(parties entered into manure easement agreement over plaintiff’s property with plaintiff receiving reduced fertilizer costs and expenses in return, but did not require plaintiff to pay for manure or require defendant to provide manure; when not all manure used in 2009 and 2010, defendant sold unused manure to third parties and plaintiff sued claiming right to unused manure based on oral agreement; trial court granted summary judgment for defendant because evidence related to oral agreement was inadmissible parol evidence; appellate court affirmed on basis that oral agreement addressed same subject matter as written easement and was inconsistent; easement contained integration clause).