Fertilisation in perennial crops like grapes requires extra attention, because the plant needs to build reserves for the development of fruit-bearing branches in the next cycle. Two formulas: Ultrasol® Vegetative 8,4-10-22-9,3 (MgO) + micronutrients and Ultrasol® Generative 3-7-33-8 (MgO) + micronutrients were developed to meet both the need of the crop post-harvest, and during flowering, fruit set and maturation. Compared to the farmers practice, a consistent yield increase of more than 1 MT/ha was achieved in the 2018/2019 season. The number and weight of the bunches was higher following the SQM programme, but also vegetative parameters before flowering and fruit qualities like colour intensity and taste were greatly improved.
The customer defined the objectives of this trial. He required that it would result in a superior performance of the crop to fulfill a higher potential to yield more and better quality bunches. At the same time he requested that the programme would be easy to apply. A further objective, developed by Juan Palma Mendoza and Juan P. Berrios, was to calibrate the software application “CalQ Open Field”, which was piloted in Latin America to perfect the tool for the use of building recommendations on use of SQM’s specialty products in farm practice.
CalQ APP "Open Field” is an easy-to-apply, time-saving tool that all our field agronomists can have installed on their tablet, cell phone or PC. SQM's market developer Juan Palma Mendoza provides trainings on how to use this APP for our technical sales colleagues.
To feed CalQ Open Field with the required information, the technical sales team of SQM Mexico gathered information on grape cultivation in the desert of Sonora, Mexico. They collected and interpreted soil analyses, analyses of nutrients in leaf tissue and diagnosed the current farm practice.
Cultivation of table grapes in a desert requires a high supply of especially K, N and Mg. The alkaline soils limit uptake of micronutrients such as Zn and Fe. The main challenges for growers in the region are negative soil nutrient balances and depletion of organic matter, manifested in low nutrient use efficiency and nutrient deficiencies. Deficiency of K, B, Zn and Fe are frequently encountered.
The two Ultrasol® stage specific formulas were developed in excellent collaboration between SQM’s market development manager Juan Palma Mendoza, the SQM Mexico team in the region of Hermosillo (Juan P. Berrios, Julio Soto and Jesus Valdez) and local customers. A combination of scientific insights, experience in grape growing and flexibility of Mexico’s blending facilities helped to greatly improve the quality of the farm fertiliser practice. By introduction of basic NPK formulas combined with the software application CalQ Open Field it is now easier for SQM’s agronomists to adapt nutrient programme.
With a good understanding of these challenges, SQM Mexico successfully developed a programme containing two stage-specific formulas, to provide the crop with a good balance of nutrients from high-quality sources throughout the growing season. Ultrasol® Vegetative 8,4-10-22-9,3 (MgO) + micronutrients and Ultrasol® Generative 3-7-33-8 (MgO) + micronutrients (Table 1). In addition to providing an optimal amount of nutrients for each stage of the crop, Ultrasol® Vegetative and Ultrasol® Generative provide acidity. Their application reduces the pH in the root zone, which improves the availability of phosphates, Zn and Fe, and helps to control the pH of the tank mixture used for the fertigation.
The grower's request for ease of application was also solved with the design of these formulas in combination with the app CalQ Open Field. The two Ultrasol® formulas reduce the need to handle many different generic formulas as is the case in traditional practice. The benefits for the farmer are lower labor costs and prevention of common mistakes when mixing the nutrient solution. In addition, the identification in the storage of the fertilisers allows for a better control of the stock at the farmer's warehouse.
As is customary in SQM Mexico, the programmes with Ultrasol® Vegetative and Ultrasol® Generative were tested in a demonstration trial on a farm plot of 7,2 ha per treatment. The farm was located in the city of Guaymas, Hermosillo region, in the desert of Sinaloa, Mexico. A programme including both Ultrasol® formulas was compared with the normal farm practice (Table 1). Farm practice included straight fertilisers like MKP, potassium nitrate, magnesium nitrate, calcium nitrate and high-cost N, P, K and Ca products based on plant and/or algal extracts and oxidised forms of micronutrients. During the trials, field visits and field exhibitions were organized to show the benefits of the application of Ultrasol® Vegetative and Ultrasol® Generative.
