Sowing date affects the success of pasture establishment and persistence.
Right sowing date
Sowing date is particularly important in summer-dry areas. In autumn, sow early so individual plants have time to develop and reach over 20 tillers in size, prior to the following (potentially dry) summer.
Late sowing means slower establishment due to the cooler temperatures.
The minimum soil temperature at sowing should be greater than 12 degrees.
Also, the potential to pug and damage new pastures in winter and spring is greater, and smaller, weaker plants are less tolerant of a potentially dry summer.
A firm seedbed greatly improves pasture establishment, particularly clover.
Seedbed consolidation conserves moisture and makes it easier to achieve the right sowing depth.
Research in the Manawatu showed sowing with a V-roller into a well-consolidated seedbed gave 50% better white clover establishment than sowing into a poorly consolidated seedbed.
In this case a Cambridge roller was weighted with concrete posts, to compact the soil until the roll form held under normal walking pressure.
This research also highlighted the bad practice of using rubber wheeled rollers, which do not compact the soil as well as a Cambridge roller.
The particular consolidation technique for every farm will vary.
This picture illustrates how good seedbed consolidation, by the tractor wheels, can improve establishment of new pastures.
PERENNIAL RYEGRASS SOWING RATE
From time to time there is some industry debate as to what is the ‘correct’ ryegrass seed sowing rate for New Zealand farms. However, there is no single answer to this question. This sheet summarises the key points on this topic.
These pages summarise the current knowledge on this topic and has been agreed by the Pasture Renewal Leadership Group. This Pasture Renewal Group is a DairyNZ-led industry group that includes researchers, the seed industry, farmers and agricultural contractors, and was formed to develop better tools, resources and advice for farmers.
It has been suggested low sowing rates may improve ryegrass persistence. DairyNZ is testing this theory in plot trials.
Pro’s and con’s – standard vs low perennial ryegrass sowing rates
Good conditions a must for low sowing rate
If low ryegrass sowing rates are to be successful, you must have excellent conditions for the new pasture to establish. This includes producing a good seedbed (fine, firm, consolidated). As well as conserving moisture, this allows seed to be sown at the right depth.
Control flatweeds with herbicide(s) in the first 6 weeks after sowing, regardless of ryegrass sowing rate.
Standard rate increases yield
Using a higher ryegrass sowing rates usually gives a temporary (not long term) increase in DM yield over the first 1-3 grazings. This varies, but might be an extra 500kg DM/ha, with a value of $150-200/ha (using 30-40c/kg DM for this high quality late autumn/winter feed). Cost of an extra 6kg/ha seed may be $60-90/ha.
Lower rate increases clover
Lower ryegrass sowing rates generally gives higher clover content in the pasture, which in turn improves the feed quality and the animal performance.
Lower rate increases weeds
Lower ryegrass sowing rates also generally means more weeds in a pasture. If weeds are a problem (particularly grass weeds such as browntop, poa etc.) we recommend using standard sowing rates and taking into account sowing method (see below).
Sowing method affects sowing rate, as the diagram below shows. Where weeds are a problem we recommend method jbelow.
Summary - standard vs low perennial ryegrass sowing rates
Sow ryegrass/white clover seed mixes at 5-10 mm deep to get the best establishment. White clover seed is very small and sensitive to sowing depth and establishes much faster when sown at this depth, as shown in the graph below. Ryegrass is less sensitive to sowing depth and still establishes well sown at 20 mm. At a depth of 50 mm neither species establishes well.
The exception to sowing shallow is in dry conditions, when it is sometimes better to drill seed a little deeper into better soil moisture. In these conditions white clover may struggle.
A consolidated seed bed is critical to allow good depth control with a seed drill. In a soft seedbed wheel tracks are pushed down, and coulter depths vary, leading to both uneven seed depth and establishment.