NOVELTY - Soilless cultivation method for improving organic selenium content of tomato involves (a) mixing crushed crop straw, animal urine, industrial and agricultural byproduct and selenium dioxide, fermenting mixture, and mixing the fermented mixture and sand to obtain soilless cultivation matrix, (b) selecting robust tomato seedlings, soaking roots of the seedlings in potassium permanganate, washing seedlings using water and drying seedlings, (c) compacting the matrix and planting the seedlings in greenhouse conditions, and (d) managing plant growth and harvesting ripe fruits.    USE - Soilless cultivation method for improving organic selenium content of tomato (claimed).    ADVANTAGE - The soilless cultivation method enables to produce tomatoes with high organic selenium content, at high yield, and hence improves nutritional and healthcare value of tomatoes. The method reduces the use of fertilizer and pesticides, suitable for large-scale production, and is cost-effective and environmentally-friendly.    DETAILED DESCRIPTION - Soilless cultivation method for improving organic selenium content of tomato involves (a) mixing 250-400 parts crushed crop straw (0.5-2 cm), 100-200 parts animal urine, 100-500 parts industrial and agricultural byproduct and 0.1-0.5 parts selenium dioxide, fermenting mixture at 28-35 degrees C for 14-21 days, where the mixture is stirred once every 12 hours of fermentation, and the mixture turns red after fermentation, and mixing the fermented mixture and 400-1000 parts sand uniformly to obtain soilless cultivation matrix containing nano selenium, (b) selecting robust tomato seedlings with 6-10 cm height, soaking roots of the seedlings in 0.3-0.6% potassium permanganate for 2-6 minutes, washing seedlings using water and drying seedlings, (c) compacting the soilless cultivation matrix to 15-18 cm thickness and planting the seedlings in the matrix in greenhouse conditions, and (d) managing plant growth by pruning and preventing diseases, and harvesting ripe fruits with high organic selenium content.