R B Thompson, District Agronomist, West Wyalong - 2004

The principal purpose of the Weethalle Farming Systems demonstration is to satisfy the questions of local farmers. Can you sustainably continuously crop this land? Will we get herbicide resistant weeds? Which crop rotations are the most profitable? What is happening to nitrogen in the rotations? What impact does continuous cropping have on soil chemistry and soil water levels? Well after three years we have enough data to begin to make a few observations.

The Farming Systems demonstration is located 17km north of Weethalle along the Kikiora Road on the property "Anona", belonging to the Rutledge family. The demonstration occupies an area of approximately 4.0 hectares. The plots are 100m long x 20m wide. This is a demonstration - not replicated. Essentially we are taking the small plot data and up-scaling it to put the information into a "model farm". The model is based on 900ha of crop land and 1,200ha of lucerne pasture.

Like all models it has some weaknesses because of practical constraints. It cannot produce all the answers in the form that everyone wanted. It is up to those interested to manipulate the data to find their own answers. Some members wanted to have the entire 2,100ha under continuous cropping but it makes the economics too difficult because you introduce the capital costs of loan debt, interest, depreciation, extra labour, etc. Other members indicated that on their own farm paddocks were variable, continuous cropping of all paddocks was not feasible. The decision to maintain 1,200ha did not please everyone, but it was the only easy way to make simple comparisons.

The decision to base DSE value of the pasture and ley phase on Merino wethers also did not please those who wanted a self-replacing flock or heavy export lambs, but the variables of weaning percentages, extra handfeeding, additional labour, etc, make it too hard to cost out. By all means play with the data and put in some of your own numbers. After all the intention is for the members to manipulate the model to assist them in making more informed choices. It was never intended for the model to be a granite monument.

A little history on the demonstration site. The paddock was a clover paddock for 4 years or more. The block was fallowed in August in 1998. In 1999 a 3.4t/ha Cunningham crop was harvested; and in 2000 the Rutledge family allowed us to fence off 6.0 hectares and we set up the demonstration

Model Farm 1 is the Traditional phase farming system. Lucerne is long fallowed in June then sown to 300ha wheat the following May. The next crop is 300ha milling oats and the block is sown out to lucerne.

Model Farm 2 has 900ha devoted to continuous cropping, based on wheat-fallow rotation. Both phases are represented each year. The 450ha wheat has 100kg urea applied pre-plant each year. Following harvest the stubble is maintained on the fallow for 15 months (until April), then it is burnt and cultivated prior to sowing.

Model Farm 3 is continuous cropping, rotating 450ha wheat with 450ha of winter pulse. To date we have used lupins.

Model Farm 4 is continuous cereal cropping, alternating between wheat and milling oats. Due to land limitations and weed management plan only phase is represented each year. For the members unhappy with the use of oats - simply use the oat yield as hard wheat and adjust the budget.

Model Farm 5 is continuous cereal cropping, alternating between wheat and milling oats with 100kg Urea/ha applied pre-plant each year.

Model Farm 6 is continuous ley farming, where 450ha of wheat rotates with 450ha of subclover ley.

The wheat-fallow system is of particular interest to a few members. The average local sole operator is sowing approximately 4,000 acres of crop to produce 2,500 tonnes of grain. Some operators have found it a stretch with the late breaks. The possibility of only having to sow 2,000 acres and still produce 2,500 tonnes of grain is very tantalising. The stored soil moisture in long fallow underpins and secures yield and reduces the risk of pinching. If the area to be sown is halved then only about half the funds are required, half the labour is required, all the crop is sown on time (late sown wheat crops usually have yield potentials reduced by 30%), all of the crop is sprayed on time (delayed weed control usually lowers wheat yield potential by 15%), all the crop is harvested on time (the last crop frequently has 5% more grain shelled out) and if you are only cropping half the area the machinery should last twice as long.

In the past the concept of maintaining 2,000 acres of fallow using only steel for 15 months would be unpalatable. Fortunately many herbicides like glyphosate now cost equivalent to widelining, so we can now maintain stubble cover and still control weed growth. Boomspraying is about twice as quick as widelining.

One interesting aspect from last year was the wheat on fallow yielded 2.13t/ha while the wheat on lupins yielded 1.15t/ha. The extra tonne of wheat in Farm 2 came from moisture stored back in 2001. 2002 was so dry we did not sow the demonstration. The site was kept weed free but it required only one application of glyphosate early and a follow up 2,4-D amine application as it was too dry for weed growth.

The choice of using Mortlock milling oats was based on the premise that it yields about the same as wheat in the same situation, it minimises the incidence and risk of Take-all, and leaf diseases in the site, and that the milling price is usually equal to hard wheat. Now last year there was a bit of a blip on the market. Mortlock was worth $180.00 per tonne while the AH wheat price was $156.00 per tonne, so Farms 4 and 5 capitalised on that opportunity bonus.

Of interest was Farm 5. The Mortlock with 100kg Urea/ha pre-plant seemed to get caught in flag and yielded 0.5 tonne less than Mortlock without the urea. Another member had a similar result. Neither the wheats on lupins or clover stubble, or the long fallow wheat with urea showed any signs of suppressed growth from nitrogen. The wheat on clover (Farm 6) yielded a little less than the wheat on lupins (Farm 3) but that was due to a small Rosewood tree in the corner of the plot.

In general, the addition of nitrogen in Farm 5 in the past has been more profitable than Farms 3, 4 and 6 and consequently urea seems both less risky and more reliable than the pulse or ley in increasing wheat yield. So keep watching for future results. If adding 46kg/ha nitrogen on an annual basis begins to have a very negative yield response then we will have to debate and rethink things. We don't want to lose the answer to the original questions. Does urea acidify the soil more than a pulse or ley? Does a pulse or ley supply enough nitrogen to the next wheat crop?

The problem with both the pulse and ley options has been late breaks and slow growth due to dry winters. The productivity of the ley in 2000 was very profitable, which was a relatively average year. The pulse component has struggled each year with the dry winters. The lupin yields we have obtained have been very similar to those in the Condobolin trial.

The issue of soil chemistry and soil water are not yet addressed. There has only been four harvests. We hope to have neutron probes installed this year if it gets wet enough. We will look at soil testing for acidity and nutrient decline in 2005.

It is early days but we are making progress. The assistance from the Rutledge family and the local chairman, Rodney Tait is greatly appreciated. As is the funds contributed by both NSW Agriculture and GRDC. NSW Agriculture has annually contributed around $600.00 in Q-Fleet and 800 hours in man hours to this demonstration via the Western Wheat Project.