Agroekosistem

Degradasi Ekosistem: Tanggungjawab Moral terhadap Planet Bumi

Kegiatan manusia telah berdampak pada degradasi ekosistem. Karena planet, binatang dan lingkungan semuanya saling berinteraksi, maka perubahan yang berlangsung dalam ekosistem akan mempunyai dampak negative terhadap kehidupan dan planet bumi ini. Oleh karena itu, kita semua wajib untuk mengendalikan kegiatan-kegiatan manusia guna mewujudkan kelestarian planet bumi di masa mendatang yang lebih nyaman dan lebih aman. Kita semua manusia perlu bernafas dalam udara segar, hal yang tidak mungkin terjadi kalau pembakaran bahan bakar fosil masih berlebihan. Hal ini akan menyesakkan nafas berbagai spesies oprganisme dan mengakibatkan perubahan iklim yang menjadi ekstrim.

Aktivitas manusia telah mengakibatkan perubahan pola lingkungan hidup dunia. Aktivitas lainnya yang juga menyebabkan kerusakan ekosistem adalah perikanan, pemanfaatan air tawar, dan penebangan /penggundulan huitan. Penebangan hutan telah mengakibatkan kandungan CO2 atmosfir meningkat dan mengakibatkan punahnya beberapa spesies. Siklus lingkungan telah mengalami perubahan drastic akibat kegiatan manusia. Ada kerusakan parah pada lapisan ozon. Bagaimana kita akan dilindungi dari bahaya radiasi ultraviolet?

Bagaimana kita harus melindungi lapisan ozon ini? Masing-masing dari kita semua , harus mengambil rtanggung-jawab ini untuk mereduksi emisi CO2 dengan jalan menanam lebih banyak pohon sehingga jalur-jalur hijau melindungi semua kehidupan. Oleh karena itu penyelamatan planet bumi dari kepunahan berada di tangan kita manusia semuanya.

(Sumber: http://EzineArticles.com/3784225)

Gambar berikut ini menunjukkan keterkaitan antara tekanan penduduk, fenomena kekeringan, proses-proses degradasi, desertification, dan kerentanan pangan.

Sumber: http://ag.arizona.edu/~lmilich/envsec.html ….. diunduh 2/7/2011

Keterkaitan antara Ketahanan pangan rumahtangga dan Ketahanan Lingkungan:

Siklus Kemiskinan-Degradasi Lingkungan

Sumber: http://ag.arizona.edu/~lmilich/envsec.html ….. diunduh 2/7/2011

Mencegah Degradasi Ekosistem

Memulihkan kembali degradasi ekosistem sangatlah sulit, dan banyak sekali risiko kesehatan manusia telah bermunculan akibat dari hilangnya kesehatan ekosistem, pendekatan yang paluing efektif sebenarnya adalah mencegah terjadinya kerusakan ekosistem. Akan tetapi pendekatan seperti ini tidak mudah dilaksanakan, ada beragam kendala menghadang. Di Negara-negara sedang berkembang dan Negara-negara maju ada inklinasi yang kuat untuk melanjutkan pertumbuhan ekonominya, meskipun dengan biaya mahal berupa kerusakan lingkungan yang parah. Terlepas dari motivasi ego-kemandirian, argumentasi yang diambil ialah bahwa pertumbuhan ekonomi mempunyai banyak manfaat nyata bagi kesehatan, seperti penyediaan sarana yang lebih efisien untuk distribusi pangan, penyediaan pangan yang lebih baik, dan penyediaan layanan kesehatan yang elbih bagus, serta pendanaan untuk penelitian memperbaiki standard kehidupan. Ini semuanya memang manfaat dari pembangunan ekonomi, dan telah berhasil meningkatkan status kesehatan penduduk dunia.

However, at the dawn of the twenty-first century, the past is not necessarily the best guide to the future. The human population is at an alltime high, and associated pressures of human activity have led to increasing degradation of the earth's ecosystems. As ultimately healthy ecosystems are essential for life of all biota, including humans, current global and regional trends are ominous. Under these circumstances, a tradeoff between immediate material gains and long-term sustainability of humans on the planet may be the only option. If so, the solution to sustaining human health and ecosystem health becomes one of devising a new politic that places sustaining lifesupport systems as a precondition for betterment of the human condition.

Pertanian = Agriculture
The word agriculture is the English adaptation of Latin agricultūra, from ager, "a field", and cultūra, "cultivation" in the strict sense of "tillage of the soil". Thus, a literal reading of the word yields "tillage of a field / of fields".
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the development of civilization. The study of agriculture is known as agricultural science. Agriculture is also observed in certain species of ant and termite, but generally speaking refers to human activities.

The history of agriculture dates back thousands of years, and its development has been driven and defined by greatly different climates, cultures, and technologies. However, all farming generally relies on techniques to expand and maintain the lands suitable for raising domesticated species. For plants, this usually requires some form of irrigation, although there are methods of dryland farming; pastoral herding on rangeland is still the most common means of raising livestock. In the developed world, industrial agriculture based on large-scale monoculture has become the dominant system of modern farming, although there is growing support for sustainable agriculture (e.g. permaculture or organic agriculture).

