Rotation Diversity: Exploring Break Crops and Nitrogen Efficiency in the West Midlands
By Simon Kruger, WMG Project Communications Officer
In the West Midlands region, many growers are shifting away from continuous cereal cropping, choosing instead to integrate legumes, pastures, or even double break crops. This diversity creates the opportunity for positive implications for nitrogen (N) management and strategies. Over a range of our 2024 events we have facilitated— from the Crop Nutrition Days to smaller farmer discussion events—producers and agronomists have openly shared the rewards and challenges associated with diversified rotations. In this article, we explore how these approaches can reduce input costs, mitigate risk, and potentially strengthen long-term soil fertility.
Legume crops such as lupins often emerge as the first step in rotation diversity because of their capacity to fix atmospheric nitrogen. Farmers who have trialled lupins often report improved yields in the subsequent cereal crop, thanks to higher residual nitrogen levels. At one of our Participatory Action Research (PAR) group meetings last year, several participants described how lupin stubble fed the soil, not only boosting N but also contributing organic matter. However, legumes add complexity: they typically command different prices than cereals, can require specialised weed control, and may be more sensitive to certain pests or diseases. Another discussion in our region revolved around matching legumes to soil type. While some soils are perfectly suited to lupins, other heavier soil types require a different solution. It highlights that no single legume is a universal fix, reinforcing the need for accurate soil testing and locally relevant trial data.
One of the greatest benefits of rotational diversity is the potential for “carryover” N. A strong legume crop could reduce the need for top-up nitrogen in the following cereals. From our WMG trial observations, a typical scenario might be 50 to 60 kg/ha of free nitrogen left behind—though actual amounts depend on factors like residue management, rainfall, and soil pH. By the second year after the legume, residual N often tapers off, meaning the financial benefits peak in the immediate rotation cycle.
A note of caution: if the subsequent cereal or canola crops exhibit highly vigorous early growth due to leftover N, they might become susceptible to haying off if the season ends poorly. Multiple farmers at the Crop Nutrition Day observed that a strong canopy in winter can sometimes lead to nutrient or moisture stress late in spring. The trick, they emphasised, is balancing the advantages of carryover N with an in-season monitoring approach that can rein in excessive biomass if conditions turn dry.
Another angle our members discussed is weed and disease control. Introducing a break crop can disrupt the life cycle of cereal-loving pathogens, reducing fungicide needs and thus indirect fertiliser costs for the following crop. Likewise, legumes can shade out certain weeds and reduce the weed seedbank if managed well. However, if not carefully planned, a legume rotation might encourage different weed species—broadleaf weeds, for instance—and require alternative herbicide regimens. This interaction between biology and chemistry underscores the broader risk–reward equation: a diverse rotation can reduce some problems but may invite new management challenges.
From an economic standpoint, stepping out of continuous cereals can reduce exposure to a single commodity market. If wheat prices dip sharply, having lupins or canola in the rotation can buffer the blow. Yet, farmers note that niche or less common break crops can also encounter price fluctuations or limited marketing avenues. As always, the question is whether the N savings and agronomic benefits justify the added marketing complexity.
Some members in our network have begun to investigate novel options like faba beans, chickpeas, lentils or even intercropping cereals with pulse species. Although still at a trialing stage, these approaches could offer further efficiency in nitrogen use, water use efficiency, and pest management. Similarly, more niche legumes, like serradella, show promise on certain sandy or acidic soils, providing additional fodder for livestock while adding nitrogen to the system.
Rotation diversity stands as a powerful lever for enhancing nitrogen management in the West Midlands. By introducing legumes, pastures, or novel break crops, growers can reduce their reliance on synthetic N, break disease cycles, and often see better soil structure over time. Yet each of these benefits comes with associated risks—whether in marketing, weed control, or operational complexity. Based on our collective learning events, the best outcomes arise when farmers tailor break-crop choices to their soil types, equipment capacity, and risk tolerance, and when they integrate regular soil testing to track the evolving nutrient profile.
WMG continues to facilitate trials, field walks, and peer discussions that probe these topics in depth. We believe that by balancing economic realities with long-term sustainability, local farmers can maintain both resilience and profitability. Rotation diversity is not a silver bullet, but it is a dynamic strategy—one that, if handled with care, can open new avenues for sustainable growth in our region.
For more information on how the GRDC funded RiskWise project is helping WMG growers discuss and better understand risk and decision making, such as the crop selection and nitrogen management decisions covered in this article, head to the project page.
