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  • Rob Banks SoilFutures

Indonesian Soils - Lessons in Sustainability

How long can we farm for? Lessons from Indonesia (Plus A Bonus Soil Type)

As the NSW COVID lockdown has curtailed most work activity for now, I thought I might take the time to present some interesting findings I came across whilst working in Java between 2011 – 2013. I have been privileged to work with local people, both academics and farmers, from one end of Java to the other. Unlike Australia, Indonesia has been heavily populated for tens of thousands of years and has sported intensive agriculture for at least 5000 - 6000 years.

And I found that Indonesia is an excellent place to see long term impacts of agriculture on soil.


To my embarrassment as an Australian, I really had not learned much about our closest neighbour as I grew up, so Java has been a great place for me to learn yet another language as well as about a whole lot of cultures. During my time in the field, I was amazed by the landscapes, the soils, the history and the beautiful inclusive people of the island of Java whom I found to be some of the most kind and generous people that I have met anywhere in the world. This was despite them being generally very poor by our standards.

Locations mentioned in this text.


A little bit about Java Geology, Size, Population

Java forms a long island tending east - west and has a population of 148 million people in an area of 128 297 km2 (roughly twice the area of Tasmania), whereas Australia, in comparison, has 25 million people in an area of 7.692 million km2.

Yes. Java is a very crowded island.


Despite this, Java is also generally self-sufficient in basic agricultural produce, despite intense pressures on the land.


Most of Java is a volcanic arc island formed by the Indo-Australian plate moving north and under the Eurasian tectonic plate: a subduction zone where one plate is forced up, fracturing the rocks deeply to magma. A chain of 45 main volcanoes has formed along the spine of Java, and at least 15 of these volcanoes are highly active and can be dangerously explosive at times.


Soil types found in Australia that also have long farming history in Java


1. Ngawi Vertosols – East Java

Ngawi is a region situated near the boundary of east and central Java on the Bengawan-Solo River floodplain (elevation about 70m AHD) and features associated quaternary and tertiary alluvium. The Bengawan-Solo River drains a large volcano (Mt Lawu) with mostly mafic geology (mostly alkaline volcanic rocks rich in iron, magnesium, calcium, silicon, and aluminium). The dominant sediments that occur on the floodplain are smectite clays derived from basaltic material, with very minor occurrences of marl and sands.


Ngawi is well known archeologically, firstly for a site by a local village (called Trinil) being where Pithecanthropus sp. “Java Man” was discovered, and additionally due to agricultural artifacts found all over the region dating back to at least 12 000 years BP.

Some artefacts within vicinity of Java Man indicate that his people may even have had a crude agriculture as long as 80 000 years ago. This has not been concretely proven, but it does provoke some thought on what other species of humans did in the area. Regardless, Ngawi is still one of the earliest settled agricultural districts in the world.


The climate of Ngawi is a wet-dry tropical one with a dry season that extends from May to October. Reported rainfall is highly variable, ranging from 2500 to 4860mm since 2006. It appears that the climate in Ngawi may be partly under the influence of the southern oscillation index which determines drought and rain periods in Australia, to the south of Java.


Vertosol Definition: Clay soils with shrink-swell properties that exhibit strong cracking when dry and swelling when wet, and at depth have slickensides and/or lenticular peds. Although many soils exhibit gilgai microrelief, this feature is not used in their definition. Australia has the greatest area and diversity of cracking clay soils of any country in the world and includes soils with the following: 1. A clay field texture or 35% or more clay throughout the solum except for thin, surface crusty horizons 3cm or less thick 2. When dry, open cracks occur at some time in most years. These are at least 5mm wide and extend upward to the surface or to the base of any plough layer, peaty horizon, self-mulching horizon, or thin, surface crusty horizon; and Slickensides and/or lenticular peds occur at some depth in the solum. (Australian Soil Classification Edition 3) Note: Most Australian Vertosols are at least 10 million years older than those found in Indonesia! In Australia, our Vertosols in the > 500 mm rainfall zones provide high fertility soils for cereal and fibre production, as well as high quality irrigation lands where water is available.

