Evaluation of Aquaritin 19 vs Urea on Fairways
We are pleased to share with you the results of an independent research comparing Aquaritin 19 with traditional Urea applications on golf fairways. We were encouraged by the feedback we got from our customers who began using Aquaritin 19 on fairways in the last couple of years. This research confirms their experience.
- Aquaritin 19 on its own, applied at label rates delivered the same turf quality as Urea applications with 280 times less N (0.0007 Lbs/1000 vs 0.19 Lbs/1000)
- When adding PGRs and Surfactants, Aquaritin 19 at label rates delivered similar turf quality and growth to Urea with 25% lower rate of PGR and Surfactant
- Soil analysis confirmed that nutrient uptake was greatest under Aquaritin 19 treatment compared to all other treatments
- Leaf analysis confirmed greater accumulation of NPK under Aquaritin 19 treatment as compared to all other treatments
Summary
This field study was carried out to assess if the application of low rates of Aquaritin 19 alone, and in combination with reduced rates of PGR and surfactant, will lead to comparable, and/or enhanced levels of growth, turfgrass quality, tissue, and soil nutrient levels, versus applications of conventional Urea inputs with full rate PGRs and surfactants. The trials were carried out at a private member’s golf club in Ireland using 2 x 1 m trial plots, on a Fescue/Poa annua sward growing on a natural links sand rootzone maintained as a golf course fairway using standard management practices and mown at 8mm height of cut. Treatments comprised 1: Aquaritin 19, 2: Urea, 3: Aquaritin 19/Plant Growth Regulator/Surfactant, 4: Urea/Plant Growth Regulator/Surfactant and 5: Untreated control. These were applied at 28-day intervals as a randomised design with four replications commencing mid July 2023 continuing until late September 2023. All data collected were analysed using SPSS 24 statistical software to determine and separate any statistical differences.
The results provided interesting and at times statistically significant results. In the areas of VWC, EC and NDVI assessments the treatments faired quite similarly and as expected. Volumetric Water Content was greater in the surfactant treated plots; this is what is expected of a surfactant treatment when applied to drier sandy rootzones.
Electrical Conductivity the highest levels were obsevered in the two treatments which included the Evolve surfactant. This is directly related to the overall higher moisture levels in these treatments. There were a greater number of of available nutrients available, due to the higher moisture levels, but this did not correalate to increased growth due to the growth inhibitory effects of the PGRs applied with the surfactant.
The NDVI results, showed that all trial plots receiving any of the nutrient treatments produced higher readings than the untreated controls.
The main points and most relevant of the results of this trial were in the areas of treatment effect on turfgrass growth and quality.
Aquaritin 19, applied sequentially, at label rates, gave rise to greater turfgrass leaf growth, and enhanced turfgrass quality, when compared with standard applications of Urea, although it should be noted that statistically there are no differences.
Secondly, Aquaritin 19, when applied in combination with a PGR, applied at a reduced rate of 75% label rate, provided the same growth suppression as the Urea, when applied in combination with the PGR applied at the full 100% label rate.
Soil analyses showed that that nutrient uptake was greater in the Aquaritin 19 treated samples compared with all other treatments. Nutrient uptake in the Urea treated samples was greater than in the samples which received the PGR application and also greater than controls. Leaf tissue analyses showed that there was an increase in leaf tissue levels of Nitrogen, Phosphorus and Potassium in all samples, except the controls, but that there was a greater accumulation of NPK in the Aquaritin 19 treated samples compared to all others.
Research outline
A field study carried out to assess and compare the effect of sequential treatments of Aquaritin 19, applied at the label rate, to a conventional foliar fertiliser (Urea) and in combinations with Plant Growth Regulators (PGRs) and Surfactants. The objective to assess if the application of low rates of Aquaritin 19 alone, and with reduced rates of PGR and surfactant, will lead to comparable, and/or enhanced levels of growth, turfgrass quality, tissue, and soil nutrient levels, versus applications of conventional NPK inputs with full rate PGRs and surfactants. The field trials were carried out a private member’s golf club in Ireland. Treatments were applied, data collected and analysed using SPSS 24 statistical software to determine and separate any statistical differences. A full report including all raw data on Excel is presented.
