What type of methods are used before grains are stored for future use?

Vividha told Vasudha that she will show her some magic. Vividha took a metallic pipe. She asked Vasudha to hold one of its ends close to her ears. She gently tapped the other end of the pipe with a metallic object. She asked Vasudha what she heard. Vasudha said she heard two sounds.
$(a)$ Was this magic? Why did Vasudha hear two sounds?
$(b)$ What values are imbibed by Vividha?

The preventive and control measures which are used before grains are stored for future use include:

Cultivation practices and crop yield are related to environmental conditions. Explain.

Based on the kind of biological material used,what are the two kinds of manures? How are they prepared?

The level of vitamins $A$ and $K$ is kept high in poultry feeds.