Amazingly, Ngawi is one of the first areas in the world for irrigated rice agriculture to have developed. The area has been farmed continuously for at least 6,000 years, and still produces 2- 3 crops a year. Generally, there are two crops of rice followed by a break crop (i.e. corn or tobacco, or legumes such as peanuts).


One Ngawi farmer I met personally had records documenting crops and weather data on his land that dated back 500 years! These were annual summaries, burned in a beautiful ancient script onto very thin boards, that were kept as a reference library for the farm.

Although buffalo were once used to pull ploughs, they have since been replaced by small hand driven tractors – which are ironically cheaper to maintain than a single buffalo due to land being so tied into human food production that there is no space for grazing animals, making animal fodder very expensive. Tractors are generally shared between 10 – 15 farming families, and small blocks of about 2 Ha feed and supply a small income for up to 18 people!


What I found amazing about Ngawi is that despite being farmed (or “absolutely hammered”, as we Aussies would say) for about 6 000 years, the soils looked and behaved like Australian vertosols that have been farmed for less than 50 years. This was very encouraging as it indicated that if we take care, we can use these soils for many generations in Australia for sustainable food and fibre production.


However, signs of wear and tear were apparent when we investigated soil chemistry. CEC is a simple measure of soil fertility and is the total capacity of a soil to hold exchangeable cations. It is hard to change the CEC of a soil, but it can become depleted over many years of cultivation.


Ngawi’s soils had quite low (CEC) of about 20. Organic matter has a very high CEC as do swelling clays like the ones commonly found in Vertosols. Similar soils in the Liverpool Plains in Australia have a CEC of 60 – >200. Available calcium was quite low, despite the profile having a large amount of natural lime in the subsoils. Soils were sodic by Australian standards, yet the high clay content (>90%). Its massive shrink and swell capacity was able to prevent unwanted effects of sodicity.


Below is a full soil profile description of one of the Ngawi soils:


Ngawi Soil Profile Descriptions by Horizon. November 10 -11, 2011


Soil Profile Descriptions

Site location: Soil Pit 1 in Rice-rice tobacco Rotation under irrigation at “Plosolor” Village, near Ngawi – East Java. Recorded by Robert Banks and Matthias Lebert.

Map reference: WGS 84 Lat -7.4481240, Long 111.6099255


Physiography: Non active meander plain or low terrace in a stagnant alluvial plain. Parent material is clay alluvium derived from alkaline volcanics such as basalt.

Soil type: Imperfectly drained very deep to giant Calcic Vertisol.

Soil Surface: Self-mulched with evident of former cracking at surface. Surface disturbed and cultivated frequently. Soil is often puddled prior to going into rice rotation. Soil moisture status – wet.


Soil Description

Layer 1, Ap1 horizon, 0 - 0.04 m. Very dark grey (10YR 3/1) whole-colored medium heavy clay with strong pedality. Smooth-faced peds (polyhedral 1 – 4 mm) no coarse fragments present; field pH is 7.0; HCL test is no effervescence; clear (20-50 mm) boundary to...

Layer 2, Bp1 horizon, 0.04 - 0.25 m. Dark grey (10YR 4/1) medium heavy clay with strong pedality (peds angular blocky 20 – 30 mm), strong secondary polyhedral peds (<2mm): <10% orange mottles present. No coarse fragments present; very few (< 2%) calcareous segregations; field pH is 8.0; HCL test is audible, slight effervescence; gradual (50-100 mm) boundary to...

Layer 3, B2 horizon, 0.25 – 0.75 m. Dark grey (10YR 4/1) medium heavy clay with strong pedality (peds prismatic 50 – 100 mm), strong secondary polyhedral peds (<2mm), prominent slickensides abundant: no coarse fragments present; fine calcareous fragments can be felt in bolus and <2% calcareous fragments or nodules present (2 – 5 mm). Field pH is 8.5; HCL test is audible, slight effervescence gradual (50-100 mm) boundary to...

Layer 4, B22 horizon, 0.75 – 1.25 m. Dark grey (10YR 4/1) medium heavy clay with strong pedality (peds lenticular 100 – 200 mm), strong secondary polyhedral peds (<2mm), prominent slickensides abundant: no coarse fragments present; fine calcareous fragments can be felt in bolus and 2 - 5% calcareous fragments or nodules(2 – 5 mm) present; <2% manganese nodules (1 – 5 mm) present; field pH is 9.0; HCL test is moderately visible effervescence; diffuse (>100 mm) boundary to...

