Tools for crop farmers

At a recent course on biological farming, presented by Nutri-Tech Solutions, Wilma den Hartigh found out about valuable tools used to measure soil pH and brix levels, and plant sap extractors for monitoring plant health, as well as why more farmers are using foliar feeds.


There are a number of easy-to-use monitoring tools to help farmers establish how their crops are performing. These tools have a range of functions, such as measuring deficiencies or excesses in soil and plants, determining soil suitability for crops, and measuring the suitability of spray mixtures.

A sap extractor and a sap pH meter are two useful pieces of equipment. With either do-it-yourself sap analysis or conventional leaf analysis, a farmer can monitor plant health, establish the plants’ nutritional requirements throughout the crop cycle, and determine corrective action, if needed. “Nutrient problems are often related to lock-ups in poorly balanced soil,” explains Graeme Sait, CEO of Nutri- Tech Solutions. What brix levels reveal Brix levels (levels of dissolved solids) are another important aspect of plant health. Refractometers that measure brix levels give an indication of sugar and mineral levels in the plant, as well as general plant health.


Crops with high brix levels have higher sugar, mineral and true protein contents, and higher densities. They are also sweeter-tasting, minerally more nutritious and have lower nitrate and water contents, as well as better storage characteristics and a longer shelf life. Plants with higher sugar contents will also have lower freezing points. “This offers protection against frost damage,” Sait said. “It is a major benefit for farmers.

With the threat of climate change, frost is becoming more of a problem. We are seeing frost in places we haven’t seen it before.” Brix levels in crops are an indicator of soil fertility. Soils producing plants with high brix levels also experience lower weed pressure. Broadleaf weeds and “sour” grasses grow more prolifically in soils lacking calcium and phosphate.

Factors influencing brix levels
Sait explains that storms or impending weather changes will lower brix readings. “Plants can anticipate changes in atmosphere, and translocate sugars to the roots when they anticipate periods of stress,” he said. “Droughts can raise brix levels, as the water content is low and plant juices are more concentrated. On the other hand, several consecutive cloudy days will cause brix levels to drop, as sunlight is required for photosynthesis and sugar production in the plant.”

The lower the humus content of the soil, the faster the brix readings will drop following a prolonged cloudy or rainy period. Sait explained that brix levels should remain uniform throughout the plant. “If there is a marked variation from the leaves to the roots, a soil imbalance is the most likely cause. Potassium is the chief suspect here,” he said. “But there should always be a variation in brix levels at different times of the day. Plants translocate sugars to the roots at night.

Early-morning readings should always be lower than afternoon readings when sugars formed during photosynthesis have accumulated in the leaves.”
Water monitoring
Sait predicted that as water increasingly becomes an issue with climate change, infrared technology will become more valuable to farmers. “An infrared water-monitoring tool is a simple way to know when to water,” Sait said. “A sensor measures infrared radiation, an indication of surface temperature.

Before use, calibrate the instrument first by measuring the temperature of a sheet of white paper. This will indicate the ambient temperature. Then measure the temperature of the crop surface.” Sait explained that if the crop has sufficient water, its temperature will be below the ambient temperature as the plants are using evaporative cooling. If the crop is stressed by a shortage of water, it can’t cool itself down and will be as hot as, or hotter than, the ambient temperature.

Use the infrared sensor when the leaf surfaces are dry. The wind velocity should be below 16,1km/h, and readings should be taken during peak sunlight hours between 11am and 3pm. If the air temperature is far lower than normal, stress won’t be reliably detected. “Point the gun directly at the foliage and keep the sun behind you when taking the reading,” Sait advised. “The reading must be taken in the field, not when merely driving past. The greatest fertiliser is the farmer’s footsteps in the field.”