With the ever rising cost of nitrogen many producers are looking for more sustainable and cost effective ways to provide necessary nitrogen reducing their dependence on granular or liquid nitrogen products. One such method that has caught the attention of growers over recent years has been to sow and effectively manage a “living mulch”. There has been much discussion over what these should consist of. The most popular opinion being a blend of up to three different white clover varieties. Usually the clover varieties are a mixture of small and medium leafed sizes. The idea being that a carpet of white clover, once established, will provide a living cover for the soil during periods of non cropping and also fix good levels of nitrogen that will be available to the next crop once it has been sown.

It is clear that timing is vital for success and trials indicate that sowing the clover living mulch into the targeted crop, in this instance spring barley, is best done at growth stage 31-31 of T1 stage. At this point in the barley’s development the crop will easily recover from the disturbance of a light drill passing whilst also allowing still enough space for the white clover to establish quickly before any type of canopy closure. Trials have shown that cereals sown at 20cm row spacing’s have been most successful as they allow good sunlight penetration to the newly emerged clover. It has been observed also that establishment of the clover carpet can be rather hit and miss and growers may not quite get the lush mat beneath the barley they may have expected. This soon changes after harvest when the cereal crop is removed and the clover can enjoy full sunlight. A further benefit to the living clover mulch has come not from the nitrogen fixation but also the availability of other key nutrients that may have leached out of the soil between cereal cropping’s. Clover has been shown to hang on to several other trace elements that can then be cycled as the clover naturally dies or is incorporated.

Grower reports have shown that visually crops look healthier and darker than those on similar soil types in neighboring fields without a clover carpet. On higher altitude farms or those further north where conditions can remain colder for longer trials have shown that a cereal crop once planted my emerge slower and be at risk of competition by its clover counterpart. To combat this and given that farms in these areas regularly have sheep or access to them a short period of grazing pre emergence of the cereal crop can knock the clover back enough to allow the cereal crop to get up and away without issue. The clover living mulch is not only reserved for a cereal cropping rotations. Growers are also having further levels of success by sowing other legumes such as beans into their clover mulch. Reports indicate a significant yield increase in the following crop. This has been put down mainly to the increases nitrogen availability thanks to the clover.

Purely arable farms may add further value to the living mulch system if they are able to come to a working agreement with local sheep farmer. A study has shown that the cost of sowing a clover based mulch can almost be written off if over winter stubble grazing is offered to sheep for a small rent. This again adds a further dimension to the benefits of a living mulch as the potential nitrogen additions to the soil now increase still more by the grazing sheep.