Agrotechnology

Environmental impacts of nutrient recycling and integrated nutrient management

3^rd International Conference on Agriculture & Horticulture

October 27-29, 2014 Hyderabad International Convention Centre, India

K Jeevan Rao

Scientific Tracks Abstracts: Agrotechnol

Abstract:

Nutrients in an ecosystem recycle through soil organisms, plants, and grazing livestock. Appropriate management can enhance the nutrient cycle, increase productivity, and reduce costs. Rising levels of gases in the Earths atmosphere have the potential to cause changes in our climate. Some of these emission increases can be traced directly to organic wastes. The disposal and treatment of waste can produce emissions of several greenhouse gases (GHGs), which contribute to global climate change. The most significant GHG gas produced from waste is methane. It is released during the breakdown of organic matter in landfills. Other forms of waste disposal also produce GHGs but these are mainly in the form of carbon dioxide. The annual contribution to global methane budget from Indian rice paddies is less than 4 Tg and not 37 Tg as was propagated by the western agencies. CO2 equivalent emissions from agriculture have also been quantified. These estimates helped Indian policy makers greatly in their negotiations on global climate change. The possible strategies for mitigating methane and nitrous oxide emissions from agriculture have also been identified. Forms of N (NO3 and NH+4) which are taken up by plants can be made available for crop production through chemical fertilizers, natural and anthropogenic biological N fixation and through recycling of plant and animal wastes. These can be then converted into several other forms (NH3, NOx, N2O), which can move readily among terrestrial, aquatic and atmospheric realms. Galloway et al. labelled this diverse pool of N forms as reactive N and defined the term to include all biologically, radiatively and/or photochemically active forms of N. The fate of reactive N in agroecosystems in India assumes great importance since reactive N fixed biologically or applied as fertilizer not only leads to increased crop production, but can also leak from agroecosystems in the form of N2O, NH3 and NOx gases, depending on how efficiently plants use it. The National Agricultural Policy envisages annual growth of 4 per cent in agricultural production. Government of India has already initiated concerted action to double the agricultural production by 2010-11, which means increasing production from agricultural crops, horticultural crops, animal husbandry and fishery sectors. The country will need 301 million tonnes of food grains by 2025 to feed its 1.4 billion population. This will raise demand for supply of nutrients through chemical fertilizers to the extent of 35 million tonnes in addition to around 10 million tonnes coming from organic manures and use of bio fertilizers. It will be a gigantic task to supply such a huge quantity of nutrients through chemical fertilizers and also organic manures. Though the total potential for organic sources in the country is estimated as about 442 million tonnes with the nutrient content of 10.75 million tonnes, the present utilization is only about 1/3 indicating meager supplies of nutrients through this source. Since either of the sources cannot be totally depended upon to produce the targeted level of food, and as fertilizers are becoming costly and availability of organic manures is becoming difficult due to mechanization and decline in domestic animal populations, it is becoming imperative to find out options to blend both these inorganic and organic sources for crop production purposes. Integrated Plant Nutrient Supply System (IPNSS) or Integrated Nutrient Management (INM): Crops remove nutrients from soil. However, the soil is not an eternal supplier of nutrients required for crops growing on it. There is always a need to supplement the nutrient supply to crops through external sources like fertilizers and manures. Continuous use of inorganic fertilizers might harm the soil though the nutrients are supplied in adequate amounts. Though several types of organic manures are available, they are not having considerable amounts of N, P and K in their composition to facilitate their application alone to meet the crop needs. Application of organic manures has long term beneficial effects leading to improvement in soil conditions and making them favorable for sustainable agriculture. Excess usage of fertilizers also leads to loss of energy spent on their manufacture besides leading to increase chemical loads in soil and water. Integrated plant nutrient management is the combined application of chemical fertilizers along with organic manures, green manures, bio fertilizers and other organic recyclable materials for crop production. The INM encourages the use of in house organic wastes, which also helps in keeping environment clean and safe. The INM or IPNSS as a concept is much more complex and does not end at combined use of chemical fertilizers, organic manures and bio fertilizers and when fully put into practice, holds key for sustainable agricultural production.