evaluasi lahan dan indikator lahan

EVALUASI LAHANDAN

INDIKATOR LAHAN

BAHAN KAJIAN: STELA-SMNO.FPUB.APRIL2013

CONCEPTS, DEFINITIONS AND PRINCIPLES

"Lahan adalah area tertentu di permukaan bumi, yang melingkupi semua atribut biosfir di atas dan di bawah

permukaan, termasuk iklim di dekat permukaan, tanah dan bentuk lahan, hidrologi permukaan (termasuk

danau dangkal, sungai, rawa-rawa), the near-surface sedimentary layers and associated

groundwater reserve, populasi tumbuhan dan binatang,

pola permukiman dan sifat fisik akibat aktivitas manusia (terras, bangunan air dan drainage, jalan raya

dan bangunan gedung, dll.).“

Sumber: FAO Land and Water Bulletin No. 5. 1997

Fungsi-fungsi lahan:

1. Fungsi Produksi2. Fungsi Lingkungan Biotik3. Fungsi regulasi iklim4.· hydrologic function5.· storage function6.· waste and pollution control function7.· living space function8.· archive or heritage function9.· connective space function


FUNGSI PRODUKSI

Lahan merupakan basis bagi berbagai sistem penunjang kehidupan, melalui produksi

biomasa yang menyediakan makanan, pakan-ternak, serat, bahan-bakar, bahan bangunan

dan material biotik lainnya bagi manusia, secara langsung atau melalui budidaya ternak, termasuk akuakultur dan perikanan tangkap.


FUNGSI LINGKUNGAN BIOTIK

Lahan merupakan basis bagi buiodiversitas terrestris dengan

menyediakan habitat biologis dan plasma nutfah bagi tanaman,

binatang, dan mikroba yang hidup di atas dan di bawah permukaan.


FUNGSI LAHAN: REGULASI IKLIM

land and its use are a source and sink of greenhouse gases and form a co-determinant

of the global energy balance - reflection, absorption and transformation of radiative

energy of the sun, and of the global hydrological cycle


Fungsi Lahan: Koneksi Ruang

land provides space for the transport of people, inputs and produce, and for the movement of plants and animals between discrete areas of

natural ecosystems

FUNGSI LAHANFUNGSI HIDROLOGI

Land regulates the storage and flow of surface and groundwater resources, and influences their

quality


FUNGSI PENGENDALI PENCEMARAN DAN LIMBAH

land has a receptive, filtering, buffering and

transforming function of hazardous compounds

FUNGSI GUDANG

land is a storehouse of raw materials and

minerals for human use

FUNGSI RUANG KEHIDUPANland provides the physical basis for human settlements,

industrial plants and socialactivities such as sports and recreation.

FUNGSI ARSIP ATAU WARISAN

Land is a medium to store and protect the evidence of the cultural history of humankind,

and source of information on past climatic conditions and past land uses.


Lahan mempunyai Atribut, Karakteristik, Sifat & Ciri, dan Kualuitas (atau Kondisi/Pembatas):

1. an attribute, or variable, is a neutral, over-arching term for a single or compound aspect of the land;

2. a characteristic is an attribute which is easily noticed and which serves as a distinguishing element for different types of land; it may or may not have a practical meaning (e.g., soil colour or texture, or height of forest cover are characteristics without giving direct information on land quality);

3. a property is an attribute that already gives a degree of information on the value of the land type;

4. a land quality (or limitation) is a complex attribute of land which acts in a manner distinct from the actions of other land qualities in its influence on the suitability of land for a specified kind of use.


Land qualities are not absolute values, but have to be assessed in relation to the functions of the land and the specific land use that one

has in mind. Some examples:1. Land recently cleared from forest has a positive quality in respect of arable cropping

(clearing, as "development costs", adding to the value of potential agricultural land), but has a negative quality in respect of sustainable use of the natural vegetative cover;

2. Land with a high degree of short-distance variation in soil and terrain conditions has a positive quality for biodiversity, is a large drawback to large-scale mechanized arable farming, but has a smaller limitation - or even an advantage - for smallholders' mixed farming;

3. The presence of scattered clumps of trees or shrubs in an open savannah area with harsh climatic conditions is a positive quality for extensive grazing (shelter against cold, heat or wind) but may be less important, or negative, for arable farming;

4. The presence of small land parcels, of woody or stony hedgerows and terraces, or of archaeological remains, is a positive quality in relation to the archival function of the land, but can conflict with its production function;

5. The propensity of the soil surface to seal and crust is a negative quality for arable farming (poor seedbed condition; reduced moisture intake of the soil), but is an asset of the land as regards water harvesting possibilities for crop growing in lower parts of the landscape wherever rainfall is submarginal.


KUALITAS LAHAN & PRODUKTIVITAS TANAMAN1. Crop yields (a resultant of many qualities listed below).2. KETERSEDIAAN LENGAS TANAH.3. KETERSEDIAAN HARA.4. KETERSEDIAAN OKSIGEN DI ZONE AKAR.5. Adequacy of foothold for roots.6. KONDISI PERKECAMBAHAN.7. Workability of the land (ease of cultivation).8. SALINITAS ATAU SODISITAS.9. TOKSISITAS TANAH.10.RESISTENSI TERHADAP EROSI TANAH.11.Pests and diseases related to the land.12.Flooding hazard (including frequency, periods of inundation).13.REGIM SUHU.14.RADIASI ENERGI DAN FOTOPERIODE.15.Climatic hazards affecting plant growth (including wind, hail, frost).16.Air humidity as affecting plant growth.17.PERIODE KERING UNTUK PEMASAKAN/PEMATANGAN TANAMAN.


Crop yields (a resultant of many qualities listed below).

Sumber: http://agriinfo.in/?page=topic&superid=1&topicid=311

Crop production provides the food for human beings, fodder for animals and fiber for cloths. Land is the natural resource which is

unchanged & the burden of the population is tremendously increasing, thereby decrease the area per capita. Therefore it is necessary to

increase the production per unit area on available land. This necessitates the close study of all the factors of crop production viz.

1. The soil in which crops are grown2. The water which is the life of plant3. The Plant which gives food to man & fodder to his animals4. The skillful management by the farmer himself5. The climate which is out of control of man & but decided the

growth, development & production.6. The genetic characters of crop plant which is the genetic makeup &

can be exploited for crop production.

KETERSEDIAAN LENGAS TANAH

Sumber: http://soils.usda.gov/sqi/publications/files/avwater.pdf

Available water capacity is the amount of water that a soil can store that is available for use by plants.

It is the water held between field capacity and the wilting point adjusted downward for rock fragments and for salts in solution.

Field capacity is the water retained in a freely drained soil about 2 days after thorough wetting.

The wilting point is the water content at which sunflower seedlings wilt irreversibly.

Available water is expressed as a volume fraction (0.20), as a percentage (20%), or as an amount (in inches). An example of a

volume fraction is water in inches per inch of soil. If a soil has an available water fraction of 0.20, a 10 inch zone then contains 2 inches

of available water.

KETERSEDIAAN LENGAS TANAH

Sumber: http://soils.usda.gov/sqi/publications/files/avwater.pdf

Tekstur Tanah Fraksi air tersedia

Sands, and loamy sands and Less than 0.10sandy loams in which the sand isnot dominated by very fine sand

Loamy sands and sandy loams 0.10 - 0.15in which very fine sand is thedominant sand fraction, andloams, clay loam, sandy clay loam,and sandy clay

Silty clay, and clay 0.10 - 0.20

Silt, silt loam, and silty clay loam 0.15 - 0.25

KETERSEDIAAN HARA.This soil quality is decisive for successful low level input farming and to some extent also for intermediate input levels. Diagnostics related to

nutrient availability are manifold. Important soil characteristics of the topsoil (0-30 cm) are:

Texture/Structure, Organic Carbon (OC), pH and Total Exchangeable Bases (TEB).

