NO TILL FARMING AND SUSTAINABLE DEVELOPMENT*
The increase of the Brazilian agricultural production in the last decades is largely the result of making crop production possible on soils of very low initial fertility, as is the case of the great region of the Cerrado of the Central Region of Brazil, the natural grasslands in the South and soil impoverished by agricultural use in the South and Southeast regions. For this, liming and fertilization have been fundamental.
However soon it became apparent that the fertility created with chemical inputs would not be enough for a sustainable agriculture, as the insidious process of erosion wore out the soil and even destroyed it, reducing productivity, many times forcing the change from agriculture to pasture or even abandonment of the land, with serious social consequences, not only for the producers, but for the entire communities.
Thus, much more important than introducing low fertility soils into agriculture was the outstanding development that finally made that important achievement sustainable, by putting erosion under control by the so-called “no-till”, “direct sowing”, “minimum tillage”, or “zero-till”. Based on the soil permanently covered, undisturbed and with crop rotation, direct sowing on the straw is defeating erosion. That way, by not plowing, scarifying and cultivating, no till revolutionized concepts of thousand years.
Recognized by Brazilian farmers as an outstanding instrument to achieve sustainable agricultural production, producers started to adopt direct planting since 1972. Few in the first years, adoption increased with time and the area under no till grew in an exponential way to an estimated 22 million hectares nowadays.
In order to understand what this means for sustainable development of agriculture, it is important to understand the soil ecological roles, how they are affected by erosion and how seeding on top of residues can reverse the degradation process.
THE ECOLOGICAL ROLE OF THE SOIL
Soil is the most valuable natural resource for agriculture. Situated between the lithosphere and the atmosphere, it supports a great part of the Earth"s biosphere. The difference of soil and other types of non-consolidated matter existent in nature is the presence, in the former, of organisms that produce and degrade organic matter, promoting its transformation. Microorganisms provoke mineralization of the organic matter from remains of plants and of other organisms. In this process, not all organic matter is mineralized. A more resistant part remains as humus, conferring outstanding properties to the soil, such as aggregation, porosity, and water and nutrient retention. This allows the development of plants, which take from the soil, through their roots, water and mineral nutrients. Carbon and nitrogen, non-existent in rocks, are incorporated to the soil from the air, by photosynthesis and CO2 inclusion in organic compounds and by natural nitrogen fixation processes. As a result of the intimate interaction with the biosphere, the soils of the World hold more carbon than either the atmosphere or the biosphere.
On the other hand, soil cultivation results in great losses of organic matter with CO2 release into the atmosphere, therefore, contributing to the greenhouse effect. Curiously, soils are seldom remembered as one of the main sources of CO2 release into the atmosphere that contributes to the greenhouse effect. Important for this discussion is the fact is that no till is preserving soil organic matter, reversing the continuous reduction that occurs in conventional tillage. In other words, besides improving the physical conditions of the soil, by itself a very important improvement, no till is also providing, by the accumulation of organic matter, an important sink of atmospheric carbon dioxide, thus an important system of carbon sequestration.
The soil has another fundamental ecological role represented by its participation in the water cycle. A stable soil covered with natural vegetation, usually supports a great number of plant and animal species and microorganisms that exist in equilibrium. In natural conditions, the soil is always covered, infiltration level is high and water from
rain penetrates easily. The soil is capable of retaining and storing water for long periods, which enables the survival of plants even during long periods of drought. The moisture excess, which takes place when the level of water in the soil reaches the so-called field capacity, infiltrates and can reach the underground aquifer. The aquifers, on the other hand, provide water to springs that originate streams and rivers. Part of all the water is transformed into steam, through evaporation and transpiration by plants, and returns to the atmosphere, closing the water cycle.
Plowing has always been an important practice in agriculture, especially for short cycle or "annual" crops. It was believed that the soil needed to be loosed and aerated to receive seeds and facilitate the seedling roots to penetrate the soil without difficulty. Plowing also had the merit of easing weed control. Once the crop was established, weeds had to be removed and the crop kept free, in order to avoid competition for water and nutrients. Only the cultivated plants should occupy the area, all other plants that could compete for water and nutrients and should be eliminated.
As time went by, this type of soil management was considered inappropriate. Uncovered exposed soil in a slope terrain is a vulnerable soil. How much has been written on the disaggregating power of the water drop! Yes, about those raindrops that falling on the recently plowed soil release the so awaited "smell of wet land", the starting sign of the rainy season. But those same drops also destroy and disperse soil aggregates. And many water drops follow and soon they cannot be recognized anymore as they become part of a rushing stream of water that moves downhill. When there is erosion, the muddy water takes with it the best part of the soil, the finest portion called clay, which contains most of the organic matter and nutrients. Researchers estimate that soil losses caused by heavy rains falling on unprotected soil can reach tens of tons of lost soil per hectare in a single year.
