(a(i))[3]
Use the information shown in the graph to describe the effect on crop yield of adding a greater mass of fertiliser.
(a(ii))[3]
The nitrogen in the fertiliser is present as nitrates. Describe how nitrogen from the fertiliser is absorbed by crop plants and then used to produce a higher yield.
(a(iii))[3]
Suggest and explain why a farmer may decide to use a mass of fertiliser per hectare that is lower than that required for maximum crop yield.
(b)[2]
Name one kind of mineral ion, other than nitrate, that a plant needs and state its importance to the plant.