For the subsoil (30-100 cm), the most important characteristics considered are: Texture/Structure, pH and TEB.

The soil characteristics relevant to soil nutrient availability are to some extent correlated. For this reason, the most limiting soil characteristic is combined in the evaluation with the average of the remaining less

limiting soil characteristics to represent soil quality.

Soil Qualities Soil Characteristics Nutrient availability Soil texture, soil organic carbon, soil pH, total

exchangeable bases

Sumber: http://www.fao.org/nr/land/soils/harmonized-world-soil-database/soil-quality-for-crop-production/en/

pH – KEMASAMAN TANAH

Crops vary in their response to pH; calcifuge plants dislike lime while calciphilous plants are lime-loving.

There are very few crops that grow well in calcareous soils that do not grow equally well at a pH above 6 under lime-

free conditions. Several crops, such as tea, require acid conditions. Many crops are affected by micro-nutrient

deficiencies or toxicities at certain pH levels.

The availability of various macro and micronutrients over the pH scale is illustrated ; however, this availability varies

from crop to crop.

Sumber: http://www.fao.org/docrep/X5648E/x5648e0e.htm#a.10%20sodicity

Relative availability of common elements in mineral soils with pH (after Truog 1948)


http://www.fao.org/docrep/X5648E/x5648e0z.gif



KAPASITAS RETENSI HARANutrient retention capacity is of particular importance for the

effectiveness of fertilizer applications and is therefore of special relevance for intermediate and high input level cropping conditions.

Nutrient retention capacity refers to the capacity of the soil to retain added nutrients against losses caused by leaching. Plant nutrients are held in the soil on

the exchange sites provided by the clay fraction, organic matter and the clay-humus complex. Losses vary with the intensity of leaching which is determined by the rate

of drainage of soil moisture through the soil profile. Soil texture affects nutrient retention capacity in two ways, through its effects on available exchange sites on the

clay minerals and by soil permeability.The soil characteristics used for topsoil are respectively: Organic Carbon (OC), Soil Texture (Text), Base Saturation (BS), Cation Exchange Capacity of soil (CECsoil), pH, and Cation Exchange Capacity of clay fraction (CECclay). Soil pH serves as indicator

for aluminum toxicity and for micro-nutrient deficiencies. Kualitas Tanah:

Nutrient retention capacity

Karakteristik Tanah:

Soil Organic carbon, Soil texture, base saturation, cation exchange capacity of soil and of clay fraction


Ketersediaan Oksigen di Zone Perakaran

Oxygen availability in soils is largely defined by drainage characteristics of soils. The determination of soil drainage classes is based on

procedures developed at FAO (FAO 1995). These procedures take into account soil type, soil texture, soil phases

and terrain slope. Apart from drainage characteristics, the soil quality of oxygen

availability may be influenced by soil and terrain characteristics that are defined through the occurrence of specific soil phases.

Kualitas Tanah:

Oxygen availability to roots

Karakteristik Tanah:

Soil drainage and soil phases affecting soil drainage.


TEMPAT PANCANGNYA AKAR TANAMAN

Sumber:http://soils.usda.gov/sqi/publications/files/avwater.pdf

The rooting depth affects the total available water capacity in the soil. A soil that has a root barrier at 20 inches and an

available water fraction of 0.20 has 4 inches of available water capacity.

Another soil, that has a lower available water fraction of 0.10, would, if the roots extended to a depth of 60 inches,

have 6 inches of available water capacity. For shallow rooting crops, like onions, the available water

below 1-2 feet has little significance. For deeper rooting crops, like corn, the available water at

the greater depth is very important.

KONDISI UNTUK PERKECAMBAHAN

KONDISI PERAKARANRooting conditions include effective soil depth (cm) and effective soil volume (vol. %)

related to presence of gravel and stoniness. Rooting conditions may be affected by the presence of a soil phase either limiting the effective rooting depth or decreasing

the effective volume accessible for root penetration. Rooting conditions address various relations between soil conditions of the rooting zone and crop growth.

The following factors are considered in the evaluation:1. Adequacy of foothold, i.e., sufficient soil depth for the crop for anchoring;2. available soil volume and penetrability of the soil for roots to extract nutrients; 3. space for root and tuber crops for expansion and economic yield in the soil; and4. absence of shrinking and swelling properties (vertic) affecting root and tuber

crops.

Soil depth/volume limitations affect root penetration and may constrain yield formation (roots and tubers). Relevant soil properties considered are: soil depth, soil texture/structure, vertic properties, gelic properties, petric properties and presence

of coarse fragments. This soil quality is estimated by multiplying of the soil depth limitation with the most limiting soil or soil phase property .


KONDISI PERAKARAN.

Soil phases that relevant for rooting conditions vary somewhat with source of soil map and soil classification used. In the HWSD these are:

1. FAO 74 soil phases: stony, lithic, petric, petrocalcic, petrogypsic, petroferric, fragipan and duripan.

2. FAO 90 soil phases: rudic, lithic, pertroferric, placic, skeletic, fragipan and duripan.

3. ESB soil phases and other soil depth/volume related characteristics: stony, lithic, petrocalcic, petroferric, fragipan and duripan, and presence of gravel or concretions, obstacles to roots (6 classes), and impermeable layers (4 classes).

Rooting conditions Soil textures, bulk density, coarse fragments, vertic soil properties and soil phases affecting root penetration and soil depth and soil volume


Workability of the land (ease of cultivation).


Workability or ease of tillage depends on interrelated soil characteristics such as texture, structure, organic matter content, soil

consistence/bulk density, the occurrence of gravel or stones in the profile or at the soil surface, and the presence of continuous hard rock at shallow depth as well as rock outcrops. Some soils are easy to work independent of moisture conditions, other soils are only manageable at an adequate moisture status, in particular for manual cultivation or light machinery. Irregular soil depth, gravel and stones in the profile and rock outcrops, might prevent the use of heavy farm machinery.

Kualitas Lahan:

Land Workability (constraining field

management)

Karakteristik Lahan:

Soil texture, effective soil depth/volume, and soil phases constraining soil management (soil

depth, rock outcrop, stoniness, gravel/concretions and hardpans)

Salinity or sodicity.KELEBIHAN GARAM

Accumulation of salts may cause salinity. Excess of free salts referred to as soil salinity is measured as Electric Conductivity (EC in dS/m) or as saturation of the exchange complex with sodium ions, which is referred to as sodicity or sodium

alkalinity and is measured as Exchangeable Sodium Percentage (ESP). Salinity affects crops through inhibiting the uptake of water. Moderate salinity

affects growth and reduces yields; high salinity levels may kill the crop. Sodicity causes sodium toxicity and affects soil structure leading to massive or coarse

columnar structure with low permeability. Apart from soil salinity and sodicity, conditions indicated by saline (salic) and sodic soil phases may affect crop growth

and yields. In case of simultaneous occurrence of saline (salic) and sodic soils the limitations are combined. The most limiting of the combined soil salinity and/or sodicity conditions

and occurrence of saline (salic) and/or sodic soil phase is selected.

Excess salts. Soil salinity, soil sodicity and soil phases influencing salt conditions


SalinityThe adverse effects of soil salinity on plant growth vary with the

crop being grown. The presence of salinity in the soil solution resulting from either indigenous salt in the soil, or from salt

added by irrigation water can affect growth (i) by reducing water available to the crop (the osmotic effect) and (ii) by increasing

the concentration of certain ions that have a toxic effect on plant metabolism (the specific ion effect).

Many plants, for example, barley, wheat and maize, are sensitive to the osmotic effect during germination and the early seedling stages, but have greater tolerances at later stages (USDA 1954).

