Enhancing growth and biomass production of plantation and associated vegetation through rainwater harvesting in degraded hills in southern Rajasthan,India

Natural resource conservation and rehabilitation are the best options to control land degradation and enhance biomass for fodder and fuelwood. Rainwater harvesting structures viz. Contour trench (CT), gradonie (G), box trench (BT) and V-ditch (VD) with a control were prepared in <10%, 10–20% and >20% slopes and Acacia catechu L. seedlings were planted in August 2005 to enhance soil water, nutrient and biomass and to rehabilitate degraded hill. Soil pH, SOC and NH₄-N decreased while EC, NO₃-N and PO₄-P increased in June 2009. Soil water, nutrients, plant growth and biomass were highest (P < 0.05) in <10% and lowest in 10–20% slopes. Soil waters were 13 and 52% greater in >20 and <10% than in soil at 10–20% slope. The soil waters were 18, 16, 24 and 14% greater in CT, G, BT and VD treatments, respectively over control, which enhanced plant height and collar diameter in December 2009 over 2005. The highest growth and biomass were in CT and VD plots, respectively. Herbage biomass was highest (P < 0.05) in <10% slope in 2005, 10–20% slope in 2006/2008 and >20% slope in 2007/2009. Harvesting of rainwater increased herbage biomass by 24–71%, and was highest in VD plots. Conclusively, rainwater harvesting enhanced soil water, nutrients, vegetation covers and plant growth and biomass during restoration of degraded hills. Gradonie and CT/BT facilitated herbage and plant growth, respectively, whereas V-ditch was effective for both.