N in 52d old dhaincha is from biol. N-fixation.  N is a net gain through N fixation, but P & K are not  88% of total N is in above ground portion  50-60% of GM-N is “Fast-N” and rest is “Slow-N”  65% of GM-N is mineralised during 1st crop, 14% during 2nd crop & 3.3% during each succeeding crop (Bouldin, 1988)  NH4 conc. from incorporated dhaincha steadily increases to a peak at 3-4 WAT & gradually declines to a peak about 3 wk later  Each t of dhaincha DM adds 26.2 kg N, 7.3 kg P2O5, 17.8 kg K2O, 1.9 kg S, 1.4 kg Ca, 1.6 kg Mg, 25 ppm Zn, 105 ppm Fe, 39 ppm Mn, 7 ppm Cu………..  GM can save up to 60-120 kg N /ha  Common green manure crops Crop GM (t/ha) N (%) N addition (kg/ha) Fresh Dry Sunhemp 16.5 0.43 3.01 71 Dhaincha 14.8 0.42 2.67 62 Mung 10.0 0.53 2.63 53 Guar 7.0 0.34 3.53 24 Cowpea 12.0 0.49 2.82 61 Nutrient content (%) of weeds on dry weight basis Weed N P K E.colonum (suan) 1.75 0.24 0.67 C.dactylon (duba) 1.00 0.19 0.37 C.rotundus (mutha) 2.25 0.27 0.37 D.aegypticum (kaogodia) 2.00 0.23 0.54 A.aspera (apamaranga) 2.21 0.71 1.09 A.spinosus (khada saga) 1.92 0.68 2.75 A.mexicana (agara) 1.01 0.60 1.10 C.album (bathua) 3.99 0.66 8.29 C.viscosa (ana sorosia) 1.96 0.67 2.55 C.benghalensis (kanasiri) 2.02 0.64 1.54 T.portulacastrum (puruni) 2.64 0.43 1.30 P.hysterophorus (gajar grass 2.68 0.68 1.45 ) I.carnea (amari) 2.01 0.33 0.40 C.gigantea (arakha) 2.06 0.54 0.31 C.fistula (bana chakunda) 1.60 0.24 1.20 L.camara (nagaairi) 2.50 0.25 1.40  Nutrient content (%) of aquatic w eeds on dry weight basis Weed N P K Azolla pinnata 3.08 0.20 0.15 Eichhornia crassipe 1.85 0.46 3.07 s Lemna minor 3.66 0.23 0.18 Monochoria vagina 3.44 1.90 1.62 lis Pistia stratiotes 2.17 0.82 2.38 Salvinia 1.59 0.48 2.70 Spirodela 4.06 0.78 1.96 Potential N contribution of some legumes in Indian soils Fertilizer N equivalent (kg/ha) Crop N fixing Residual effect on succe potential eding cereal crop Cowpea 53-85 60 Greengram 50-55 30 Arhar 68-200 20-49 Pea 46 20-32 Lentil 35-100 18-30 Groundnut 112-152 60 Source : Subba Rao (1988) Thank You