Green Manuring and Cultivation Practices

Green Manuring and Cultivation Practices:

Introduction to Green Manuring:- Well, composting your field or garden is one of the expensive and tedious tasks. Especially commercial growers should spend a lot of money for these garden composts. Apart from this, inorganic fertilizers became expensive. Using chemical fertilizers has a very bad effect on soil life and fertility hence there should be an alternative method of providing nutrient to the soil. This is possible only through growing green manure crops. What is green manuring? well, it is nothing but a process of turning green crops cultivated in the field into manure by incorporating back into the soil. The crops grown for this purpose are called green manure crops. Green manure crops provide organic matter which can play a major role organic farming by reducing compost cost drastically. Green manuring helps farmers to increase the soil fertility or restores the previously lost nutrients. Once can be sure that these green manure crops are environmentally friendly which can reduce the application of chemical fertilizer and herbicides as part of agricultural practices.

Ways To Grow Green Manuring Crops:- There are two ways one can grow and use green manure.

When lands are ideal or fallow between crops:

In this method, Once the main crop is harvested, the growing field becomes ideal. In this empty land, you can sow the green manure seeds thickly. Depending on green manure crop, it may be some time to get these crops to flowering stage. When they are about a flower, you can plough them back into the soil or you can the crop and leave in the field.

When there is already a crop growing in the field (mixed crop method):

This process is mostly used in maize growing areas. In this method, seeds of green manure are sown at the same time of maize crop. You can dig this green manure crop when it is time to carry the weeding operation in maize crop usually after a month if sowing. At this in point in time, you can sow the green manure seeds and it can be cut and left in the field after harvesting the maize crop. You plough the soil with these green manure to make the soil more fertile. You should be aware of certain things before growing green manure crops.

Green manure crops should be cut and left in the field or plough the crop back into the soil before seed set or at the flowering stage.

You can grow green manure crops in all seasons without any problem.

If you are growing climbing green manure crop, they may smother the main crop hence climbing stems needs to be pulled from the main growing crops.

Green Manuring Crops:-What type crops can be grown for green manure? choosing a particular green manure crop depends on the main crop it is growing with or in between. Usually, in case of tall growing crops like maize (corn), tall green manure crops like velvet bean or Sesbania should be taken into consideration. In case of short growing crops such as vegetables, you can choose to have green manure crops like mustard green manure or buckwheat green manure.

The following are some of the green manure crops used for Green Manuring

  • Sesbania.
  • Dhaincha (Sesbania aculeata and S. rostrata).
  • Sunhemp.
  • Mung bean (Green gram).
  • Berseem.
  • Madras Indigo.
  • Buckwheat.
  • Sunflower.
  • Wild Indigo.
  • Pillipesara.
  • Cowpea.
  • Cluster bean (Guar).

Green Leaf Manuring:- Green leaf manuring is the process of collecting green leaves and incorporating into existing crop fields. It is nothing but gathering green biomass from nearby sites and adding to the soil. In this method, we don’t grow green manure crops rather we collect green leaves of other areas and supplement in the soil.

The following trees and shrubs are used as green leaf manures in preparation of Green Manuring

Purpose or Objective of Green Manuring:- The main purpose of green manuring is to fix the nitrogen ‘N’  in the soil so that main crops can take advantage of this. Green manuring also helps in adding organic matter in the soil thus improving the fertility. Organic farming or Organic agriculture is the main segment of growing crops can be benefited very well with green manures.

  • Neem.
  • Thespesia populnea.
  • Glyricidia.
  • Cassia tora.
  • Vitex negundu.
  • Cassia auriculata.
  • Derris indica.
  • Ipomoea cornea.
  • Jatropha.
  • Tephrosia candida.

Note: For growing green manure crops, you should be aware of cultivation practices of the same.

Other related objectives of green manuring: Apart from the main objective of green manure, the following also indirectly support green manuring concept.

