Primer on the “5Rs” of nutrient management efficiencies, benefits of sap testing part of 2026 NSCIA Grower Day

British Columbia agrologist Rick DeJong discussed crop nutrition at the Norfolk Soil and Crop Growers’ Day.

By Diane Baltaz

Cash crop farmers who attended this year’s Norfolk Soil and Crop Association (NSCIA) growers’ day in Courtland on March 12 gleaned many nutrient tips from agrologists, and even heard a long-term weather forecast. But the morning began with a British Columbia-based agrologist who grounded the day with his primer on the “Five Rights (5Rs)” of balanced nutrient management.

Agrologist and “self-confessed nutrient geek”, Rick DeJong, works for Rowena, a Spanish-based agricultural firm that operates in 80 countries. He began his presentation on “making fertilizer dollars count” by outlining the Five Rights for fertilizer applications: right nutrient, right place, right form, right mix and right time.

“I am science-driven,” said DeJong, while explaining how he derived the 5Rs. “They follow the core principles of nutrient management: better application equals better outcome, higher yields, better quality fruit… “

DeJong advocated for “timely nutrient testing” in order for assist the application of the 5Rs, from determining the right nutrient down to the right form, mix and timing of its application. Soil testing should be done every three to five years; he also recommended fruit testing for apples. He added that multiple crops benefit from plant tissue testing and sap testing to determine the right nutrient combinations – including micronutrients.

“Micronutrients help the big three -nitrogen, potassium and phosphorus -- work and then you may need less of these macros. Macronutrients by themselves are never 100 per cent efficient; it’s how we manage the micros that we get more response.

“Every nutrient has a role to play.”

Using tomatoes as an example, DeJong said that the micronutrient manganese, which is required for chlorophyll formation in plants, “slows down and regulates the potassium.”

“Some nutrients play well with others in the sandbox while others don’t,” explained DeJong about right mix.

For example, while some micronutrients “don’t mix well with potassium, but calcium and boron do.” Potassium moves through plant when needed; this movement becomes more efficient when combined with a calcium-boron application, two nutrients that work symbiotically. However, improper mixes such as excessive applications of boron often leads to cell mortality.

Using the right form of fertilizer ensures that the right nutrients go into the right place. For example, many micronutrients (iron, copper, zinc, molybdenum, copper, calcium) are best managed through the use of drop and foliar sprays in order to maximize rapid absorption into plants when they most need it. But liquid forms of EDTA chelated iron works well in soil for plants to access, but not when applied on leaves.

Because every field and crop has different needs; their conditions vary annually. DeJong suggested that growers should consider adding sap analysis to their nutrient efficiency tool box.

“Sap testing is different from tissue tests,” said DeJong. “I recommend sap analysis for determining nutrition for 200 crops.”

Sap analysis measures the active liquids in the vascular tissues, the xylem and phloem. It provides a nearly real-time assessment of the nutrients available in the plant.

Proponents state that sap analysis can detect nutrient issues often long before visible symptoms appear. For example, sap analysis detects nitrogen deficiencies long before a plant’s older leaves turn yellow due to prolonged, insufficient chlorophyll synthesis.

Sap reports, as DeJong indicated in his talk, identify the deficiency long before the visual symptoms occur. Sap reports also identify when nitrogen has persistent levels, thereby indicating when fertilizer rates can be decreased. This helps reduces problems of pests and disease associated with excess nitrogen.

By contrast, plant tissue analysis measures nutrient concentrations in plant tissue. It is most useful when combined with visual inspections of the crop and soil conditions, knowledge of past field management and current soil testing.

“Sap testing protocols are different from those of a tissue test,” said DeJong. “You send in the leaves and the sap is extracted.”

DeJong discussed related issues related to the 5Rs, from the use of different solvents in spray tanks to plugged nozzles: “Plugged nozzles are a common problem. I see a lot of that in Ontario.”

The talks ended with atmospheric physicist-meteorologist Ron Bianci outlining how to read cloud formations to determine if a severe storm is forming nearby, and this growing season’s long term weather forecast. He said that all of the international weather models indicate a cool, wet spring which extends into the summer with the “heat moving in during the autumn.”

Bianci indicated that alterations in the jet stream and a “significant” heat dome that will dominate the US mid-west and the prairies throughout the spring and summer constitute two major factors for the southwestern Ontario growing season.

NSCIA is affiliated with the Ontario Soil and Crop Association (OSCIA) which is involved in the delivery of many education workshops, financial assistance programs, demonstrations and applied research. OSCIA’s vision is “farmers actively seeking testing and adopting optimal farm production and stewardship practices”. 