Measurement. Agronomy 2

Infiltration rate

The infiltration rate is the rate at which water moves vertically from the surface to the underlying layers. This parameter is quantified by the hydraulic conductivity saturated, which is measured using a Infiltrometer double concentric ring.

The outer ring of this device serves to prevent the horizontal movement of water from the inner ring. This ensures that all movement is downward for a specific period of time, which allows the infiltration rate to be calculated.

A sports surface can have a low infiltration rate due to various factors:
Excessive compaction, a poor drainage system, the presence of impermeable layers, among others. Official values should be measured with a approved infiltration tester and standardised.

According to the United States Golf Association (USGA), infiltration values of 150 mm/h are recommended for the construction of greens. The Consejo Superior de Deportes recommends an infiltration greater than 100 mm/h for greens and greater than 50 mm/h for football pitches.

Other types of non-approved infiltrometers may be used, such as the portable infiltration meterswhich, although not as accurate as the approved ones, are more practical. They can help to get an idea of how infiltration values vary across the areas managed by the greenkeeper.

It is essential to keep a continuous record of infiltration metrics over time. These records make it possible to relate changes in infiltration rate to the different agronomic activities carried out during the year, such as aeration, verticutting...

All this contributes to maintaining the quality and playability of sports surfaces, as well as prolonging their lifespan.

NDVI

The Normalised Difference Vegetation Index (NDVI) is an essential tool in the analysis of vegetation health and vigour. This index is based on the unique characteristic of chlorophyll, a pigment that absorbs red light (660-680 nm) and reflects far-red light (720-740 nm).

NDVI is calculated using the following equation:

NDVI values range from 0 to 1. A value of 0 indicates an area with no vegetation cover and a value of 1 indicates dense and nourished vegetation.

Frequent NDVI measurements on turfgrass allow for early detection of potential problems. NDVI can identify photosynthetic stress on a natural turf surface earlier than visual monitoring.
We can measure it through instruments laptopsor continuously through remote imaging, the latter with much lower resolution.

Below is a case of NDVI analysis performed by Tiloom. We obtain temporal and spatial evolution data of NDVI in maps and graphs.

The use of NDVI and similar metrics provides an accurate assessment of plant health, as well as optimising management and maintenance practices. In addition, these data can be integrated into broader management systems, improving the efficiency and sustainability of agronomic operations.

Thatch and Root Measurement

The thatch, or felt layer, is an accumulation of undecomposed organic matter, such as roots, rhizomes and stems, located between the soil surface and the base of the turf.

The measurement of the thatch and the root through a sampler is essential in the agronomic assessment of turfgrass, as its volume can have a significant impact on the health of the green surface.

Excessive thatch can promote fungal diseases, negatively affect the moisture retention capacity and have biomechanical consequences on the use of the sports field. To maintain a healthy turf, thatch should be maintained at a thickness of less than 10 mm.

Excessive accumulation of thatch can create an ideal environment for pathogens, limit water and nutrient penetration, and restrict proper root growth. Regular measurement of thatch is essential in order to implement appropriate management practices, such as aeration and verticutting.

There are also products such as OxyTurf which degrades organic matter and removes excess thatch.

The root system of the turfgrass is crucial for its anchorage in the substrate, water and nutrient uptake, stress tolerance, hormone balance and the long-term future viability of the plant. The depth and health of the root system are key indicators of turf quality and vigour. For optimum functionality, root depth should be greater than 50 mm.