  • Catch Crops: Legume crop are inter-sown in standing crops before or after harvest to utilize nitrates.
  • Shade crops: These crops are sown in young orchards with the objective of shading the soil surface to prevent high soil temperature. In tea and coffee plantation, Glyricidia is used as shade crop first and then incorporated as green manure in the soil.
  • Cover crops: To avoid soil erosion and runoff especially during the rainy season in hilly slopes, green manure crops are grown as a vegetative cover.
  • Forage crops: Legume crops are grown for livestock feed purpose and cut early stages and later as green manure. Pillipesara seeds should be broadcasted in the standing rice crop just 4 to 5 days before harvest.

Selection Criteria for Crops in Green Manuring:- Well, you must choose best green manure crops for improving soil nutrients. The following should be taken into consideration.

  • Make sure green manure crop plants are fleshy and soft.
  • They should have fast growing in nature in short duration.
  • They should have high nutrient accumulation ability.
  • These green manure crops should be tolerant to shade, flood, drought and adverse temperatures.
  • They should have the ability to decompose at very fast pace with ease.
  • They should have quick soil cover for soil protection and suppressing weeds.
  • They should have high biomass production.
  • They should have increased nitrogen availability.
  • It is better to have Leguminous manure crops.
  • Green manure crops should not attract any pests and diseases.
  • The selected green manure crops should not compete with the main crop especially in terms of water and fertilizers.
  • There should be easy and abundant seed formation in case legumes.
  • They should provide nutrients needed in the soil.
  • They should have high nitrogen ‘N’ accumulation rates.
  • They should have efficiency in the use of water.

Nutrient Content of Green Manuring:

The following table shows Nitrogen (N) content and accumulation of green manures. 

Green Manure NameNitrogen (%)Nitrogen Accumulation kg/haBiomass
Dhaincha2.55-3.21130 to 18526
Sithagathi2.29-3.10115 to 16020
Sunnhemp2.80-3.1580 to 13017
Manila agathi3.20-3.37175 to 22025
Wild Indigo2.90-3.2275 to 11516.8
Pillipesara2.16-2.7785 to 12517.5

 In case of Non-conventional green manuring:

Non conventional green manuresTotal Nitrogen (N %)C:N RatioTotal Phosphorus P (%)Total PotashK (%)
Trees (leaves or twigs)
Neem
Delonix elata
Delonix regia
Peltophorumferrugenum
Cassia nigricans
2.83
3.51
2.76
2.63
2.73
70:1
27:1
32:1
34:1
0.28
0.31
0.46
0.37
0.18
0.35
0.13
0.50
0.50
0.50
Weeds
Adathoda vesica
Parthenium hysterophorus
Eicchornia crassipes
T portulacastrum
Ipomoea cornea
Calotropis gigantea
Cassia pistula
1.32
2.68
3.01
2.64
2.01
2.06
1.60
60:1
30:1
29:1
32:1
43:1
64:1
120:1
0.38
0.68
0.90
0.43
0.33
0.54
0.24
0.15
1.45
0.15
1.30
0.40
0.31
1.20

(The above table source is from agritech.tnau.ac.in).

Cultivation Practices of Green Manure Crops:

DHAINCHA (Sesbania aculeata)

  • Growing Season: All seasons with adequate soil moisture.
  • Suitable Soil: All types of soils.
  • Seed rate: 45 to 50 kg/ha for green manure and 18 to 20 kg/ha for seed purpose.
  • Seed treatment: Seeds should be mixed with specific rhizobium strain @ 5 pkts /ha.
  • Spacing: Broadcasted and Recommended spacing is 45 cm x 20 cm for seed purpose.
  • Irrigation: It should be given once in 21 to 30 days.
  • Harvest: You can incorporate the green matter after 45 to 55 days of sowing and 100 days after sowing for seed harvest.
  • Yield: In case of green biomass, one can obtain 25 tonnes/ha whereas seed yield could be 500 to 550 kg/ha.

