Effects of Azadirachta indica Canopy Manipulation and Nitrogen Fertilization on Diversity and Productivity of Herbaceous Vegetation in an Arid Environment of India

• Published in: Arid land research and management 2011-04, Vol.25 (2), p.128-149
• Main Authors: Singh, Genda, Shukla, Smita
• Format: Article
• Language: English
• Subjects: arid lands; Azadirachta indica; biomass; canopy; canopy manipulation; delimbing; Effects; Fertilizers; Flowers & plants; forage; forage production; grasses; herbs; Nitrogen; nitrogen fertilizers; PAR; Photosynthesis; photosynthetically active radiation; rangelands; soil resources; soil water; species diversity; trees; Vegetation; vegetation dynamics; woody plants
• ISSN: 1532-4990; 1532-4982; 1532-4990
• DOI: 10.1080/15324982.2011.554955

Effects of Azadirachta indica A. Juss and nitrogen fertilizer on herbaceous diversity, productivity, and soil improvement were monitored with aims to enhance productivity of desert pasturelands. Fifty four plots of 1 m² area were laid with lopping of 36-month old Azadirachta indica plants and nitrogen fertilization. Plots without plant (C₀), intact plant (C₁) and lopped plant (C₂) were canopy, whereas plots without nitrogen (N₀), 10 mg N kg⁻¹ soil (N₁₀), and 20 mg N kg⁻¹ soil (N₂₀) were nitrogen treatments. Both treatments influenced resource availability and vegetation diversity and biomass. Intact plants reduced photosynthetically active radiations (PAR) by 53–55% more PAR in C₀/C₂. A. indica plants were associated with 15 herbs/grass species belonging to 7 families. Nitrogen fertilization increased soil nitrogen, species richness, diversity, and biomass but negatively affected soil water and species evenness and dominance. Plots with intact plants showed highest soil available nitrogen, species richness, diversity, and evenness indices. However, soil water and species dominance were highest in the control plots. Herbage biomass increase was 2.0-fold more under intact plants and 1.4-fold more under lopped plants than in the control (C₀N₀). The highest species diversity and biomass in C₁N₂₀ suggest the benefit of tree association and nitrogen fertilization in enhancing rangeland productivity. Conclusively, application of nitrogen fertilizer enhances herbage productivity but retaining/introducing tree component in rangeland improves soil conditions, diversity, and herbage productivity in aridisol. Therefore, woody plants with canopy and addition of nitrogen fertilizer may be a viable option for increasing forage production in the forage-deficient dry lands.