Agriculture and Environment: Soybeans | WWF

Agriculture and Environment: Soybeans

Better Management Practices: No-Till/Conservation Tillage

No-till production is increasingly common in both Brazil and the United States.

In Brazil it has increased in the cerrado from 180,000 hectares in 1992 to 6,000,000 hectares in 2002. Producers have found that no-till techniques within certain planting sequences each year as well as longer-term crop rotations allow producers to increase production by 10%.

However, they also allow producers to reduce use of lime, pesticides, and fungicides by 50% or more, and the use of other chemicals by 10%.

Reduced costs, higher returns
In short, the net return per hectare is almost 50% higher than that of producers using conventional methods. Less machinery is required for no-till planting than for conventional tillage. Even so, for farmers who have already invested large amounts in machinery for conventional cultivation, this could be a burden.

In addition, while no-till cultivation requires less machinery, it requires some specialised pieces that would have to be purchased. However, the new machinery could be phased in over time or custom planters could be hired to plant the crops. In general, there do not appear to be any significant financial barriers to the adoption of no-till technology.

Resistance to change and adopt
If anything, the main barriers are cultural - producers are not comfortable with the new technology because it runs counter to how they have farmed in the past. In addition to the financial returns from no-till, there are also a number of conservation gains. In Brazil conventional tillage typically causes soil losses of some 23.6 metric tons per hectare per year.

No-till reduces soil erosion
With no-till, soil erosion can be reduced to as little as 5.6 metric tons of soil per hectare per year. The rainfall runoff on fields under conventional tillage is typically on the order of 137.6 millimetres per month. With no-till practices the runoff can be reduced to about 42.4 millimetres. The reduced runoff is the result of crop residues on the soil surface slowing the movement of water, allowing more time for the water to be absorbed by the soil and stored for later plant use or released more slowly over time.

Brazilian case-study
There are also benefits at the landscape or ecoregional level. These have been estimated for the cerrado of Brazil, where the practice is most common. The study summarises the estimated (annual) benefits of adopting no-till agriculture techniques in Brazil to the tune of $1,386.3 million on 35% and $3080.7 million on 80% of a total cultivated area of 15.4 million hectares.

The numbers are interesting and give insights into the possible benefits of this practice if adopted on a wide scale. For example, many of the benefits are mutually reinforcing - e.g., more organic matter means better utilisation of other inputs (fertilisers, pesticides, water, machinery, energy, and irrigation systems) and thus fewer expenses for them or impacts from them.

Fewer expenditures for the individual and the government
The findings also suggest that government support for the conversion to no-till practices would be more than offset by societal benefits. For example, fewer roads would be washed out from runoff, and there would be less siltation of rivers and lakes and fewer impacts on local sources of drinking water.

All of these benefits of no-till would result in fewer government expenditures to fix the impacts of conventional tillage. The current rate of soil erosion in the United States (which averaged 15.75 metric tons per hectare per year in 1992) could be halved with the adoption of no-till cultivation and other basic conservation practices (Schnittker 1997).

Employing a variety of conservation measures
The reductions described earlier in the section on soil erosion were not accomplished by growing fewer row crops. In fact row crop cultivation has intensified in the United States. Rather, investments in a variety of conservation measures such as constructing terraces, strip cropping, contour tillage, and rotations led to the reduction in soil erosion rates.

Increaseed use of conservation tillage in the US
By 1994 nearly 40% of crop acreage in the United States was under some form of conservation tillage compared with only 3% in 1984. No-till-cultivation was in use on 12% of row crops in the United States, and other forms of reduced tillage on 26% of planted crops. In addition, about 18% of the most highly erodible acres were entered in the Conservation Reserve Program (CRP), where producers were paid not to cultivate those areas (Schnittker 1997).

Conservation tillage and carbon offsets
In the future it may be possible to provide payments to encourage particular land use practices that link conservation tillage to carbon offsets. Conservation tillage offers the possibility not only of reducing carbon loss from the soil as a result of cultivation, but also of increasing soil carbon in the form of organic matter, with positive impacts on both soil productivity and greenhouse gas reductions.

For example, Reicofsky (as cited in Tengnas and Nilsson 2002) reports tests in which carbon loss following conventional ploughing was 13.8 times as much as soil that was not ploughed. Carbon loss from four different conservation tillage methods averaged 4.3 times the loss from unploughed soil (Tengnas and Nilsson 2002). Another way to structure such a program would be to pay producers with subsidies for building up specific amounts of carbon in their soil.


Extracts from "World Agriculture & Environment" by Jason Clay - buy the book online from Island Press

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