Making farmland

The virgin land needs to be prepared for agriculture. This is called melioration and can be done with principal changes like "cleaning" from shrubs and trees, draining, dike constructions, and terracing.

Land cleaning

At the beginning of agriculture, in forest and bushland regions was the shifting cultivation the way from gathering the preparation of fields for crop growing. Trees and shrubs have been cut and burned to give space for cropping. After the harvest, or with decreasing soil fertility or weed infestation, new plots have been cleaned and used for agriculture. The rotation was up to 20 years, before people came back to the same plots. This way of slash-burning-cultivation is still practiced. It is the main way of deforestation we see in the rainforests as well in boreal forests. The limitations of space do not allow the degraded plots to recover as fallow land. Today, deforested land must be used permanently.

Photo: In the case of Malawi - since decades, one of the poorest countries on the world - agriculture is the most important activity for livelihood, and obligatory in rural areas. The hard farm work is often done by women. They care for agriculture and food for the family. New farmland was always necessary for the growing population in Malawi (1962: 3,8 million inhabitants with 5.2% growth rate, 2021: 19.9 million, 3.3%). For centuries, slash-and-burning (deforestation) was the way for creation of new farmland. This was done in 1989 by the women of the village of Chigwere, close to Mzuzu in the north. They were proud about their work and happy to have farmland for family food production. But fallow land and natural forest became scarce over the time. In the year 1962 were 82% (3,843 m2, 44% of country area) and in 1989 still 20% (2,534 m2, 56%) more cropland per capita available compared to 2024 (1,912 m2, 72%). And the population will grow till 2050 toward 45 million people. In 2024, the natural forest had already nearly disappeared. Intensification of land use is necessary to harvest higher yields to feed a still growing population. This is a challenge, particularly for the young and the women.

The soils in the tropical rainforests are usually poor in productivity. After some years of agricultural utilization, the rainforest soils becoming low in nutrients. The subsoil is mostly of granitic origin with an average elevation above sea level of 300 m to 500 m. The annual rainfall averages 1500 mm per year, between 50% (dry season) and 100% humidity in the rainy season (November to March with 80% of annual rainfall). The average temperature is 24-27°C, the sunshine 1,800 to 2,600 hours per year. The granitic soils are quartz-rich and sandy and, with a pH of 4.5 to 5.5, typically acidic for rainforests and with >1% poor in humus (VW do Brasil 1980). To create grazing land, the area is measured and marked out. Then all the large trees are felled with a chainsaw and the smaller ones with a large chain between two bulldozers. Everything is left in this state for about a year until it is dry enough to be burned in the dry season. Afterwards, this area is either worked again with the chain or immediately sown (grass species like Panicum maximum and Brachiaria spp. as well as legumes like Pueraria phaseoloides) into the ashes by plane (1000 ha / day). Furthermore, the fences are drawn, and missing water points are created. Every four years, the wooded growth is burned off again and reseeded (Rahmann 1986). By 1986, around 50,000 hectares had been cleared. but via Satellite (google earths) nearly nothing remains in 2024.

Photo: A lot of potential farmlands are rocky. This is difficult to manage for crop cultivation, especially with machines. The farmland needs to be cleaned from stones.

Water infrastructure

Land preparation to control water is needed in regions with too much or not enough water. Dikes prevent flood damages after high water in rivers and open sea. Swamps and peatland need to be drained (Lin et al. 2021) and dryland needs irrigation facilities (MacDonald et al. 2023) to do agriculture. This can be done as individual farmer or – better – as group work or governmental action.

Figure: There is enough groundwater in Africa. 

Source: MacDonald et al. (2012)

MacDonald et al (2012)  estimated the total groundwater storage in Africa to be 0.66 million km3 (0.36–1.75 million km3). Groundwater resources are unevenly distributed: the largest groundwater volumes are found in the large sedimentary aquifers in the North African countries Libya, Algeria, Egypt and Sudan. The estimations for the Nubian Sandstone Aquifer System (NSAS) are between 133,000 and 150,000 km3, the North-Western Sahara Aquifer System (NWSAS) is estimated with 40,000 and 60,000 km3. but mostly too deep for plant roots. Only some plants have roots, which go more than 30 meters deep (e.g. Acacia spp.). Pumping of groundwater is an option to use it for irrigation in agriculture or animal watering.

Photo: The erg of Ibi el Akhdar is huge. And in the valley are palm trees for date production. The water is not too deep, but moving dunes are the risk for agriculture.

Photo: People from dry countries may ask, why are there so many wells on the fields, and why do they have a pole in the middle. The answer is simple: that are drainage wells, and the poles are necessary for harvest time and high crops (wheat, maize) to avoid damages for tractors and combines, because they would not see the wells without poles fast enough and would crash the machines on the wells.

Figure: Model of a dyke

Source: Rimoldi et al. (2021)

Photo: Dikes are protecting the Texel Island from floods from the harsh Northern Sea, if there is no low tide. Sheep help to maintain the dikes with their grazing and trampling.

Photo: The Aswan dam has flooded huge areas and brough whole year water access to southern Egypt. Tilapia aqua cultivation, crop production with irrigated water from the dam became possible to help to feed this heavily populated country, which is depending nearly 100% from the water of the Nile stream. Every water drop is used 9 times: first time at the Aswan dam and last time in the Nile delta. Contamination of this water is the most crucial issue, but chemical pesticides are the main pest management strategies. The plan was, to develop ‘organic villages’ adjacent to the lake.

Photo: Water in the desert is scarce and essential for humans and livestock. Yellow canisters are everywhere in Africa used for household water for humans.

Photo: Before the Katse Dam  for fresh water supply of Johannesburg, no one on the remote farms of Lesotho - the roof of Southern Africa - could believe, that a tared street, a big dam or a long-distance water pipe through the mountains could be constructed. After the dam was filled thousands of farmers have lost their farmland which they utilized hundreds of years.

Terracing

Not only cleaning, draining and irrigation is necessary to start agriculture. In the old agriculture cultures in Asia, the terracing of the slopes of the mountains are old and perfect for rice cultivation. The work to elevate the fields for irrigation is enormous.

Photo: Rice cultivation in hilly regions makes the construction of terraces necessary.

Agricultural landscapes are produced by land preparation for agriculture, if many adjacent farms or large-scale agriculture have a regional impact. Some of them got UNESCO World Heritage Sites, like the rice terraces on Bali and on the Philippines. But there are more than those two on any continent. For example the Neusiedlersee in Austria, pre-historic pile dwellings around the Alps in Switzerland, France and Germany, the Pantanal in Brazil, Landscape of Grand Pé in Canada, Coffee cultural landscape in Columbia, the Gedeo Cultural Landscape in Ethiopia, and the Budj Bim cultural landscape in Australia.

Photo: Refugees from the Kongo DCR have settled down in the western region of Uganda. The land scarcity forced them to settle down and cultivate steep mountainous areas. With the high and seasonal rainfall comes the risk of washed away soils.