Potassium is a critical nutrient for the proper ripening of fruit and vegetable crops. Without appropriate potassium levels, your crop may also experience poor fruit set and small fruit.
When fertilising, however, it’s essential to consider the impact of interactions between nutrients. Potassium has an antagonistic relationship with magnesium which can lead to complications in nutrient uptake.
Roots, Shoots and Fruits’ K-Forte and Biomin Magnesium solutions can help you find a balanced nutrient program to maintain optimum levels.
Importance of potassium in ripening crops
Potassium is a critical part of the photosynthetic process, controlling the opening and closing of stomata. It also transports water and sugars around a plant. Inadequate potassium levels lead to poor sugar accumulation in ripening fruits, affecting quality. Potassium is also linked to dry matter accumulation in developing fruits, so deficiencies result in reduced fruit size.
Potassium is present in cell fluid and helps regulate nutrient transport across cell membranes. It also contributes to cell wall structure which is important for a strong growing crop. A thick cell wall is vital to plant health as it prevents fungal pathogens from entering cells. A potassium deficiency may lead to developing fruits becoming susceptible to fungal diseases, as does calcium deficiency.
Deficiency challenges
A crucial element of soil that governs its ability to retain nutrients is cation exchange capacity (CEC). CEC is a measure of the negative charge in the soil. This negative charge attracts positively charged ions (cations) and makes them available for uptake by roots. CEC is especially important for the availability of potassium and magnesium, as they are both cations.
Low CEC soil often suffers from potassium and magnesium deficiencies. Soil CEC is determined by clay particles and you can increase CEC by adding organic material, or by incorporating humic or fulvic acid. Our Humax and Mobilizer products are high CEC soil amendments that promote nutrient bioavailability.
Cations compete for uptake through a root surface’s own cation exchange capacity. This means excess magnesium can often lead to a potassium deficiency and vice versa. It’s essential to understand the current nutrient levels in your soil to ensure a balanced fertilisation regime. Taking soil tests will tell you what nutrient levels your soil contains. A magnesium/potassium ratio of around 2:1 is generally appropriate.
Supplementing nutrients
Potassium and magnesium are both crucial nutrients for healthy ripening. Once you’ve ascertained and balanced your soil’s nutrient levels, it is equally important to check plant tissue levels. Soils are complex and often during ripening periods, plants are unable to take up adequate potassium and or magnesium to ripen large crops and therefore reach quality parameters for profitability. Applying foliar K-Forte fertiliser will bypass any mineral lockup conditions in the soil, rectifying potassium deficiency fast. K-Forte provides a potassium and phosphorus boost to promote healthy root growth, vigorous flowering, fruit development and ripening, promoting quality parameters of colour, flavour and sugars.
Magnesium is essential to photosynthesis and synthesising carbohydrates. Large quantities are required and can be applied to soil through our Biomin Magnesium or via foliar application of this bioavailable mineral.
If you are a commercial grower and would like to discuss your growing operation further, please don’t hesitate to contact us – rsf@rd2.co.nz
