In the last decades, environmental pollution, chemical treatment and upgrading food using additive substances has created a new dimension to the problem of rational nutrition, with direct implications on human health. It has become vital and necessary to explore seaweed and promote its practices in agriculture. Use of seaweed extract is one of the safest way to conserve environmental resources, avoid pollution and obtain food and agriculture crops. Seaweeds are organic and biodegradable in nature. Seaweed extracts have the potential to substitute the chemical fertilizer and to improve the health and growth of plants. This book describes the fertilizer potential of seaweed saps on growth and quality of sugarcane, rice, soybean and green gram. Application of seaweed extract, Kappaphycus alvarezii and Gracilaria spp. along with recommended dose of fertilizer improves growth and quality of sugarcane, rice, soybean and green gram. It acts as a source of nutrients and thereby increasedthe nutrient content of crops. Foliar spray of seaweed saps can improve yield and quality of sugar cane, rice, soybean and green gram.