A small, portable mini-lysimeter was tested to measure crop water use in barley and potato plants. The mini-lysimeter was compared to a larger, more expensive lysimeter over two growing seasons. Results showed that the mini-lysimeter slightly underestimated barley water use and slightly overestimated potato water use. However, overall, the measurements were in good agreement with the larger lysimeter. This means that the mini-lysimeter could be a cost-effective alternative for monitoring crop water needs. The study also calculated crop coefficients for barley and potato, which can help farmers accurately estimate how much water their crops require.