Beans are a great consumer of nitrogen, one of the primary nutrients found in general fertilizers. Bean plants can also benefit from other nutrients commonly found in all-purpose chemical fertilizers, providing the current status of the soil is taken into consideration before applying. However, adding too much fertilizer or the wrong blend can result in damage to the bean plants and a reduced crop.
Fertilizer is any soil amendment that adds nutrients to the soil to enhance plant growth. Plants require some combination of 16 different nutrients in order to grow well. General chemical fertilizers typically provide the three most common nutrients--nitrogen, phosphorus and potassium--in varying levels depending upon the plants being grown. Specialty fertilizers and other soil amendments can be added if necessary.
If you are confident your soil is in good shape nutritionally, a general fertilizer in a 10-10-10 or 12-12-12 configuration is adequate for bean plants. However, if you are uncertain of its condition, a soil test conducted by your local extension office can provide you with invaluable information. Results will indicate any deficiencies, and recommendations that accompany the results will guide you in selecting the proper fertilizer for your bean plants.
Nitrogen is the most commonly needed nutrient provided by general fertilizers. It is the N value in the NPK ratio system and is the first value stated on fertilizer labels. It is important to beans, and plants in general, because it affects foliage production. Without healthy leaves, bean plants cannot photosynthesize and feed themselves. On the other hand, too much nitrogen can produce large leafy, bean plants that do not flower or produce beans.
Phosphorus is the P in the NPK value and is the second value listed on labels. Its aids bean plants in several ways but it is primarily used to enhance root production. Strong roots are important to the bean plant because the roots are responsible for the intake of water and nutrients for the plant. A poor root system leads to an unhealthy plant and minimal bean production.
Potassium is commonly called potash. It is the K value in the NPK value system and appears as the third value on fertilizer labels. Potassium helps bean plants develop sturdy stems and contributes to the bean plant's ability to distribute water. It aids in photosynthesis and also helps roots develop well.
Bean plants are highly susceptible to fertilizer burn when fertilizer makes contact with seed or seedlings or if too high of a concentration is used. Leaves will display a scorched appearance. Immediate irrigation can reduce further damage. Follow fertilizer instructions carefully with regard to amount, type, timing and method of application to avoid such injury.