Please give an overview of the trial/programme on controlled-release fertilizers – what are the main objectives? What is the expected timeline from start to finish? Spanish (Horticulture) As part of its range of field trials services, SynTech Spain conducts CRF trial programs for its clients, in agricultural and horticultural crops, to study the properties of candidate formulations, especially the time-course of release and the effects on development of the target crop. The trials can be conducted year-round, in the greenhouse or growing chambers. Current trials on different species of potted ornamental plants, involve CRF formulations and doses in a range of substrates. These are monitored regularly for pH, water content, conductivity, and temperature, to understand how these affect release. As candidate CRF formulations are frequently coated; SynTech uses purpose-built techniques to recover the fertilizer from the substrate at intervals and analyse the degradation of the coat and the core of the granule. For ornamentals we assess plant colour and size, phytotoxicity, quality, fresh weight, leaf cover, stem and flower numbers.
France (Broadacre Arable & Perennials): The main objective is to make nutrients gradually available to plants without peaks of release or risks of phytotoxicity, even under high temperature conditions. Release of the fertilizer can go up to 16 months. SynTech France is conducting CRF trials on rapeseed, corn, cereals and perennial crops. Assessment parameters include development of the root system, height of the plants, resistance to water stress, number of ears, flowers, fruits, number of seeds per ear or per pod, fruit diameter, weight and size of the seeds and fruits, protein content, and sugar content. Precision seeders are used for CRF trials and are equipped with micro-granulators or spreaders to spread or incorporate the granules or liquids. Liquid fertilizer solutions are delivered using precision metering pumps and may be coupled with drip irrigation.
When designing the experiments, what were the key decisions you had to make in advance? – eg Why did you select particular crop/variety? Was soil type a consideration? Were other aspects of the trial site taken into consideration? What sort of reference product was used? The target crops, soil types and reference products are chosen by the customer. Experimental design is critical – horticulture trials such trials can last 7-8 months, so phytosanitary (weed/disease/pest control) products need to be selected, the optimum pot size to allow proper root development determined, and ensure homogeneity of the substrate and the fertilizer mix. Irrigation needs must also be determined. Soil type is very important: plots need to have very homogeneous soils with a high average organic content. Arable CRF trials need to be made on flat plots, to avoid the effects of leaching if heavy rains occur. Pre-trial mapping by drone imagery is used to study the fertility and homogeneity of the soil.
When analysing the results, how will you show statistical significance and identify possible errors (if relevant)? Experimental variation is managed by using treatment replicates in the trials, and a high number of plants per plot. Statistical analysis software is used to analyse significance of the results at Least Significant Difference (LSD) 90% - since this type of product is affected by independent variables due to external factors. These may require that the data is analysed using mathematical models. Determination of dose response curves help to validate the study.
Do you have any general results that you can share? Eg did the CRF treatments improve on ”normal” fertilisers, and was this agriculturally significant. Were there any very obvious observations or anything unexpected that you’ve noticed in the trials ? The ornamental trials are at their initial stages, no results until July [2022] earliest. In the French trials we have observed temperature effects on the release of nutrients from CRFs. CRFs have brought a significant increase in yield and nutrient content. In arable crops, fewer passages of application equipment undoubtedly reduce energy usage and soil compaction There are therefore production and environmental benefits. The arable crop trials have also shown that CRFs are easy to use, that application costs are lower than traditional fertilizers and have less impact on the environment.
When the project is concluded, what general knowledge do you hope to have learned to help the optimisation of controlled-release fertilizers? Did you learn anything about experimental design, e.g. how best to investigate a particular technology in future? For arable crops, large area trials, with a large number of repetitions (6 minimum) are best, to mitigate soil effects and obtain precise and reliable results. SynTech Research already uses imaging devices, including satellites and smartphones for trials assessments and is developing AI-based applications to use the images for digital phenotyping. Imagery analysis will enhance the ability to use growth-room, glasshouse and field trials assessments and conclusions such as yield estimates, particularly useful for CRF trials. Too early to give a view on experimental design resulting from the horticultural trials, apart from the experimental approaches described above.
Product-specific information will focus on the rate needed from one application i.e.to cover the crop cycle without needing to add additional fertilizer, but delivering crop quality and commercial requirements. We hope to show how the external parameters affect the time-course of release and in this case, the best combination of substrate and fertilizer. The client will determine how our results affect product design and further development. ●
