Conventional agricultural practices in the world, such as tillage, have led into the deterioration and degradation of soils and decrease in their productivity. It became more and more evident that the existing production systems are no longer sustainable and that they need to be replaced. Fortunately, since a couple of decades a new approach is being evolved, termed as Conservation Agriculture, which presents high potential for sustainable land use, economic benefits and environmental gains.
Continuous soil degradation and desertification with increasing water scarcity are threatening agricultural productivity in most Arab countries, because of conventional agricultural practices. Symptoms of soil degradation are soil erosion by water and wind, soil compaction and increasing frequency of dry soil conditions. Yield levels are decreasing but farmers are maintaining them only with ever increasing inputs, fertilizers and water.
The present situation of conventional agriculture calls for a drastic change of agricultural production systems. What is required are production systems which protect fields from water runoff and soils from erosion, and which maintain soil fertility by restituting organic matter and plant nutrients detached from the field, in addition to the maximization of soil’s water storage capacity. CA is responding to these requirements and it works in harmony with nature.
Conservation agriculture (CA) aims to achieve sustainable and profitable agriculture and subsequently aims at improved livelihoods of farmers through the application of the three CA principles: minimal soil disturbance; permanent soil cover; and, crop rotations. CA is a way to combine profitable agricultural production with environmental concerns and sustainability and it has been proven to work in a variety of agro-ecological zones and farming systems. It has been perceived by practitioners as a valid tool for Sustainable Land Management. It can also be referred to as resource–efficient / resource-effective agriculture.
CA promotes minimal disturbances of the soil by no-tillage (zero tillage,), balanced application of chemical inputs (only as required for improved soil quality and healthy crop and animal production), and careful management of agricultural residues
CA fields are not plowed to bury weeds, and desiccated vegetation, stover and stubble provide a protective cover to the soil. This helps to minimize erosion, provides habitats for beneficial insects and other wildlife, and undisturbed soil builds higher levels of organic matter, key to good soil structure and fertility. For a fertile soil it is required to satisfy the formula “feed me to feed you”. Organic material available in the soil feeds the billions of micro-organisms present in it, which improve the soil fertility and thus boost crop yields, to feed people. So, burning of agricultural residues in the field starves the micro-organisms.
As mentioned previously, CA is distinguished from conventional or traditional forms of agricultural practices by the following three principals: minimal soil disturbance; permanent soil cover; and, crop rotations.
Soil is a living medium, it is an accumulator of organisms, and therefore has to be treated as such. Soil organisms are destroyed by exposure to solar radiation and rapid drying of the soil. Soil tillage enhances the drying of the soil and leads to soil compaction, reduced water infiltration and reduced aeration.
Practical solutions include direct planting through mulch, using special implements or minimum tillage where just a planting line (furrow) is opened with a tine implement.
2. Maintenance of a soil cover:
Soils need to be protected against the impact of raindrops, the speed of wind and the heat of solar radiation by a cover of crop residues or cover crops such as vetches. Soil cover, which is composed of plant residues, effectively reduces soil erosion by water infiltration and reduced evaporation. The soil cover (mulch or soil organic matter -SOM) also creates a favorable environment for soil life. It suppresses weed growth, thus reducing labor requirements and costs of weeding. Main functions of SOM include: improvement of soil structure; increased water storage capacity; slow release of plant nutrients; “food” for soil biota.
The diversity and frequency of soil life of CA fields resemble that of undisturbed soils under forests. It has been identified by researchers that the yearly biomass production rate in a natural forest is about five times that of a similar size plot of a conventional farm with full scale agrochemical inputs.
Main constraint for CA in dry regions is the establishment of a soil cover, as not only biomass production is low but crop residues are utilized as forage for livestock, especially grazing of sheep and goats. Also the bad habits of farmers in burning the plant residues with the false belief that they “clean” their plots from pests.
In the case of rain-fed agriculture, there is an urgent need for production systems that make more efficient use of scarce rainwater and reduce the risk of crop failure due to drought and dry spells during the growing season. This can be achieved by increasing water infiltration and water storage in the root zone of plants. In this regards traditional soil and water conservation techniques that focus on erosion control, water harvesting and reduced or no-till CA systems are the main options. Therefore, CA can be regarded as a form of water harvesting, where runoff is impeded and soil water is stored in the root zone of the crop
3. Crop rotation:
A suitable crop rotation, that combines cereals and legumes helps in the management and maintenance of rich soil nutrient regime and contributes toward the prevention of outbreaks of pests and diseases.
World wide Application of CA Practices
The agricultural land under CA is increasing from year to year. The most rapid spread is observed with no-tillage in Latin America, especially in Brazil, Argentina, and Paraguay, where over 60% of cropped land is under no-till based farming systems. Other countries with large surface under CA are the USA, Canada and Australia.
In the US, cropland under conservation tillage has continued to increase year on year as farmers see the value in putting away their plows. The Conservation Technology Information Center (CITC) estimates that over 40% of all crops in the US are now under conservation tillage practices.
