Cardamom, mandarin and nitrogen-fixing trees in agroforestry systems in India's Himalayan region. II. Soil nutrient dynamics

✍ Scribed by R. Sharma; E. Sharma; A. N. Purohit

• Book ID: 104621028
• Publisher: Springer
• Year: 1996
• Tongue: English
• Weight: 868 KB
• Volume: 35
• Category: Article
• ISSN: 0167-4366
• DOI: 10.1007/bf00044457

✦ Synopsis

A study on seasonal soil nutrient dynamics was made in large cardamom (Amonum subulatum) and mandarin (Citrus reticulata) agroforestry systems in the Sikkim Himalaya, India. Alnus nepalensis was the N2-fixing associate in the large cardamom system, and Albizia stipulata in the mandarin agroforestry system. Sites without N2-fixing species in both agroforestry types comprised native non-symbiotic mixed tree species. Soil was acidic in the cardamom agroforestry and slightly acidic to neutral in the mandarin agroforestry system. Total-N in soils was the highest in the forest-cardamom stand and the lowest in the mandarin-based agroforestry systems. Soil ammonium-N and nitrate-N concentrations were highly seasonal, and the ratio of seasonal maximum and minimum varied up to six times. The C/N ratio was higher in cardamom agroforestry indicating lower N availability than in the mandarin agroforestry. Cardamom stand with Alnus showed a relatively narrower C/N ratio. N2-fixing species help in maintenance of soil organic matter levels with higher N-mineralization rate as land use change from naturalforest system to agroforestry systems with sparse tree populations. Ratios of inorganic-P/total-P were lower in cardamom agroforestry than the mandarin agroforestry. Seasonal fluctuation in Ca-PO4, AI-PO4 and Fe-PO4 contents regulated the availability of phosphates to some extent for plant uptake.