I'm a long-term investor at heart, and there are a few S&P/ASX 300 Index (ASX: XKO) shares in my portfolio I expect to own forever.

I can't say that about all of my holdings. Thinking that something is going to be a 50-year investment seems to be a fairly rare decision.

I'm going to talk about my largest investment and another that I've already owned for several years. I'll start with the smaller holding.

Rural Funds Group (ASX: RFF)

Rural Funds is a farmland real estate investment trust (REIT) that has been on the ASX for more than a decade. More importantly, farmland has been an important asset for many hundreds, if not thousands, of years. I think it'll remain essential for the rest of my lifetime.

It owns multiple types of farms, including cattle, almonds, macadamias, vineyards, and cropping. I like that diversification strategy, partly because it lowers risks and partly because it opens up more opportunities.

While agriculture can be a cyclical sector, it's Rural Funds' tenants that take on the operational risks, and Rural Funds receives consistent rent every year.

One reason the business is easy to commit to for a long-term investment is that it signs tenants on for many years. The business has a weighted average lease expiry (WALE) of 13 years, with some significant leases for almonds and macadamias expiring in FY38 and FY63, respectively.

One reason it's so easy to hold this ASX 300 share each year is that it pays a large distribution to investors. It expects to pay a distribution of 11.73 cents per unit in FY26, which translates into a forward distribution yield of 6.4%.

Washington H. Soul Pattinson and Co. Ltd (ASX: SOL)

My biggest investment is Soul Patts shares, though I don't view this as just one company. It's a diversified investment conglomerate with numerous ASX shareholdings, such as Brickworks Ltd (ASX: BKW), New Hope Corporation Ltd (ASX: NHC), Tuas Ltd (ASX: TUA), TPG Telecom Ltd (ASX: TPG), Macquarie Group Ltd (ASX: MQG), Wesfarmers Ltd (ASX: WES), and Nexgen Energy (Canada) CDI (ASX: NXG).

The business has already existed for 120 years, and I wouldn't be surprised at all if it succeeds over the next 120 years as well. That's because it has the investment freedom to invest in whatever industry and asset class it sees as opportunities. This will allow the business to adjust its portfolio in the coming years if and when it wants to, allowing for enduring long-term returns.

It's my biggest holding because I like its investment process, the focus on assets that produce defensive cash flows and its long-term dividend track record.

The ASX 300 share has increased its annual ordinary dividend every year since 2000. I appreciate the consistency (and growth) of the Soul Patts dividend, which will become increasingly useful for my personal finances as I get older.

It currently has a grossed-up dividend yield of 3.8%, including franking credits.