(plaintiff, a distributor/seller of fertilizer to farmers, sued defendant, bulk seller of farm fertilizers to distributors on claim that contract they entered into in July of 2008 for delivery of anhydrous in April of 2009 was not valid because it lacked defendant's signature; plaintiff had signed the contract and made downpayment, but market price of anhydrous dropped significantly below contract price by fall of 2008; court upheld validity of contract - downpayment made and defendant's practice was to file contracts without signing them and contract language did not require defendant's signature; plaintiff accepted contract by signing it and making downpayment).