Agronomist (Special Project) NSW Agriculture. Queanbeyan. NSW 2620
The Prime Pasture Program is a unique cooperative effort between NSW Agriculture and the National Soil Conservation Program (now National Landcare Program), four commercial companies, their 200 dealers throughout the State, District Agronomists, Landcare Coordinators and farmers.
The program has been running since 1991 at a time when there is an increasing awareness of the role and benefits of perennial pastures within farming systems, particularly on the slopes. However, surveys in the late 1980s suggested there was a large variation in the rate of success in establishing perennial pastures on both slopes and tablelands.
The Prime Pasture Program aims to help farmers more successfully establish perennial pastures and thus reduce soil degradation. To do this nearly 100 commercial sized, on-farm sowing demonstrations covering 900 ha were established and field days run in association with those sites. An 8-point pasture establishment check list was produced and, based on those checks, an establishment field guide written covering 28 practical topics.
The printed material was based on experience developed in the southern tablelands at a large number of sites and particularly some comparative work between direct drilling and conventional sowing using a wide range of sowing machinery. This comparative work was done at Bungendore in 1987, an extremely dry year which effectively highlighted those factors that were absolutely critical to ensure pasture sowing success.
These factors were called the 3As. They are:
• absolute weed and pest control;
• adequate soil moisture at sowing time; and
• accurate seed placement.
Experience has shown that if those three factors are correct then there is a very good chance of achieving establishment success.
The Prime Pasture Check was developed to help ensure those three critical factors were achieved.
The Prime Pasture Check
The Check is a series of 8 steps designed to reduce the risk of failure. The first check is selecting, assessing and planning what you propose to do in a particular paddock. Such planning really needs to start about 12 months before the sowing operation. This allows weed and pest control to commence the year before sowing (the second check) and is vital for effective control of free seeding annual grasses in particular.
The third check is preparation over summer and prior to sowing to reduce weeds and trash either by grazing or cultivating. In other words the first three checks are steps to achieve the fourth check (one of our three critical factors) - absolute weed and pest control at sowing time.
Another critical factor - adequate soil moisture at sowing - is the fifth check. Moisture is required both at the surface for quick germination and also in the sub-soil for survival of the seedlings. With these soil moisture conditions, dry weather after sowing over which there is no control is not so critical and there is far less risk of losing the young pasture plants.
Dry sowing or sowing on the opening autumn rains without any subsoil moisture is conversely very high risk, placing the pasture completely at the mercy of the subsequent weather.
The sixth check is the third of our 3As - accurate seed placement. So often tiny pasture seeds are thrown into a paddock and a big set of following harrows pulls amounts of soil over the seed. A large percentage of sown seeds do not manage to get to the surface because they are buried too deeply.
Placing the seed accurately and achieving the right amount of soil cover above the seed for both protection and to provide germinating moisture without burial is absolutely critical. We have found that direct drilling pasture, with a greatly reduced amount of moving soil, provides a major advantage in achieving this.
The important feature of seed placement is that the slot needs to be open so that when looking in you can still see 5-10% of the seed and fertiliser. If that occurs there is a fair chance that the rest of the seed is not buried too deeply underneath the loose tilth in the slot.
While the Prime Pasture Program strongly promotes direct drilling, even to the extent of direct drilling lucerne, there are situations where conventional seedbeds and sowing are required. In those situations band seeders and the very careful use of covering "harrows" is recommended.
Perennial species by their nature have weak, slow growing seedlings that are very prone to attack and damage. Regular monitoring for both weeds and pests while the pasture is small and vulnerable is the extremely important seventh check.
Finally, pastures are sown to be grazed. The eighth check provides guidelines on initial grazing. Provided there is good soil moisture, the pasture is 10-15 cm tall and well anchored, it should be quickly grazed. However, in the absence of good moisture plants should not be placed under more stress by grazing.
In the right conditions (as outlined above) the pasture will benefit greatly by being grazed - seedlings will tiller, not only above ground but in the root system as well as giving a much better anchored and stronger plant to go through that first summer.
Conventional vs Direct Drill Establishment
At Bungendore in 1987, direct drilling was compared to conventional sowing for pasture establishment. Few of us believed that direct drilling pastures could be as effective and as reliable as conventional sowing.
Long and short conventional fallows and both Roundup and Spray.Seed direct drill seedbeds were compared using a wide range of seeders. Direct drilling, when properly done, was just as effective as conventional sowing.
However, if either are done poorly, particularly if weed control is poor, then there will be a poor result. Figure 1 shows that both the Roundup seedbed and the conventional long fallow produced about 3 tonnes/ha of pasture dry matter in an 8-week period between mid-April to mid-June 1988 when the pasture was just 12 months old, but the two treatments in the middle, a Spray.Seed direct drill block and the conventional seedbed with a "normal" southern tablelands 3 month fallow (ploughed in February and sown in May) have only produced a miserable 1.5 tonnes/ha.
Figure 1. Pasture Production vs Seedbed Treatment
The reason for the poor establishment and subsequent pasture production in both cases was poor weed control. The short fallow was not able to control sorrel, which was just chopped up and replanted and the Spray.Seed was not able to control either sorrel or another perennial weed, plantain. In the very dry conditions of the winter and spring after sowing both of those weeds used most of the scarce soil moisture and many young pasture seedlings died.
Direct drilling has many advantages in flexibility:
• being able to get on the country after rain;
• being able to get on the country after sowing for follow-up pesticide spraying;
• permitting grazing right through until sowing time.
It is now the preferred method for sowing pasture.
