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The price of the green gold

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First the rainforest is cut down, cattle farming is what follows and finally soy grows all the way to the horizon. In the Brazilian Amazon region, enormous areas of untouched nature are lost every year. One reason for this: areas that already have been cleared are often not managed efficiently enough. PhD student Anna Hampf is investigating to what extent sustainable intensification in these fields can increase yields and thus counteract further deforestation.

Green Desert or Green Gold – there are several metaphors for a phenomenon that has been changing the face of South America for years. Soy cultivation is rapidly expanding and devastating thousands of square kilometers of land every year. In the Brazilian state of Mato Grosso, where three million people live on an area as large as Germany and France combined, this change is particularly noticable. Here, in the southern Amazon region, which was once dominated by rainforests and savannahs, the landscape is increasingly dominated by pastures and arable land. 

Scientist Anna Hampf from the Leibniz Centre for Agricultural Landscape Research (ZALF) has travelled through the area several times in recent years. For the research project Carbiocial, funded by the German Federal Ministry of Education and Research, she investigated strategies for sustainable land management with partners from Germany and Brazil. The researcher knows the country well – after all, she studied here for three years. She has driven past the endless soy plantations and talked to the administrations of the huge farms. ​

 

Soy for the world

The rainforest is first converted into grazing land for livestock breeding. After a few years, large enterprises buy up the small farms and turn the land into soybean plantations. The corporations are thus circumventing the so-called soy moratorium, which has banned deforestation of rainforests in favor of soy cultivation since 2006. 

"Measures such as the moratorium were visibly successful from 2004, but deforestation rates have risen again in the past three years", Hampf explains. A system of deforestation, livestock farming and soybean cultivation is spreading in ever wider circles. Brazil exported almost 52 million tonnes of soy in 2017. The researcher believes that the main importers such as China, the USA and Germany also bear a great deal of responsibility for this, as the majority of Brazilian soy ends up in their cattle sheds as protein-rich feed. "The phrase 'We are eating up the rainforest' is not that far-fetched", says Hampf.

 

Saving the rainforest is not enough

Simply banning soy cultivation is not the solution, however. "Agriculture is the only source of income for many people in Mato Grosso", Hampf stresses. Small farmers in particular depend on it, which is why it is important to find a compromise between nature conservation and agricultural production. The doctoral student considers sustainable intensification to be an opportunity to reconcile these two aspects. 

With the help of MONICA, Anna Hampf analyzed how this goal can be achieved in Mato Grosso’s fields. MONICA is a mathematical simulation model that describes how carbon, nitrogen and water are balanced in agroecosystems. If the model is fed with information on temperature, soil, climate and nutrients, it simulates the crop growth. 

But first it has to be adjusted to the local conditions, for example the climate. Data on leaf size and plant height in the individual stages of plant development are also important variables to calibrate the model, but not always easy to obtain. Thanks to good cooperation with researchers at the state university in Mato Grosso, Hampf was able to calibrate the model to the crops most frequently cultivated there: corn, cotton and soybean plants.

 

Without incentives, nothing changes

Simulation results showed that: With some adjustments to sowing dates, the cultivars used or optimized fertilization, higher yields could be achieved without significantly increasing the use of resources. However, the knowledge of the interrelationships is one thing, implementation of the derived recommendations is quite another. Farms can only cultivate their land efficiently if they have access to financial resources, new technologies, machinery and labor – at least that is the theory.

Hampf tested this with a second model, aiming to show why certain cultivation methods were chosen or not. And how land use would change if farms had unrestricted access to capital, machinery, technology and labor. The results are sobering. "Our model shows that agricultural areas would continue to expand", Hampf explains. "As the land is still very cheap, it remains more lucrative to clear the forest and expand the land instead ​of cultivating existing fields more intensively." So is sustainable intensification a concept that must fail in this specific case? 

Hampf says the responsibility lies with the politicians. More effective controls against illegal logging, loans for sustainable farming methods or an expansion of the protected areas would be necessary to stop forest clearing. New agricultural concepts – such as the mixed production of wood and cereals – could also help to make farming more sustainable. 

With a climate model, Anna Hampf is assessing the impact of climate change on future crop yields in the region. The assessment shows how urgently a new approach is needed: Large-scale rainforest deforestation can lead to lower rainfalls. "It would then no longer be possible to have two harvests a year, which is currently the case. Farmers would be faced with enormous yield losses," warns the scientist. With her work she wants to demonstrate strategies to the people in Mato Grosso for them to escape this cycle of deforestation, livestock farming and soybean cultivation.

 

Text: Heike Kampe

 

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