Given that most farmers already use chemical fertilizer rather than shit, we're not short on data for analysis. One benefit you overlooked is knowing exactly w

Given that most farmers already use chemical fertilizer rather than shit, we're not short on data for analysis. One benefit you overlooked is knowing exactly what and how much you're putting in your soil. A bag of ammonium nitrate gives you a known quantity to factor with while shit is far from homogeneous in its makeup.