Machinery and Modifications
What else have we learnt from the Prime Pasture Program? An important lesson was that the old single disc seeders, so common on the
southern tablelands, were abysmal when it came to direct drilling pasture except in favourable years with good follow-up rainfall. Conversely, any of the tyned machines with narrow points do a great job.
Many people have sowing machinery that is not suitable for direct drilling. However, there are some cheap but effective machinery modifications to convert older machines for direct drilling.
Figure 2 shows the modification for an International 511 spring release tyne. It costs about $50 and a day's work in the workhop with a welder and oxy gear to cut some of the steel. By simply moving the "J" bolt tensioner forward an extra position on these machines the tyne tension can be increased.
Figure 2. Modified 511 Spring Release Tyne
Tyne Force Deflection (mm)
Type (N) Horizontal Vertical
Spring Tyne 196 26 2 (optimum)
Position 1 196 238 83
Position 2 196 93 18
Position 3 196 25 2 (optimum)
Position 4 196 15 -4
This then provides the ideal amount of flexibility in the tyne without the tyne dragging back so far that the point is not working in the ground properly (a common problem on many older machines of this type as they wear). The table below Figure 2 compares this modification with the force deflection properties of a strong direct drill spring tyne.
The spring tyne is deflected back 26 mm with a force of 196 newtons (approximately 45 psi) and has a vertical change of only 2 mm. This is the optimum deflection for direct drilling most friable soils. At position 3 on the modified spring release tyne we have a horizontal deflection of 25 mm and 2 mm vertical at the same tyne tension - exactly what is required for very little expenditure.
There are also commercial modifications to suit most machines that will cost between $1000-$2000 for a 14 or 16 run seeder.
When sowing the demonstration sites throughout the tablelands, slopes and coastal districts over the 3 years (1991-1993), a range of different sowing points was tested and compared. The conclusions were that the inverted "T" blade type pasture sowing point is the very best point for direct drill pasture sowing. However, all narrow points such as lucerne points or the new cast super seeders are also effective.
Conversely, despite what is commonly believed, wider points produce a poorer result moving too much soil and reducing the operator's control of soil coverage over the seed. Remember, the sowing point is not a means of weed control when direct drilling.
The main problem with narrow sowing points is the very high wear rates particularly in gravelling granite soils. Steel points, even when beefed up with tungsten, are totally unsatisfactory. They require continual maintenance (hard facing) to protect the steel
not covered by the tungsten. By comparison, the new cast sowing points, again with a tungsten piece down the front, do a fabulous job and are well and truly worth the cost of $20-$30 each.
Cast blades cost less than steel blades with 3 pieces of tungsten (to protect the nose and both wings). They do not require hard facing to maintain the material that is supporting the tungsten as a steel point does. I have some cast super seeder points that have sown 600 hectares in West Australia's abrasive, hard setting sandy soils.
To use the inverted "T" type blades an adaptor is required for each tyne. These cost about $50 each. When using super seeders or lucerne points, adaptors are not required.
Cover Crops or Smother Crops
I would like to relate to you our experiences at Boorowa, firstly in 1991 which was a dry spring. The pasture was sown in early July and by November plants were like those on the left in Figure 3 where sown without a cover crop. The only way to get them out of the ground was to cut them out with a pocket knife. The plants on the right were sown with 15 kg/ha of Echidna oats and were twice as tall as they appear here. However, they could be pulled out of the ground with two fingers in November when the ground was extremely dry. It was fortunate that the 1991/92 summer was quite wet otherwise the pasture would not have survived where a cover crop was used.
However, we noticed that wherever the oats in a row did not germinate pasture seedlings, not only within that row but on either side, they were quite strong and healthy. On this basis, in 1992 we examined alternate row spacing of the cover crop. Grass establishment (sown in every row) was well above the target of 60 plants/square metre, pasture seedlings were healthy and well tillered and there was an excellent oat yield.
The advantage in using a cover crop was in gaining a cash flow and therefore helping to pay for the cost of the pasture establishment and lime application. Full economic details are contained in Denis Manion's paper "Whole farm management - a profitable weed control system"
in the 1994 Grassland Society of NSW Annual Conference Proceedings, page 86.
We recommend alternate row spacing if using cover crops together with light cover crop sowing rates, but which is the best cover crop? Barry Smith, from Temora, who has a paper in these Proceedings, has had excellent success establishing cocksfoot and lucerne pasture under barley. He has seen other species, such a lupins, used successfully in his district and believes they may be even better adapted to being used as a cover crop.
Perennial pastures can be reliably established provided close attention is paid to a number of factors. These are embodied in the 8 step Prime
Pasture Check and practical issues amplified in the Prime Pasture Field Guide.
I would like to conclude with an advertisement. For just $20 you can still join the Prime Pasture Program - there are currently over 2600 members. Simply write to us at NSW Agriculture, PO Box 408, Queanbeyan, 2620, enclose payment and your name and address. You will receive your 64 page Field Guide and Pasture Check and the opportunity to participate in the company-sponsored cashback until July 1995. Quarterly Prime Pasture newsletters are being produced and mailed out until 1997. Members will also have the opportunity to join at a concessional rate the second stage of Prime Pastures - a pasture management package for persistence and productivity of perennial pastures due in 1995.
The work reported here during the last three years is a joint project with John O'Connor, technical officer with the Prime Pasture Program, without whose assistance this work could not have been completed. I particularly want to thank the cooperating landholders who made their properties available for the sowing demonstrations and district agronomists, Landcare coordinators, company staff and rural resellers who have supported this project. Finally, I acknowledge the tremendous support and backing by the four commercial supporters - Incitec Ltd, Monsanto, Primary Sales (Aust), and Wrightson Seeds.