Erosion carries away the best part of the soil and it results in lower productivity of agricultural crops. Erosion can also change the soil surface by digging furrows that hinders the traffic of machines over the land. These furrows acquire, in some soils, great dimensions, forming the so-called gullies.
The solids in suspension originated by soil erosion provoke silting up of rivers, lakes or reservoirs; the mud reduces the space for water reservoirs or rivers, intensifying the risk of floods. The water content of aquifers is reduced because of less water infiltration. The capacity of water reservoirs is reduced and the treatment of muddy water for city supply becomes more difficult and expensive.
Research on planting without plowing is not new and projects were conducted since the first half of last century, but the experimental results were not stimulating and the capability of performing such type of planting did not advance. But it is important to remember that the modern machinery and herbicides that are so important for the actual no till technology did not exist by that time. Thus no till was made possible by a combination of factors, that in Brazil includes the outstanding efforts of the pioneering farmers.
No till started in Brazil around thirty years ago by State of Paraná producers that were seeking primarily the sustainability of their properties, since erosion threatened to make agricultural production impossible. The process that followed with an increasing adoption of no till by producers, recognition by technicians and researchers, diligence of equipment manufacturers, among others, is in itself a remarkable story of Brazilian agriculture that has been publicized and approved by an increasing number of enthusiasts.
No till, also known as minimum-tillage, zero-tillage, minimum tillage and direct sowing, has been named as “conservation agriculture” by FAO. The essence of the
process is maintaining the soil permanently covered with vegetation, dead or alive; never revolving the soil and practicing crop rotation whenever possible. One important point is that perennial crops are also included under conservation agriculture after weed mowing instead of cultivating.
ENVIRONMETAL IMPACT OF NO TILL
No till has several positive environmental impacts, such as returning to the soil some of its ecological roles, especially water recycling. The most sought effect, erosion control and its consequences, brings beneficial consequences to the soil that includes reduction of soil losses and silting up of superficial water bodies. Erosion is minimized by better water infiltration that reduces the running off throughout the land. This has several consequences. Through water infiltration and less water lost by running off, floods are less intense and, through greater water supply to the underground aquifers, there is a better water supply during the drought periods. That way, the soil recovers it’s function,- substantially lost through conventional cultivation-: the ecological role of water recycling. Furthermore, no till promotes the stabilization of the soil surface, reducing dust and its damaging consequences, such as the direct effect on man’s health, dirt in the houses, and nematodes and pesticides transport trough the air.
Another important impact is soil organic matter accumulation, reverting the continuous decrease observed in soils under conventional cultivation. This can be explained by the non-revolving of the soil through plowing and cultivation, that way protecting the soil from exposure to the air and organic matter oxidation. As a consequence the soil accumulates more carbon and nitrogen, reestablishing at least part of the original carbon and nitrogen lost in the recycling process. It is important to remember that the degradation of organic matter under conventional tillage occurs independently of erosion.
Non-revolving the soil has favored soil biodiversity, which has contributed to porosity improvement and some proliferation of natural enemies of pests.
How can we position no till in relation to the so-called “sustainable development”? For what has already been said, one can notice that the system has an outstanding effect, by guaranteeing agricultural production, reducing erosion and the consequent pollution of superficial water bodies, increasing water supply of underground aquifers, increasing carbon sequestration and contributing to soil biodiversity.
However, this is not enough, since the sustainable development concept should be considered not only within the no till area , but also assessed with a perspective of the effects that farm management and preservation of non-agricultural farm land have on the environment and on human beings. Therefore, one should also analyze how the producers that have no till can be seen within the concepts of sustainable development. First, however, we must define what is understood by sustainable development.
The Brundtland Commission UN report of 1987, "Our Common Future”, defined sustainable development as the one that "meets the needs of the present without compromising the ability of future generations to meet their own needs”. Another important landmark is Agenda 21, approved at the United Nations Conference on Environment and Development in Rio de Janeiro, 1992, the so-called ECO-92. Agenda 21 is a kind of consolidation of several reports, treaties, protocols and other documents elaborated during decades by the UN, starting in 1948 with the Universal Declaration of Human Rights. It is a very comprehensive document, with information, guidelines and recommendations, and it can be considered as an action plan in order to implement sustainable development, which should conciliate economic results, environment preservation and social interest.
NO TILL AND SUSTAINABLE DEVELOPMENT
No till farmers that seek sustainable development should follow other requirements,
which are flora and fauna preservation, reduction of energy use and decreasing use of
resources that are not renewable, reduction of environmental contamination, etc. One of the critical points of agriculture is land occupation that should look after streams and springs preservation, isolating them from the agricultural areas and protecting them by forest or other native vegetation.
No till utilizes less energy than conventional tillage, by reducing soil tilling operations, therefore being in the right direction when sustainability is considered.
