Some gardeners use Tums tablets to treat calcium deficiency in the soil. This does not work since calcium needs to be dissolved in water to be taken up by the tomato plants. A better approach is to pretreat the soil with a fertilizer that contains calcium. If the soil is kept unevenly moist, the calcium will not be taken up and bottom rot will occur.
Tums chemically are calcium carbonate. The principle behind adding Tums to the garden soil is based on its formulation. Some gardeners crush the tablets and add them to the soil, others place a whole Tums tablet in the hole with the plant. Another approach is to add crushed Tums to the water given to the tomatoes. This approach can work, in theory, if the tablets dissolve. Foliar application of Tums and water does not aid in calcium absorption.
Bottom rot is a plant disorder with an environmental cause. It appears on the bottom of the tomato as a sunken area that turns dark brown to black. The skin of the tomato on the bottom also develops a leathery appearance. The cause of bottom rot is uneven watering that prevents the tomato plant from absorbing calcium. To reduce bottom rot, water regularly and mulch with grass clippings, compost and even red plastic. Mulching tomatoes will also reduce the need to weed the garden space. This will reduce the chance that the roots of the tomato plants will be disturbed through weeding. Disruption of the roots is another cause of bottom rot.
To determine if calcium is a problem in the soil, a soil test must be performed. This is done by the homeowner and sent to a college or county extension for testing. If the homeowner is confused on how to do the test an extension agent will help with the test. The results will be sent to the homeowner with recommendations on how to deal with any macronutrient and micronutrient deficiencies.
A soil high in nitrogen or using a fertilizer too high in nitrogen can also cause bottom rot. To prevent this problem always have the garden soil tested before gardening season and do not over fertilize. While fertilizer helps plants grow, it can also be harmful to the plants and the environment if over used.