Tillage: farming practices in Thailand and environmental consequences
Namfon Unthapanya & Lysa Bonfils, Sep 2021
Farming has been an essential human activity for several millennia, and since the early days of agriculture, farmers have known how to break down the soil into small pieces to favor the growth of their crops. Tillage modifies the soil structure, enabling the topsoil to better absorb fertilizers. Tillage also supports the development of the crops, by allowing their roots to access nutrients and water more easily. Therefore, it is used for the vast majority of crops, and sugarcane is no exception to this rule. This article focuses on the tillage practices in the Thai sugarcane industry, and their consequences on the environment.
In 2020, according to the office of sugarcane and board, farmers in Thailand grew more than 10,000,000 rai of sugarcane (1,600,000 Hectares) in 47 provinces (out of 77). Because of the variations in practices and climatic conditions, sugarcane production cycles vary depending on the location. Thus, sugarcane planting in Thailand happens at three different times:
Before the rainy season for an irrigated area in February - April
Before the rainy season for a rainfed area in April - June
After the rainy season in October - December
Regardless of the planting timing, Thai sugarcane farmers practice tillage at least twice a crop year: at the beginning of the planting cycle, and around 3-4 months after planting when fertilizer is applied. This second tilling aims at increasing the penetration of the fertilizer nutrients into the soil, making their absorption by the sugarcane roots easier.
In Thailand, the type of equipment used for tillage depends on the size of the farm. Smallholders use small driving tractors or sometimes walking tillers with a connected disc harrow. Bigger tractors are usually used in large exploitations, that is to say, farms having a sugarcane production surface superior to 62 rai.
1. Walking tractor in a sugarcane farm with a tillage tool connected in the back
2. Small size driving tractor in a sugarcane farm with a tillage tool connected in the back
3. Big size driving a tractor in a sugarcane farm with a tillage tool connected in the back
While tillage has benefits for the cultivation of crops, the latest studies highlight the risks of over-tilling, especially from the perspective of sustainability. Indeed, tillage fractures the soil structure, accelerating surface runoff, dryness, soil erosion, soil acidification, and reducing organic content. The augmentation of soil acidity can be explained as follows: in the rainy season, water and carbon dioxide mix creating carbonic acid, which turns into hydrogen. The more H+ is contained, the more acid the soil will be, pushing calcium and magnesium away. As for the diminution of organic content, the process of tillage lowers the number of crop residues and destroys the vegetal cover. This organic matter, vegetation, bacteria, and fungi living in the soil consume carbon and release nutrients beneficial to the plant's growth. The process of tillage breaks this cycle, therefore reducing the natural nutrients present in the soil, and increasing the liberation of carbon dioxide in the air. The destruction of the superficial layer of vegetation also weakens the land protection against wind and water, causing important soil erosion.
To avoid these drawbacks, a new model of agriculture without tillage has been introduced. By keeping the vegetal cover and organic matter, the no-till agriculture shows many benefits: when it rains, superficial vegetation slows the evaporation process and helps the soil to keep the water. As a consequence, no-till lands are more irrigation efficient, therefore witnessing higher yields in hot and dry weather. In addition, crops in no-tilled soil benefit from nutrient-enriched soil. Farmers use fewer fertilizers, spending less money on these products, reducing the number of chemical inputs in the soil, and thus cutting the greenhouse gas emissions from fertilizing (see our article Chemical Fertilizer in Agriculture: A big source of Greenhouse Gas Emissions). Studies show that no-tilled lands when combined with organic fertilizing, witness an increase in soil organic matter by 9 percent within 2 years and by 21 percent within 6 years. The combination of no-tillage and organic fertilizers practices improves the environmental footprint as fewer greenhouse gases are emitted from the fertilizers and more carbon is sequestered by the organic matter, enriching the soil biodiversity. Finally, no-till farming has an economic interest as it avoids the spending on tillage equipment which can cost up to 30,000 THB, a substantial sum for smallholder farmers.
Tillage has been a key activity in our agriculture for centuries, and the shift to new practices will be a great challenge. However, the environmental crisis urges agriculture stakeholders to rethink the production model, and develop innovative solutions for a more sustainable world.