Sustainable agriculture

Non-selective herbicides such as paraquat are essential to the efficient conservation of water for use by crops in dry regions. Low rainfall during the growing season means that in these regions crops rely mainly on stored soil moisture.
Ecofallow is a system of soil management developed in the dry mid- and western states of the US and Canada to conserve moisture throughout the crop rotation.
The ecofallow system (also known as ‘chem fallow’) is based on no-till cultivation and herbicides to ensure weeds do not deplete the reserves of soil moisture being accumulated during the fallow (uncropped) period between crops.1,2
Crops are thirsty
As a general rule, one litre of water has been used to produce one calorie of food. Considering average requirements for adults are 2000 – 3000 calories per day, this fact emphasises the importance of water to food security. In regions where rainfall is low and irrigation is not feasible, crop yields are restricted by insufficient water.
The United Nations Food and Agriculture Organisation (FAO) has recently published a report emphasising that to meet global food security needs it will be essential to adopt best practices in soil and water management.
By 2050, rising population and consumption are expected to demand up to 70% more food production globally, and 100% more in developing countries, compared to current production levels.1
Higher yields … at a price
In the report, ‘The state of the world’s land and water resources for food and agriculture’, FAO point out that over the past 50 years agricultural productivity has grown by 150 – 200%, despite the total area of cultivated land increasing by only 12%. Yields have increased, but the cropland available per head of the burgeoning population has steadily reduced (Fig. 1).2
Moreover, the achievements of higher crop yields in some regions have been associated with degradation of land and water resources. According to FAO, soil degradation issues include erosion, loss of organic matter, compaction and loss of biodiversity. Soil degradation is also closely associated with poverty. Some 40% of the world’s degraded land is found in areas with high degrees of poverty.
Tea production is continuing to grow rapidly, especially in China and Vietnam, and paraquat is helping to achieve sustainable cropping systems. Tea is often grown on hillsides where the soil is very prone to erosion. Paraquat only removes the top growth of well-established weeds, keeping roots intact, and does not affect the germination of new seedlings, allowing vegetation to re-establish after 1-2 months. This helps to stabilise the soil and resist erosion.
Research in Sri Lanka has found that paraquat-based weed control systems are superior to those using glyphosate. Intensive use of glyphosate has led to weed shifts in plantations as more tolerant species survive and become more dominant. ‘Soft’ weeds, typically prostrate annual grasses which are easily controlled, are replaced by re-invasion of cleared land by more aggressive ‘noxious’ species, typically creeping and climbing annual and perennial broad-leaved weeds. These aggressive weeds compete with the tea crop, reducing yields and make spraying, fertilizer application and picking difficult.
Other facts about tea Read more about the use of paraquat in tea here
Read an in-depth article about tea cropping here
Using paraquat for weed control in oil palm plantations can address a number of the criteria for sustainability defined by the Roundtable on Sustainable Palm Oil (RSPO). These include protecting soil and water quality, and reducing erosion. As part of a wider approach, smallholders undergoing RSPO certification are being shown how to grow more profitable crops while using all inputs more effectively and safely.
Worldwide, 33% of palm oil is produced from crops grown by smallholders. In Thailand, however, smallholders supply 70% of the palm oil produced in the country, so this important group of growers has been a focus of attention for improving sustainability1.
The Roundtable on Sustainable Palm Oil
Facts about Thai oil palm smallholders 120,000 farmers in Thailand grow oil palm
98% of these are smallholders
76% of land under oil palm in Thailand is cultivated by smallholders
7 hectares average holding size
70% of production is supplied by smallholders
Tea is a thriving crop in Vietnam and farmers rely on paraquat for a weed control system that reduces soil erosion.  Much of the tea crop is grown on sloping land prone to losing very significant amounts of soil each year.
Results of research conducted by the Northern Mountainous Agriculture and Forestry Science Institute show that using paraquat for weed control instead of hand hoeing can save huge amounts of soil. Paraquat is more effective than glyphosate because it leaves roots intact to anchor the soil.
Tea in Vietnam
Tea is an important industry in Vietnam with six million people involved in production, processing and exporting1. Tea is a native plant to the country and has been cultivated for thousands of years. The industry has been experiencing a rapid expansion since the mid 1990s. Yields have also improved, more than doubling over this period, and now approach the best in Asia2. Exports of tea are increasing and efforts are being made to improve the international image of Vietnamese tea. Vietnamese black tea is generally used in blends. However, fine quality green teas are produced and drunk by the Vietnamese people.
