A timely and carefully planned cropping program, starting during the previous spring, is a vital step in minimising expensive yield reductions.

Weighing up grain prices, rainfall outlook and overall enterprise risk is just the first step in pre-season planning. Just as important are sound crop rotations, based on an understanding of paddock specific agronomic issues such as disease potential, weed-seed set and herbicide resistance status.

Producers need to balance profitability and sustainability and carefully spread their production risk, according to Jake McGuire Elders Agronomist, Albany Western Australia.

“Making informed decisions about paddock selection and carefully planning rotations before sowing will help set crops up for high yields” Jake said.

“High yields and high prices per tonne are the key drivers of profitability."

“The identification of potential weed, disease and nutrition issues as early as possible enables producers to take control, plan to limit risk and maximise opportunities and water use efficiency,” Jake said.

Elders’ farm and paddock planning services, offered by experienced Elders agronomists, can help producers plan the most appropriate crop rotations in order to maximise returns.

Feedback from agronomists indicate that rotations have become less diverse, despite recommendations to growers to avoid sowing a cereal following a cereal crop or a canola crop following a canola crop.

“Wheat on wheat has swung back in favour as many growers look to reduce their risk profile and boost their resilience to seasonal variations,” Jake said.

Including a range of cereals, broadleaf and legume crops in rotations is a vital risk management tool.

Rotations that include 25–30% break crops such as canola and lupins will reduce the impact of disease, weeds, pests, frost and herbicide resistance while improving soil health and water use efficiencies.

Growing a range of crop types and varieties will also diversify income streams and production risks as well as improve machinery and labour use efficiencies by spreading the workload during sowing and harvest.

Vigorous legume pastures can provide a nitrogen benefit and reduce the nitrogen fertiliser requirements of the subsequent crops. Elders’ soil testing service can provide vital soil fertility information to help producers make informed decisions on fertilisers prior to sowing.

Disease risk – prior preparation

Disease inoculum levels will be high going into the 2011 season as a result of wet conditions across much of eastern Australia during 2010. So adopting a crop rotation that includes a 1-3 year break between crops of the same species and growing more resistant varieties using disease-free seed treated with a registered fungicide seed dressing will be critical to reduce the incidence of many diseases. For example trial work has shown that wheat crops grown after canola can yield, on average, 20% more when compared to wheat-on-wheat rotations.

Growing back-to-back cereal crops can lead to a rapid build-up of soil- and stubble borne diseases such as take-all, crown rot, cereal cyst nematode, Rhizoctonia root rot, yellow leaf spot and Septoria. These can cause significant yield losses in cereal crops — a high incidence of Rhizoctonia, take-all or crown rot can reduce cereal yields by at least 50 per cent.

Consider more than crop type

But a break crop does not automatically provide a benefit — good agronomy is vital to break the disease cycle.

“Many growers will be restricted by their choice of variety but where possible they should choose high-yielding varieties with good disease resistance, that may also attract a price premium,” Jake said.

Growing more resistant varieties is not a substitute for good rotations and avoiding paddocks with a high risk may be more profitable in some circumstances. Using Predicta B® DNA soil tests prior to seeding helps identify soil borne pathogens that could pose a significant risk to future crops.

Herbicide resistance

Herbicide resistance to 11 herbicide groups has been found in about 35 grass and broadleaf weed species. This poses a serious risk to the long-term productivity of Australian broadacre cropping systems. Crop rotations are an important component of an integrated weed management strategy and can help minimise the potential for herbicide resistance.

The adoption of no-tillage practices and more intensive cereal rotations has increased the use of selective grass weed herbicides. Growing a diversity of crops allows herbicide groups to be rotated and the use of a range of weed control methods including selective, non-selective herbicides together with crop-topping and brown manuring.

Rotations that include a pasture phase allow the use of a wider range of chemicals including non-selective knockdown herbicides together with strategic grazing and hay and silage production which can help reduce weed populations.

Identifying herbicide-resistant weeds as early as possible through herbicide resistance testing can be a valuable tool when planning rotations, allowing producers to choose more appropriate crops and weed control options.

Long term view

Elders Agronomist in Yarrawonga, Victoria, Mathew Coffey says while it is important crop rotations are based on sound agronomy they also need to remain flexible to deal with seasonal variations, commodity prices and changing circumstances.

“Farming has some inherent risk but producers can limit their exposure to many yield limiting factors by planning early. This will enable more timely decisions and help to make the best decisions possible.”

“With access to specialist Agriplanner software Elders staff work with the grower to develop a block-by-block plan which includes a documented operating budget and plan in terms of rotations, inputs and operations as well as projections of expected profits.”

“They provide advice on all aspects of crop production including crop variety selection, fertiliser programs and weed, insect and disease control options,” Mathew said.

According to Mathew it is important to remember that gross margins of break crops may not appear ideal when viewed in isolation.

“The benefits need to be evaluated as part of the whole rotation and farming system.”