Nitrogen determination is an essential component tested in fertilizers for farmers’ crop performance. The application of nitrogen over the growth phases of a plant influences and produces a specific yield, and therefore controlled release of this element is important for a specific anticipated crop outcome.
Mangwe Marubela (pictured left) and Mandlakazi Thafeni (pictured right) and the two Büchi Kjel Line units that use steam distillation to determine the nitrogen content for fertilizers.
“Farmers have become Scientists. They need to ensure they get the maximum performance from their products with more detailed analysis for crops to succeed,” says Salie Isaacs, at SGS soil testing lab in Somerset West, Cape Town. Their soil and fertilizer laboratory has been in operation for over 20 years and receives samples from all over South Africa, as well as the neighbouring countries. During this time of over two decades, they have always used Buchi’s steam distillation units for nitrogen determination. The newest replacements, installed and commissioned by Labotec, are two Büchi Kjel Line units, which are contributing to a higher degree of automation and double the turnaround time compared to the older more mechanical Buchi units of a decade ago. “Now the lab technicians don’t mind running a quick sample on a Friday afternoon at 2 pm, and finishing before home time”, says Salie. The processing time has thus halved.
SGS is a leading testing, verification, and certification company, with headquarters based in Switzerland. The Soil and Fertiliser laboratory in Somerset West forms part of this network, offering complete agricultural soil sample testing solutions for nutrients and physical properties, testing leaves, soil, minerals, pH, and heavy metals. “Based on this information, the farmer can ascertain the fertilizing needs, and replenish the soil for the new crop growing season”, explained Rudie van Zyl, Laboratory Manager.
A simple quick process
Samples of chemical fertilizer are sent from farmers countrywide. These samples are then sorted, riffled, and ground. To process the laboratory needs 100 grams, which is ground into a homogeneous powder with a coffee grinder. A solution is made from this, then digested for total nitrogen, distilled on a distillation unit, and then the nitrogen is calculated via titration. The Büchi Kjel Line Distillation unit services nitrogen determination and distillation for chemical, organic and inorganic fertilizers, compost, liquid fertilizer, leaf, and fruit.
According to Salie, “Some farmers send a ton of fertiliser”. “This is not necessary, only 100 grams is needed for analysis. The turnaround time was normally 10 days, but for now we are running on 5 days”, he added.
The new Büchi Kjel units have simple operation, and no real maintenance is required. Salie added, “you can take the whole machine apart and clean and maintain the pieces separately”. He added, “this is a more integrated machine that automatically carries out the distillation, and it has modular functionality.” The units can be equipped with titrators and electrodes where titration dosage and endpoint recognition via suitable electrodes is carried out automatically, giving a high level of automation and unattended operation.
Fertilizers haven’t changed much
Work used to be seasonal, but the soil laboratory has found they are busy throughout the year now. The market trend now demands a more detailed analysis of the components, for instance individual split nitrate in, urea in. The importance is knowing the absorption periods of the compost and fertilizers; whether its liquid, organic or inorganic, and thereby regulating the amount for maximum absorption.
So, the fertilisers haven’t changed much, but the analysis have increased over the last two decades, and thankfully the analysis time has decreased.
