Tropical agriculture
Worldwide more human beings gain their livelihood from agriculture than any other endeavor; the majority are self-employed subsistence farmers living in the tropics[citation needed].
Funded initially by the Rockefeller Foundation, it aimed to improve corn, rice, and other cereal cultivators – breeding plants that would produce more grain for the same amount of effort.
Plants faced conflicting evolutionary pressures: the need to attract pollinators and seed dispensers, and to minimize the damage caused by herbivores.
This produces thick mulch on top of the ground that both inhibits weed growth and adds vital nutrients to the soil.
Slash/mulch is popular in southern Mexico, Guatemala, and Honduras; and in recent years has gained a following in many areas of the tropics, from Brazil to central Africa.
In most places in the tropics sufficient precipitation occurs to grow enough food to feed the local population; however, it may not fall in a timely or convenient manner.
The ability to collect and store water at a low cost and without damaging the environment, is what opens up deserts and other arid regions to farmers.
One of the simplest forms of irrigation - the farmer digs bathtub-sized pits into his fields and lines them with plastic sheets to collect rainwater.
During years with normal precipitation, the growing season can be increased by an extra month or more by using harvesting pits.
During times of drought, what rain does fall can be collected in the pits and used to secure the farmers' main crops.
Rotations are used to prevent or at least partially control several pests and at the same time to reduce the farmer's reliance on chemical pesticides.
Farmers end up using more and more chemicals with diminishing effect as pests quickly adapt –while at the same time natural predator insects are eliminated from the farm.
Under IPM, chemicals should be a secondary line of defense, while building up the number of natural predators on a farm is the main goal.
The IPM approach calls for keeping the pest populations below the levels at which they cause economic injury, not total eradication.
Pioneering crops are used in places where the land has been striped bare, and the topsoil has been entirely lost to erosion, or where desertification has started.
One way of mitigating the effects of the hunger season is growing some non-seasonal crops close to the family home, such as bananas in humid areas, or cassava where it is arid.
As an example, a family that has ten banana plants producing fruit during the hunger season is unlikely to experience excessive hardship.
Standard temperate strategies for improving nutrient-poor soil, such as composting, have limited application in such an environment due to rapid leaching.
In a soluble state, it is highly toxic to plant life, as it inhibits root growth; however, in neutral and alkaline soils common to the temperate zones, it is insoluble and therefore inert.
Winrock International states, "In the humid tropics, the relative importance of acid soils is greatest in Latin America (81%), but also significant in Africa (56%) and Asia (38%)".
In time, acidity increases and only native plants will grow, forcing the farmer to move on and clear a new area.
Salinization occurs naturally in arid areas where not enough rain falls to wash soluble salts down and out of the root zone.
A combination of factors make the tropics one of the world's most vulnerable regions to the negative impacts of climate change on agriculture.
These include: The fact that climate change and temperature increases are expected to negatively affect crop yields in the tropics could have troublesome implications for poverty and food security, mainly because populations in the area are so dependent on agriculture as their only means of survival.
[10][11] These include regions such as West Africa which are already dependent on drought- and stress-resistant crop varieties and thus left with little room to manoeuvre when the climate becomes even drier.
[10] The study says that East and West Africa, India, parts of Mexico and Northeastern Brazil will experience a shortening of growing seasons by more than 5%, negatively impacting a number of important crop staples.
