Third War for Protection of Motherland:

Battle to combat land degradation

by Patali CHAMPIKA RANAWAKA

Based on the famous book "One Straw Revolution" written by Mr. Fukuyako, I contributed a series of articles, 20 years ago, to a Sinhala newspaper (Divayina). Mr. Fukuyako was one of the pioneers who practised the modern world technique of "Do Nothing Farming". His motto on this particular technique was "grow what you want and reap your harvest, let straw and other residue remain on earth where they have come from". He practised what he preached and observed that there was no absolute need for ploughing or using fertilizer, if every season, a few layers of straw are allowed to digest as a means of increasing the quality and the organism of topsoil.

Agriculture is considered to be one of the most important technological innovations of the mankind. Over the years wild crops have been tested and modified to suit our food behaviour. About 12,000 years ago, people in this country had used the plough for agricultural purposes and there is evidence that during this period, people who lived in Maha Eliya or Horton Plain had done some form of maize farming. There is parallel evidence of having had early agricultural activities in Mesopotamia, Egypt, China and North India. The farmers during the early period had used a vertical piece of hard wood for ploughing and it had done very little damage to the soil. Sri Lanka was a pioneer in the art of iron and steel manufacture and it had been established by the 2000-year-old iron claded plough found in the vicinity of Sigiriya. It was John Deere (1837), a blacksmith in American Middle West who had produced the modern moulded plough which subsequently was mechanized. It is a fact that the use of machines instead of bulls and slashing of virgin forests had caused serious damage to soil.

The British Conquerors had to encounter stiff resistance by our patriots living at the time. Our ancestors never exploited the virgin forests in mountains as they were very much conscious of the fact that those areas remained as watersheds in our country. However, they were compelled to make use of these mountainous territories to wage their national liberation struggle against the British imperialists. After having brutally crushed the uprising, the British colonials, with much haste took steps to clear the forest in the up country area paving way for serious damage to our water resources and soil condition. The introduction of tea and coffee plantation to the up country had caused irreversible damage by way of soil erosion. It has been estimated that during the past 150 years, a 30cm thick layer of topsoil had eroded in Nuwara Eliya, Kandy and Badulla Districts. Subsequently, the potato farming and similar agricultural activities carried out in the area by our local farmers had aggravated the situation resulting in serious soil erosion and landslides. In order to arrest these serious soil degradation, new laws have been promulgated prohibiting farming activities on areas exceeding an angle of 60 degree. Also, the accelerated Mahaweli Project and its reservoirs in mountain areas had caused much damage resulting in frequent earth slips and soil erosion.

In relation to the climate change and carbon cycle, soil is an important means of carbon storage. It is reported that soil stores as much as 4 times the carbon that all the plants on earth store put together. It is twice as much as currently in the atmosphere. Carbon is being sequestrated to soil through a natural phenomenon of plants and trees. Decaying of old and dead trees, leaves, plant roots, tree trunks etc pumped carbon into soil and soil in return cycled some of these carbon to atmosphere which produces carbon for photosynthesis process connecting carbon cycle. Fungi bacteria and like micro organisms helped to decompose organic matter and thus enhance carbon content of soil. So, if we open up these carbon to atmosphere by way of clearing forest slashing, burning and unnecessary ploughing it effects the climate change seriously.

It has been estimated that nearly 1500 Million ha. of lands in the world are now under cultivation while one million ha. of land are subjected to "no till or do nothing" farming techniques. This shows the gravity of the problem. Making and using pesticide, weedicide and mechanized equipment like tractors and threshers eventually releases much carbon as they need more and more fossil fuel for their movement and usage. It has been observed that one Kg of herbicide release 6kg of carbon. So, it clearly shows that modern agricultural techniques not only cause damage to the soil but also it contributes to increase the global warming.

Land degradation is the reduction or loss of the biological or economic productivity and complexity of rain-fed cropland, irrigated cropland, or range, pasture, forest or woodlands resulting from natural processes, land uses or other human activities and habitation patterns such as land contamination, soil erosion and the destruction of the vegetation cover. It generally signifies the temporary or permanent decline in the productive capacity of the land.

Land degradation is as old as civilization itself, stretching the plains of China to the peaks of the Inca Empire. The world's first ever written story, a Sumerian epic, tells how a man felled forests of Mesopotamia, bringing down a curse. The ancient Sumerians failed to heed the parable and went on cutting the trees. As early as 2000 BC their literature carries evocative description of land degradation. Their great city state of Uruk, which once contained 50,000 people and produced crop yields comparable to those of North America today, is now just a bump in the sand. According to our history, on-site and off-site impacts of land degradation were one of the major reasons for the collapse of the world's longest ruling kingdom of Anuradhapura.

It is no accident that our planet is called Earth. All terrestrial life depends on the fragile, friable crust of soil that coats the continents. Without it, living things would never have emerged from the oceans: there would no plants, no crops, no forests, no animals- and no people. The top soil of the land is painfully slow to form, and can be destroyed terrifyingly fast, just a single inch of soil can take centuries to build up but, if mistreated, it can be blown and washed away in a few seasons.

