11% grapefruit yield increase with soil-applied Ultrasol® NKMag and foliar-applied Speedfol® NKMag

SQM China conducted a demonstration trial in grapefruit to show the benefits on grapefruit yield and quality characteristics of Ultrasol® NKMag soil applications in combination with foliar sprays of Speedfol® NKMag in the main grapefruit growing area (33.000 ha) near Zhangzhou (Tables 1 and 2) in Fujian province. Ultrasol® NKMag and Speedfol® NKMag SP are potassium nitrate based formulations, enhanced with magnesium (13%N, 42% K2O and 1,6% MgO) developed for the Chinese market.

In Table 1 the soil-applied traditional fertiliser programme for grapefruit is compared with SQM’s soil-applied SPN programme. Table 2 shows the foliar programme with Speedfol® NKMag.

Table 1. Comparison between the soil applied traditional fertiliser programme and SQM´s soil applied Specialty Plant Nutrition programme including Ultrasol® NKMag.

The first reference to this trial was made in the InterQonnection nr 4 (2013). Now, after a follow-up visit with SQM China staff and distributor (Figure 1), Sonny Moerenhout (Market Development Manager water soluble SPN at SQM) reports about the results of this trial.

Table 2. SQM´s foliar applied Speedfol® NKMag programme.

Figure 1. From left to right: Mr Dai (GD Tianhe), Kevin Li (SQM China), Sonny Moerenhout, Mr Zhang (retailer) and Henry Li (SQM China) at the grapefruit trial field in Zhangzhou, Fujian province.

At the moment of harvesting clear differences between the two plots were observed. In Table 3 the various plant performance characteristics for both treatments are compared.

The fruit peel was evenly coloured with SQM’s SPN programme, compared to the mottled fruit appearance obtained with the traditional programme (Figure 2). In addition, with SQM’s SPN programme fruits were harvested 10 days earlier, which resulted in a greater fruit selling price for the grower.

It is noteworthy to mention that after harvesting it was observed that trees, which received the traditional programme, manifested severe Mg deficiency symptoms. This was not the case in the SQM SPN programme, thanks to the inclusion of magnesium in the Ultrasol® NKMag and Speedfol® NKMag formulations.

Table 3. Comparison of the effect of both treatments on various plant performance characteristics.

With SQM’s SPN programme, the grapefruit yield was increased with 5625 kg/ha (+11%). In combination with the greater fruit selling price, and after deducting the costs of the fertilizers applied, this resulted in a net income increase of 8663 US$/ha (+17%) (Figure 3).

Figure 2. SQM’s programme resulted in evenly coloured fruits, whereas the traditional programme resulted in a mottled fruit appearance.

Figure 3. The financial benefits of SQM’s SPN programme.

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