In order to have economically sustainable and profitable farms, farmers need to manage and understand factors that impact farm output and costs. Many factors can influence farms' output and costs, such as soil quality, environmental conditions, farm size, farm system, farmers' experience, and so on. This study investigates how much investment increase and investment decrease may have an impact on farm gross output and direct and overhead costs. The paper utilizes the Deep Neural Networks method to carry out the study. A farm survey of pastoral-based livestock systems from 1996 to 2018 is utilized as the data source. The findings show that on average Irish farmers from the bottom second gross output decile up to the fifth decile will see an increase of 9% to 12.6% in their gross output if they increase their investment in machinery, livestock, and buildings by 10%, while a modest increase of about 2% to 7.2% in sixth to eighth gross output deciles. Surprisingly, farmers in the first, ninth, and tenth deciles will see a decrease of 7.7%, 0.05%, and 3.77% in their gross output, respectively, should they increase their farm investments by 10%. On the contrary, if farm investments are decreased by 10%, then all farm gross output deciles will observe a decline of 3.5% to 21% gross output on average. Unsurprisingly, with a 10% increase in investments, direct and overhead costs also increase in most deciles, while with a decrease of investment by 10%, all deciles of overhead costs will decrease. However, with a 10% investment decrease, all deciles of direct costs will go down, except for the second to fourth deciles. The output of the paper demonstrates the importance of farm investments to agricultural output and costs, which can be used by agricultural policymakers and other stakeholders to make research-based decisions