Layer 5, B23 horizon, 1.25 – 1.41 m. Dark grey (10YR 4/1) medium heavy clay with strong pedality (peds lenticular 100 – 200 mm), strong secondary polyhedral peds (<2mm); prominent slickensides abundant, and few mangan ped coatings: distinct light grey colored mottles (10 – 20%), : no coarse fragments present; fine calcareous fragments can be felt in bolus and 2 - 5% calcareous fragments or nodules (2 – 5 mm )present; <2% manganese nodules (1 – 5 mm) present; HCL test is moderately visible effervescence; field pH is 9.0. Ground water or soil water seeping in at 1.25 m. Soil continues….

Substrate:alluvium substrate.


Soil Profile: Ngawi Grey Vertosol (FAO – Vertisol)

Classic feature of Vertosols – Slickenside coatings (Shiny ped surfaces) and lenticular shaped peds caused by the shrinking and swelling of the soil mass, polishing ped surfaces.

​This photograph shows the site of the profile, as well as a break crop of tobacco that had mostly been harvested. Break crops like peanuts and tobacco, help dry the profile, and enable the soil to crack and naturally turn over a little, bringing some subsoil to the surface and cycling organic matter down the profile.


Take note of the size of the paddy area, only about 800 m2.One important ingredient in the productivity of this area is the massive rainfall and abundant shallow groundwater.Take note of the size of the paddy area, only about 800 m2. One important ingredient in the productivity of this area is the massive rainfall and abundant shallow groundwater.





2. Sukamaju Red Ferrosols – 60 km west of Bogor in West Java

The area around Sukamaju village forms a large network of eroded valleys where the overlying Quaternary andesitic and ashy volcanic material has been largely removed to reveal the former Tertiary surface. Quaternary andesite and ashy, glassy rich volcanic deposits generally remain on some broader hillcrests and form a colluvial dressing over the underlying sandstone pumiceous tuff and lime dominated sediments.


The landform pattern is generally undulating to rolling low hills, with small areas of steep to precipitous mountains jutting through the dominating terrain.

The sites investigated at Sukamaju Village were on minimal midslopes, which had been terraced for both non-irrigated vegetable gardening and flood irrigated cropping. Elevation was approximately 240m.


The local climate data is expensive to obtain, but some summary data were retrieved: the city of Bogor itself is known as the “City of Rain”, and rain is reported to occur there for 320 days per year. Annual average rainfall is said to range from 3500 – 4500 mm. There is a very short (2 month) dry season in July and August which does not occur in some years.


Red Ferrosol Definition: These soils are almost entirely formed on either mafic or ultramafic igneous rocks, their metamorphic equivalents, or alluvium derived therefrom. Although these soils do not occupy large areas in Australia, they are widely recognised and often intensively used because of their favourable physical properties. The most common forms of ferrosols have B2 horizons with a strong grade of pedality; such horizons typically have polyhedral compound peds up to 10-15 mm, usually with smooth and often shiny faces, which break down readily to primary peds about 5 mm or less in size. However, forms also occur with a very fine granular structure which may appear massive in place. Horizons are usually high in clay and subplastic. Note: Australian Ferrosols are at least 10 million years older than those found in Indonesia In Australia, these soils are often used for high production horticulture, vegetables and some crops depending on rainfall or irrigation water availability. They are relatively rare in Australia but can be locally common in basaltic land with high rainfall from N Queensland to Tasmania. The fine structure of these soils promotes great drainage and rooting medium, although they can be depleted in phosphorous which tends to become locked onto the iron minerals in the clays, rather than being available to plants.



The sites we visited near Bogor generally were split between irrigated rice with break crops or vegetable gardens under cassava trees. In short, the vegetable gardens, under a canopy of cassava trees, and the soils were in good health in a kind of food forest.


