High rate of technological development in the agricultural systems has led to the embracement of smart farming where technology as represented by wireless communication network is highly involved in data collection and interpretation. The paper focuses on the analysis of performance of a Wireless Sensor Networks (WSNs) with Smart Agriculture using OPNET Modeler 14.5. The research will be able to assess the effectiveness of WSNs in measuring key agronomical attributes such as soil moisture, temperature and humidity of the soil that are crucial in attainment of optimum crop yield and preservation of environmental resources. In the simulation, the sensor nodes are placed in a virtual farmland to collect and transmit the environmental information to sink node in the center where it is to be analyzed. The critical key performance indicators such as network throughput, end to end delay, packet delivery ratio and the consumption of energy are put to the test under variations of the node densities and communication ranges. The assumption is that the results will show impacts of the network design on the efficiency and reliability of communication of data in smart agriculture systems. This study will be applied in the development of the energy efficient and cost-effective network models in coming up with precision agriculture, therefore, aid sustainable agriculture and improved environmental management. The paper is able to fill the gap existing between the agricultural production and the new communication technologies.