Semi-intensive Farming Systems Research Articles

Aquaculture feeds and the environment: The asian experience

Asia, the birth place of aquaculture, supplies 85% of global aquaculture production and has had along tradition in the development and use of different dietary feeding strategies, ranging from & use of fertilizers and simple supplementary feed mixtures to the manufacture of ‘water-stable’ pelleted shrimp feeds. The present paper reviews the different aquaculture feeding strategies used within semi-intensive and intensive farming systems in selected Asian countries, and in particular examines their relative impacts upon the aquatic environment. Emphasis is placed on the environmental compatibility and central rote played by small scale polyculture-based integrated farming systems in Asian aquaculture, and the need to carefully balance exogenous supplementary feed inputs with the endogenous supply of natural food organisms within semiintensive pond farming systems. In the case of intensive pond/cage-based farming systems attention is focused on the need to further improve feed formulation, feed manufacture, and on-farm feed and water management so as to maximize feed intake and feed efficiency, and minimize feed wastage and water pollution. Furthermore, in view of the negative experiences of some countries in the region with deteriorating water quality and disease outbreaks within intensive pond/cage-based farming systems, there is an urgent need to improve farm husbandry methods and reduce the current reliance of the aquaculture sector on chemotherapeutants; including limiting the use of the antibiotics only to qualified personnel by developing appropriate Codes of Practice. In this respect there is also a need to recognize the important rote played by nutrition in disease resistance. In addition, the paper reviews the legislative controls concerning aquafeed manufacture in selected Asian countries, and highlights the implications of applying government feed legislative controls (i.e. relating to feed composition, feed manufacture, feed efficiency or water pollution) directly from one environmental setting or country to another, and urges countries to develop their own solutions depending upon the farming system employed (i.e. intensive or semi-intensive; tank, cage or pond; coldwater or warmwater; freshwater or seawater), national government policies and priorities, and the resources available to them. In conclusion the paper stresses the key role which can be played by the resident aquafeed manufacturing sector in helping farmers, not only in the provision of feed inputs, but more importantly concerning the management of the feed on the farm and in the use of appropriate environmentally sound husbandry practices; feed manufacturers usually having the closest contact with farmers and in many countries being the only fink in the chain between the farmer and the government legislature.

A decade of fertilizer research on groundnuts (Arachis hypogaea L) in the savannah zone of Nigeria

Field experiments on fertilizer requirements of groundnuts carried out between 1970 and 1980 were reviewed and discussed. Results of the various studies seem to suggest that existing recommendations which are based on short term annual trials carried under non-intensive or semi-intensive traditional farming systems are becoming inadequate under a system of continuous intensive cultivation. Besides phosphorus and sulphur which have long been known to be deficient in the Nigerian savannah soils, the availability of the other nutrients in these soils can no longer be taken for granted. Potash and micronutrient deficiencies, notably those of B and Mo, hitherto rare, are now showing up with increasing frequency.