It is very hard to get a Ferrosol to hold water in a flood irrigation situation, but the high rainfall of the region helps to offset this problem. The irrigated lands were not as highly productive as I would have expected, with some significant soil structure decline and low organic matter. The bare soil was exposed to intense tropical heat, creating high moisture stress at the time of observation. I suspect the leakiness of the soils was also responsible for leaching a lot of nutrients away from the root zone


Below is a full soil profile description of one of the ferrosols near Bogor (west Java):

Sukamaju (near Bogor – West Java) Soil Profile Descriptions by Horizon. November 19, 2011

Soil Profile Descriptions

Site location: Soil Pit1 in Non paddy – non-irrigated horticultural cropping, mostly cassava, bananas and vegetables. Recorded by Robert Banks and Matthias Lebert on 19/11/2011.

Map reference: WGS 84 Lat -6.5367481, Long 106.5172761

Physiography: Landform pattern of hills and mountains, local landform element is terraced minimal midslope derived from ashy volcanics. Parent material is breccia, lava flow and andesitic colluvium with some minor influence of limestone and sedimentary materials. Slope 5%, Roots extend through entire profile.

Soil type: Deep Haplic Ferralsol


Soil Surface: Self-mulched – frequently cultivated by hand. Soil moisture status – moderately moist.

Soil description

Layer 1, Ap1 horizon, 0 - 0.15 m. Dark reddish brown (5 YR 3/4) subplastic light medium clay, with strong pedality. Peds (polyhedral <2mm), no mottles; field pH is 5.0; gradual (50 – 100 mm) boundary to…

Layer 2, AB horizon, 0.15 - 0.35 m. Reddish Brown (5 YR 4/4) subplastic light medium clay with moderate pedality, peds (angular blocky 10 – 20 mm) with strong secondary peds (polyhedral 2-5 mm): < 1% fine coarse sand size quartz visible;; field pH is 5.0; diffuse (>100 mm) boundary to...

Layer 3, B2 horizon, 0.35 – 0.85 m. Yellowish Red (5 YR 4/6) subplastic medium clay with strong pedality; peds (angular blocky to polyhedral 5 – 10 mm) secondary polyhedral peds (2 – 5 mm); < 1% fine coarse sand size quartz visible, <5% charcoal; dark biological mottles (<10%); field pH is 5.0; gradual (50 – 100 mm) boundary to…

Layer 4, B22 horizon, 0.85 – 1.35 m. Strong brown (7.5 YR 4/6) subplastic medium to heavy clay with strong pedality; peds (polyhedral 5 – 10 mm) and secondary peds (polyhedral 1- 4 mm) < 1% fine coarse sand size quartz visible, 5% fine gravel to boulders including weathered intermediate to acid volcanics. Field pH is 4.5; Soil continues….

Substrate: mixed intermediate to acid colluvium over deeper lithic sandstone and limestone member.




​The paddy soils on Ferrosols lacked the high production of the nutrient rich and high water holding Vertosols, and plants were spaced out a lot more than in a normal paddy. Interestingly this is probably an artefact of the soil having been farmed continuously under flood irrigation for hundreds to thousands of years. Crop rotation and eventually paddy to vegetable garden rotation might have made this soil look more impressive.

Of interest was also that the paddy soils were very hard to compact, and the only reason that they could be flood irrigated was that the rainfall in the region is so high.




The paddy soils on Ferrosols lacked the high production of the nutrient rich and high water holding Vertosols, and plants were spaced out a lot more than in a normal paddy. Interestingly this is probably an artefact of the soil having been farmed continuously under flood irrigation for hundreds to thousands of years. Crop rotation and eventually paddy to vegetable garden rotation might have made this soil look more impressive.


Of interest was also that the paddy soils were very hard to compact, and the only reason that they could be flood irrigated was that the rainfall in the region is so high.


Soil types unique to ashy volcanic regions – The Andosols


An almost unique feature of Java is that you are never very far from a huge volcano (2200 – 3670 m high, and 20 – 80km in diameter). As one can imagine, the slopes of the most active volcanoes are repeatedly top dressed with heavy ash loads. This ash forms a juvenile soil that is incredibly fertile and productive, and grows just about any conceivable crop type.

The altitude of the high ash fall zones is such that the climate is much more moderate than the coastal plains below, allowing for a mix of both tropical and temperate crops to be grown.