Modern agronomy, plant breeding, pesticides and fertilizers, and technological improvements have sharply increased yields from cultivation, but at the same time have caused widespread ecological damage and negative human health effects. Selective breeding and modern practices in animal husbandry such as intensive pig farming have similarly increased the output of meat, but have raised concerns about animal cruelty and the health effects of the antibiotics, growth hormones, and other chemicals commonly used in industrial meat production.
The major agricultural products can be broadly grouped into foods, fibers, fuels, and raw materials. In the 21st century, plants have been used to grow biofuels, biopharmaceuticals, bioplastics, and pharmaceuticals. Specific foods include cereals, vegetables, fruits, and meat. Fibers include cotton, wool, hemp, silk and flax. Raw materials include lumber and bamboo. Other useful materials are produced by plants, such as resins. Biofuels include methane from biomass, ethanol, and biodiesel. Cut flowers, nursery plants, tropical fish and birds for the pet trade are some of the ornamental products.


Sistem Produksi Tanaman

Cropping systems vary among farms depending on the available resources and constraints; geography and climate of the farm; government policy; economic, social and political pressures; and the philosophy and culture of the farmer.^[47][48] Shifting cultivation (or slash and burn) is a system in which forests are burnt, releasing nutrients to support cultivation of annual and then perennial crops for a period of several years.^[49]

Then the plot is left fallow to regrow forest, and the farmer moves to a new plot, returning after many more years (10-20). This fallow period is shortened if population density grows, requiring the input of nutrients (fertilizer or manure) and some manual pest control. Annual cultivation is the next phase of intensity in which there is no fallow period. This requires even greater nutrient and pest control inputs.

Further industrialization lead to the use of monocultures, when one cultivar is planted on a large acreage. Because of the low biodiversity, nutrient use is uniform and pests tend to build up, necessitating the greater use of pesticides and fertilizers.^[48] Multiple cropping, in which several crops are grown sequentially in one year, and intercropping, when several crops are grown at the same time are other kinds of annual cropping systems known as polycultures.

In tropical environments, all of these cropping systems are practiced. In subtropical and arid environments, the timing and extent of agriculture may be limited by rainfall, either not allowing multiple annual crops in a year, or requiring irrigation. In all of these environments perennial crops are grown (coffee, chocolate) and systems are practiced such as agroforestry. In temperate environments, where ecosystems were predominantly grassland or prairie, highly productive annual cropping is the dominant farming system.
“The last century has seen the intensification, concentration and specialization of agriculture, relying upon new technologies of agricultural chemicals (fertilizers and pesticides), mechanization, and plant breeding (hybrids and GMO's). In the past few decades, a move towards sustainability in agriculture has also developed, integrating ideas of socio-economic justice and conservation of resources and the environment within a farming system.^[50][51] This has led to the development of many responses to the conventional agriculture approach, including organic agriculture, urban agriculture, community supported agriculture, ecological or biological agriculture, integrated farming and holistic management, as well as an increased trend towards agricultural diversification”.

Sistem Produksi Ternak

Animals, including horses, mules, oxen, camels, llamas, alpacas, and dogs, are often used to help cultivate fields, harvest crops, wrangle other animals, and transport farm products to buyers. Animal husbandry not only refers to the breeding and raising of animals for meat or to harvest animal products (like milk, eggs, or wool) on a continual basis, but also to the breeding and care of species for work and companionship. Livestock production systems can be defined based on feed source, as grassland - based, mixed, and landless.

Grassland based livestock production relies upon plant material such as shrubland, rangeland, and pastures for feeding ruminant animals. Outside nutrient inputs may be used, however manure is returned directly to the grassland as a major nutrient source. This system is particularly important in areas where crop production is not feasible because of climate or soil, representing 30-40 million pastoralists.^[49] Mixed production systems use grassland, fodder crops and grain feed crops as feed for ruminant and monogastic (one stomach; mainly chickens and pigs) livestock. Manure is typically recycled in mixed systems as a fertilizer for crops. Approximately 68% of all agricultural land is permanent pastures used in the production of livestock.

Landless systems rely upon feed from outside the farm, representing the de-linking of crop and livestock production found more prevalently in OECD member countries. In the U.S., 70% of the grain grown is fed to animals on feedlots. Synthetic fertilizers are more heavily relied upon for crop production and manure utilization becomes a challenge as well as a source for pollution.
Menurut Jongbloed and Lenis (1995), beberapa pendekatan untuk mereduksi limbah ternak dan pencemaran lingkungan adalah:

1. 
   Supply nutrients to the required level. This can be accomplished by better knowledge of nutrient availability (N, P) in the feed, a better knowledge of the animals requirement and a better agreement of supply and requirement.
   
2. 
   Enhance digestibility of P and protein. Use of microbial phytase to improve digestibility of P reduces needs for supplementation; enzyme treatment of non-starch polysaccharides; reduce anti-nutritional factors through treatment of ingredients and processing of complete diets.
   
3. 
   Change feedstuff composition. For example selection of highly digestible sources of P (mono-calcium phosphate rather than di-calcium); use of amino acid supplementation and reduction in protein levels.
   
4. 
   Memperbaiki efisiensi pakan.
   

Dampak lingkungan lainnya:

1. 
   Levels of potassium supply exceed demand by a factor of 3-5 and levels in fresh water can exceed accepted levels by a factor of 2-4.
   
2. 
   High moisture level of livestock waste increases transport costs for disposal.
   
3. 
   Although feed additives may reduce excretion of N and P as a result of better feed conversion, copper and zinc growth promotants can accumulate in soils.
   
4. 
   Free-ranging pigs requiring more fibre in the diet have lower feed conversion and more waste per unit of meat produced.
   
5. 
   Specific pathogen-free herds can improve feed conversion by 10-15 percent.
   

Sumber: Jongbloed and Lenis (1995)