Replacing KCl by Qrop® K as main source of potassium in the farmers practice in Ecuador, resulted in 33% higher yield and revenue from bananas. The higher productivity of the crop was attributed to a significantly higher retention of leaves with Qrop® K in presence of Black Sigatoka in the plantation.
The higher total yield was achieved with the same amount of N and K2O applied per ha. Higher quality of yield was reflected in a significantly higher bunch weight and numbers of hands/bunch and boxes/bunch.
Black Sigatoka (Mycosphaerella fijiensis) is a fungal disease representing a serious threat for banana production globally. The fast growing banana crop has a high need for potassium, an important nutrient to support plant resistance to fungal attack. Banana plants provided with optimal potassium nutrition can overcome damage caused by Black Sigatoka. Unfortunately, growers still choose to use potassium chloride as the main, but not optimal, potassium source. Dr. Carmen Suárez and Dr. Ignacio Sotomayor of the Technical University in Quevedo, Ecuador supervised a study initiated by SQM country managers Eng. Antonio Cabezón and Eng. Diego Monteros. The research aimed to show the benefits of the preferred potassium source - potassium nitrate in Qrop® K - for increasing plant resilience to Black Sigatoka.
Image 1. Individual suckers were marked at the start of the trial to ensure that a homogenous set of plant was evaluated in all tratments.
Image 2. Assessment of the number of leaves.
The trial was performed from January till August in the province of Los Ríos-Ecuador, in collaboration with the technical state-university of Quevedo. Treatments and observations were executed in three replicates of 7 plants each, in a completely randomized design on new suckers measuring 1,3 - 1,5 m at the start of the trial. Farmers practice included potassium chloride as sole K source, whereas all K was supplied with potassium nitrate in the Qrop® K-based programmes. Two SQM programmes were tested, providing either equal or 1,5 times the N and K2O supply of the farmers practice (351 kg N/ha; 576 kg K2O/ha) (Table 1). All fertilisers were applied in 11 split applications during the trial period.
Table 1. Fertiliser programmes applied in the trial. The total amount of fertilisers was split over 11 applications in 8 months (one application every three weeks). This programme does not contain the fertilisers applied in the period before the trial (with plants less then 1,30 m. high). P is applied only in these earlier vegetative stages.
Image 3. A bunch harvested from a Qrop® K treated plot.
Image 4. Determination of export quality yield per bunch.
Banana plants fertilised with Qrop® K as only K source, retained 20% more leaves at harvest compared to the farmers practice. This was mainly attributed to the increased resilience of the plants to prevailing Black Sigatoka infestation. By retaining a higher level of photosynthetic potential, the plants were able to produce larger and heavier bunches, more boxes/bunch (at 20 kg/box) and filling 33% more boxes per bunch (Table 2).
Increasing the total N and K2O dose with the Qrop® K based programme did not result in an increase of crop development and yield parameters compared to the lower dose.
Financial analyses of the treatment was performed for the SQM programme that was equivalent to the farmers practice in delivery of N and K2O (Table 3). The SQM programme added to the cost of fertilisers, raising the proportional investment in nutrients from 7% to 10% of the total cultivation costs. The 33% higher revenue from 840 extra boxes/ha, more than compensated the higher price of the SQM programme: Break-even point is reached with 3% extra yield (81 boxes/ha).
Table 2. Plant development and yield parametes measured in the course of the trial and at harvest.
Table 3. Financial analyses of the benefit of application of a Qrop® K- based fertiliser programme.