Research has revealed that, aside from the environmental benefits of conservation tillage, the economic gains are also huge. Under CA practice much less equipments are required and the life time of the tractor, because of less use, is much longer
There are numerous advantages and environmental gains under CA practice, such as:
Less soil erosion
Better soil structure and fertility
More biodiversity
Quick crop establishment
Less labor
Less machinery requirement
Less fuel used
Reduced greenhouse gas emissions
Lower costs
Cheaper food
The major factor causing soil degradation, particularly in arid and semi-arid regions is conventional tillage, i.e. excessive plowing by tractor, together with the removal, burning or grazing of crop residues, leaves the soil exposed to climatic hazards such as rainfall, sun and wind action. This practice has led to loss of organic matter from the upper layer of the topsoil and caused serious soil compaction and pulverization of the topsoil during the last decades, particularly in Arab countries. Over the years, crop yields have declined significantly due to soil degradation combined with the reduced ability of rainwater infiltration and storage. In other words, the use of mechanical tillage for weed control and seedbed preparation has caused significant decline in soil organic matter content, which has led to soil compaction and reduction of soil quality and crop yields.
The standard CA practice in the world is no-till in which there are no soil cultivations at all. The basic forms of conservation tillage include:
- No-till: No soil cultivations are involved and remains of previous crops are spread over field providing at least 30% coverage throughout the year. Seed is planted in a slot cut through the soil. Weed control is often done by herbicides.
- Ridge-till: No soil cultivations apart from making ridges. Seed is planted along ridges and remains of previous crop are left between ridges.
- Minimum-till: Ripping planting lines that improve water infiltration, saves
costs, allows for timely sowing, and is a valid alternatives for semiarid to arid
regions with a low groundcover (30% or less).
- Mulch-till: A shallow cultivations system similar to minimum-till, which leaves more than 30% of the field covered by straw, stover, stubble or cover crop (e.g. vetches) remains.
It is very important to note that once practicing CA there is no need for periodic plowing as this disturbs the achieved improvement of soils and leads back to square one. The need for plowing is in the minds of many farmers but it is not necessary when fields are managed appropriately under CA, with the exception of very light sandy soils. It should be kept in mind that the soil surface of plowed fields tends to crusting and sealing under the impact of intense rains.
CA in Lebanon
In Lebanon, with the increase of land degradation and competition on land and water and significant decline in water resources indicate that there is the need to adapt new farming methods that improve land quality and lead to produce “more crop per drop”.
The German technical cooperation (GTZ) in Lebanon has started the first Conservation Agriculture project: “Development of rain-fed agriculture under zero-tillage in Lebanon” jointly with ACSAD (Arab Center for Studies of Arid Lands and Dry Zones) in 2007, in collaboration with the American University of Beirut (AUB), the Ministry of Agriculture represented by the Lebanese Agriculture Research Institute (LARI) in Tel-Amara (Bekaa) and farmers. The number of farms and acreage under CA management have increased from 2 farmers and 2 research stations with a total of 8 ha of the first year (2007) to a total of more than 60 farmers and more than 1100 ha in the third year (2009). These farmers have decided to double their acreage under CA in the 2009/10 season.
Yield of barley-vetch mixture at AREC site (2008/09) under CA management has registered an average increase of 32% in 4 plots compared with the conventional agriculture with tillage. It was also found out that applying the No-Till farming technique, reduces water losses through evaporation.
The data of the first two years have indicated that, with time and under good management weed infestation goes down in the CA cultivated fields and becomes less than the infestations in the conventionally cultivated fields.
Increase in biologic activity has been also registered with CA. Earthworms are good indicators of proper soil life. A living soil is a precondition for a high productivity. The number of earthworms have increased more than 5 times at AREC, within only two years after the introduction of CA.
The reduction of production costs has been the most attractive advantage of CA to farmers. Only by time they would learn to appreciate the other advantages of CA.
Production costs have been reduced from the first season on, especially costs of fuel, seeds and labour. It was revealed that production cost of field crops was reduced about $ 350/ha compared to the conventional practices.
Irrigated summer crops like maize for silage, potatoes or vegetables (e.g. tomatoes) have been successfully grown, as crop rotation, in the experimental sites in the Bekaa valley. Trials with direct planting of maize and drip irrigation have become very promising.
CA techniques have been also applied in fruit tree orchards. Traditionally farmers plow the soil under fruit trees, grapes, and olives, as they fear competition for water by weeds. However this practice is not only costly but also favours soil erosion and risks to injure tree roots thus reducing root activities and favouring root infection by fungal diseases. Research institutes in Syria (ICARDA) and Mediterranean countries like Spain and Italy have shown that the story of water competition is only half true. Controlled growth of forage legumes or even spontaneous vegetation, on the contrary, prevents run-off and thus loss of water, stops soil erosion and builds up soil productivity. Farmers now trying to practice sowing of a clover/grass mixture and vetch as a cover crop in their orchards.
In Lebanon, there has become increased interest in CA by all stakeholders of the agricultural sector. Researchers confirm that CA will continue to grow in Lebanon and will be more and more accepted as a way towards sustainable agriculture, economic benefits and environmental protection.
Berthold Hansman is GTZ technical advisor, and Boghos Ghougassian is director of research at Al-Bia Wal-Tanmia magazine
