(1)洪水威脅; (2)干旱缺水威脅; (3)水環(huán)境惡化威脅;
(1)專業(yè)種植大戶 (2)家庭農(nóng)場(chǎng) (3)機(jī)械化農(nóng)場(chǎng) (4)合作農(nóng)場(chǎng) (5)工廠化專業(yè)隊(duì)
(1)適度原則; (2)堅(jiān)持農(nóng)民自愿原則; (3)堅(jiān)持土地公有制的原則;