Precision silviculture: optimization of water and nutrient scheduling for high-density tree plantation of Dalbergia sissoo

The study was conducted by applying the principles of precision silviculture to standardize optimal water and nutrient requirements. It also evaluated effects of balanced fertilization on tree physiology and analyzed distribution of nutrients in soil sub-surface using GIS technology, specifically SURFER 7 software in high density Dalbergia sissoo tree plantation. The plantation was given spacing of 3 x 2 meters in split plot design with three levels of irrigation viz., 100% pan evaporation (PE), 125% PE and 150% PE in main plots and three levels of fertigation regimes in subplots which consisted humic acid @ 62.5 l ha-1, 150:100:100 kg N, P2O5, K2O ha-1 and humic acid @ 62.5 l ha-1 + 75:50:50 kg N, P2O5, K2O ha-1. The study revealed that higher height (5.28 m), basal diameter (51.19 mm) and volume index were found in the treatment that received irrigation @ 125% PE and fertigation with the fertilizer dose of 150:100:100 kg N, P2O5, K2O ha-1 (I2F2). I2F2 Recorded improved photosynthetic rate (7.73 m mol.m-2 s-1), transpiration rate (8.83 m mol.m-2 s-1) and stomatal conductance (0.16 m mol.m-2 s-1). Maximum available nitrogen (190 kg ha-1), phosphorus (19.2 kg ha-1) and potassium (346 kg ha-1) were recorded at 30 cm lateral distance and the corresponding values were 188, 12.80, 362 kg ha-1 at 0 to 30 cm sub-surface soil at 7 months after plantation (MAP). The SURFER maps showed that the mobility of nutrient concentration in the sub-soil surface decreased as the distance from the plant increased. A significant increase in N P and K in soil was recorded in I2F2 as compared to fertigation with humic acid 62.5 l ha-1 and irrigation level @150% PE (I1F1).