Our vegetable crops require the absorption of specific elements in order to survive and thrive. However, our garden soil may be lacking in one or more of these nutrients. That is the reason why we apply fertilizer to our gardens. A fertilizer, by definition, is a substance that improves plant growth directly by providing one or more necessary plant nutrients.
When applying fertilizer, take care to apply the correct amount. More is not better. In fact, overfeeding can do more harm than good.
Applying too much nitrogen (usually in the form of manure) will cause the plants to produce an overabundance of leaves and a dearth of flowers and fruit. Plants need phosphorous to produce flowers and fruit. That’s why, if you use manure in your garden, you should also provide supplemental phosphorous.
Many fertilizers are also salts. Overfeeding of fertilizers can cause a build-up of salt in the soil. According to Texas A&M’s AgriLife Extension Service, when the soil absorbs too much salt, it eventually loses the ability to absorb water. In addition, overfeeding can cause an over accumulation of boron and chloride, which can result in slowed or stopped plant growth, yellowing foliage and even the death of the plants.
So how do you avoid overfeeding? Probably the best way is to test your soil before applying anything. You can purchase soil test kits from local nurseries or from gardening catalogs. You can also send samples of your garden soil into a lab for testing. The results of the test will show what nutrients are deficient, optimum, and in excess. This will establish a baseline that will guide you in choosing the right fertilizers and applying the right amounts to insure that your plants get all the nutrients they need – not too much and not too little.