Fertilizers are essential products for agriculture and are used in large quantities in the no till planting system. Two aspects should be considered: the use of non-renewable natural resources and environment pollution. In case of non-renewable natural resources, the main ones are phosphates, obtained from mines with life limits, although distant; and the nitrogen fertilizers, produced mostly from natural gas, which is also a non-renewable natural resource. What is not usually commented is the great economy that soybean, -the most important crop in no till areas of Brazil-, brings into the agricultural economy, since it fixes nitrogen directly from the air. The amount of nitrogen introduced by soybean into the Brazilian production systems is twice the amount of all nitrogen contained in mineral fertilizers used in agriculture. Savings are double. First, due to the natural gas that is not used for producing nitrogen fertilizers. Second, due to the lower soybean production cost without having to pay for nitrogen, which brings a direct social benefit for the population after the impact on price reduction of poultry and pork meat, for example, besides the extensive use of vegetable protein in several food types. It is obvious that soybean is not specific for no till, but it is this system that guarantees both the production sustainability and subsequent double cropping, that way increasing profits and avoiding serious problems of soil degradation that occur under conventional tillage.
As for pollution in agriculture, in any production system, the main problems are nitrate in underground water, and nitrate and phosphate in superficial water. In none of these cases, great problems are expected within the large areas of deep soils under no till, but they can eventually happen in high productivity corn plantations and in regions of
intensive production of dairy cattle and swine, where waste is used in shallow soils and inputs are high. In order to fit into the sustainable development concept, mineral or organic fertilizers should not be applied above the required quantities, to avoid losses and water pollution.
Plant protection is another complicated problem due to the risk that pesticides present to those who apply them and to the environment, besides the possibility of agricultural products contamination. The way to sustainability, in this case, is to avoid calendar applications and to implement measures that reduce pests at their origin, such as crop rotation, protection of natural enemy habitats, diagnosis of problems, decisions on pest control using integrated pest management (MIP), preference for less toxic products and correct application to avoid drift and contamination of forest areas, water streams and lakes. All these practices, although not belonging specifically to no till, are nevertheless compulsory and must be used for the systems qualified as sustainable.
SUSTAINABLE DEVELOPMENT AS AN INSTITUTIONAL IMAGE
Since the 90s, many companies have sought to show the society a commitment to the environment, adopting environmental standards and certification, as the case of ISO 14000. Although at first the intent was to create a favorable image of the companies facing their customers, shareholders and the general public, in many cases the measures taken reflected in a favorable way for the economy of the companies, which certainly constitutes a very interesting incentive. Everything points to the direction that, also in agriculture, the use of "good farm practices" will reflect not only on the image of the producers, but also on the positive financial results of the production systems.
An example of how certain initiatives can be implemented is given for the great water reservoir of Itaipu, one of the largest hydroelectric plants of the world that had been suffering great silting up due to erosion of the agricultural areas. The responsible company, Itaipu Binacional, in partnership with EMATER/PR (Technical Assistance and Rural Extension Company of Paraná State) and the Federação do Plantio Direto (No
Till Planting Federation), created a project in order to reduce the solid load deposited into the reservoir, with outstanding results. That way no till is now part of the institutional image of the Company
More recently, the social component has been adopted as well, especially on customer demands. In the case of agriculture, demands for fulfilling the principles of sustainable development come from importers that want to quality products produced with environmental respect and social responsibility. This is already happening for meat, fruit, coffee and other products in Brazil. The no till system will possibly follow this path, since it has already guaranteed continuity and improvement of the productive process by preserving soil and water.
While Europe and the United States have already incorporated sustainable development into agriculture in the 90s, the theme has taken great impulse in Brazil the last years, but greater progress should be obtained with increasing consciousness from all sides, showing that producers and consumers are two sides of the same coin. Let’s go back to the soybean case in order to illustrate this point, seen as a "deforesting" crop, replacing forests that do not provide jobs. Of course these are false information that put the city population against soybean producers. But very few know that the low price of chicken, the famous R$ 1,00 per kg of the Government Plan, would not be possible without soybean and corn. Society is simply not aware of the outstanding effort reality that agriculture has done and is doing to provide the population with cheap food while protecting the environment at the same time. And very few people know the importance that no till has to recover both the naturally poor soils as well as the degraded pasture areas, bringing them back into production, thus avoiding the opening of new areas.
Brazil has great accomplishments in agriculture and it seeks that most of the cultivated area is conducted in a sustainable way through no till. The no till system is the central component of a sustainable agriculture, a sine qua non condition for responsible agriculture. It is a part of a successful story that points to the future, an accomplishment that Brazilians willingly share with other tropical areas, thus contributing for a more sustainable and happier World.
*Paper backed by the Agrisus Foundation handed over by the president of FEBRAPDP to Mrs Bruntland on her visit to S.Paulo, 11.17.05