Methodology
Experimental location and design
Trial plots were 2 x 1 m on a Fescue/Poa annua sward growing on a natural links sand rootzone maintained as a golf course fairway using standard management practices and mown at 8 mm height of cut. Treatment, application rates, and timings as shown in Table 1 applied as randomised design with four replications (n=4) commencing mid July 2023 and applied at 28-day intervals until mid
September 2023. Treatments were applied as a foliar application using 10 L pressure sprayers calibrated to operate at 4 bars. The entire trial area received 125 kg/ha urea = 57 kg of N, April 2023 prior to commencement of trial. No nutritional inputs or surfactants, except for those in the treatment list, were applied during the trial period.
Treatments
Table 1 Treatment applications, rates and timings for trial plots commencing July 2023 continuing at 28-day intervals until end of September 2023.
Assessments
- Percent Volumetric Water Content (VWC): measured using a Pogo (Stevens Water Monitoring Systems Inc.). The Pogo also recorded canopy temperatures in degrees C, and electrical conductivity (EC ds/m).
- Turf quality: this is defined as the degree to which a sward conforms to an agreed standard that is a composite of uniformity, shoot density, leaf texture, growth habit, smoothness, and colour. This was assessed visually and marked on a scale of 1 to 10 (1 = poorest possible quality, 5 acceptable and 10 = best possible quality turf). Assessments were carried out prior to treatment applications and at five periods until the end of the trial period.
- Normalised difference vegetation index (NDVI): using a Sunseeker handheld NDVI meter, 0 to 1 scale with 0 poor and 1 best. This will complement the Turf quality assessments and allow for a quantitative determination of turfgrass health.
- Leaf tissue growth: was determined by collecting cuttings from each plot using a pedestrian cylinder mower and determining cumulative leaf dry weights
- Nutrient levels: Soil nutrient levels were analysed prior to treatment applications and at conclusion of the trial.
Leaf tissue samples were analysed for major and minor elements, prior to initial treatment applications, trial and at conclusion of the trial. All analyses carried out by IAS Laboratories, Co Carlow, Ireland.
Reporting & Data Analysis
All the above assessments were carried between July and September 2023, all raw data were collated and recorded in MS Excel. Each separate assessment, along with the mean results for the full trial period, are presented in the attached Excel, along with the statistical analyses which were carried out using one-way Anova with statistical differences separated using Tukey HSD at P=0.05. (SPSS 24 analytical software).
Results
The aims of this trial were to assess and compare the effect of sequential treatments of Aquaritin 19, applied at the label rate, to a conventional foliar fertiliser (Urea 46:0:0) and in combinations with Plant Growth Regulators (PGRs) and Surfactants. This was a short trial period, with three treatment applications July 25th, August 23rd, and September 18th, 2023. The trial site was assessed in the areas detailed above, prior to treatment application, and then five times throughout the trial period.
Turfgrass quality.
A major aim of the research was to determine if low-rate applications of Aquaritin 19 could provide similar or enhanced results in areas of turfgrass quality, when compared to the industry standard of a straight Urea application program.
Following initial treatment Turf quality was assessed five times and the mean values of these are shown in Figure 1.
Turf quality mean of 5 assessments
As can be seen all nutrient treatments led to significantly better turf quality than the controls. There were no statistical differences between the nutrient treatments with the exception of Aquaritin 19 being significantly better than the Urea/PGR/Evolve combination.
At the start of the trial there were no differences between turfgrass quality, by two weeks post application, quality in all nutrient treatments had improved compared to controls, but not significantly so. However, by four weeks post 1st application, turfgrass quality in all the nutrient treated plots were significantly better than controls and remained so until trial termination. This consistent enhancement of turfgrass quality can be clearly seen in Figure 2.
Despite there being no significant differences between the nutrient treatments, the Aquaritin 19, by the end of the trial, had produced the highest rated value, this is a good result as the application rate and costs are much less than the Urea. The addition of the PGR and Evolve surfactant led to slightly lower turfgrass quality but again it was not statistically significant.
NDVI
Closely connected to the turfgrass quality ratings are the NDVI data, these complement the quality assessments and allow for a quantitative determination of turfgrass health. The mean values are shown in Figure 3. As can be seen all nutrient treatments gave rise to significantly higher readings compared to the controls.