The photographs below show you the steps in development of an andosol, from the volcanoes to the ash beds to an example of the fully developed soil in West Java.


The photographs below show you the steps in development of an Andosol, from the volcanoes to the ash beds to an example of the fully developed soil in West Java.


Mt Bromo in Eastern Java forms a mega volcano with Mt Sumeru, the highest volcano in Java (on the far horizon) and is repsonsible for top dressing tens of thousands of hectares regularly with deep volcanic ash, which weathers to Andosols.

Climbing the main ash cone of Mt Bromo to peer into its depths is a popular pastime, but hard work for most Javanese who live at a few hundred metres above sea level.This photograph was taken at about 3000 m.


Peering into the vent – the source of Bromos huge ash influence over East Java.


An ashfall from a few months previous to the photograph. Please note that you can see the old soil surface and that the ash has already been planted and is growing crops.


Because of the structure of the Andosols, having excellent stability and drainage, they can be farmed on slopes where most soils would be at the bottom of the mountain within minutes. Spectacular farms occur on volcanic slopes both on raw ash as well as Andosols in Java.


As ash begins to age, the glassy material in it starts to break down and the soil forms a very light and highly structured and well-drained soil called an Andosol. The soil is very high in trace elements and nutrients for plants and is an incredible agricultural soil.


Another fun fact about andosols is that as they continue to mature, they transition to another soil type. Andosols are, in fact, a temporary or transitional state from raw volcanic ash to another soil type.



Andosol Definition (from Wikipedia): Andosols (from Japanese an meaning dark and do soil, a synonym of kuroboku[1]) are soils found in volcanic areas formed in volcanic tephra. In some cases, can Andosols also be found outside active volcanic areas.[2] Andosols cover an estimated 1–2% of earth's ice-free land surface. Andosols are a Reference Soil Group of the World Reference Base for Soil Resources (WRB). Andosols are often rich in vitreous materials (such as volcanic glass) and are therefore also called Vitric Andosols. Because they are generally quite young, andosols typically are very fertile except in cases where phosphorus is easily fixed (this sometimes occurs in the tropics). They can usually support intensive cropping, with areas used for wet rice in Java supporting some of the densest populations in the world. Other andosol areas support crops of fruit, maize, tea, coffee or tobacco. Note: There are so few andosols in Australia that we do not have a specific place for them in the Australian Soil Classification. However, there are a few andosols around just the Mt Gambier district in SA in areas of very recent (<3000 year) volcanic activity.


As glass-rich volcanic ash breaks down, stable organic complexes with silica and aluminium form, which give the soil excellent structure and both a very high water holding capacity as well as good drainage. The structure can also be broken up so that these soils can also hold water in a paddy situation.


Bulk density is the actual weight divided by its volume measured in grams per cubic cm or tons per cubic m. Of special note is that andosols are some of the lightest soil materials in the world with a bulk density (even in subsoils) of 0.4 t/cubic m or less. These soils are easy to work, and one can literally cut large blocks out and carry them because they are almost as light as polystyrene. In comparison, most Australian soils have a bulk density of 1 – 1.3 t/cubic m in the topsoils, reaching to over 1.5t/cubic m in subsoils, with some of our poorer soils having a density of close to 2t/cubic m.


A strange aspect of andosols is that they are a temporary soil. They form relatively quickly after ash is deposited and the leaching environment they form under, tends to break the materials down further over a relatively short time (500 – 3000 years) to form other soil types.


Below is a full soil profile description of one of the andosols near Sukabumi (West Java):

Site location: Soil Pit 3 in Paddy-paddy – Vegetables (Bok Choi). Perbawati Village, near Sukabumi – West Java. Recorded by Robert Banks and Matthias Lebert on 18/11/2011.

Map reference: WGS 84 Lat -6.8799836, Long 106.9410210

Physiography: Landform pattern is volcano; local landform element is terraced hillslope on lahar derived ashy volcanics. Parent material is highly weathered glassy tuff and some andesitic material and some Tuffaceous lithic sandstone, usually less weathered and present as boulders.

Soil type: imperfectly drained deep Haplic Andosol.

