Foliar potassium nitrate: More yield and shelf life for our crops

The FAO has anticipated that, between now and 2050, agricultural production worldwide will have to double if we are to meet the food demand of a growing population that will reach 9.8 billion people in another 30 years.

Selecting the right fertilizers will continue to be an important part of the equation for improving crop yield, quality and shelf life. But even more vital will be their application.

Let's look at foliar spray: both laboratory and field trials (see tables) conclude that foliar application of _KNO3 is a powerful tool for improving both crop quality and quantity. Scientific research has shown that about 29 crops benefit from foliar sprays of _KNO3. This includes field crops such as beans, cotton and grains.

In addition, crops treated with foliar sprays tend to acquire higher nutritional value. Enhanced total soluble solids (TSS) contribute to increased sugar, vitamins, minerals and protein in harvested crops. It is not enough to grow more. Crops must be better for those of us who consume them.

Potassium (K) regulates plant functions and increases nitrogen efficiency. By increasing the salt concentration in the cells, plants can better resist frost. Applied at the right time and in the right amount, potassium promotes the development of a stronger cell structure, allowing crops to better resist drought, disease and pests. Better internal structure promotes longer shelf life by reducing losses and generating food for millions.

Dr. David Dunn, a scientist at the Delta Agriculture Center in Qulin, Missouri, and SQM researchers were able to prove that foliar sprays of _KNO3 resulted in increased resistance to stalk breakage in rice, which reduced lodging incidence. Tipping or lodging (hurricane season) does not necessarily reduce yield, but it will slow down the harvest operation, which ultimately leads to a higher operational cost per acre.

Foliar application of Potassium Nitrate (_KNO3 ) has an immediate effect: it improves yield and fruit size, reduces fruit splitting and spoilage in storage and therefore reduces wastage of harvested food, a saving that could feed millions.

Originally, it was thought that the use of _KNO3 was only appropriate when a nutritional deficiency existed. Ongoing scientific research, however, has consistently shown that periodic applications can have a positive effect on both the quantity and quality of fruit, nut, vegetable and grain crops. These studies include soil and weather conditions, as well as yield data collected after applying foliar sprays of a _KNO3 solution not only to nutritionally deficient crops, but also to crops that have adequate potassium levels, such as wheat, almonds, tomatoes, citrus, cucurbits, among others.

Potassium nitrate sprays improved plant growth performance and storage capacity of cucumber.

The objective of this study was to evaluate the effects of sprays with calcium nitrate, potassium nitrate and the growth stimulator Anfaton on plant growth, yield and fruit storage capacity of soil-grown cucumber cv. Al-Hytham in Iraq.

Table 1. Effect of potassium nitrate sprays on plant characteristics of cucumber cv. Al-Hytham.Hytham in Iraq.

Three concentrations of Amphaton; 0. 600 and 1000 mg/L and five concentrations of spray solutions; 0 mM (control), 10 and 15 mM calcium nitrate and 10 and 15 mM potassium nitrate were used in addition to the combination of Amphaton and the two nutrients. The experiment was conducted on a silty clay soil in a complete randomized block design (CRBD) with three replications. Spraying was carried out three times; the first was applied 20 days after transplanting and repeated every 15 days for the second and third sprays.

Relative to potassium nitrate sprays alone, foliar applications with _KNO3 15 mM (1.5 g _KNO3 / L) resulted in statistically significantly higher values for plant height, leaf area, chlorophyll content, average fruit weight, total fruit number, and total yield compared to the control (Table 1 and 2). _KNO3 sprays were also beneficial in controlling fruit weight loss and maintaining total soluble solids at a higher level during storage.

Table 2. Effect of potassium nitrate sprays on yield characteristics of cucumber cv.Al-Hytham.

On behalf of the Potassium Nitrate Association (PNA), the Landlab research station in Quinto Vicentino (Italy), conducted a trial to test the effect on winter wheat yield of two foliar applications with potassium nitrate (_KNO3) in spring, based on KCl dressing at four levels of _K2O/ha.

Potassium nitrate was sprayed at active tillering and panicle initiation stages at 10 kg _KNO3 / 400 L spray / ha. (9.6 lbs. _KNO3 / 43 gal. Spray / ac). Results show that foliar application of _KNO3 is promoting higher yield compared to untreated entries mainly due to more ears / m². The yield results are clear and statistically supported with a very high level of confidence.

The study confirms the benefit of potassium nitrate for wheat yield, applied twice as a foliar spray, at the key time in the crop cycle, even if KCl is provided in the base dressing at planting.

Wheat grain yield (MT / ha) Recommended _K2Olevel, applied as KCI on dressing basis.

Effect of different dressing base applications and two foliar applications of potassium nitrate (10 kg/400 l spray/ha) or (9.6 lb/43 gal. spray/ac.) at growth stages and panicle initiation on wheat grain yield.

Above, the control yielded 107 bushels / acre at 0% recommended _K2Olevel. Foliar application of _KNO3 increased yield by 10.7 bushels / ac. At 75% KCL base, foliar application _KNO3 increased yield by 17 bushels / acre. At 100% of the recommended base, _K2Oof KCL K source control yielded 111.5 bushels.

Foliar _KNO3 increased total yield to 130.5 bushels/acre, a 17% (19 bushel) increase over KCl alone.

BY JW LEMONS National Sales Agronomist SQM North America - Published in CropLife magazine, June 2019CropLife magazine, June 2019.