If more salt is present in the water used to water a bean plant, then that bean plant will grow less than the bean plant with less salt in water.

Literature shows that increased salt in water and soil in dry and semi dry areas happens wherever irrigated agriculture is practiced. It seriously affects productivity on about 50 million acres (20 million hectares) of the worlds’ irrigated land. In Mesopotamia, Sumerian irrigation practices caused a salt build-up in water and soils that inhibited food production and with no doubt this contributed to the decline of Sumerian culture. Salt in water and soil can lead to decline in world food production and can lead to hunger and starvation. During winter many areas in Canada put lots of salt on the roads to try to melt the snow and ice. In the spring, when it rains, the salt gets swept away and goes into the soil and onto the fields. Plants get affected and die because of the salt.

Rain water does not have any minerals or salt in it. However, any water from wells or rivers can have small traces of salt or other minerals. When water with minerals or salts evaporates, the concentration of these salts or minerals increase. Continuous use of water from rivers or wells will cause the build up mineral and salts in the soil.  If little rain falls than this will not be able to wash off the salt from the soil.

Manipulated Variables: Water and different concentrations of salt, NaCl and CaCl2, in water. Concentrations are 0.5%, 1%, 2%, and 5%.

Controlled Variables: Amount of sunlight, amount of water, amount of soil, temperature, beans.

Responding Variables: Height of plant.

1. Have 27 cups, fill each cup with the same amount of potting soil.

2. Place the beans inside the soil.

3. Prepare different concentrations of salt, NaCl and CaCl2 in water.

1. 0.5% - 0.5g of salt in 99.5ml of water
2. 1% - 1g of salt in 99ml of water
3. 2% - 2g of salt in 98ml of water
4. 5% - 5g of salt in 95ml of water

4. Give the same amount of water or salt water to each cup.

5. Place all cups next to a window so they have the same amount of sunlight.

6. Water the plants regularly. 

7. Observe and record plant height and condition of plant, ex. Is the plant wilted/withery?

On Day  7, one water and one 0.5%NaCl beans sprouted.

On Day 10, one more water, one more 0.5%NaCl, one 0.5%CaCl beans sprouted.

On Day 13, both plants with water and the first one that sprouted from 0.5%NaCl continued to grow.

On Day 16 beans plants wilted slightly and these cups had soil that looked dry.

On Day 20 and forward salt residue was observed on all bean cups watered with 2%NaCl, 2%CaCl, 5%NaCl, and 5%CaCl.

Some beans even with water did not sprout.

Plants with just water continued to grow throughout the experiment.

Plants with low concentrations of salt sprouted but grew little as the salt accumulated.

Beans with high salt concentrations never sprouted.

Plants wilted and soil looked dry because the plant used up all water.

Salt residue occurred because the water evaporated leaving the salt behind.

Even with water not all seeds sprouted.

Based on my research I hypothetized that if more salt is present in the water used to water a bean plant, then that bean plant will grow less than the bean plant with less salt in the water. Historical studies show that in agricultural areas where the soil was irrigated with water that has salt, less plants will grow and more eventually withered and died. If too much salt was present in the soil, then plants did not grow at all. My hypothesis was correct.

My experiment showed that the bean plants that were irrigated with just water continued to grow after sprouting. When little salt, whether it was table salt, Sodium Chloride, NaCl, or Calcium Chloride, CaCl, plants will sprout but they do not grow well and eventually stop growing at all. Also, in my experiment when concentration of salt was 1% or more then no sprouting happened.

When just water is used to irrigate the plants then the plants have to salt to prevent sprouting and decrease grown. However, when even little salt is present then the water will eventually evaporate leaving the salt in the soil. This will eventually lead to accumulation of salt in the soil slowing down the growth of plant. If too much salt is present, then nothing will grow as too much salt will be present from the start. Interestingly, not all beans that were watered with just water sprouted.  This is possibly because not all seed sprout at the same time. Also, the water may evaporate too soon for the beans to be able to use it for sprouting. Another unexpected finding was that the soil where the plants grew dried up much quicker. This is because the plants used up the water for growth. 

One unexpected finding I observed was that Calcium Chloride had the least amount of growth from all the seeds that sprouted. From my background research I found that Calcium Chloride should be better for the plants but my results showed that it was worse.

In conclusion, my experiment showed that salt in water decreased plant growth and prevented sprouting of beans verifying my initial hypothesis.

Governments can use this study to decrease the use of NaCl and CaCl2 on roads that are close to agricultural areas.

It is useful to know what concentration of salt in water causes problem with bean plants. There are agricultural areas in the world where a lot bean plants are grown.  Those could be kidney beans, soy beans, or other types of beans. If the roads are salted close to the fields, this could lead to a lower harvest.  Also, if the fields are irrigated with water with even a small amount of salt, then over the months and years the soil will accumulate the salt causing the same problem again. The best water for growing plants is rain water, because it does not contain any minerals or salt. 

When there is snow or ice on the roads, salt is used to melt it. If we can find a good substitute for the salt, then this will prevent the negative effects of salt on plants. 

Some studies showed that CaCl2 was safer than NaCl for plants. My study shows that it is worse, so CaCl2 should not be used as a substitute.

It is possible that the temperature in my home is not right for the plants to sprout and grow. Maybe too little or too much water and solutions were used on the plants. The cups with beans were put where the sun shone well and that might have been too sunny for the beans.  Also, my measurements of salts and water to prepare the solutions might have not been exact. I used a kitchen scale that may not be the best method of measuring small amounts. 

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https://www.sciencedirect.com/science/article/abs/pii/S0048969716318794 (2025). I.N. Daliakopoulos,  The threat of soil salinity: A European scale review

https://www.noaa.gov/jetstream/ocean/sea-water (2025). Sea Water

https://openknowledge.worldbank.org/server/api/core/bitstreams/78b9fa85-83e6-549b-9c2c-d33099c0bc50/content (2025). Jason Russ, Salt of the Earth

https://www.scienceworld.ca/resource/bean-garden/ (2025). Bean Garden

https://www.sciencedirect.com/science/article/abs/pii/S0022169421004741 (2025). Lee Dong, Evaporation-induced salt crystallization and feedback on hydrological functions in porous media with different grain morphologies

https://www.degruyter.com/document/doi/10.1515/opag-2017-0064/html (2025). Eric B. Kouam, Genotypic variation in tolerance to salinity of common beans cultivated in Western Cameroon as assessed at germination and during early seedling growth

https://www.bluelinetrans.com/plant-tolerance-to-calcium-and-magnesium-chloride-concentrations (2025). Plant Tolerance to Calcium and Magnesium Chloride Concentrations

https://roam.macewan.ca/items/7893d495-802a-4d1e-badd-8ab4c2286277 (2025). Brittany Tonsi, Effects of NaCl and CaCl2 salinity stress on the germination, seedling and root morphology of Dalea candida

https://ars.els-cdn.com/content/image/1-s2.0-S0048969716318794-fx1_lrg.jpg (2025).

I would like to acknowledge my teacher, Mr. Baillie for helping me with the project and my mom and dad for giving me pointers after I presented in front of them.