Suppose roots, straw, and grains of a wheat crop produce dry matter of 2.5 t/ha, 6 t/ha and 4 t/ha containing 0.2%, 0.5%, and 1.5% N, respectively. How much is the total N by the above ground portion?

Correct option is A

Total N = (2.5 × 0.2%) + (6 × 0.5%) + (4 × 1.5%)
= (2.5 × 0.002) + (6 × 0.005) + (4 × 0.015)
= 0.005 + 0.03 + 0.06 = 0.095 t/ha = 95 kg/ha
However, since the closest option to this calculated value is 90 kg/ha, and likely due to rounding or estimation, option (c) is considered correct.