KULIAH MINGGU KE-14

AGROEKOSISTEM

Istilah umum digunakan– Agroecosystem– Farming system– Agricultural System

Pengertian Agroekosistem

Menggambarkan interaksi antara manusia dan sumberdaya penghasil makanan di lahan atau area tertentu

Agroekosistem merupakan sistem terbuka: menerima input dari luar menghasilkan output output menuju sistem eksternal

1. Agroecosystem is the major ecological unit2. The function of agroecosystem is related to the flow of energy &

the cycling of materials through the structural components of ecosystem, which is modified through the level of input management

3. The total amount of energy depends upon the amount fixed by plants or producers, and inputs provided through management

4. The total volume of living material can be expressed in terms of its biomass bervariasi tergantung jenis organisme, lingkungan fisik, tahap perkembangan dan aktivitas manusia

5. Agroecosystem tend toward maturity dari kurang menuju keadaan kompleks. Namun tren pertanian modern MONOKULTUR yang berkarakteristik Low diversity & low maturity

Prinsip Dasar terkait Struktur dan Fungsi Agroekosistem

6. The major functional unit is the crop population7. A niche within a given agroecosystem cannot be simultaneously

&indefinitely occupied by a self-maintaining population of more than one species

8. When a population reaches the limits imposed by the ecosystem, its number must stabilize or, failing this, declines (often sharply) from disease, predation, competition, low reproduction, and so on

9. Changes and fluctuations in environment (exploitaion, disturbance, competition) represent selective pressure upon the crop population

10. Species diversity is related to the physical environment. A more complex vertical structure generally holds more species: Agroforestry system will contain more species than a cereal system Predictable environment holds more species than a harsher or more

unpredictable Tropical agroecosystem exhibit greater diversity than temperate ones

11. In crop situation which are similar to island situations, immigration rates tend to balance extinction rates (Island biogeography): The nearer the crop island, the greater its immigration rate per unit time The larger the crop island, the higher its carrying capacity for each species In any island situation, immigration of species declines as more species

become established & fewer immigrants are new species

Prinsip Dasar terkait Struktur dan Fungsi Agroekosistem

Faktor yang Mempengaruhi jenis Agroekosistem

• Setiap wilayah memiliki kekhasan faktor yang mempengaruhi kondisi dan jenis agroekosistem

• Faktor-faktor tersebut adalah• Faktor fisik -> iklim,

tanah, curah hujan dll.

• Faktor biotik• Sosial ekonomi• Kultur/budaya

Kriteria dan Klasifikasi Agroekosistem• 5 kriteria untuk mengklasifikasi Agroekosistem

1. The crop & livestock association2. The methods used to grow the crops & produce the stock3. The intensity of use of labor, capital & organization, & resulting output

of product4. The disposal of the product for consumption (used for subsistence or

sold for cash or other goods)5. The ensemble of structure used to house & facilitate farming

operations.• Klasifikasi Agroekosistem berdasar kriteria di atas

• Shifting cultivation system• Semi-permanent rain fed cultivation systems• Permanent rain fed cultivation systems• Arable irrigation systems• Perennial crop system• Grazing systems• System with regulated leys farming (alternating arable cropping &sown

pasture

Sumber Daya Agrokosistem• Sumber daya alam

• Tanah, air, iklim dll.• Sumber daya manusia

• Jumlah• Kapasitas kerja• Inclination to work tgt status ekonomi & budaya• Fleksibilitas ketersediaan susuai kebutuhan kerja

• Sumber daya kapital• Permanent resournces: tanah & air yang diperuntukan

khusus bagi pertanian• Semipermanent resournces: bangsal, pagar• Operational resources or consumable items: pupuk dll• Potential resources: kredit, bantuan tenaga dll

• Sumber daya produksi• Output

Proses Ekologi dalam Agrokosistem• Energetic prosesses: fotosistesis• Biogeochemical proses: siklus hara dll• Hydrological Processes: water is fundamental part of all

agricultural system• Keseimbangan air pada agroekosistem secara umum

S = R + Li – Et – P – Lo + So, S : kelembaban tanah, R : effective rainfall, Li : lateral Flow, P : deep percolation, Lo : lateral outflow, So: original soil mositur content

• Succesional processesThe process by which organisms occupy a site and gradually

change environmental condition so that other species can replace the original inhabitants, is radically changed with modern agriculture (Fig 35)

• Biotic regulation ProcessesControlling succession (plant invasion & competition) & protecting

against insect pest and diseases are major problem in maintaining production continuity in agroecosystem

Proses Ekologi dalam Agrokosistem

Successional process yang dapat terjadi pada dua tipe agroekosistem. Polikulture dapat menghasilkan ekosistem yang lebih kompleks

Pengaturan waktu tanam yang dapat dilakukan untuk memperbaiki proses biologi yang terjadi pada agroekosistem

Stabilitas Agrokosistem• Under conventional agriculture, human have simplified the structure of

the environment over vast areas, replacing nature’s diversity with a small number of cultivated plants and domesticated animals.

• This process of simplification reaches an extreme form in a monoculture• The objective of this simplification is to increase the proportion of solar

energy by the plant communities that is directly available to humans

Simplifikasi menghasilkan satu sisi produksi yang jauh lebih tinggi, tetapi di sisi lain mengurangi berbagai aspek terkait kesetabilan ekosistem seperti terlibat pada Tabel 3.4

Stabilitas pada Berbagai Agrokosistem

Tipe agroekosistem memiliki karakteristik yang berbeda satu dengan yang lainnya dalam hal keragaman, stabilitas, kebutuhan pengandalian dll

Lanskap yang ideal untuk Agrokosistem• Agroekosistem pada umumnya mengubah sistem alamiah yang

memiliki kestabilan ekosistem yang sangat baik• Kestabilan pada agroekosistem dapat diupayakan seoptimal mungkin

dengan memperhatikan berbagai aspek, terutama faktor-faktor yang dapat menyebabkan degradasi lingkungan

• Desain lanskap seperti pada gambar perlu diupayakan diaplikasikan sehinga upaya peningkatan produksi diimbangi dengan perhatian terhadap kelestarian lingkungan