Upload
yusi-listiawati
View
130
Download
4
Embed Size (px)
Citation preview
HUBUNGAN TANAH, AIR DAN
TANAMAN
Batasan Tanah dari sudut ekologi Tumbuhan
Komponen penyusun tanah dan perannya bagipertumbuhan dan produksi tanaman
Profil Tanah dan pengaruhnya terhadap vegetasi
Faktor yang mempengaruhi sifat tanah
Sifat fisika, kimia, biologi, hidrologi danmorfologi tanah
Faktor yang berpengaruh terhadap hasil tanaman
Tanah? akumulasi tubuh alam bebas,
berdimensi tiga,
menduduki sebagaian besar permukaan
daratan bumi, yang
mampu menumbuhkan tanaman, dan
memiliki sifat sebagai pengaruh iklim (I) dan
organisme (O) yang bertindak terhadap
bahan induk (B) pada kondisi topografi (L)
tertentu dan selama waktu (W) tertentu”
(Donahue, 1970).
GAS
CAIRAN /
LIQUID
PADATAN /
SOLID
RUANG PORI
(VOID)
MINERAL LEMPUNG
BAHAN ORGANIK
RUANG PORI
(VOID)
BAHAN ORGANIK
20- 30%
20- 30%
< 5%
45% MINERAL LEMPUNG
Tanah Pertanian Ideal
Tanah yang baik untuk pertumbuhan
tanaman darat non padi: tersusun
atas komponen
• bahan mineral 45%,
• bahan organik 5%,
• udara 20-30% dan air 20-30%
• (atas dasar volume).
Media
Tumbuh
Tanah
BahanOrganik
AIR
Hara
SifatFisik
SifatKimia
• KompleksPertukaran
• Nutrisi
Biologi• Mikroorganisme
• Dekomposer
SIFAT FISIKA TANAH
• Tektur• Pori• Struktur
TEKTUR TANAH
Faktor penentu tekstur tanah?
Mengapa tekstur tanah penting?
Particle sizes:
• Gravel: >2.0 mm
• Sand: 0.05-2.0 mm
• Silt: 0.002-0.05 mm
• Clay: <0.002 mm (microscopic)
Fig
. 6.7
, C
am
pbell
& R
eece,
7th
ed.
Pengaruh ukuran partikel pada permukaan :volume ratio
Importance of soil particle size—
Critical in determining soil physical properties.
Clay has much higher surface:volume ratios (due to small particle size) than larger particles.
Electrostatically negative charges on clay micellespermit stronger adsorption of water and nutrients, reducing leaching, especially of cationic nutrients (e.g., NH4, Ca, Mg, K, Na, Cu, Mn, Zn, Fe all have + charges)
Too much clay results in reduced pore sizes
Sand—with its larger particle sizes—has characteristics opposite to those of clay
Silt is between clay and sand in size and traits
Best agricultural soils are classed as loams, varying broadly around a 40:40:20 ratio of sand, silt, and clay, respectively
SIFAT KIMIA TANAH
• Macronutrients• micronutrients• Pertukaran ion
Macronutrients—
Macronutrients are defined as elements that make up >0.1% of plant tissue dry weight
C, H, and O—the basic constituents of organic molecules—make up about 96% of plant dry weight.
Other macronutrients include N, P, K, Ca, S, Mg
Macronutrients—
Their functions
Ta
ble
6.1
, S
mith &
Sm
ith 7
thed. (p
. 120
)
Micronutrients—
Micronutrients (a.k.a., “trace elements”) are needed in small quantities (<0.01% by weight)
Although required in tiny amounts, micronutrients are nonetheless essential
Often serve as cofactors, facilitating enzyme activity
E.g., Cu, Mn, Zn, Fe
Using hydroponic culture to identify essential plant nutrients
Fig
. 37.2
, C
am
pbell
& R
eece (
6th
ed)
Identifying essential plant nutrients—
Magnesium deficiency in a tomato plant
Fig. 37.3, Campbell & Reece (6th ed)
Gas exchange and the uptake of water and nutrients by a plant: an overview
Fig
. 37.1
, C
am
pbell
& R
eece (
6th
ed)
Cation exchange capacity (CEC) of soil—
Capacity of the soil to adsorb cations
Strength of cation retention depends on number of “exchange sites” and the intensity of the charges on them.
Largely determined by clay and humus content
Clay micelles have numerous negative charges. Because of the tiny size of the clay particles and the resulting small soil pore sizes, clayey soils tend to a high CEC.
Plant roots use cation exchange to assist in nutrient uptake from the soil—
(a) Soil moisture surrounding the roots
(b) Absorption of soil mineral nutrients by cation exchange
Where does the plant get this CO2 that it’s putting into the soil??
