..."Cannot be accessed with an instance reference, qualify it with a type name instead" error

So I have a script called “GrowBerries” and I have it set up so I can harvest the berries, but when I try to run a non-static method in another script, I get this “Static member `Inventory.AddItem(int)’ cannot be accessed with an instance reference, qualify it with a type name instead”

Here is the script I am getting the error on, Line 12 specifically:

using UnityEngine;
using System.Collections;

public class GrowBerries : MonoBehaviour {
	public GameObject berries;
	public GameObject inv;
	public bool harvested = false;

	// Use this for initialization
	void Start () {
		Inventory i = inv.GetComponent<Inventory> ();
		i.AddItem (4);
	}

	void OnTriggerStay(Collider other)
	{
		if (other.tag == "Player") 
		{
			if(Input.GetKeyDown("h"))
			{
				berries.SetActive(false);
				harvested = true;
				StartCoroutine(Regrow());
			}
		}
	}
	IEnumerator Regrow()
	{
		while (harvested) 
		{
			yield return new WaitForSeconds(5);
			berries.SetActive(true);
			harvested = false;		
		}
	}
}

Thank you in advance, and I can provide clarification if need be.

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