Therefore, for sustainable agricultural management, practice of application of biomass in soil is imperative to augment the yield of crop. This is true and not a new thought in this line but the question naturally arises why steps were not taken as such in serious consideration by the learned researchers and agricultural scientists? Everybody in our country agrees that soil has became very much deficient in organic matter content and there is no concrete suggestion or advice as to how the content may be enriched to get a better fertility status and maximum crop yield. Unless the efficiency of our soil is enhanced, no better output of crop production and vegetables can be achieved.

This is true that the people across the world have now become very much conscious of their health and prefer to choose vegetables grown under the judicious application of organic manures along with chemical fertilisers. The farmers may be acquainted with the importance of organic manures and other farm residues as a source of plant nutrients also due to short supply and five fold increase in price of fertilisers. The organic manures can increase water holding capacity and play an important role in the activity of the microbial population and base exchange capacity in soil. No doubt, chemical fertilisers are instrumental for increasing crop yield but the production of these fertilisers cannot fulfil the demand of the users also from both supply and economic points of view.

Moreover, it should be clarified that the use of chemical fertilisers in soil undergoes various chemical reactions resulting in the state of synergistic and antagonistic relationship among and between the nutrients for their availability to the plants. The increase in nitrogen and phosphorus content in soil due to excessive use of N and P fertilisers may interfere with the uptake of other nutrients like zinc and sulphur by the plants. It is a matter of great concern to know that pesticides which are internationally identified harmful have been used indiscriminately in Bangladesh. This is very ironic to note that though most of the poisonous chemicals produced in foreign countries are restricted to use in their own countries, but are sold to developing countries to earn money and keep the producer countries safe from environmental pollution.

Over use and misuse of pesticides affect the environment to a large extent with serious implications on public health, will life, useful insects, food, prey animals, aquatic food chains and other habitats. There is definitely a need of application of insecticides in the country in order to eradicate insects which damage the crop yield. Actually the use of pesticides cannot be avoided but at the same time organic insecticides should be used and the scientists may come forward to conduct further researches on the production of bio-insecticide for use with chemical fertilisers. This will be helpful to reduce health hazard and may add substantial organic residues towards conserving the desired characters of soil.

A farmer in southern part of Bangladesh has recently prepared and applied in his soil organic insecticides instead of using chemical insecticides, could make optimum yield of rice and maintain safety of the environment especially of soil which is one of its component.

Concerned about the range of inter-connected problems, there is a need to set up an international research and development network on perception and management of pests and pesticides (PMPP). The awareness may be created among the people about the application of organic manures to compensate the loss of fertility of soil due to addition of fertilisers when their use cannot be avoided overnight. Another important organic fertilizer may be the waste from biogas plant using cow-dung mixed with other such materials.

The fermented material or in other wards, degassed manure flown out as a slurry or effluent from the gas plant might be used as manure which retains the manorial value.

It is an accepted fact that direct application of cow-dung as organic manure for better crop yield and increasing quality of soil is not so effective like the slurry obtained at the end of the production of biogas because it contains more N, P and K contents. These are the considerations to be taken into account of the sources of organic matter required to accelerate the rate of biological activity maximizing crop yield.

It should be urged that under the pressure of multinational companies and donors our present popular government should not take any decision which may not serve the interest of the country. Priority should be given first to make a correct policy for security of agriculture and organic matter and immediate promulgation of bio-diversity act maybe declared in order to ascertain our food and bio-security and if needed, help from new technology maybe sought. The problem of adulterated fertilisers now allegedly sold in the market is a serious one and threaten security of agriculture. The government should take stern measure against those responsible.

Dr. Md. Shahjahan Ali is Professor, Department of Agricultural Chemistry, Bangladesh Agricultural University.