table of contents i list tables ii figures appendices iii glossary acronyms symbols and definitions iv executive summary viii 1 0 introduction 2 agricultural land resource paddy production at the national level local 3 usangu plains mbarali district 4 regional 6 comparison yields 7 costs marketing profit margins 8 rice commodity chain prices productivity irrigation water 9 12 returns to labour 15 imports exports consumption food security 17 19 balance sheet 23 irrigated in its implications