Synergistic Effect of Potassium Humate on Fertilizers

1. Its Synergistic Effect on Nitrogen Fertilizers
Nitrogen fertilizers are mostly carbonic acid and urea. Ammonium nitrogen is unstable and highly volatile. Because humic acid contains functional groups such as carboxyl and phenolic carboxyl groups, it has strong ion exchange capacity and adsorption capacity. And thus it can reduce the loss of ammonium nitrogen when they are mixed together. Urea is a kind of amide nitrogen fertilizer, and the nitrogen contained in it needs to be decomposed and converted into ammonium carbonate by the ureasereleased by ureabacteria before it can be absorbed by plants. If urea is applied to the calcareous soil, the ammonium bicarbonate produced by the decomposition of urea will also suffer volatilization loss due to the alkalinity of the soil, which is one of the reasons why the nitrogen utilization rate of urea fertilizer is not high. Obvious synergistic effect on urea can be achieved after mixing it with humic acid. First of all, humic acid enhances the activity of urease, slows down the decomposition of urea and reduces its volatilization; Secondly, humic acid can form a complex with urea, gradually decompose and release nitrogen and thus prolongs the fertilizer effect of urea. In addition, the biological activity of humic acid can enhance the growth of the plants’ roots as well as the nitrogen metabolism in the plants, thereby promotes nitrogen absorption.

2. Its Synergistic Effect on Phosphate Fertilizers
When quick-acting phosphorus fertilizer is applied to the soil, soluble phosphorus is easily fixed by the soil. In acidic soil, phosphorus is mainly fixed by free iron and aluminum ions while in calcareous soil, phosphorus is principally fixed by calcium ions, resulting in the conversion of quick-acting phosphorus into slow-acting phosphorus, or even ineffective phosphorus, with a 10-20%current-seasonutilization rate of phosphorus. Humic acid fertilizer, when mixed with phosphorus fertilizers, can inhibit the fixation of water-soluble phosphorus in the soil, slow down the transformation of quick-acting phosphorus to slowor ineffective states. Degraded nitro-humic acid increases the movement distance of phosphorus in the soil and promotes the uptake of phosphorus by the root system.

3. Its Synergistic Effect on Potassium Fertilizers
With functional groups that can absorb and store potassium ions, humic acid can not only prevent the loss of potassium caused by drainage in sandy soil and leached soil, but also prevent the fixation of potassium in cohesive soil. Some parts of humic acid are low-molecular humic acids such as fulvic acid, which have a dissolution effect on minerals such as potassium silicate and potassium feldspar and can slowly decompose them, increase the release of potassium, and increase the content of available potassium.

4. Its Synergistic Effect on Trace Element Fertilizers
There are considerable reserves of trace elements in the soil, but few of them can be absorbed by plants. Humic acid can undergo complex reaction with insoluble trace elements to form complexes with good solubility and easy absorption by plants, which is conducive to root absorption or foliar absorption, and promotes plants’absorption of trace elements from roots and then the transfer of nutrients from the root to the stem and leaves.