Effect of organic liquid manures on crop growth and productivity

Unscientific use of chemicals in agriculture leads to several health hazards and environmental problems. To protect our crops and the environment we have to follow sustainable and eco-friendly agriculture, which minimizes the use of harmful and energy intensive inputs and adopts use of organic manures and bio fertilizers. Among the several methods of eco friendly agriculture, liquid nutrition occupies an important position. Foliar nutrition with organic compounds in vegetables is especially important as they provide quality foods, which are very important for providing health security to people. India has vast potential of organic resources and the extract prepared from these resources can be effectively utilized to sustain yield, improve physical, chemical and biological properties of soil and to maintain soil health. Commonly used liquid manures are compost tea, vermiwash, biogas slurry and cow’s urine along with the extracts of oil cakes like groundnut cake, poultry manure and neem cake. Several studies were conducted on the nutrient content of common organic liquid manures. Biogas slurry, the common by product of biogas has a nutrient content of 0.5-1.0 % N; 0.5-0.8 % P and 0.6-1.5 % K (Dhobighat et al., 1991). The nutrient content of cow’s urine was reported to be 0.9-1.2% N, 0.2-0.5% P and 0.5-1% K (Bertram, 1999). Vermiwash contains 0.5% N, 0.39% P and 0.46% K (Jasmine, 1999). Compost tea is rich in soluble nutrients, but the tea collected during early stages of composting may contain pathogens (Diver, 2002). As per the reports of Ingham (2003), the nutrient content of compost tea is 0.5-0.75% N, 0.25-0.5% P and 0.5-0.75% K.