Evidence of declining productivity in cereals in India: A source for concern
The reduced response of food grain production to fertilizer application is now widely observed in many parts of India. To address this issue, a two-day brain storming session on "Low and Declining Response of Crops to Fertilizers" was organized by the National Academy of Agricultural Sciences (NAAS), India and held in New Delhi, India (20-21st February, 2006).
This concise policy paper first describes the background of reduced foodgrain production and outlines the main causes for "Low and Declining Crop Response to Fertilizers". Among these, inadequate P and K application which leads to soil mining is placed high on the list. At the section that describes the required agenda for research, nutrient budgeting and precise site specific fertilizer recommendations and application are highly graded. The role of extension is highlighted with an array of action items that needs to be implemented. Finally, various policy actions are recommended.
It is interesting to note that this policy paper also emphasizes the need to increase productivity through balanced fertilization of macro and micro nutrients in order to achieve higher nutrient use efficiency, especially that of N. Yet, negative K balance is widespread in many countries. Ladha et al., (2003) reported that as many as 94% of the long term experiments in Asia were showing negative balance for potassium, 50% with a deficit of more than 100 kg K2O/ha pa. Moreover, all the long term experiments that demonstrated yield decline had large negative K balance.
Balanced fertilization, coupled with precise fertilizer recommendations based on soil and plant analysis, has great potential to restore productivity and decrease inputs and the risk to the environment.
References NAAS. 2006. Low and Declining Crop Response to Fertilizers. Policy Paper No. 35, National Academy of Agricultural Sciences, New Delhi. pp 8.
Ladha, J.K., Hill, J.E and J.M. Duxbury (eds.). 2003. Improving the Productivity and Sustainability of Rice-Wheat Systems: Issues and Impacts. ASA, IRRI, CIMMYT. ASA special publication 65 (data adapted from page 63-64).
Biofuels - and the energy cost of nutrients
The cost of producing biofuels varies greatly between the various sources. For example, production cost of fuel from sugarcane in Brazil costs only 16 U.S. cent/litre, from cassava in Thailand it costs 26 U.S. cent/litre and from maize and wheat in the US and Europe it costs 30 and 55 U.S. cent/litre, respectively. At the time of this analysis, the price of 1 litre petroleum was 59 U.S. cent, making all the sources of bioethanol cost effective in various degrees (von Brown, 2005, citing Henniges and the European Commission in 2005).
In addition to the total cost of producing bioethanol, the energy balance for growing, harvesting and processing of each biofuels crop is extremely important. In this respect, the energy cost of the fertilizers, among other inputs, has to be taken into account.
Potassium fertilizers mined from underground mines or produced in evaporation ponds have a low energy demand as compared to other macro nutrients. With continuous strong demand for biofuels and supporting policies adopted in many countries, the various aspects of effective fertilization of biofuel crops will probably be high on the agenda.
Reference von Brown, 2005. The world food situation, an overview. A paper Prepared for CGIAR Annual General Meeting, Marrakech, Morocco, December 6, 2005.
