Potato Review

12 POTATO REVIEW JANUARY/FEBRUARY 2021 COVER CROPPING puts priority on the success of cover crops by focusing on multiple aspects of management. It is important to de ne the objectives and purpose of sowing a cover crop. Is it reducing soil erosion or mitigating water pollution and ooding, soil structure, nutrient recycling, disease or pest management, or providing habitat and wildlife bene ts? Will you replace a cash crop or force cover crops between harvest and spring sowing? Create a management plan that creates a exible approach, start small and repeat, building on previous achievements. e key to success is the proper seed mix for your soil, and facilitating cover crops to grow for as long as possible to reap the greatest bene t. Why grow cover crops? ere is an increasing social responsibility for growers to look after their soils, apparent in government policy and the general public agenda, but the technical and nancial bene ts start on the farm. It is not a binary choice, there is a win- win for all. Consequently, there may be opportunity to o set growing cover crops costs through agri-environment scheme participation. Cover crops have a clear role in protecting soils over winter, retaining nutrients and therefore protecting water bodies. ere is also evidence that cover crops, particularly when grown for a number of successive years across rotations, can result in improvements in soil physical, chemical and biological properties which bene ts yield and quality. Cover crop choice crucial to success Although there have been advances in understanding in recent years, there is still so much to learn about the best mix, together with establishment and destruction methods. It is important to match the individual attributes of a cover crop to the intended purpose, taking into account how it might interact with other partners and any potential rotational con icts. To get the best results, assess your soil conditions on-farm before you start. e soils that see the greatest bene ts from cover crops are those that are light to medium-textured. Heavier soils are generally less suitable as they can be more di cult to establish and destroy the cover crop. Choose your cover crop according to what you want it to do. For example, soils with the tendency to compact can bene t from an oil radish cover crop. It establishes and grows very quickly, developing a deep tap root and laterals that extend out and can help to break up deeper compaction down the soil pro le, helping to improve soil structure as well as scavenging mineral N. Brassica cover crops are the most e ective at taking up nitrogen and reducing nitrate leaching, but cereals and phacelia are also e ective if drilled early. ‘Bio-drilling’ is a term used to describe the creation of ‘biopores’ by deeply penetrating plant roots that allows the subsequent use of these pores by the roots of succeeding crops by o ering low resistance to growth. Cover crop planting date crucial to success Timing is of the essence because of the need to establish them while soil conditions are still suitable. Part of the problem is that most have a small seed so an autumn-planted cover crop should be sown earlier rather than later - before mid-August. Remember by growing a larger amount of biomass, you are increasing your own homegrown chemistry toolkit. After that date you can still grow oil radish or winter rye, as they are frost hardy and can continue to grow over the winter period, but it is too late to establish vetches. How to maximise your cover crop planning With clever management, cover cropping works at a number of levels. Planting the right species and variety can reduce the spread of disease, suppress free living nematodes and create more resilient soil architecture. Utilising “ ying” ocks of sheep to graze o cover crops can further increase organic matter returned to the soil. ADDING VALUE TO LAND An estimated 80% of potatoes are grown on rented ground. While land agents generally appraise land as a commodity on a short-term basis, few until now have insight into sustainable production systems without granular nematicides or future earning capacity of the land if infested with potato cyst nematodes. “Growing cover crops requires a di erent mindset as it is function, not yield, that is key.”