About 10% of greenhouse emissions are from agriculture, especially from wet rice cultivation. Rice plants need a lot of nitrogen which is often provided as urea, a chemical fertilizer which is usually broadcast by hand into the irrigation water: this is easy, but wasteful. Some 60% of the nitrogen fertilizer is lost as it is transformed into gases and enters the atmosphere. Some nitrogen is washed away by irrigation water. A practical alternative known as â€śurea deep placementâ€ť makes much better use of nitrogen.
Urea usually comes in round grains, the size of fine gravel. For deep placement, the small grains are pressed into larger, oval pellets, about the size of your thumbnail. The farmer pushes these â€śsuper granulesâ€ť of urea into the soft soil, between four rice plants. This deep placement puts the urea underground, near the plantsâ€™ roots, so less nitrogen escapes into the air and water. The rice crop yields more and the farmers save money because they only need to use half as much fertilizer.
The efficiency of urea deep placement was demonstrated by 1980. The practice has not been adopted more widely because of the lack of supply of the super granules, the additional labor required and the difficulty of correctly placing the super granules in the field. Â But by the early 2000s, urea deep placement re-emerged in parts of Asia. The manufacture of small briquetting machines meant that the super granules could be made at the village level, and has led to a dramatic increase in their use, e.g. in Bangladesh (Giller et al. 2004).
There are two types of innovations: some you can try alone and others need to be adopted by a network. A solitary person can plant a new crop variety, for example, but it takes many people to start using super granules. Â A manufacturer has to build the briquetting machines. A second manufacturer has to buy a briquetting machine, make the super granules and sell them. Extensionists have to teach farmers how to place the super granules in the rice field. Then the farmers have to use the super granules, and make the idea their own.
It is kind of a chicken and egg problem. Farmers can’t use the super granules until someone makes them. Nobody will make them if there are no customers.
A step in the right direction is to show farmers the value of the super granules. The IFDC (International Fertilizer Development Center) commissioned Agro-Insight to make a farmer learning video on how to use urea deep placement. The video was filmed in West Africa, but the concepts also apply to Asia or even Latin America.
Of the 80 million hectares of irrigated rice worldwide, two million are in Latin America and the Caribbean, where 800,000 smallholders make their livings growing rice: 59% of which is irrigated (i.e. appropriate for urea super granules). And the region has the most potential of any to expand irrigated rice production. Rice is a popular food; tropical Latin Americans eat an average of 37 kilos of milled rice every ear, equivalent to a generous portion of 1.3 cups of cooked rice per day. As incomes increase, Latin Americans eat (and import) more rice.
As Latin America and the Caribbean grow more rice, it will help to make better use of nitrogen. So the urea deep placement video was recently translated to Spanish (there was already a Portuguese version). The video is a start, as it can teach farmers and extensionists about the importance of using fertilizer more efficiently, so that farmers can start to demand super granules and encourage companies to make and stock them. Even without super granules, growers of any crop will harvest more and save money if they grasp the idea that urea goes further if it is buried in the soil. This innovation makes a small contribution towards solving the problem of global warming.
Bent, Elizabeth 2015 The ground exhales: reducing agricultureâ€™s greenhouse gas emissions http://theconversation.com/the-ground-exhales-reducing-agricultures-greenhouse-gas-emissions-40795
Giller, Ken E., Phil Chalk, Achim Dobermann, Larry Hammond, Patrick Heffer, Jagdish K. Ladha, Phibion Nyamudeza, Luc Maene, Henry Ssali, and John Freney 2004 â€śEmerging Technologies to Increase the Efficiency of Use of Fertilizer Nitrogen,” pp. 35-51. In Arvin R. Mosier, J. Keith syers and John r. Freney (Eds.) Agriculture and the Nitrogen Cycle: Assessing the Impacts of Fertilizer Use in Food Production and the Environment. Washington: Island Press.
Pulver, Eduard 2010 â€śManejo EstratĂ©gico y ProducciĂłn Competetiva del Arroz bajo Riego en AmĂ©rica Latina,â€ť pp. 350-362. In VĂctor Degiovanni B., CĂ©sar P. MartĂnez R., & Francisco Motta O. ProducciĂłn Eco-Eficiente del Arroz en AmĂ©rica Latina. Volume 1. Cali, Colombia: CIAT. http://ciat-library.ciat.cgiar.org/Articulos_Ciat/2010_Degiovanni-Produccion_eco-eficiente_del_arroz.pdf
Savant, N. K. and P. J. Stangel 1990 â€śDeep Placement of Urea Supergranules in Transplanted Rice: Principles and Practices.â€ť Nutrient Cycling in Agroecosystems 25(1):1-83