We know that plants require nutrients. If we supply these in excess,will it be beneficial to the plants? If yes,how? If no,why?

(N/A) $\Rightarrow$ Each plant has a requirement for micronutrients in very low amounts. $A$ moderate decrease causes deficiency symptoms,while a moderate increase causes toxicity.
$\Rightarrow$ Any mineral ion concentration in tissues that reduces the dry weight of tissues by about $10 \%$ is considered toxic.
$\Rightarrow$ Toxicity levels vary for different micronutrients and different plant species. For example,$Mn^{+2}$ toxicity is a common issue. Concentrations above $600 \mu g g^{-1}$ are toxic for many plants,while $300 \mu g g^{-1}$ is toxic for soybean and sunflower.
$\Rightarrow$ Toxicity symptoms are often difficult to identify because the excess of one element may inhibit the uptake of other nutrients.
$\Rightarrow$ For example,the prominent symptom of manganese toxicity is the appearance of brown spots surrounded by chlorotic veins.
$\Rightarrow$ Manganese toxicity occurs because:
$(i)$ It competes with $Fe^{+2}$ and $Mg^{+2}$ for uptake.
$(ii)$ It inhibits the binding of $Mg^{+2}$ to enzymes.
$(iii)$ It inhibits the translocation of $Ca^{+2}$ to the shoot apex.
$\Rightarrow$ Thus,excess $Mn^{+2}$ induces deficiencies of iron,magnesium,and calcium.