NDVI mean of 5 assessments
EC (Electrical Conductivity)
EC (Electrical Conductivity) is the measurement of the soil’s ability to conduct an electrical current and indicates the concentration of soluble salts within the soil. The higher the concentration of soluble salts, the higher the electrical conductivity of the soil. High levels of EC can indicate a high concentration of nutrients, while low levels may indicate a lack of these nutrients. In many cases, as moisture goes up, salts in solution go up and therefore EC goes up. But this is not always the case and EC-to-moisture ratios change from many affecting variables.
Figure 4 shows the mean EC levels from 5 assessments carried out, the highest levels were obsevered in the two treatments which included the Evolve surfactant and this is directly related to the overall higher moisture levels in these treatments. So, while there were a greater number of available nutrients available, due to the higher moisture levels, this did not correalate to increased growth due to the growth inhibitory effects of the PGRs also included in the treatments.
VWC
The mean VWC values for the full trial period are shown in Figure 5, and as can be seen there were significant differences between the treatments. Statistically there were no differences between the Aquaritin 19, Urea and controls, however, the Aquaritin 19 and Urea treatments which were combined with the Evolve surfactant had significantly higher levels of VWC %. This is of no surprise as the surfactant is applied to help maintain adequate moisture levels, especially under conditions of rapid percolation such as with the sandy rootzone of the trial site.
What is of interest here is that there were no differences between the two treatments containing the Evolve surfactant, this, despite the lower application rate of 9.35 L/ha with Aquaritin 19 compared to 12.5 L/ha combination with Urea. The effect on VWC over the trial period can be seen in Figure 6.
Shoot Growth
The key target of this research was to determine if low-rate applications of Aquaritin 19 could provide the nutrients requirements of turfgrass and compare favourably with standard application rates of Urea. This was assessed by collecting leaf cuttings from each trial plot using a pedestrian cylinder mower with a grass collection box, gathering the cuttings, and drying for 48 hours to determine the leaf dry weights. The mean values of the cumulative dry weights are shown in Figure 7, as can be seen, over the full trial period there were no significant differences between the Aquaritin 19 and Urea, which were both significantly greater than the three other treatments.
The inclusion of the PGR significantly suppressed growth when applied in combination with the Aquaritin 19 and Urea. There were no statistical differences between the Aquaritin 19+PGR and the Urea+PGR, this is of interest as the PGR rate applied with the Aquaritin 19 was 75% of the rate applied with the Urea.
While the overall mean values of the effects on shoot growth showed no differences between Aquaritin 19 and Urea, a better understanding of how these treatments effected growth is shown in Figure 8.
Here we can see how the various treatments effected growth week by week following treatment applications. Two weeks post first applications The Urea treatment had greatest growth, significantly better than all others. The Aquaritin 19 and controls were the same and the two treatments containing PGR were significantly less.
However, following the second treatment application in August, shoot growth in the Aquaritin 19 plots was greater than the Urea plots, although not statistically significant, and remained greater until the conclusion of the trial. Both these treatments produced significantly greater growth than the other three, with the controls remaining constant but the treatments containing PGR’s lower but producing a spike in growth in early October, possibly as a rebound effect.
Soil & Tissue Analysis
To determine the reason for these differences in growth we can examine the results of the soil and leaf tissues analyses which were carried out prior to, and at the trial conclusion.
Soil Analysis
Soil nutrient levels prior to and at trial termination are shown in Table 3. Pretrial the nutrient levels are normal and what would be expected of a golf course rootzone based on a sandy links environment. Following the three treatment applications and two months of growth the nutrient levels, as shown in the post-trial results had varied somewhat. In most cases the nutrient levels had reduced, this is not unusual given that all nutrient inputs were foliar and of small quantities. The factors involved in the reduction of soil nutrients are that there would be some losses through leaching, bearing in mind the high levels of precipitation experienced during the trial, but also the fact the turfgrasses were taking up nutrient for growth.
