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Improvement of fertilization strategies in Mozambican rice production: reconciling environmental sustainability and equitable socioeconomic development
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The overall importance of rice production has been increasing over the last few years. It is one of the main cereals consumed, ensuring world food security. Rice is the staple food in Africa which represents the most consumed crop compared to others, such as sorghum, maize, and cassava crops. In addition, rice is one of the main sources of energy in West Africa. According to the Food and Agriculture Organization of the United Nations, rice production in Africa has increased by 74% against the prospects and by 2018 the eventual target will be 28 million metric tons, with Nigeria and Tanzania as the major producers. Rice production is one of the main sources of agricultural greenhouse gases emissions (GHG), such as methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) and contributes concretely to more than 10% of global methane emission. In Mozambique, rice production remains at a subsistence level, which is characterized by low production and low productivity levels despite a long production practice of more than 500 years. Mozambique has 900.000 ha of land for rice production but only 34% are being used, Mozambique has potential to become rice exporter to regional scale. National demand for consumption of this cereal fluctuates at around 621.000 tonnes, with over 350.000 tonnes supplied by imports with an underlying cost of over 140 million dollars. The national sector rice is still subject to several constraints. Most of rice production in Mozambique is done by small farmers in rain-fed conditions, with low financial resources, poor technical support regarding soil fertility with average productivity of 1.0-1.2 tons per hectare in rainfed systems and 2.8-3.5 tons per hectare in irrigated systems and relying on the use of practices such as burning of cultural waste as well as the use of fire to open new areas for production. Nevertheless, most of fertilizers are used without any knowledge about soil, needs with negative consequences in terms of rice production, farmers’ economy, and the environment. Thus, it is extremely important to develop agricultural practices of rice production that are environmentally sustainable, economically viable and that can respond to social needs, mainly those related to the population growth consequently increasing demand of imported rice. With an increase in rice prices on the world market and the effects of climate change, it is of the utmost importance to design national strategies and to respond to the requirements of the national rice sector development. Considering the high percentage of smallholders who still use rudimentary farming practices, it is necessary to encourage the optimal use of inputs (optimal fertilizer and water) to be developed that ensure high yields with low GHG. The main goal of this PhD research was to provide technical and scientific information to improve fertilization strategies on rice production addressed to small-holder’s rice producers. Chókwè Irrigation Scheme (CIS) is the major irrigation scheme area in Mozambique. Using CIS as a case study, we aim to explore which typologies of Rice Farming Systems (RFS) are predominant in the CIS; which factors affect the production and productivity of smallholder farmers in the CIS; and what kind of policies/incentives can be proposed to enhance the production and the productivity of rice in the CIS. Based on the main constraints that affect smallholders’ rice production, we evaluated the agronomic results and the economic benefits of using mineral fertilizers and organic nitrogen sources. Finally, we evaluated the effect of fallow time, organic and inorganic fertilization on GHG emissions in the soils. The results showed four different kinds of rice farming systems: the subsistence FS, specialised rice FS, mixed crops FS, and rice–livestock FS. At the same time, the combination of different three source of nitrogen such as, urea, beef cattle manure and poultry litter at a rate of (40%:30%:30%) produced good results and is thus recommended to smallholder farmers for better optimum crop production on Chókwè Irrigation Scheme. Finally, the results observed demonstrate that the period of fallow can be an important source of GHG emissions with relative importance on CH4 and N2O. This study contributes to fight a knowledge gap about GHG emissions by rice paddies in Mozambique.
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Fertilization strategies Socio-economic development Rice farming systems Greenhouse gases emission Sustainability