In addition to population growth, rural and urban migration, the major features of most Pacific island countries include limited arable land, poor topography (volcanic soils, slopey land, atolls etc.) and social/economic isolation within and between island countries. However, agricultural policy in some countries of the region is geared towards intensification in terms of crop yield per hectare, output per animal, use of improved breeds of animals and planting materials, mechanisation, chemical and pesticides applications. A major by product from the intensification of the livestock industry is animal waste (faeces) and waste products (bedding and litter materials). In developed countries such as Canada, U.S.A., New Zealand and Australia there are by-laws and regulation on the proper disposal and utlisation of livestock waste. as a result of which waste management is an integral part of the commercial livestock industry.  methods of utilisation include use for energy (biogas), fertilizer, animal feed and aquaculture. However, in most south pacific island countries, livestock waste management is still  in its infancy or rudimentary stages. For example many commercial pig producers simply drain pig manure or effluent into creeks, streams and rivers. To, them, this is the easiest, most efficient, cheap and practical method of waste disposal. But as a potential pollution problem, this system of waste disposal is counter productive and wasteful. Valuable marine resources and underground water are threatened. Also potential organic fertilizer, livestock feed and energy resource is lost or wasted. the combination of population in the region, inefficient agricultural practices and the diminishing capacity of available arable land to sustain his population growth from the basis for the potential of integrated bio-systems in small Pacific island countries. To ensure food security and promote economic, social and ecological benefits within and between island countries, the sustainable use of natural renewable agricultural resources must be facilitated by the synergistic relationship between humans, livestock, crops and land. 
 

Nutrient Recycling of Livestock Waste in the South Pacific. 

Integrated Bio-System. 

The concept of  integrated bio-system is beginning to generate interest in the region, in particular amongst NGO, colleges and university with livestock farms. For example at the university of the south pacific, college of agriculture samoa, the author is in the process of integrating pig production, tilapia farming and biogas production. The unit is based on the designed at Montforts Boy’s Town Fiji, by Professor George Chan an Environmental Engineering consultant with the United Nations University.  An overview of a proposed model is shown in Figure 1 and 2. This system can provide all the means of production for high yield of fish, livestock, crops and processed good at very competitive prices, and no pollution (Chan, 1997). Recently, Doelle, (1997) stated that the bioconversion of animal and domestic biological waste into non-polluting biogas and biofertiliser is also very important from a public health stand point of view, by the elimination of enteric parasites and micro-organisms through anaerobic digestion process. 
 
 

Figure 2. Integrated Bio-System, Apia with Dr. A Ajuyah in the  background (photo: J Foo, 1997)

The major component of organic agriculture in the region is the use of livestock waste in crop production. The term livestock manure refers to a mixture of animal waste or effluent, which consist of voided undigested feed materials (faeces), urine (polygastic and pigs), bedding and litter materials. The quality and composition of livestock manure depends on factors such as, type of animal, age, weight, feed and type of bedding/litter materials (Figure 3 and Table 1). The major elements in the manure and urine of livestock are nitrogen, phosphorus and potassium (Table 2). 
 

Figure 3: Tons of Manure (free of bedding) produced per year  per 1,000 pound weight. (Source: Ensminger, M.E. 1980)   On the average, each class of confined qanimals produces  per year per 1,000 lb weight the tonnages of manure free  of bedding shown above

Table 1: Composition of value of chicken manure, fresh vs different degrees of dryness¹ (Source: Ensminger, M. 
E. (1980)). 

The major sources of water are urine and external water (washing, cleaning water, etc.). The inorganic fraction consist mainly of minerals such as potassium and  phosphorous with major sources as undigested feed, beddings/litter materials and urine. 

Use of Livestock Manure in Organic Agriculture 

Livestock waste if properly conserved is rich in organic and inorganic materials. Historically it has been used primarily as fertilizer. A number of farmers in North America and Western Europe including Australia and New Zealand are returning to organic farming, thus increasing the economic value of livestock waste. In Fiji and Samoa some vegetable growers are changing to organic farming because of the reduced cost of production and price advantage of organically grown fruits and vegetable over that produced from chemical fertilizer. Studies carried out in the United States (Ensminger, 1980) has shown that 5 to 20 tons of poultry manure could be applied to one acre year after year with benefits, and greater than 20 tons application could also be made, but probably should not be repeated every year, since excess rates will lead to salt and nitrate build-up, polluting streams and ground water resulting in toxic level of nitrate in crops. Ensminger (1980) concluded that maximum rate of application should be based on soil type, rainfall and temperature. Based on commercial pig and poultry population from six countries in the region (Fiji, Samoa, Tonga, Solomon Islands, Vanuatu and Cook Islands), it is noteworthy to state that the estimated manure output for 1991 was 83 tons per day for chicken and 299 tons per day for pigs (Ajuyah, 1996). It will be worthwhile to calculate the actual monetary value of livestock manure in relation to equivalent amount of chemical fertilizer and N, P₂O₅ and K₂O content. 

Precautions When Using Manure as Fertilizer 

Ensminger (1980) highlighted that the following precautions should be observed when using livestock manure in organic agriculture: 

(i) Poultry manure should be properly handled, to prevent putrefaction. With poor handling much of the uric acid will be changed to ammonium carbonate, with consequent loss of fertilizing value (note: birds excreta contain more nitrogen (uric acid) than that from other animals). 
(ii) Avoid applying livestock manure closer than 100 feet to waterways, streams, lakes, wells, springs, or ponds. 
(iii) Do not apply in poorly drained soils. 
(iv) Distribute the manure as uniformly as possible on the area to be covered. 
(v) Incorporate the manure into the soil as quickly as possible after application. This will maximise nutrient conservation, reduce odors, and minimize runoff pollution. 
(vi) Minimize odor problems by: 
- Spreading raw manure frequently, especially during the summer. 
- Spreading early in the day as the air is warming up, rather than late in the day when the air is cooling. 
-  Spreading only on days when the wind is not blowing towards populated areas. 
(vii) in irrigated areas: (a) irrigate thoroughly to leach excess salts below the root zone, and (b) allow about a mouth after irrigation before planting, to enable soil microorganisms to begin decomposition of the organic fraction of the manure. 

Conclusion 

The economic and social potential of livestock in Organic Agriculture has long been known. Livestock manure is produced whether or not it is wanted and may be available at only the cost of handling. For example at the USP/SOA Poultry farm a 45 kg of poultry manure (droppings and litter materials - wood shavings) is sold at WS$4-5. However, in recent years, health and pollution concern has created a "niche market" for organically grown produce, in particular fruits and vegetables. Some consumers are prepared to pay premium prices for food grown without chemical fertilizer, pesticides and weedicides. In the future, the economic value of livestock manure will increase, and it will be looked upon as a resource not as a waste product that presents disposal problems (Ensminger, 1980). More and more livestock manure will be used as fertilizer to produce food for the expending market for organically grown produce. However, more research is still needed in the South Pacific region to determine the amount of manure per hectare without depressing crop yield, creating salt problems in soil, and nitrate problems in feed, ground water or surface streams. 

References 

Ajuyah, A. O. (1996). AG 273. Livestock Production I Course Book I and 2. Published by University Extension. The University of the South Pacific. 

Ensminger, M. E. ( 1980). Poultry Manure. In Poultry Science (Animal Agriculture Series). Published by Intestate Printers and Publishers, Inc. USA. 

Kangmin, L. ( 1997). Integration of Aquaculture into Macro-Agriculture. Presented at the UNDP/UNU Integrated Biomass System Workshop. Suva, Fiji, May 5-9, 1997.