Table 1. SQM’s programme including Ultrasol® Vegetative (8,4-10-22 + 9,3 MgO + mn) and Ultrasol®Generative (3-7-33 + 8 MgO + mn) and nutrients applied, in comparison with the farm practice. Ultr. = Ultrasol®. The SQM formulas contain chelated micronutrients: Zn EDTA, Fe EDDHA / HBED, Mn EDTA, Cu EDTA, and according to plant need, extra Fe, Mn and Zn were applied with Ultrasol® micro Rexene® XQ-58, Mn-13 and Zn-15. Calcium is additionally provided by calcium nitrate with Ultrasol® Calcium. In the SQM programme, additionally 3 post-harvest applications with Ultrasol® PK (2-36-32) at 6-8 kg/ha were performed by foliar spray.
*a.o. Organic nitrogen (16% N), potassium nitrate, MKP, Prophos 20, Pro magnesium nitrate, calcium nitrate, calcium 880.
Figure 1. View of the two sectors at the time of application of after the post harvest fertigation with Ultrasol® Vegetative 8,4-10-22-9.3 (MgO) and Ultrasol® Generative 3-7-33-8 (MgO) in 2018, at the start of the trial. A higher amount of branches were developed in the SQM sector, quantified as the weight of pruned branches in the sectors: 1,4 kg SQM (left picture), 0.6 kg for the farm practice (right picture).
Results Highlights
The trial in the region of Hermosilio in the season 2018/19, started with the post-harvest applications (Figure 1, Table 1). In the SQM treatment, additionally to the fertigation in that period, 3 applications with Ultrasol® PK (2-36-32) at 6-8 kg/ha were performed by foliar spray at weekly intervals. Analyses of the root reserves showed a clear response to the postharvest application of Ultrasol® formulas, which predicted a higher potential for sprout and fruit formation. The concentration of arginine – an important amino-acid stored in the roots – at 4,3% in root dry matter in the SQM plot, was 59%increased in compared to the control (2,7%), and these roots additionally contained 26% more dry matter and 17% more starch. The crop showed a clear visual response at sprouting to the postharvest applications of Ultrasol® Vegetative and Ultrasol® Generative in 2018 (Figure 2).
This resulted in a higher yield (Figure 3), recorded from the 7,2 ha plots by the grower, who also supplied details on fertiliser cost and price received for the harvest. A higher number of boxes was harvested from the plot following SQM recommendations (Table 2). At the same price per box, a 10% higher income was received for the harvest. Additionally the taste of the fruit was improved, due to a higher soluble solids:acid ratio. This ratio was 22 in the SQM programme compared to 19 in the farm practice. This is important for an export market, where a high quality product improves the growers success to obtain good contracts with the traders.
Because of lower cost for the SQM programme compared to the farm practice, the difference in net income for the farmer between the treatments was even higher: 14%. The much higher cost for the farm practice treatment was mainly due to the use of N, P, K and Ca fertilisers derived from plant or algae extracts, which are sold at a higher price per kg of nutrient applied. For instance, per unit of N, P2O5 or CaO per kg of fertiliser, the cost of organic sources was 13-30 times higher compared to the mineral sources. Cost for potassium (in units K2O/kg fertiliser) applied with Pro K is 20 times higher compared to mineral potassium nitrate.
Table 2. Yield results and financial results for the farmer.
*Only fertiliser costs (including post-harvest applications) are included, the benefit of saving in labour costs by greater ease of preparation of the fertiliser solutions is not included.
Figure 2. Positive effect of the application of Ultrasol® Vegetative 8,4-10-22-9,3 (MgO) and Ultrasol® Generative 3-7-33-8 (MgO) (left) in 2019 on advanced sprouting compared to the farm practice (right), end of February 2019.
Figure 3. Pre-harvest evaluation Juan P. Berrios (left) and Juan Palma Mendoza (right), May 2019. More bunches in the SQM sector (left), with greater fruits and earlier coloration compared to the farm practice (right).
What's next?
The results of the trial were disseminated through various media, e.g videos for promotion of the Ultrasol® Special formulas in Grapes were prepared. Finally, a seminar was organized to disseminate these results to the production managers and important advisers of the main agricultural and export companies of fresh grapes from Mexico to the United States. The trial also yielded important data for calibration of the application CalQ Open Field for grape-growing, and trainings of SQM's agronomists by Juan Palma Mendoza are being conducted.