What can be observed is the uptake of soil nutrients was greater in the Aquaritin 19 and Urea treated samples compared with the other two treatments and controls. Soil Nitrogen levels in the Aquaritin 19 and Urea rootzones reduced by 8.61% and 6.58% respectively. Nitrogen levels in the Aquaritin 19/Plant Growth Regulator/Surfactant, Urea/Plant Growth Regulator/Surfactant and Control rootzones reduced by 4.55%, 3.57% and 0.54% respectively. These differences in nutrient uptake were observed across all the nutrients correlates directly with the different growth observed and highlights that the Aquaritin 19 led to a greater uptake of nutrients than all other treatments.
The lower nutrient uptake observed in the Aquaritin 19/Plant Growth Regulator/Surfactant and Urea/Plant Growth Regulator/Surfactant treatments would correlate to the reduced growth due to the PGR inhibitory effect.
Table 3 Rootzone nutrient content (ppm) prior to the start of treatments in July 2023 and at the conclusion of the trial in October 2023.
Leaf & Tissue Analysis
Leaf tissue nutrient levels prior to and at trial termination are shown in Table 4. Again very little change in levels, the main points of interest are the increased levels of Nitrogen, Phosphorus and Potassium observed. Nitrogen, Phosphorus and Potassium in the Aquaritin 19 treated tissues increased by 38.84%, 20.93% and 24.16% respectively. In the Urea treated samples, Nitrogen, Phosphorus and Potassium 21.45%, 5.12% and 2.54% respectively. There were similar observations made in the in the Aquaritin 19/Plant Growth Regulator/Surfactant, Urea/Plant Growth Regulator/Surfactant and Control tissues.
Table 4 Leaf tissue nutrient content prior to the start of treatments in July 2023 and at the conclusion of the trial in October 2023.
One point of note re the reduction in rootzone soil nutrient levels, the results here could be interpreted to indicate that long-term sequential applications of these foliar treatment could lead to significant deficiencies. It should be noted that the trials were carried out on a links rootzone with very low Cation Exchange Capacity during a period of high precipitation and that the results would be different on a soil-based location.
Conclusions
This field study was carried out to assess if the application of low rates of Aquaritin 19 alone, and with reduced rates of PGR and surfactant, will lead to comparable, and/or enhanced levels of growth, turfgrass quality, tissue, and soil nutrient levels, versus applications of conventional NPK inputs with full rate PGRs and surfactants.
The results provided interesting and at time statistically significant results. In the areas of VWC, EC and NDVI assessments the treatments faired quite similarly and as expected.
- Volumetric Water Content was greater in the surfactant treated plots; this is what is expected of a surfactant treatment when applied to drier sandy rootzones.
- Electrical Conductivity the highest levels were obsevered in the two treatments which included the Evolve surfactant. This is directly related to the overall higher moisture levels in these treatments. There were a greater number of of available nutrients available, due to the higher moisture levels, but this did not correalate to increased growth due to the growth inhibitory effects of the PGRs applied with the surfactant.
- The NDVI results, showed that all trial plots receiving any of the nutrient treatments produced higher readings than the untreated controls.
- Soil analyses showed that there was an uptake of soil nutrients, as evidenced by the reduction in soil levels in all trial rootzones, but that nutrient uptake was greater in the Aquaritin 19 treated samples compared with all other treatments. Nutrient uptake in the Urea treated samples was greater than in the samples which received the PGR and also greater than controls.
- Leaf tissue analyses showed that there was an increase in leaf tissue levels of Nitrogen, Phosphorus and Potassium in all samples except the controls but that there was a greater accumulation of NPK in the Aquaritin 19 treated samples compared to all others.
The main points and most relevant of the results of this trial were in the areas of treatment effect on turfgrass growth, quality, and nutrient uptake.
Aquaritin 19, applied sequentially, at label rates, gave rise to greater turfgrass leaf growth, and enhanced turfgrass quality, when compared with standard applications of Urea, although it should be noted that statistically there are no differences.
This enhanced growth and quality is supported by the soil and tissue analyses which showed the Aquaritin 19 samples had better uptake and greater accumulations of nutrients. The Aquaritin 19, when applied in combination with a PGR, applied at a reduced rate of 75% label rate, provided the same growth suppression as the Urea, when applied in combination with the PGR applied at the full 100% label rate.