Oil palm is the world’s leading vegetable oil crop. As a foodstuff, palm oil is believed to have several important benefits, particularly in lowering the risk of heart disease. As a very high yielding crop, it has become a major feedstock for biodiesel production. The Roundtable on Sustainable Palm Oil has been established to ensure that as production rises environmental issues such as biodiversity and soil erosion are addressed. Integrated pest management (IPM) approaches are widely used and ensure that crops are protected in a sustainable way.
Paraquat has a key role in IPM systems. Although it is termed a non-selective herbicide, paraquat is safe to spray around crops such as oil palm. Paraquat is strongly adsorbed and deactivated on contact with the soil. It cannot move to roots and be taken up into plants and it cannot leach. Mature bark is a very effective barrier to paraquat and even if small amounts land on leaves there is little or no crop damage because paraquat is not systemic.
Other facts about oil palm Read more about the use of paraquat in oil palm here
Read an in-depth article about oil palm cropping here
The UN Food and Agriculture Organisation (FAO) has begun to implement its strategy for Sustainable Crop Production Intensification (SCPI). By 2050, FAO estimates that to feed each person on the planet there will only be 0.16 ha of agricultural land available, compared 0.26 ha in 1999 and 0.4 ha in 1960, hence the need to intensify production. The goal of SCPI is to support countries and their farmers to grow more food and the focus will be on developing technologies and policies that will ensure sustainability1,2.
Conservation Agriculture
In practice, this will be achieved by encouraging the global development of the approach to farming known as Conservation Agriculture. This is quickly gaining ground as the best means of securing a stable and sustainable food supply for the world’s population of 9 billion estimated for 2050.
Conservation Agriculture integrates the best appropriate technologies to work within three main pillars which support the overall concept. These all acknowledge the importance of creating and maintaining a healthy soil. Integrating diverse approaches to the management of weeds, pests and diseases, as well as plant nutrients, is also essential.
Three pillars of Conservation Agriculture Minimal soil disturbance: not plowing and ideally no soil cultivations, eg ‘no-till’
Integrated weed management and no-till are advanced agronomic tools with common aims to improve efficiency and profitabilty, while reducing the environmental impact of crop production. Although advanced in concept, these tools are straightforward and can be adapted for use in all cropping systems, from highly mechanised ones to subsistence farming, all around the world.
Tillage is a well proven means of controlling weeds, so are other methods good enough to use in an integrated approach to weed management in no-till systems? This article examines how farmers can reap the rewards of both techniques together.
Farmers around the world know just how hard it is to control weeds. They tend to come back with a vengance, especially when the many elements causing weed problems have not been appreciated and addressed. Aiming to manage weeds rather than control them is not only more realistic, but if Integrated Weed Management (IWM) is applied properly, it can reduce costs, protect the soil, and support pest and disease control.
No-till systems also provide economic and environmental advantages. However, in no-till, the traditional means of weed management by ploughing to prepare a field for cropping is not used. Plowing, even though it effectively removes weeds by burial, is costly, time consuming, and can cause soil erosion and compaction.
Paraquat is used to control a huge range of weeds worldwide, but to control weeds effectively and sustainably it is important to understand them.
Why does a plant become a weed? How can different types of weeds be described? What are the features of weeds and the way they grow which can be targeted by herbicides for successful control? Why is paraquat such a useful tool for farmers?
What are weeds?
Weeds are usually described as unwanted plants.  Weeds grow on arable land which is waiting to be planted and then a new flush of weed seedlings emerge with the crop.  In perennial crops like fruit, vines, rubber and oil palm, weeds grow continuously with new growth prompted by the weather and changing seasons.
Weeds are unwanted for many reasons: They compete with crop plants for sunlight, water and soil nutrients, reducing yields and quality.
They may provide a habitat for pests and diseases from which these can attack the crop.
Large, climbing or spiny weeds can make it difficult to get into the crop for pest and disease control, fertilizer application, harvesting and other operations.
Paraquat and sustainable agriculture, by Richard H. Bromilow
In his paper “Paraquat and sustainable agriculture,” author Richard H. Bromilow studies the role paraquat plays in supporting sustainable agriculture around the world.
Abstract: Sustainable agriculture is essential for man's survival, especially given our rapidly increasing population. Expansion of agriculture into remaining areas of natural vegetation is undesirable, as this would reduce biodiversity on the planet. Maintaining or indeed improving crop yields on existing farmed land, whether on a smallholder scale or on larger farms, is thus necessary.
One of the limiting factors is often weed control; biological control of weeds is generally of limited use and mechanical control is either often difficult with machinery or very laborious by hand. Thus the use of herbicides has become very important. Minimum cultivation can also be important, as it reduces the power required to work the soil, limits erosion and helps to maintain the organic matter content of the soil.
This last aspect helps preserve both the structure of soil and its populations of organisms, and also sustains the Earth's soil as a massive sink for carbon, an important consideration in the light of global warming.