The estimated rate of global topsoil loss is 24 billion tonnes per year. Over the last two decades as much has been lost worldwide as covers the entire crop land of United States. And it is getting worse. Nowhere is the crisis more acute than in the dry lands which stretch across more than a third of the Earth's land surface. Some 70% of the 5.2 billion hectares of dry lands which are almost 30% of the total land area of the world, used for agriculture are already degraded.

Land Degradation has emerged as a serious problem in Sri Lanka. The population has been expanding rapidly and this has led to an increased demand for land for economic purposes and social services. The demands from various users such as agriculture, industry, transport and settlements have set up pressures on the land, and these in turn have inevitably resulted in the misuse and degradation of land in many areas. Evidence of onsite and offsite impacts of this degradation can be seen in heavy soil loses; high sediment yields; decline in soil fertility, salinization and the marginalization of agricultural land.

In Sri Lanka, major contributors to land degradation are soil erosion and soil fertility degradation. Over exploitation of ground water, salinization, water logging and water pollution are also becoming important contribution to land degradation. According to the Global Assessment of soil degradation, about 50 percent of land is degraded. The area affected by soil fertility decline is 61 percent of the total agricultural land.

It has been estimated that nearly one -third of the land in the country is subjected to soil erosion; the proportion eroded ranging from less than 10 percent in some districts to over 50 percent in others. Much of the erosion has been taking place in the hill country, the problem being given over to the cultivation of highly erosive temporary crops such as vegetables, potatoes and tobacco, seedling tea. The highest figures of soil loss in mid country wet zone and intermediate zone are 40 tons/ha/year for old seed tea plantation and 70 tons/ha/year for tobacco cultivation with no soil conservation measures adopted respectively.

Human activities such as cultivation of steep slopes, deforestation, burning of natural vegetation, construction of roads and buildings have been responsible for the major share of soil erosion. As a offsite impact, reservoir sedimentation has already reduced reservoir capacity of some of our major reservoirs. High sediment yield from poorly managed market gardens is the main source of the sediment. The 1992 measurements summary shows Rantambe to have a storage loss of 11 percent (at the rate of 4-6 percent /year) while Polgolla has lost 44 percent of its capacity.

Monitored Sedimentation rates of reservoirs and sediment yields from different catchments (See Table )

In general not only large reservoirs, but both big and small tanks of the cascade system in the dry zone have been silted considerably due to change of the ancient landscape such as reserve forest above the tank (Tahanam kele), Silt storage ponds within the forest (Kulu wawa), Silt trapping tree belt just above the tank bed (Kattakaduwa) and low sloping channel system etc. Economics of land degradation indicates that offsite economic value of soil erosion in Sri Lanka is considerably very high. The Annual cost of removing yearly deposited sediment load (1,246,000m3) from the Rantambe reservoir would be Rs. 52,332,000.

According to the National Report on Desertification/Land Degradation in Sri Lanka (2000), the on-site and offsite costs of soil erosion have been estimated in recent studies. Some of the estimates are: (A) Onsite cost - 1) Value of loss of productivity - Rs. 3529 ha/yr; 2) Value of loss of nutrients - Rs.5068 ha/yr; 3) Estimated cost due to nutrient loss in Upper Mahaweli watershed - Rs. 953.0 million (B) Offsite cost - 1) Based on value of loss of productivity - Rs. 3952 ha/yr; 2) Based on value of loss of nutrient - Rs. 5481 ha/yr; 3) Estimated loss in hydro-power production and irrigation from the Upper Mahaweli Watershed - Rs. 15.0 million per annum.

Soil fertility decline is caused by soil erosion and nearly 1.6 million ha. of agricultural land in Sri Lanka is affected.

Decline in crop yields have been reported during the last two decades due to soil fertility and degradation. The loss of 1 cm of top soil cover of tea and rubber lands is associated with a decline in yield of 44kg/ha/yr and 174kg/ha/yr respectively. Eutrophication of water bodies due to excess plant nutrition by soil erosion increased the growth rate of aquatic invasive plants such as Salvinia and Eichornia ("Japan Jabara").

Although soil conservation is the main responsibility of the Ministry of Agriculture and only a partial responsibility of the Ministry of Environment and Natural Resources, it has been keen to address this problem and several measures such as reforestation, adopt regulatory framework for soil conservation, develop policy framework for combat land degradation under the Convention to Combat Land Degradation and reduce soil and water pollution have been adopted over the past few decades to control the land degradation. However these have only had a limited impact and this is reflected in the spread of settlements into environmentally fragile areas; eroded uplands; low and unreliable crop yields, and other offsite effects of soil erosion such as sedimentation of reservoirs and foods. These trends need to be reversed early; if not there could be serious economic and social consequences.

Writer is the Minister of Environment and Natural Resources.