Green Manuring Crops – Sithagathi (Sesbania speciosa)

  • Growing Season: All Seasons.
  • Suitable Soil: All types of soils.
  • Seed rate:35 to 40 kg/ha for green manure and  14 to15 kg/ha for seed purpose.
  • Seed treatment: Seeds should be mixed with specific rhizobium strain @ 5 pkts /ha.
  • Spacing: Usually broadcasted.Recommended spacing is 45 cm x 20 cm for seed purpose.
  • Irrigation: It should be given once in 2 to 3 weeks.
  • Harvest: You can incorporate the green matter after 50 to 60 days after sowing and  125 days after sowing for seed.
  • YieldIn case of green biomass -16 to 17 tonnes/ha,  and in case of seed, expect 500 to 600 kg/ha.

Green Manuring Crops – Sunnhemp (Crotalaria juncea)

  • Growing Season: All seasons with adequate soil moisture and it is quick growing fiber green manure crops.
  • Suitable Soil: Loamy soils are suitable and do not withstand waterlogged conditions.
  • Seed rate: 30 to 35 kg/ha for green manure and 19 to 20 kg/ha for seed production.
  • Seed treatment: Seeds should be mixed with specific rhizobium strain @ 5 pkts /ha.
  • Spacing: Broadcasted and Recommended spacing is 45 cm x 20 cm for seed purpose.
  • Irrigation: It should be given once 4 weeks.
  • Harvest: You can incorporate the green matter after 50 to 60 days of sowing and 145 to 150 days after sowing for seed harvest.
  • Yield: In case of green biomass, one can obtain 14 to 15 tonnes/ha whereas seed yield could be 350 to 400 kg/ha.

Green Manuring Crops – Manila Agathi (Sesbania rostrata)

  • Growing Season: All Seasons. Sowing in Feb to May yields more biomass and best seed production, sow in March to May.
  • Suitable Soil: Black and red soils and avoid alkaline soils.
  • Seed rate: 35 to 40 kg/ha for green manure and 7 to 8 kg/ha for seed purpose.
  • Seed treatment: Seeds should be mixed with specific rhizobium strain @ 5 pkts /ha.
  • Spacing: Broadcasted and Recommended spacing is about 45 cm x 20 cm for seed purpose.
  • Irrigation: It should be given once in 2 to 3 weeks depending on climate.
  • Harvest: You can incorporate the green matter after 45 to 50 days of sowing and 95 to 100 days after sowing for seed harvest.
  • Yield: In case of green biomass, one can obtain 20 tonnes/ha whereas seed yield could be 500 to 600 kg/ha.

Green Manuring Crops – Pillipesara (Phaseolus trilobus)

  • Growing Season: Good for green manure and fodder for livestock and works as a cover crop with creeping nature. This crop can be grown in all seasons with adequate soil moisture.
  • Suitable Soil: Rice fallow clay soils.
  • Seed rate: 12 to 15 kg/ha for green manure and 10 kg/ha for seed purpose.
  • Spacing: Broadcasted for green manure and Recommended spacing is 30 cm x 10 cm for seed purpose.
  • Irrigation: It should be given once in 3 to 4 weeks depending on soil moisture/climate.
  • Harvest: You can incorporate the green matter after 55 to 60 days of sowing and 150 days after sowing for seed harvest.
  • Yield: In case of green biomass, one can obtain 5 to 6 tonnes/ha whereas seed yield could be 450 to 500 kg/ha.

Green Manuring Crops – Wild Indogo(Tephrosia purpurea)

  • Growing Season: This is hardy and drought resistant crop grows very slowly and not used for cattle grazing. It can be grown in all seasons.
  • Suitable Soil: It can be grown in a wide variety of soils. However, sandy soils are best.
  • Seed rate: 15 to 20 kg/ha for green manure and 10 to 12 kg/ha for seed purpose.
  • Seed treatment: Seeds should be soaked in concentrated sulphuric acid (100 ml /kg seed) for half hour. Thereafter wash the seeds in water 15 minutes and make them shade dry.
  • Spacing: Broadcasted and Recommended spacing is 30 cm x 10 cm for seed production.
  • Irrigation: It should be given once in a month.
  • Harvest: You can incorporate the green matter after 2 months after sowing and 5 months after sowing for seed collection.
  • Yield: In case of green biomass, one can obtain 8 to 10 tonnes/ha whereas seed yield could be 450 to 500 kg/ha.

Read about Green Fodder.

Read about Custard Apple Cultivation.

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