Soil Surface: Firm. Surface disturbed and cultivated frequently puddled . Soil moisture status – moist. Rice harvested. Root penetration about 80 cm.

Soil description

Layer 1, Ap1 horizon, 0 – 0.15 m. Dark brown (7.5YR3/3) silty clay (moderately dilatent) with strong pedality. Peds (polyhedral <2mm); orange mottles (<2%); fine volcanic glass fragments visible to naked eye and under hand lens; weathered Tuffaceous rock (5%); field pH is 5.5; plough pan at base of horizon; clear (20-50 mm) boundary to...

Layer 2, A12 horizon, 0.15 - 0.30 m. Brown (7.5 YR 4/4) silty clay with moderate pedality, peds angular blocky (10 – 20 mm) secondary peds (polyhedral 2-5 mm): orange and red mottles present (10%); up to 10% un-weathered gravel, fine volcanic glass fragments visible to naked eye and under hand lens; 5% weathered tuffaceous stone; field pH is 5.5; diffuse (>100 mm) boundary to...

Layer 3, B1 horizon, 0.30 – 0.80 m. Brown (7.5YR 4/4) light clay with moderate pedality; peds prismatic (20 – 50 mm) secondary peds (polyhedral 2 – 5 mm); grey mottles (10%); manganese nodules (5 – 10%); 65% gravel (weathered tuff), some manganese coatings on weathered material; (5 - 10%) unweathered andesitic gravel; fine volcanic glass fragments visible to naked eye and under hand lens; field pH is 6.5; gradual (50 – 100 mm) boundary to…

Layer 4, B2 horizon, 0.80 – 1.30 m. Brown to strong brown (7.5YR 4/4 - 4/6) silty clay to light clay with weak pedality; peds (polyhedral 2 – 5 mm) parting to crumbs (<1 mm) (Soil very wet): andesite and scoria gravel to boulders (20 – 30%); fragments of weathered vitreous tuff parent material (10%); some grey mottles (10%); Abundant fine volcanic glass fragments visible to naked eye and under hand lens; field pH is 6.5; soil continues….

Substrate: Tuffaceous lahar deposit with some andesitic boulders, and pieces of scoria.



​A typical landscape on fresh Andosols in Eastern Java (altitude 2,200m)


In short - Andosols grow anything and grow it well. I have never seen such a variety of crops growing so well, and often in specataular locations.


A Short Summary of trips to Java and my lessons learned


It is well worth the journey to see how farming systems have operated for thousands of years and to see the soil still relatively healthy and productive after feeding so many people for so long. The farmers are proud of their land and its productivity and were happy to share their methods and experiences. It is heartening that, in Australia, we have some of the same soils that have just started under more intensive agriculture. The longevity of these same soils under agriculture in Java suggests that we can feed and clothe ourselves for a very long time from these soils if we are clever.


Of course the Andosol landscapes around the giant volcanoes are nothing like Australian soils, but being amongst the giant active volcanoes with such stupendous productivity, I learned what Australia was like during its volcanic periods, which have left a legacy of large and fertile mountains like Mount Warning, or Mount Kaputar and many other locations in Eastern Australia. Sometimes it helps to understand the present a lot more by observing the processes of the past that created the present soils and landforms.


Java is not a normal tourist destination. It is very crowded, and one cannot count on travelling much faster than 30 km/hr over large parts of the island - I have spent up to 8 hours to travel 60 km. In a way this was fun because whilst my car and driver were in traffic, I got out and walked a lot of the way. On the way, being a tall European man was a curiosity to many. I was given many cups of tea and even food on my long walks out of the car. This was typical of working in Java.


If you want to go to see Java, best access is through Surabaya at the less crowded eastern end of the island. Air transport within the island is cheap and reliable and regular although if you have time it is worth hiring a car with a driver, which costs about A$30/day.


SoilFutures Consulting has taken one Farmer Tour to Java, and when Covid 19 settles down, we would love to do it again! A chance to enjoy a completely different set of farming systems and see some of the worlds more spectacular volcanic landscapes. The trip was an excellent cultural exchange and enjoyable for all who came along. For those of you interested in soils and the history of agriculture, experiencing Java is a must for giving perspective on what we do in Australia and other so-called “first world” countries.

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