Salt damage is aggravated by hot, dry conditions and may be less severe in cool humid conditions.

Salt tolerance data for any given crop cannot be considered as fixed values, but should be used as guidelines.


Salt tolerances of various crops to salinity as measured in the saturation extract ECe. Field crops.

Sumber: Maas and Hoffmann 1977; James et al 1982.

EFEK FISIKA SODISITAS

The presence of excessive amounts of exchangeable sodium in soil promotes the dispersion and swelling of clay minerals.

The soil becomes impermeable to both air and water. The infiltration and hydraulic conductivity decrease to the

extent that little or no water movement occurs. The soil is plastic when wet and becomes hard (brick-like)

when dry. Tillage becomes difficult and soil crusting occurs. Recent

research (Frenkel et al. 1978) has indicated that dispersion blocks soil pores, whereas swelling reduces pore sizes.


EFEK FISIKA SODISITAS

The effect is most pronounced on soils containing clays which swell and shrink. Soils containing non-expanding clays such as kaolinite and sesquioxides are relatively insensitive to the physical effects of exchangeable sodium. However,

heavy cracking clays may be so impermeable when wet that the decreased permeability associated with a high sodium

content may not matter.

Sodicity is determined as the exchangeable sodium percentage (ESP). In rating sodicity one should take into

account the changes in ESP which will take place after the land is irrigated.


CRITICAL LIMITS FOR SODICITY TOLERANCE

1. 1/ Ratings may be raised one level if permeability is more than 2 cm/hr (e.g. as in loamy and sandy soils).

2. 2/ Soil depth ranges in cm. 3. 3/ SAR may be used if ESP figures seem unreliable.


Factor Ratings 1/

ESP % ESP % SAR 3/ SAR

(0 - 30) 2/ (30 - 90) (0 - 30) (30 - 90)

s1 <10 <20 <8 <18

s2 10 - 20 20 - 35 8-18 18 - 38

s3 20 - 35 35 - 50 18 - 38 38 - 68

n >35 >50 >38 >68

Sodium toxicity

Plants vary considerably in their ability to tolerate sodium ions. Most tree crops and other woody-type perennials are particularly sensitive

to low concentrations of sodium. Most annual crops are less sensitive, but may be affected by higher

concentrations. Sodium toxicity is often modified and reduced if calcium is also present, therefore a reasonable evaluation of the

potential toxicity is possible using the SAR for the soil water extract and the SAR of the irrigation water.

Symptoms of sodium toxicity may appear only after a period of time during which toxic concentrations accumulate in the plant: the

symptoms appear as a burn or drying of tissues first appearing at the outer edges of leaves. Table |40 can be used to evaluate the sodium

hazard for representative crops.


TOLERANCE OF VARIOUS CROPS TO EXCHANGEABLE SODIUM (ESP) UNDER NONSALINE CONDITIONS


Tolerance to ESP and range at which affected

Crop Growth response under field conditions

Extremely sensitive(ESP = 2-10)

Deciduous fruits Nuts Citrus (Citrus spp.)Avocado (Persea americana Mill.)

Sodium toxicity symptoms even at low ESP values

Sensitive(ESP = 10-20)

Beans (Phaseolus vulgaris. L) Stunted growth at these ESP values even though the physical condition of

the soil may be good

Moderately tolerant(ESP = 20-40)

Clover (Trifolium spp.)Oats (Avena sativa L.)

Tall fescue (Festuca arundinacea Schreb.)Rice (Oryza sativa L.)

Dallis grass (Paspalum dilatum Poir.)

Stunted growth due to both nutritional factors and adverse soil conditions

Tolerant(ESP = 40-60)

Wheat (Triticum aestivum L.)Cotton (Gossypium hirsutum L.)

Alfalfa (Medicago sativa L.)Barley (Hordeum vulgare L.)

Tomatoes (Lycopersicon esculentum Mill.)Beets (Beta vulgaris L.)

Stunted growth usually due to adverse physical conditions of soil

Most tolerant(ESP = more than 60)

Crested and Fairway wheatgrass (Agropyron spp.)

Tall wheatgrass (Agropyron elongatum (Host) Beau.)

Rhodes grass (Chloris gayana Kunth)

Stunted growth usually due to adverse physical conditions of soil

Soil toxicity.


ToxicitiesLow pH leads to acidity related toxicities, e.g., aluminum, iron, manganese toxicities, and to various deficiencies, e.g., of phosphorus and molybdenum. Calcareous soils exhibit generally micronutrient deficiencies, for instance of iron, manganese, and

zinc and in some cases toxicity of molybdenum. Gypsum strongly limits available soil moisture. Tolerance of crops to calcium carbonate and gypsum varies widely (FAO,

1990; Sys, 1993). Low pH and high calcium carbonate and gypsum are mutually exclusive. Acidity

related toxicities such as aluminum toxicities and micro-nutrient deficiencies are accounted for respectively in nutrient availability, and in nutrient retention capacity.

This soil quality is therefore only including calcium carbonate and gypsum related toxicities. The most limiting of the combination of excess calcium carbonate and gypsum in the soil, and occurrence of petrocalcic and petrogypsic soil phases is

selected for the quantification.

Soil Toxicity Calcium carbonate and gypsum

KETAHANAN EROSI

Sumber: http://users.ictp.it/~pub_off/lectures/lns018/21Lobo.pdf

Climate, soil and topographic characteristics determinerunoff and erosion potential from agricultural lands. The

main factors causing soil erosion can be divided into three groups

1. Energy factors: rainfall erosivity, runoff volume, wind strength, relief, slope angle, slope length.

2. Protection factors: population density, plant cover, amenity value (pressure for use) and land management.

3. Resistance factors: soil erodibility, infiltration capacity and soil management.

Soil ERODIBILITY.

Sumber: http://mepas.pnnl.gov/mepas/formulations/source_term/5_0/5_32/5_32.html

The soil erodibility factor (K-factor) is a quantitative description of the inherent erodibility of a particular soil; it is a measure of the

susceptibility of soil particles to detachment and transport by rainfall and runoff.

For a particular soil, the soil erodibility factor is the rate of erosion per unit erosion index from a standard plot.

The factor reflects the fact that different soils erode at different rates when the other factors that affect erosion (e.g., infiltration rate, permeability, total water capacity, dispersion, rain splash, and

abrasion) are the same. Texture is the principal factor affecting Kfact, but structure, organic

matter, and permeability also contribute. The soil erodibility factor ranges in value from 0.02 to 0.69 (Goldman et al. 1986; Mitchell and

Bubenzer 1980).

Sumber: http://mepas.pnnl.gov/mepas/formulations/source_term/5_0/5_32/5_32.html

Stewart et al. (1975) also developed a table indicating the general magnitude of the K-factor as a function of organic matter content (Pom) and soil textural class.

Pom(%)

Textural Class <0.5 2 4

Sand 0.05 0.03 0.02

Fine sand 0.16 0.14 0.10

Very finesand 0.42 0.36 0.28

Loamy sand 0.12 0.10 0.08

Loamy finesand 0.24 0.20 0.16

Loamy veryfine sand 0.44 0.38 0.30

Sandy loam 0.27 0.24 0.19

Fine sandyloam 0.35 0.30 0.24

Very fine sandy loam 0.47 0.41 0.33

Loam 0.38 0.34 0.29

Silt loam 0.48 0.42 0.33

Silt 0.60 0.52 0.42

Sandy clayloam 0.27 0.25 0.21

Clay loam 0.28 0.25 0.21

Silty clayloam 0.37 0.32 0.26

Sandy clay 0.14 0.13 0.12

Silty clay 0.25 0.23 0.19

Clay 0.13-0.2

Sumber: http://rpitt.eng.ua.edu/Class/Erosioncontrol/Module3/Module3.htm

The soil texture, and other soil characteristics, affect its susceptibility to erosion. The soil K factors were determined experimentally in test plots that were 72.6 ft long and

had a uniform slope of 9%.

