Adding Manure and Fertilisers

Nila performs an experiment with two potted plants. She keeps the pots in sunlight and waters them equally. She adds manure to the soil in Pot 1. After a few days, she can see changes in the Pot 1 plant. 

What is Nila investigating?

An experiment was conducted to study the effect of a new fertilizer on the growth of two varieties of wheat. The data for growth of the plants from germination to next 10 days is shown in the figure. All other growing conditions such as water and sunlight were kept the same for both the varieties. Which of the following is the most reasonable conclusion you can draw from the data?

In which of the following agricultural practices, the nutrient requirements of one crop are fulfilled by the other crop?