Regrassing paddock selection
Topics
4 min read
Maximising pasture growth is key to increasing your dairy farm's profitability. To do this, you need to identify the lowest producing paddocks and understand their potential by comparing them with the best ones. Renewing the poorest performing paddocks offers the biggest chance for improvement. Measure performance using tools like grazing and yield records or the Pasture Condition Score Tool. Factors such as soil fertility, drainage issues, and overgrazing can affect performance. For poor-performing pastures, it's crucial to address the root cause, whether that's soil health, drainage, or overgrazing. Tools and strategies are available to assist you in making informed decisions.
Analysis of your pasture growth data will help you plan the most profitable renewal programme.
While you may instinctively know your best and worst paddocks, without measuring or assessing pasture growth paddocks cannot be accurately ranked to identify worst performance.
Paddock selection steps
- Identify the poorest producing paddocks.
- Compare those to the best performing paddocks to assess potential.
- Identify why these paddocks are the lowest producing.
Identify the poorest paddock
The best paddock(s) to renew are the poorest producers as these have the potential for greatest improvement.
For example, where the yield can be increased by 2t DM/ha the return is around 130kg MS/ha. The return will be greater if the extra growth occurs at a time of the season when animal demand exceeds pasture growth.
The highest producing paddocks on a farm indicate the property's overall potential. Under-producing paddocks highlight the opportunity for extra pasture growth.
Use grazing and yield records to identify your best and worst paddocks. The more measures and assessments you have to compare the better (and easier) the decision will be.
If records are unavailable use the Pasture Condition Score Tool and walk your farm at least six months before sowing date.
Measures of paddock performance
Three ways you can measure pasture performance are...
1. Weekly cover pasture information
Use a rising plate meter or visual yield estimates from farm walks to estimate pasture to calculate paddock growth. Software programs such as Pasture Coach and MINDA Land and Feed can be used to calculate paddock growth and provide paddock profiles.
2. Grazing records
Analysis of good grazing records can give a clear indication of paddock ranking.
With good grazing records the performance of individual paddocks can be calculated by adding up the number of cow grazing days over the year.
To calculate pasture eaten per paddock use the attached form.
3. Paddock records
A simple collection of the number times paddocks have been grazed can give a quick indication of paddock growth.
At the end of the season, grazings for each paddock can be added up to identify total grazings. Include other growth such as silage made. Where the paddocks are different sizes, divide the total grazings by the paddock size, so you can compare total grazings/ha.
Compare paddock yield
On many farms the worst paddock only produces half as much as the best paddock as shown in the diagram below.
In this example paddock 3 has the potential to grow an extra 6 tonne DM/ha/year while paddock 16 an extra 9 tonne.
In other words the best paddock (5) is producing twice as much as the worst (16).
The trick is to know which paddocks are the poorest producers.
Identify reasons for poor-performance
Introducing new plants will not increase production if you do not resolve the underlying causes of low pasture production - treat the cause and not the symptom.
Soil fertility
Test soil for pH and nutrient deficiencies. Apply fertiliser or lime as necessary.
| SOIL TEST | ASH | SEDIMENTARY | PUMICE | PEAT |
| Olsen P | 20-30 | 20-30 | 35-45 | 35-45 |
| Soil test K | 7-10 | 5-8 | 7-10 | 5-7 |
| Sulphate - S | 10-12 | 10-12 | 10-12 | 10-12 |
| Organic - S | 15-20 | 15-20 | 15-20 | 15-20 |
| Soil test Mg |
pasture 8-10 animal 25-30 |
pasture 8-10 animal 25-30 |
pasture 8-10 animal 25-30 |
pasture 8-10 animal 25-30 |
| pH | 5.8-6.0 | 5.8-6.0 | 5.8-6.0 | 5.0-5.5 (0-75mm)4.5-5.0 (75-150mm) |
Poor drainage
Improve drainage.
Pugging
Improve drainage or change wet weather management, e.g. build a feedpad, on/off grazing.
Soil compaction
Aerate by subsoil cultivation.
Soil compaction can occur, particularly on heavy (clay) soils, where pugging or repeated treading in wet conditions has occurred. This is tested with a spade digging several holes through the paddock. There are various signs of compaction.
First, you can feel compaction, or a compacted layer or pan, when digging. If unsure dig a hole in a good pasture and compare them.
Compaction can also show up through shallow rooting, or sometimes roots reaching a pan and moving horizontally. In summer compaction can show up through ‘plant pulling’ in a pasture (although this can be caused by other factors including pests).
Overgrazing
Change management practices (e.g. OAD, stocking rate, calving date, on/off grazing).
On many New Zealand dairy farms in summer dry areas, pasture persistence is severely compromised by a combination of heat and moisture stress, pest pressure and over-grazing.
Of these over-grazing is the one factor that can be controlled, and changes to the farm system should be considered to minimise overgrazing and improve future pasture persistence. These include policies around stocking rate, calving date, OAD milking, drying off, pasture species, cropping and supplements.
At a tactical level a major change is on/off grazing, where during extended dry periods stock graze down to the desired post-grazing residual, but are then removed from the paddock to protect that pasture, onto a feed pad or sacrifice paddock or similar.
Weeds and insect pests
Apply herbicide as required. Use a crop to break insect cycle; use treated seed (endophyte) or granular insecticide at renewal; insecticide at later stages.
More information on common insect pests.