The nomograph used to determine the K factor for a soil, based on its texture (% silt plus very fine sand, % sand, % organic matter, soil structure, and permeability.

The NRCS county soil maps list the K factors for all soils in each county. However, significant disturbance and modifications of the soil obviously occurs at construction

sites and care needs to be taken to ensure that the K factor is based on the actual surface soil conditions. As an example, the organic matter (decreases as the top soils are removed), permeability (decreases with compaction with heavy equipment), and

soil structure (subsurface soils more massive than surface soils) could all likely change, causing the K factor to increase for a soil undergoing modification at a construction

site.

Soil ERODIBILITY Factor (K).

Sumber: http://rpitt.eng.ua.edu/Class/Erosioncontrol/Module3/Module3.htm

USDA nomograph used to calculate soil erodibility (K) factor.

Soil ERODIBILITY Factor (K).

Pests and diseases related to the land.


The categories of problem may be listed as due to (i) wild animals, (ii) arthropods including insects and mites, (iii) parasitic nematodes, (iv) fungal pathogens, (v) bacterial

pathogens, and (vi) virus diseases. In reconnaissance studies these should be considered in selecting alternative LUTs.

Pests, diseases and weeds may be 'class-determining' because of the variability from one land unit to another in

exposure to wild animals, in microclimate or soils, or in other land characteristics. Insect problems, particularly in cotton, have led to the failure of large irrigation schemes.

Flooding hazard

Sumber: http://www.fao.org/docrep/X5648E/x5648e0e.htm#a.13.2%20flood%20hazard

In shallow water rice areas and in areas producing other crops, spasmodic floods not only affect the crop, but also damage the soil

and the infrastructure, e.g. rice-field bunds, pathways, temporary and permanent houses, roads and bridges etc. Flood damage is most likely to occur on river flood plains, alluvial and coastal plains, regions with

large seasonal variations in rainfall and liable to intensive rain over hours or days. The detailed pattern of incidence is thus related to

landforms. In setting critical limits for flood hazard, two criteria may be used:

period of inundation, and flood frequency. The period of inundation is the average number of days during the cropping season or year when

the land is covered by water. This may be obtained from records or estimated. The flood frequency is the probability of occurrence of

damaging floods during the year.

Flooding hazard (including frequency, periods of inundation).


A damaging flood is one that destroys or causes severe damage to the crop, land or infrastructure. Where required, a damaging flood may be defined quantitatively in terms of period of inundation and/or speed of flow or volume of discharge of moving water. The following scale

can be applied quantitatively where data are available, but will usually form the basis for subjective estimation.

Frequency of damaging floods:

Very rare or never Less than 1 year in 20 or never known to occur

Rare Less than 1 year in 5Infrequent Between 1 year in 5 and one per yearVery frequent More than 5 times per year

Storm, hail and wind hazard


The exposure of land to storm and wind and the susceptibility or tolerance to these for different crops often needs assessment in land evaluation. A judgement needs to

be made of the economic impact which is probable for respective land units and crops. Two aspects are the general prevalence of the hazard (e.g. wind) and the

occurrence of special events such as high intensity rainfall, cyclones and hurricanes. The latter are considerations in the selection of LUTs, but the extent of the damage and the ability of the crop to survive and sustain production after the event may be

aggravated at specific sites, which could be differentiated into factor ratings. Amongst crops there is a clear distinction between short-term crops and perennial

crops. The survival of short-term crops in the event of an infrequent storm hazard is of less consequence than for tree crops and orchards which might be completely

destroyed. Bananas have the capability of regrowth from underground shoots if the above ground parts of the plant are destroyed; most tree crops do not have this

capability. Hail can severely damage or destroy crops in many parts of the world and may have a bearing on the crops chosen. Hail damage is often very localized. The possibility of

insurance against hail damage may also affect the choice of crops.

Frost hazard


Where it occurs, frost can be an important land class-determining factor. Frost pockets occur in valley floors owing to katabatic air movements. Frost can destroy the flowers of

temperate fruit crops and consequently affect yields. Rare frosts are particularly important in the case of orchards (e.g.

citrus) where trees of all ages may be destroyed. Damaging frosts can be defined in terms of temperatures,

duration, and periods of the year during which damage may occur using data from climatic records. Local experience is often helpful in indicating the effect of landforms (i.e. the

greater incidence in valley floors and the increase in incidence with altitude).

SOIL Temperature regime.

Sumber: http://passel.unl.edu/pages/informationmodule.php?idinformationmodule=1130447033&topicorder=12&maxto=13

In soil taxonomy, soil temperature regimes are based on mean annual soil temperatures. Soil temperatures are taken at a depth of 50 cm

from the soil surface, using the Celsius (centigrade) scale. These regimes greatly affect the use and management of soils, particularly for the selection of adapted plants. The ten soil temperature regimes are cryic, frigid, hyperthermic, isofrigid, isohyperthermic, isomesic,

isothermic, mesic, pergelic, and thermic.

The cryic soil temperature regime has mean annual soil temperatures of greater than 0 °C, but less than 8

°C, with a difference between mean summer and mean winter soil temperatures greater than 5 °C at 50 cm, and cold summer

temperatures.

REZIM SUHU TANAH


The frigid soil temperature regime has mean annual soil temperatures of greater than 0 °C, but less than 8 °C, with a

difference between mean summer and mean winter soil temperatures greater than 5 °C at 50 cm below the surface,

and warm summer temperatures.

The hyperthermic soil temperature regime has mean annual soil temperatures of 22 °C or more and a difference between

mean summer and mean winter soil temperatures of less than 5 °C at 50 cm below the surface.


The isofrigid soil temperature regime has mean annual soil temperatures of greater than 0 °C, but less than 8 °C, with a

difference between mean summer and mean winter soil temperatures of less than 5 °C at 50 cm. below the surface,

and warm summer temperatures.

The isohyperthermic soil temperature regime has mean annual soil temperatures of 22 °C or more and a difference

between mean summer and mean winter soil temperatures of less than 5 °C at 50 cm below the surface.

REZIM SUHU TANAH


The isomesic soil temperature regime has a mean annual soil temperatures of 8 °C or more, but a difference between mean summer

and mean winter soil temperatures of less than 5 °C at 50 cm below the surface.

The isothermic soil temperature regime that has mean annual soil temperatures of 15 °C or more but, 5 °C difference between mean summer and mean winter soil temperatures at 50 cm. below the

surface.

The mesic soil temperature regime has mean annual soil temperatures of 8 °C or more, but less than 15 °C, and the difference between mean summer and mean winter soil temperatures is greater than 5 °C at 50

cm below the surface.

REZIM SUHU TANAH


The pergelic soil temperature regime has mean annual soil temperatures of less than 0 °C at 50 cm below the surface.

In this terperature regime, permafrost is present.

ThermicThe thermic soil temperature regime has mean annual soil temperatures of 15° C or more, but less than 22 °C; and a difference between mean summer and mean winter soil

temperatures of greater than 5 °C at 50 cm below the surface.

REZIM SUHU TANAH

Radiation energy and photoperiod.

Sumber: http://www.fao.org/docrep/X5648E/x5648e0e.htm

Three relevant aspects of radiation are (i) daylength, (ii) its influence on photosynthesis and dry matter accumulation in crops, and (iii) its effects on

evapotranspiration. Radiation levels may also be important in the drying and ripening of crops, but this is evaluated under heading B.17.

