A field experiment was conducted at the Department of Agronomy, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai, Tamil Nadu during 2014-2015 rabi season under rainfed situation to find out the effect of charred rice husk and other organic materials enriched with or without fertilizer nutrient on the moisture retention and nutrient supply during the deficit period of crop growth. The field experiment was conducted with ten treatments, replicated thrice laid out in randomized block design. Groundnut variety, VRI 2, a Spanish bunch type was selected for the study and raised under sandy clay loam textured soil. The treatment includes application of charred rice husk, biochar, lignite and farm yard manure alone and enriched with the recommended dose of nitrogen (10 kg ha-1) and phosphorus (10 kg ha-1) fertilizer and compared with the absolute control and recommended dose of fertilizer (10:10:45 kg NPK ha-1). The structural morphology of organic materials were studied using Scanning Electron Microscope (SEM) showed that the particles of charred rice husk were uneven and the diameter varied from 3-4 μm with clod and block appearance. The particles of biochar were irregular in shape, uneven sized and diameter varied from 2-3 μm with block appearance and the lignite particles found spherical and aggregated. The chemical composition of intercalated manure with nutrient examined under SEM-EDAX revealed that the charred rice husk contains 64.31 per cent carbon 28.42 per cent oxygen and 5.96 per cent silica. Whereas the biochar composed of Carbon 66.65 per cent, nitrogen 6.58 per cent, oxygen 24.55 per cent and silica 0.26 per cent and lignite comprised of carbon (63.64 per cent), nitrogen (2.56 per cent), oxygen (24.96 per cent) and silica (1.25 per cent). The different organic manures at the rate of 5 tons/ ha-1 was mixed with the calculated quantities of urea and single super phosphate and incubated for 45 days. The nutrient loaded organic manures were incorporated into the dry soil during land preparation. Total amount of rainfall received during the entire crop growth period was 179 mm in 2014-2015. Data on crop growth characteristics revealed that, among various treatments; enriched farm yard manure recorded higher values when compared to other treatments. Application of enriched biochar and charred rice husk closely followed the best treatment with respect to biometric parameters at all stages of crop growth. Incorporation of enriched FYM at 5 t ha-1 recorded significantly higher pod yield (2190 kg ha-1). The enriched biochar and charred rice husk produced comparable pod yield of 2010 kg ha-1 and 1983 kg ha-1, respectively.

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