I found solution.
1. Copy Armbian from SD card to NAND and remove card.
2. Boot from NAND.
3. Insert SD.
4. Modify "boot.cmd"
setenv bootargs console=ttyS0,115200 root=/dev/nand1 rootwait panic=10
replace
setenv bootargs console=ttyS0,115200 root=/dev/mmcblk0p1 rootwait panic=10
convert boot.cmd to boot.scr:
mkimage -C none -A arm -T script -d boot.cmd boot.scr
5. Remove boot sector from SD card
dd if=/dev/zero of=/dev/mmcblk0 bs=1k count=1023 seek=1
6. Reboot Cubieboard2. Clean directory /boot on SD card.
7. In /etc/fstab add
/dev/nand1 /boot auto default 0 0
8. Reboot