Fig. 37.6, Campbell & Reece (6th ed)
Fig. 4.11, Smith & Smith 7th ed. (p. 66)
Absorption and leaching of soil nutrients in the soil solution
Soil moisture and water uptake by plants—
Water moves in response to a gradient of water potential, from higher water potential to lower water potential.
Net water potential in the plant is determined by
(a) osmotic pressure—due to cross-membrane differences in solute concentration,
(b) water pressure—due to atmospheric pressure, and
(c) the transpiration stream—which pulls water up through xylem tissues, based on transpiration from leaves and the adhesion and cohesion properties of water.
Fig. 6.3, Smith & Smith (5th ed), p. 105
Water movement through a plant—
the “transpiration stream”
A stoma functions in gas exchange—
Stomatal openings respond to environmental cues to control gas exchange rates—
Fig. 36.14, Campbell & Reece, 7th ed. (p. 749)
Open Closed
The water balance of living cells
Fig. 8.12, Campbell & Reece (6th ed)
A wilted tomato plant regains its turgor when watered
Fig. 36.5, Campbell & Reece (6th ed)
Fungsi-fungsi Tanah Sebagai
Sumberdaya Alam
unsur produksi pertanian
unsur pengatur tata air siklus hidrologi
unsur perlindungan alam/lingkungan
unsur teknik bangunan/infrastruktur
• Mendukung aktivitas biologi, keaneka ragaman hayatidan produktivitas
• Mengatur tata air dan aliran lautan
• Sebagai saringan, buffer, degradator, detoksifikatorsenyawa anorganik dan organik, termasuk limbahindustri, rumah tangga dan limbah atmosfer;
• Menyimpan dan mendaur ulang hara dan unsur lain didalam biosfer;
• Mendukung bangunan dan melindungi kekayaanarkeologi.
Fungsi-fungsi Tanah
(Karlen et al., 1997)
Hidrologi adalah ilmu yang berhubungan dengan kejadian,
pergerakan dan distribusi air di dalam Siklus Hidrologi.
Siklus Hidrologi adalah dinamika sistem transfer air alami
dimana air secara kontinyu bergerak dan berubah dari satu
bentuk ke bentuk yang lain, dan selama itu jumlah total air
di bumi tetap.
Walaupun menurut definisi, hidrologi mencakup studi air tanah,dalam aplikasinya penekanan hidrologi masih terfokus padastudi aliran air di permukaan dan faktor-faktor sejenis yangmenentukan
Studi tentang aspek-aspek kejadian dan pergerakan air tanahdilakukan secara terpisah dan umumnya dikenal sebagaiGeohydrology (Hidrologi air tanah – groundwater hydrology)
Hydrologic Cycle
Water enters the soil, interacts with soil particles and leaves the soil (through
evaporation, transpiration or leaching).
Setelah mencapai permukaan bumi, air hujan terus bergerak danberubah bentuknya, yaitu:
bagian yang masuk ke dalam tanah – Infiltration,bagian yang mengalir sepanjang permukaan – Run-off, bagian yang kembali ke atmosfer sebgai uap air – Evaporation, bagian yang diambil tanaman dan dikembalikan ke atmosfer –Transpiration.
Bagian air hujan yang ditangkap oleh daun dan batang tanaman disebut Interception.
Bagian air hujan yang terkumpul di permukaan tanah disebut Surface Storage,
Bagian air hujan yang diikat di dalam tanah– Soil moisture danbagian yang diperkolasikan ke bagian bawah tanah yangberhubungan dengan zone jenuh air – Groundwater, sehinggasecara sederhana neraca air dapat ditulis sebagai:
Precipitation = Runoff + Evapo-transpiration + Change storage
Hydrologic Cycle and the Soil
Color
Structure
Bulk Density
Texture
pH
Temperature
Moisture
Horizon
Depths
Soil Properties that are part of the hydrologic cycle.
SIKLUS HIDROLOGI HUJAN
Hujan
Hujan lebih Intersepsi Evp & Ept, dll.
Infiltrasi
SSRO Perkolasi dalam
PromptSSRO
Delayed SSRO
Groundwater storage
Direct RO Base flow
Aliran permukaan
Total RO/Stream flow
Fungsi Tanah sebagai
Faktor Produksi Tanaman
• Tunjangan mekanis sebagai tempat tanaman tegak dan tumbuh;
• Penyedia air, udara dan unsur hara (nutrisi);
• Lingkungan tempat akar atau batang dalam tanah melakukan aktivitas fisiologinya
• Pengontrol temperatur tanah
• Tempat tumbuh dan berkembangnya organisme tanah.
TERIMA KASIH