A system for measuring soil element concentration in an agricultural field as the system moves through the agricultural field, comprising: a mobility component configured to move the system in the agricultural field; a soil probe; an extraction apparatus coupled to the mobility component, the extraction apparatus configured to receive a plurality of soil samples in succession, from different locations in the agricultural field, from the soil probe coupled to the mobility component, when the mobility component is operating, the extraction apparatus containing an extractant solution that is a solvent of the plurality of soil samples; and the extraction apparatus comprising a mixer that is configured to mix the plurality of successively collected soil samples with the extractant solution, thereby forming a solution mix; and the extraction apparatus further comprising a self-contained disposable container configured to receive the solution mix, wherein the self-contained disposable container has a lid with one or more openings for receiving / supporting the mixer, a soil sample from the soil probe and the chemical sensor; and a chemical sensor (808, 908) coupled to the extraction apparatus, the chemical sensor configured to measure a concentration level of a soil element in the solution mix; a processor coupled to the chemical sensor (808, 908), the processor configured to calculate a concentration level of the soil element in each of the plurality of soil samples after the soil sample is received by the extraction apparatus and before a successive soil sample is received by the extraction apparatus; a controller configured to control operation of the mixer, the mobility component, or the soil probe; wherein the extraction apparatus is so configured that the mixer or the chemical sensor can be coupled to the lid, the lid can fit the container and stay in place when the container is being replaced. a mobility component configured to move the system in the agricultural field; a soil probe; an extraction apparatus coupled to the mobility component, the extraction apparatus configured to receive a plurality of soil samples in succession, from different locations in the agricultural field, from the soil probe coupled to the mobility component, when the mobility component is operating, the extraction apparatus containing an extractant solution that is a solvent of the plurality of soil samples; and the extraction apparatus configured to receive a plurality of soil samples in succession, from different locations in the agricultural field, from the soil probe coupled to the mobility component, when the mobility component is operating, the extraction apparatus containing an extractant solution that is a solvent of the plurality of soil samples; and the extraction apparatus comprising a mixer that is configured to mix the plurality of successively collected soil samples with the extractant solution, thereby forming a solution mix; and the extraction apparatus further comprising a self-contained disposable container configured to receive the solution mix, wherein the self-contained disposable container has a lid with one or more openings for receiving / supporting the mixer, a soil sample from the soil probe and the chemical sensor; and a chemical sensor (808, 908) coupled to the extraction apparatus, the chemical sensor configured to measure a concentration level of a soil element in the solution mix; a processor coupled to the chemical sensor (808, 908), the processor configured to calculate a concentration level of the soil element in each of the plurality of soil samples after the soil sample is received by the extraction apparatus and before a successive soil sample is received by the extraction apparatus; a controller configured to control operation of the mixer, the mobility component, or the soil probe; wherein the extraction apparatus is so configured that the mixer or the chemical sensor can be coupled to the lid, the lid can fit the container and stay in place when the container is being replaced.