Daylength may be a relevant class-determining factor in evaluations carried out at low intensity across different latitudes as already discussed under 'Growing Period'

(Tables 32 and 33). Daylength affects photoperiod-sensitive cultivars of crops such as rice, influencing floral initiation and the onset or length of vegetative and

reproductive phases of growth and development. The interaction of daylength with water availability or temperature can sometimes prove 'class-determining' at project

level (e.g. in influencing the flowering of sugarcane, flowering and fruiting of mangoes, and in the bulbing and ripening of onions, etc.).

The influence of radiation on photosynthesis and dry matter accumulation in crops has been reviewed by Monteith (1972).

PHOTOPERIODISME.

Sumber: http://en.wikipedia.org/wiki/Photoperiodism

Photoperiodism is the physiological reaction of organisms to the length of day or night. It occurs in

plants and animals.

Photoperiodism can also be defined as the developmental responses of plants to the relative lengths of the light and

dark periods.

Here it should be emphasized that photoperiodic effects relate directly to the timing of both the light and dark

periods.



Long-day plants flower when the day length exceeds their critical photoperiod. These plants typically flower in the

northern hemisphere during late spring or early summer as days are getting longer. In the northern hemisphere, the longest day of the year is on or about 21 June (solstice).

After that date, days grow shorter (i.e. nights grow longer) until 21 December (solstice). This situation is reversed in the southern hemisphere (i.e. longest day is 21 December and

shortest day is 21 June). In some parts of the world, however, "winter" or "summer" might refer to rainy versus dry seasons, respectively, rather

than the coolest or warmest time of year.



Short-day plants flower when the day lengths are less than their critical photoperiod. They cannot flower under long days or if a pulse of artificial light is shone on the plant for several minutes during the middle of the night; they require a consolidated period of darkness

before floral development can begin. Natural nighttime light, such as moonlight or lightning, is not of sufficient brightness or duration to

interrupt flowering.

In general, short-day (i.e. long-night) plants flower as days grow shorter (and nights grow longer) after 21 June in the northern hemisphere, which is during summer or fall. The

length of the dark period required to induce flowering differs among species and varieties of a species.

Calculating Photoperiods.

Sumber: http://www.learner.org/jnorth/tm/mclass/KidsCalculatingPhotoperiod.html

sunset 9:36 convert to 24 hour clock

21:36

sunrise 6:14 - 6:14

photoperiod 15:22 15 hours and 22 minutes

Convert sunrise and sunset numbers to a 24-hour clock and subtract sunrise from

sunset.

Photoperiod: Duration of Irradiation

Sumber: http://www.ag.auburn.edu/hort/landscape/lightduration.html

Duration refers to the period of time in 24 hours that plants are exposed to light. In temperate regions where greenhouse crops are

grown, day length changes seasonally. This change results occurs because the earth's axis is tilted 23½ degrees from a line perpendicular

to the plane of the earth's orbit about the sun. At the equator, the day length is relative constant at 12 hours and 7 minutes during the year. As the distance from the equator increases (north latitude), day lengths are longer in the summer and shorter in

the winter. The longest day of the year is the summer solstice ( June 21) and the ≃shortest is the winter solstice ( December 21). Day and night lengths ≃

are equal on the autumnal equinox ( September 21) and vernal ≃equinox ( March 21). When considering day length, weather services ≃report sunrise to sunset, however many plants can perceive twilight.

So day length for plants is sunrise to sunset plus twilight.

Illustration of the radiation balance.


Solar radiation (Rs)


Solar radiation (Rs) is that part of the extraterrestrial radiation which is not absorbed and scattered when passing through the atmosphere, together with some of the scattered radiation that also reaches the

earth's surface. A proportion of this radiation (about 50%) is photosynthetically active radiation (PAR) (Szeicz 1974). Values of solar radiation can be obtained from direct measurements or approximated

by using:

Rs = (0.25 + 0.05 n/N) Ra,

where n is the actual bright sunshine hours (e.g. measured with a Campbell Stokes solarimeter) and M is the maximum possible

sunshine hours for a given month and latitude

Climatic hazards affecting plant growth (including wind, hail, frost).

Sumber: http://www.geogonline.org.uk/g3a_ki4.2.htm

Definition of a climatic hazard:1. Extreme climatic/weather event(s) causing harm and damage to

people, property, infrastructure and land uses. 2. It includes not only the direct (primary) impacts of the

climate/weather event itself but also 3. the other indirect (secondary) hazards 'triggered' by that event e.g.

land slides 'triggered' by torrential rain.

The Impact is dependent upon:4. The severity of the event and also the path/track and spatial extent of that

weather event.5. The density and distribution of the people and density and types of human

activity in the areas affected.6. The preparedness and capacity of the authorities and people to cope with the

impact of the event.

HAIL = HUJAN ES-BATU

Sumber: http://en.wikipedia.org/wiki/Hail

Hail is a form of solid precipitation. It consists of balls or irregular lumps of ice, each of which is called a hailstone. Unlike graupel, which

is made of rime, and ice pellets, which are smaller and translucent, hailstones – on Earth – consist mostly of water ice and measure

between 5 and 200 millimetres (0.20 and 7.9 in) in diameter.

The METAR reporting code for hail 5 mm (0.20 in) or greater is GR, while smaller hailstones and graupel are coded GS. Hail is possible within most thunderstorms as it is produced by cumulonimbi, and

within 2 nautical miles (3.7 km) of the parent storm. Hail formation requires environments of strong, upward motion of air with the parent

thunderstorm (similar to tornadoes) and lowered heights of the freezing level.

In the mid-latitudes, hail forms near the interiors of continents, while in the tropics, it tends to be confined to high elevations.

ANGIN

Sumber: http://en.wikipedia.org/wiki/Wind

Wind is the flow of gases on a large scale. On the surface of the Earth, wind consists of the

bulk movement of air.

Winds are commonly classified by their spatial scale, their speed, the types of forces that

cause them, the regions in which they occur, and their effect.


General wind classifications Tropical cyclone classifications (all winds are 10-minute averages)

Beaufort scale[18]

10-minute sustained

winds (knots)General term

[21]

N Indian OceanIMD

SW Indian Ocean

MF

Australian region

South PacificBoM, BMKG, FMS, MSNZ

NW PacificJMA

NW PacificJTWC

NE Pacific &N Atlantic

NHC & CPHC

0 <1 Calm

Low Pressure Area

Tropical disturbance Tropical low

Tropical Depression

Tropical depression

Tropical depression

Tropical depression

1 1–3 Light air

2 4–6 Light breeze

3 7–10 Gentle breeze

4 11–16 Moderate breeze

5 17–21 Fresh breezeDepression

6 22–27 Strong breeze

728–29

Moderate gale Deep depression Tropical depression30–33

8 34–40 Fresh galeCyclonic storm Moderate tropical

stormTropical cyclone

(1) Tropical storm

Tropical storm Tropical storm9 41–47 Strong gale

10 48–55 Whole gale Severe cyclonic storm

Severe tropical storm

Tropical cyclone (2)

Severe tropical storm11 56–63 Storm

12 64–72

Hurricane

Very severe cyclonic storm

Tropical cycloneSevere tropical

cyclone (3)

Typhoon

Typhoon

Hurricane (1)

13 73–85 Hurricane (2)

14 86–89Severe tropical

cyclone (4)

Major hurricane (3)15 90–99

Intense tropical cyclone16 100–106

Major hurricane (4)

17

107–114

Severe tropical cyclone (5)

115–119Very intense

tropical cyclone Super typhoon>120 Super cyclonic

stormMajor hurricane

(5)

http://en.wikipedia.org/wiki/Beaufort_scale

http://en.wikipedia.org/wiki/Wind

http://en.wikipedia.org/wiki/Knot_%28unit%29

http://en.wikipedia.org/wiki/Wind

http://en.wikipedia.org/wiki/Indian_Meteorological_Department

http://en.wikipedia.org/wiki/M%C3%A9t%C3%A9o-France

http://en.wikipedia.org/wiki/Bureau_of_Meteorology_%28Australia%29

http://en.wikipedia.org/wiki/Indonesian_Agency_for_Meteorology,_Climatology_and_Geophysics

http://en.wikipedia.org/wiki/Fiji_Meteorological_Service

http://en.wikipedia.org/wiki/Meteorological_Service_of_New_Zealand_Limited

http://en.wikipedia.org/wiki/Japan_Meteorological_Agency

http://en.wikipedia.org/wiki/Joint_Typhoon_Warning_Center

http://en.wikipedia.org/wiki/National_Hurricane_Center

http://en.wikipedia.org/wiki/Central_Pacific_Hurricane_Center

ENERGI ANGIN

Wind energy is the kinetic energy of the air in motion.

