The research aims to investigate the existence of a direct causal relationship between selected agricultural variables: agricultural output (as a representative of growth in the agricultural sector), agricultural terms of trade as a completely new variable in agricultural studies in recent years, agricultural labour which is an important part in the total workforce for Iraq, and finally, agricultural investment because of its importance and vital role in the production process, creating job opportunities, and then raising the level of employment, then it's role to achieving agricultural growth and development. For this purpose, the researchers used the Toda-Yamamoto causality methodology for a time series covering from 1990 to 2019. The research found a causal relationship between the agricultural terms of trade TOT and the agricultural labour LA towards agricultural product AP, and the existence of a significant causal relationship from all variables towards agricultural investment INV. Therefore, the research recommends taking in consideration the results mentioned above and working to exploit the opportunities provided by the relationships among studied variables to avoid the reasons for problems such as the presence of terms of trade not in the interest of Iraq, as well as emphasizing the good opportunities, such as the crucial role of agricultural investment in raising the level of agricultural product and employment. As well as the need to adopt the terms of trade criteria as one of the important indicators in making government policies related to the production and export of agricultural products.