1.
The most abundant metal in the earth’s crust and toxic to plants in low concentration is____________________?

2.
Point of zero change means____________________?

3.
Part of soil which is in contact with root surface is called___________________?

4.
Examples of macrobiota are______________________?

5.
Which bacteria convert nitrite to nitrate___________________?

6.
In flood rice, snail feed on bacteria called__________________?

7.
Humic acid is soluble in____________________?

8.
Which mulch reduce soil temperature?

9.
The tree sends down roots from its branches to the soil is know as:_______?