Total wind energy flowing through an imaginary area A during the time t is:

E = A·v·t·ρ·½ v2, where v is the wind velocity and ρ is the air density. The formula

presented is structured in two parts: (A·v·t) is the volume of air passing through A, which is considered perpendicular to the wind velocity;

(ρ·½ v2) is the kinetic energy of the moving air per unit volume.Total wind power is:P = E/t = A·ρ·½ v3

Wind power is thus proportional to the third power of the wind velocity.


KELEMBABAN UDARA – PERTUMBUHAN TANAMAN

Sumber: http://en.wikipedia.org/wiki/Relative_humidity

Relative humidity is the ratio of the partial pressure of water vapor in an air-water

mixture to the saturated vapor pressure of water at a prescribed temperature.

The relative humidity of air depends not only on temperature but also on the pressure of the

system of interest.

Air humidity as affecting plant growth.

Sumber: http://en.wikipedia.org/wiki/Relative_humidity

The relative humidity of an air-water mixture is defined as the ratio of the partial pressure of water vapor (H2O) in the mixture to the saturated

vapor pressure of water at a given temperature.Relative humidity is normally expressed as a percentage and is

calculated by using the following equation:

The humidity of an air-water vapor mixture is determined through the use of psychrometric charts if both the dry bulb temperature (T) and the

wet bulb temperature (Tw) of the mixture are known. These quantities are readily estimated by using a sling psychrometer.

Psychrometric charts

Sumber: http://www.pinguicula.org/pages/culture/Overview.htm

.

Psychrometric charts

Sumber: http://philipmarshall.net/Teaching/rwuhp382/wood/psychrometric_chart_ex_1.htm

.

Measuring relative air humidity with dry and wet bulb temperatures

Sumber:http://www.engineeringtoolbox.com/humidity-measurement-d_561.html

.

Relative Humidity - RH (%)

Difference Between Dry

Bulband Wet Bulb Temperatures

Tdb - Twb (oC)

Dry Bulb Temperature - Tdb (oC)

15 18 20 22 25 27 30 33

1 90 91 91 92 92 92 93 932 80 82 83 84 85 85 86 873 71 73 75 76 77 78 79 804 62 65 67 68 70 71 73 745 53 57 59 61 64 65 67 696 44 49 52 54 57 59 61 637 36 42 45 47 51 53 55 588 28 34 38 41 45 47 50 539 21 27 31 34 39 41 45 48

10 13 20 25 28 33 36 40 43

GROWING PERIOD


The growing cycle is the period required for an annual crop to complete its annual cycle of establishment, growth and production of harvested part. Perennial crops have growing cycles of more than one

year. The growing period for annual crops is the duration of the year when temperature, soil. water supply and other factors permit crop growth

and development. Thus, a growing cycle is a property of the crop (i.e. a crop requirement) whereas a growing period is a condition of the land (i.e. a land quality

or land characteristic). Growing periods can be constrained by wet or humid conditions that limit opportunities for ripening and drying the crop, or which lead to

problems of quality (e.g. reduced sugar content of sugarcane, staining of cotton, blemishes on fruits, etc.).

DRYING PERIODS FOR RIPENING OF CROPS.

Sumber: FAO 1980c, p. 355; Higgins and Kassam 1981.

MAJOR CLIMATES

Climate

Major climates during growing

period 24 hr mean (daily)

temperature (C) regime during the growing

period

Suitable for consideration for crop group

(Table 33)

No. Descriptive name

TropicsAll months with monthly mean temperatures,

corrected to sea level, above 18°C

1 Warm tropics More than 20 II and III

2 Moderately cool tropics

15-20 I and IV

3 Cool tropics 5/10 - 15 I

4 Cold tropics Less than 5 Not suitable

DRYING PERIODS FOR RIPENING OF CROPS.

Sumber: FAO 1980c, p. 355; Higgins and Kassam 1981.

MAJOR CLIMATESSubtropics

One or more months with monthly mean

temperatures, corrected to sea level,

below 18°C but all months above 5°C

5 Warm/moderately cool subtropics (summer rainfall)

More than 20 II and III

6 Warm/moderately cool subtropics (summer rainfall)

15 - 20 I and IV

7 Warm subtropics (summer rainfall)

More than 20 II and III

8 Moderately cool subtropics (summer rainfall)

15 - 20 I and IV

9 Cool subtropics (summer rainfall) 5/10 - 20 I

10 Cold subtropics (summer rainfall) Less than 5 Not suitable

11 Cool subtropics (winter rainfall) 5/10 - 20 I

12 Cold subtropics (winter rainfall) Less than 5 Not suitable

CROP ADAPTABILITY GROUPS, BASED ON PHOTOSYNTHETIC PATHWAY AND RESPONSE TO RADIATION AND TEMPERATURE

TE = Temperate cultivars; TR = Tropical (lowland) cultivars; TH = Tropical (highland) cultivars. Source: Based on information extracted from FAO 1978a and FAO 1980c.

Crop adaptability

group

I II III IV V

Photo-synthetic pathway

C3 C3 C4 C4 CAM

Optimum temperature for photosynthesis

(°C)

15-20 25-30 30-35 20-30 25-35

SugarbeetPhaseolus

WheatBarleyOats

PotatoBean (TE)Chickpea

Soybean (TR)Phaseolus; Rice

CassavaSweet Potato

Yams; Bean (TR)Groundnut

Cotton; TobaccoBanana; CoconutRubber; Oil palm

Sorghum (TR)Maize (TR)Pearl millet

PanicumMillet (TR)

Finger milletSetaria

Sugarcane

PanicumMillet (TE, TH)Sorghum (TE,

TH)Maize (TE, TH)

Setaria

SisalPineapple

GROWING PERIOD

Sumber:http://www.fao.org/docrep/X5648E/x5648e0e.htm

Type of growing period (under rainfed conditions which might be modified by irrigation) – Normal.

a - Beginning of rains and growing period

b1 and b2 - Start and end of humid period

respectivelyc - End of rains and rainy

seasond - End of growing period

P - PrecipitationPET - Potential

evapotranspiration (after FAO 1978a)

GROWING PERIOD


Type of growing period (under

rainfed conditions which might be

modified by irrigation) -

Intermediate

GROWING PERIOD


Type of growing period (under


modified by irrigation) - All

year round humid

GROWING PERIOD


type of growing period (under


modified by irrigation) - All year round dry

LAND QUALITIES RELATED TO DOMESTIC ANIMAL PRODUCTIVITY

PRODUKTIVITAS LAHAN GEMBALAAN :

1. Climatic hardships affecting animals.2. Endemic pests and diseases.3. Nutritive value of grazing land.4. Toxicity of grazing land.5. Resistance to degradation of vegetation.6. Resistance to soil erosion under grazing

conditions.7. Ketersediaan Air Minum.


LAND QUALITIES RELATED TO FOREST PRODUCTIVITY

The qualities listed may refer to natural forests, forestry plantations, or both.

