Exploring alternatives for turf sand amendments
Establishing lush, healthy turf is a challenge—especially when trying to get the perfect mix of sand and organic amendments. In his research, Turf Agronomist John Neylan explored how materials like compost, coir fibre, biochar, and processed poultry manure interact with sand. His goal? To find the best alternatives to traditional amendments like coir fibre and peat moss.
Here are the highlights from his initial study:
- Compost: mixed results on water retention and drainage. At 10% by volume, drainage rates dropped significantly.
- Coir fibre: improved water retention (capillary porosity) at 10% by volume.
- Biochar: showed the most dramatic improvement in water retention.
- Processed poultry manure: enhanced water retention at 7.5% by volume but negatively impacted drainage.
While these findings provided insights, they raised more questions than answers. So, John dug deeper with a turf establishment trial.
The couch grass establishment trial
To understand how different amendments affect turf establishment, we conducted a trial using Santa Ana couch grass sprigs. Here’s how it worked:
Setup:
- When: December 2023
- Where: 3.3L pots filled with medium-washed sand (similar to that used for golf greens and sports fields).
- Treatments: 10 sand-amendment combinations, including compost, coir fibre, biochar, and processed poultry manure. A standard program served as the baseline and was also combined with each amendment (Table 1). The sand used was medium-washed sand (table 2), typical of sand used for the construction of golf greens and sports fields.
Key details:
- Sprigs planted: 3 per pot (each with 2 viable nodes).
- Irrigation: 2-4 times daily.
- Fertilisation: Soluble fertiliser applied bi-weekly (NPK 25:5:9), plus a controlled-release fertiliser (NPK 15:2:13).
- Monitoring: Weekly measurements of turf cover (% area covered), soil moisture, and root development.
- Trial’s end: The roots were washed free of the sand, and the depth of the main root mass was measured. Root health was also rated, and the dry weight of roots was measured.
Table 1: Amendments
|
Treatment |
Application rate |
|
Compost |
2.5% by volume |
|
Compost |
5% by volume |
|
Compost |
7.5% by volume |
|
Compost |
10% by volume |
|
Coir Fibre |
5% by volume |
|
Coir Fibre |
10% by volume |
|
Biochar |
5% by volume |
|
Biochar |
10% by volume |
|
Processed poultry manure |
2% by volume |
|
Standard (stand-alone treatment as well as being applied to ALL of the above) |
The standard program included: · Processed poultry manure at 50kg/ha · NPK (10:10:10) fertiliser at 300kg/ha · Dolomite lime at 2000kg/ha |
Table 2: Physical characteristics of the sand used in the trial
|
Sieve size (mm) |
Result (% retained) |
|
2 |
0 |
|
1 |
1 |
|
0.5 |
16 |
|
0.25 |
54 |
|
0.15 |
28 |
|
0.053 |
1 |
|
Pan |
0 |
|
Physical tests |
|
|
Total Porosity at 30cm tension - (%) |
40.5 |
|
Capillary Porosity at 30cm tension - (%) |
15.9 |
|
Air-filled porosity at 30cm tension - (%) |
24.6 |
|
Saturated Conductivity - 16 drops (mm/hr) |
896 |
|
Saturated Conductivity - 32 drops (mm/hr) |
707 |
What did we find?
Here are the takeaways from 12 weeks of monitoring:
Turf coverage
Across most time points, no significant difference was observed between treatments (table 3).
At 21 and 27 days after planting (DAP), some treatments provided a noticeable boost in turf growth (table 4):
-
Compost (2.5-7.5%) gave the best results.
-
Coir Fibre (10%) and Compost (10%) lagged behind, showing reduced effectiveness.
Table 3: % Area covered
|
Treatment |
13DAP* |
34DAP |
48DAP |
62DAP |
|
Compost 25% |
5.5 |
33.0 |
84.3 |
100.0 |
|
Compost 50% |
7.3 |
39.0 |
83.7 |
100.0 |
|
Compost 75% |
5.9 |
32.0 |
84.7 |
100.0 |
|
Compost 100% |
6.6 |
31.3 |
80.0 |
100.0 |
|
Coir Fibre 5% |
6.6 |
35.3 |
80.0 |
100.0 |
|
Coir Fibre 10% |
6.6 |
26.0 |
82.0 |
100.0 |
|
Biochar 10% |
6.2 |
30.3 |
84.0 |
100.0 |
|
Biochar 5% |
5.8 |
23.0 |
62.3 |
95.0 |
|
Standard Program |
7.5 |
30.0 |
78.0 |
100.0 |
|
Processed poultry manure 2% |
6.5 |
35.7 |
75.7 |
100.0 |
|
LSD (P<0.05) |
NS |
NS |
NS |
NS |
*DAP – days after planting
Table 4: % Change in Area covered
|
Treatment |
% Change 21DAP |
% Change 27DAP |
|
Compost 25% |
51.7 |
173 |
|
Compost 50% |
88.9 |
219 |
|
Compost 75% |
57.7 |
196 |
|
Compost 100% |
2.3 |
117 |
|
Coir Fibre 5% |
30.6 |
157 |
|
Coir Fibre 10% |
-18.6 |
65 |
|
Biochar 10% |
5.3 |
149 |
|
Biochar 5% |
16.8 |
87 |
|
Standard Program |
-3.2 |
104 |
|
Processed poultry manure 2% |
22.1 |
148 |
|
LSD (P<0.05) |
54 |
85 |
Root development
While turf coverage is critical, strong roots are essential for long-term success. At the end of the trial:
- Compost and coir fibre (5%) showed promising results for root health and mass.
- Excessive amendment rates (e.g., Compost at 10%) negatively impacted both root development and drainage.
Practical tips for Turf Managers
Use amendments sparingly: overloading sand with amendments like compost or coir fibre can harm drainage and root growth. Stick to moderate rates (e.g., 2.5-7.5%).
Choose the right material: different amendments bring different benefits. Coir fibre boosts water retention, while biochar dramatically increases porosity—ideal for specific applications.
Don’t skip fertilisation: regular fertilisation ensures your turf gets the nutrients it needs to thrive, especially during the establishment phase.
Monitor early growth: early stimulation (within the first 4 weeks) can indicate which amendments are working best, but results may level out over time.
Final thoughts
Turf establishment is a science and an art. This trial highlights how minor adjustments to sand amendments can significantly influence turf growth, water retention, and drainage. While there isn’t a one-size-fits-all solution, understanding how different materials perform can help you make informed decisions for your turf projects.
Curious about the data or want more insights? Feel free to reach out!