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Providing evidence to improve practice

Action: Amend the soil with crops grown as green manures Soil Fertility

Key messages

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Two controlled, randomized, replicated studies from India and Pakistan found higher soil organic carbon, or increased grain yields when green manures were grown.



Supporting evidence from individual studies


A controlled, randomized, replicated experiment in 2000-2002 on clay loam in India (Ramesh & Chandrasekaran 2004) found 10.6% higher soil organic carbon when sesbania Sesbania rostrata was included in cropping, compared to continuous rice Oryza sativa. There were five combinations of rice and sesbania consisting of: fallow-rice-rice, sesbania-rice-rice, sesbania-rice-sesbania-rice, sesbania-rice-rice-sesbania, and sesbania-rice-sesbania-rice-sesbania. Each combination was divided into four manure treatments: control (none applied), farm yard manure (12.5 t/ha), poultry manure (5 t/ha), and dual cropping with fern Azolla hybrid. There were three replication of each crop combination. Plot size was not specified. Soils were sampled after each rice harvest (depth not specified).



A controlled, randomized, replicated experiment in 2007-2008 on clay loam in Pakistan (Ali et al. 2012) found the highest rice yield after a sesbania Sesbania rostrata green manure (3.73 t/ha), then mungbean Vigna radiata (3.57 t/ha) and berseem Trifolium alexandrinum (3.53 t/ha) green manures, compared to the rice Oryza sativa-wheat Triticum aestivum only rotation (2.59 t/ha). Wheat yield was also higher under sesbania (2.81 t/ha), mungbean (2.69 t/ha) and cowpeas Vigna unguiulata (2.63 t/ha) compared to rice-wheat only (2.59 t/ha). Soil organic carbon increased from 0.67% to 0.72% (of total soil collected) during the experiment. Four green manures were grown and harvested prior to the planting of a rice-wheat rotation, which included: mungbean, cowpeas, sunflower Helianthus annuus, sesbania. Three more green manures were sown after harvesting the rice crop including: berseem, lentil Lens culinaris, canola Brassica napus. These were compared to a rice-wheat crop only rotation. All green manures were incorporated into the soil before rice or wheat was transplanted or sown. Plots were 10 x 14 m. There were three replicates. Soils were sampled before sowing and after harvest of the rice-wheat crops to 20 cm depth.


Referenced papers

Please cite as:

Key, G., Whitfield, M., Dicks, L.V., Sutherland, W.J. & Bardgett, R.D. (2019) Enhancing Soil Fertility. Pages 627-648 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.