Mean annual increments of timber species :

1.Types and quantities of indigenous timber species.2.Site factors affecting establishment of young trees.3.Hama dan Penyakit.4.Bahaya Kebakaran.


LAND QUALITIES RELATED TO MANAGEMENT AND INPUTS

1. The qualities listed may refer to arable use, animal production or forestry.

2. Terrain factors affecting mechanization (trafficability).3. Terrain factors affecting construction and maintenance of

access-roads (accessibility).4. Size of potential management units (e.g. forest blocks,

farms, fields).5. Location in relation to markets and to supplies of inputs.


Land qualities related to vertical components of a natural land unit

ATMOSPHERIC QUALITIES1. Atmospheric moisture supply: rainfall, length of

growing season, evaporation, dew formation.2. Atmospheric energy for photosynthesis:

temperature, daylength, sunshine conditions.3. Atmospheric conditions for crop ripening,

harvesting and land preparation: occurrence of dry spells.



LAND COVER QUALITIES1. Value of the standing vegetation as "crop", such as timber.2. Value of the standing vegetation as germ plasm: biodiversity value.3. Value of the standing vegetation as protection against degradation

of soils and catchment.4. Value of the standing vegetation as regulator of local and regional

climatic conditions.5. Regeneration capacity of the vegetation after complete removal.6. Value of the standing vegetation as shelter for crops and cattle

against adverse atmospheric influences.7. Hindrance of vegetation at introduction of crops and pastures: the

land "development" costs.8. Incidence of above-ground pests and vectors of diseases: health

risks of humans and animals.



LAND SURFACE AND TERRAIN QUALITIES

1. Surface receptivity as seedbed: the tilth condition.2. Surface treatability: the bearing capacity for cattle, machinery, etc.3. Surface limitations for the use of implements (stoniness, stickiness, etc.): the

arability.4. Spatial regularity of soil and terrain pattern, determining size and shape of fields

with a capacity for uniform5. management.6. Surface liability to deformation: the occurrence or hazard of wind and water

erosion.7. Accessibility of the land: the degree of remoteness from means of transport.8. The presence of open freshwater bodies for use by humans, animals or fisheries.9. Surface water storage capacity of the terrain: the presence or potential of

ponds, on-farm reservoirs, bunds, etc.10. Surface propensity to yield run-off water, for local water harvesting or

downstream water supply.11. Accumulation position of the land: degree of fertility renewal or crop damaging

by overflow or overblow.Sumber: FAO Land and Water Bulletin No. 5. 1997


SOIL QUALITIES1. Physical soil fertility: the net moisture storage capacity in the

rootable zone.2. Physical soil toxicity: the presence or hazard of waterlogging in the

rootable zone (i.e. the absence of oxygen).3. Chemical soil fertility: the availability of plant nutrients.4. Chemical soil toxicity: salinity or salinization hazard; excess of

exchangeable sodium.5. Biological soil fertility: the N-fixation capacity of the soil biomass;

and its capacity for soil organic matter turnover.6. Biological soil toxicity: the presence or hazard of soil-borne pests

and diseases.7. Substratum (and soil profile) as source of construction materials.8. Substratum (and soil profile) as source of minerals.9. Biological soil toxicity: the presence or hazard of soil-borne pests

and diseases. Sumber: FAO Land and Water Bulletin No. 5. 1997


SUBSTRATUM OR UNDERGROUND QUALITIES

1. Groundwater level and quality in relation to (irrigated) land use.

2. Substratum potential for water storage (local use) and conductance (downstream use).

3. Presence of unconfined freshwater aquifers.4. Substratum (and soil profile) suitability for

foundation works (buildings, roads, canals, etc.)


The GLASOD criteria for degrees of land degradation tried to specify resilience as follows:

1. Light degradation: The terrain has somewhat reduced agricultural suitability, but is suitable for use in local farming systems. Restoration to full productivity is possible by modifications of the management system. Original biotic functions are still largely intact.

2. Moderate degradation: The terrain has greatly reduced agricultural productivity but is still suitable for use in local farming systems. Major improvements are required to restore productivity. Original biotic functions are partially destroyed.

3. Strong degradation: The terrain is non-reclaimable at farm level. Major engineering works are required for terrain restoration. Original biotic functions are largely destroyed.

4. Extreme degradation: The terrain is unreclaimable and beyond restoration. Original biotic functions are fully destroyed.


FIGURE 1. Some concepts of resilience of land and its productivity, comparing the situation in some industrialized countries (A) with that of most developing countries

(B). Source: Sombroek, 1993


LQILAND QUALITY INDICATOR


PSR – PRESSURE STATE RESPONSE


Three groups of LQIs have been developed to reflect the PSR structure:

Group 1. Pressure on the land resource

Indicators in this group include those activities that relate to the degree of intensification and diversification of agricultural land

uses, and result in increased pressure on land quality.

This may include :1. the number of crops in a cropping system per year or per

hectare, 2. type and intensity of tillage, 3. degree of removal of biomass, 4. integration with livestock systems, 5. number of food and fibre products produced annually, etc.


Three groups of LQIs have been developed to reflect the PSR structure: Group 1. Pressure on the land resource

These indicators must be seen within the context of major socio-demographic factors such as population pressures,

land tenure, etc., but the latter do not qualify for inclusion as LQIs.

This is because these major forces do not influence land quality directly, but rather through the land practices that

are adopted by farmers as a consequence. It is these management systems and their impacts that we

wish to capture as LQIs, although changes in the major driving forces may provide some "early warning" signals .


Group 2. State of land qualityState indicators reflect the conditions of the land as well as its

resilience to withstand change as a consequence of sector pressures.

This may include indicators which express :1. Changes in biological productivity (actual and potential), 2. Extent and impacts of soil degradation, including erosion,

salinization, etc., 3. Annual and long-term balance of nutrients (exported and imported

by the cropping systems), 4. Degree and type of contamination or pollution (by direct

application, atmospheric transport, etc.), 5. Changes in organic matter content, water holding capacity, etc.

The changes in state may be negative with poor management, or positive with good management.


Group 3. Societal response(s)The response mechanisms are normally achieved through direct

actions by the farmers themselves in evolving or adopting improved land management systems, or through complementary activities whereby adoption of conservation technologies is stimulated by

general economic, agricultural and conservation policies and programmes. In rare instances, environmental regulations may be necessary to effect proper control of land resource degradation.

Response indicators may include number and types of farmer organizations for soil conservation, extent of change in farm

technologies, risk management strategies, incentive programmes for adoption of conservation technologies, etc.

Response indicators should be distinguished into those categories promoted by governments, those undertaken by individual farmers

and those supported by agri-business.


Erosion Productivity Impact Calculator (EPIC):

EPIC was developed by the United States Department of Agriculture (USDA) and Agricultural Research Service (ARS) originally as a tool to analyse the impacts of soil management and erosion on crop yields, but more recently it has been expanded to include assessments of

water quality, pesticides, etc. EPIC consists of ten major subroutines, namely, weather, hydrology, wind and water erosion, nitrogen and phosphorus transformations,

soil temperature, crop growth, tillage, plant environment control (irrigation, lime, etc.), pesticide routines and economic crop budgets. Interim and final output is available from each subroutine, either in daily, monthly or annual increments. Although the model inputs are flexible through the use of many data defaults (for missing data), the model requires reliable data on soil properties, crop inputs and tillage

management (weather is generated through a weather generator).



EPIC generates several potentially useful outputs for LQIs, namely:

1. yield, for several economically important crops;2. erosion, wind and water, rate (t/ha) and impacts

on yield;3. change in nitrogen and phosphorus (crude

estimate).



Rates of change are calculated by running EPIC using various land management scenarios over many years (usually 30

years).

Increasingly, EPIC is being adapted to many temperate as well as tropical regions as a tool to evaluate land

management practices, particularly tillage and residue management.

It also has been integrated with large economic optimizing models to provide analytical systems for evaluation of

environmental impact prior to implementation of agricultural policies and programmes.


CENTURY

The CENTURY model simulates the effects of erosion on long-term storage of soil organic carbon under field

conditions. Briefly, soil organic matter is divided into pools with active (1.5y), slow (25y) and passive (1 000y) turnover

rates. A plant production subroutine simulates the allocation of carbon into

shoots and roots, dividing plant residue into a metabolic (0.1-1y) and a structural (1-5y) pool based on the lignin:nitrogen ratio. The model then transfers the carbon to the soil, and simulates carbon stability

through interactions with clay and organic molecules. Estimates of soil carbon change are obtained by running CENTURY under initial (usually

current) conditions, then again for future scenarios under new management technologies.


CENTURY

Output useful for LQIs include:

1. total soil carbon, used to estimate carbon sequestration;

2. rapid turn-over fraction, a surrogate for microbial biomass

In terms of land quality, rapid turn-over of carbon is a better LQI than total carbon.


NUTMON:

This is a recently developed model for estimating regional losses or gains of nutrients as a consequence of nutrient inputs (mineral fertilizers, organic manures,

wet and dry deposition, nitrogen fixation, sedimentation), compared to nutrient losses (harvested product, crop residue removal, leaching, erosion, denitrification)

(Smaling, 1993).

Data for nutrient inputs and nutrients removed by harvest are gathered for various land use systems, and estimates for the other variables are calculated using various

available models.

NUTBAL then calculates whether the systems are gaining or losing for each macronutrient. Results can be extrapolated to wider areas using GIS techniques.

NUTBAL is still experimental, but it has been used for studies in Kenya with goodsuccess.


SUSTAINABILITY REFERENCE SYSTEMS (SRS)The sustainability barometer of Prescott-Allen (1996)

Prescott-Allen (1996) has proposed a "sustainability barometer" based on a graphical representation of the location of an exploited

ecosystem on an orthogonal system in which the two axes represent indexes of human well-being and of ecosystem well-being, considered

as the two fundamental dimensions of sustainability. The aim of the barometer is to (a) give a picture of the whole system; (b) treat ecosystem and human well-being as equally important; (c) facilitate a rigorous and transparent progress towards sustainability.

Used as orthogonal axes, the human and ecological dimensions, with a scale normalized between 0 and 1, provide an orthogonal system of

reference in which the position of an exploitation system (e.g., a fishery) can be located if the corresponding values on the two axes can

be estimated.


Static representation of sustainability. The Sustainability Reference System (SRS) slightly modified from the "Sustainability Barometer" of Prescott-Allen (1996)


SUSTAINABILITY REFERENCE SYSTEMS (SRS)

The scales of the barometer include also "value judgements" corresponding to the various intervals on the axes, e.g. the 0.0-

0.2 interval is considered "Bad" while the 0.8-1.0 interval is considered "Good". Prescott-Allen stresses the importance of the

"scaling" of the barometer and the amount of case-specific judgement involved in it.

The paper does not explain how the numerical value of the coordinates is arrived at but examples are given in this paper in the

specific case of fisheries. Prescott-Allen called it a "sustainability barometer“ used to "measure" exploitation pressure, by analogy with

the instrument used to measure atmospheric pressure. Because this device does not provide a "measure" of sustainability but

helps representing it, locating an exploited ecosystem in a system of reference, in the rest of this paper I shall refer to it and to other similar

devices as "Sustainability Reference Systems“ (SRSs).Sumber: FAO Land and Water Bulletin No. 5. 1997

The indicator of change. The four quadrants represent the areas of unsustainability (U), sustainability (S), as well as social and ecological instability (SU, EU).


SUSTAINABILITY REFERENCE SYSTEMS (SRS)

Figure illustrates this additional concept.

Assuming that a fishery could be located on a SRS, the direction in which (and the rate at which) the

situation is changing would be as important as the position on the SRS.

Direction and rate of change would indeed provide useful foresight.


Dynamic representation of sustainability:combination of the SRS and the IC. The strings of white squares illustrate different

“trajectories” of the fishery in the SRS.


A sustainability kite diagram

Star diagrams are often used to represent multivariate properties of a system, e.g., to summarize the performance

of a computer with scores referring to its performance in terms of processor velocity, RAM capacity, hard disk

capacity, file transfer speed, energy efficiency, interface user-friendliness, etc.

A theoretical example of such a diagram and illustrates the fact that it can be used to compare the profile (the

"signature") of different systems including the "ideal" one with optimal values for all parameters.


Theoretical example of a star diagram


Theoretical example of a 4-axis isometric SRS. The situation of a particular fishery is represented on it by a “kite”.


SRS - SUITABILITY REFERENCE SYSTEM A theoretical example of such a diagram for fisheries, using

only 4 axes (kite diagram) for the sake of simplicity. The parameters represented are arranged in two domains corresponding respectively to ecosystem and human well-

being (in order to remain in the terminology used by Prescott-Allen (1996).

Each axis can be scaled from 0 to 1 and the grey scale refers to the assessment categories used in the preceding SRS (black= Bad, light

grey= Good). A fishery can be re-presented on this referential system by a polygon and two fisheries can be compared by comparing their polygons. In addition, the position of the polygon in relation to each

axis indicates in which sphere action might be required to improve the situation.


SEKALA SUMBU SRS

Prescott-Allen gives a detailed account of many of the problems encountered and options available when scaling the axes of the SRS.

Scaling requires the determination of the scale boundaries (0-1 or 0-100) and the relevant subdivisions of that scale according to the value judgements (e.g., deciding whether "Bad" goes from 0 to 0.2 or from 0

to 0.5).

The latter could sometimes be arbitrary or conventional, but should in most instances refer to the target and limit reference points.

In the example given by Prescott-Allen for the sustainability barometer the two axes are scaled from 0 to 1 and the value judgements (i.e.,

Good to Bad) are evenly distributed on both axes.


SEKALA SUMBU SRS

In most instances, the true values of the sustainability indicators (e.g., the size of the spawning biomass) will not be between 0 and 1 but, say,

between the value of Bv, the biomass of the virgin stock, and zero. In this case, rescaling will be needed, e.g., by using ratio indicators (e.g.,

B/Bv).

In the section on "Indicators of level", above, an attempt has been made to scale, from 0 to 1, the degree of people’s participation in a management system and arbitrary value judgements were given.

To use the SRS, the same effort would be required for all potentially useful indicators, using as quantitative methods as possible for the

estimates, and a set of criteria for the value judgements.


Theoretical example of a 4-axes anisometric SRS.


Stochastic and dynamic representation of a sustainability kite.


LAND QUALITYThree broad types of key indicators OF LAND QUALITY may be the

most important:

a. Above the soil surface, as related with yields:1. Cover close to the ground: its density, distribution, duration,

timing.2. Stress in plants: growth rates; timing and frequency of wilting;

visible nutrient deficiencies or imbalances.

b. On the soil surface, as affecting particularly soil moisture and runoff + erosion:

Porosity of at least topsoil layers, in millimetric bands: proportions of incident rainfall becoming infiltrated;

Sumber:Sumber: FAO Land and Water Bulletin No. 5. 1997

LAND QUALITYc. Below the soil surface:Organic matter content and biological activity, as affecting multiple features:

Soil architecture:. structural stability;. gas exchange. water movement and retention/release;

Cation exchange capacity:. nutrient capture and retention;. pH buffering;. nutrient availability;. source of small amounts of recycled nutrients.

Sumber:Sumber: FAO Land and Water Bulletin No. 5. 1997

EVALUASI KUALITAS LAHAN

evaluasi lahan dan indikator lahan

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